1
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Sangitra SN, Pujala RK. Temperature-dependent yield stress and wall slip behaviour of thermoresponsive Pluronic F127 hydrogels. RSC Adv 2024; 14:23772-23784. [PMID: 39077312 PMCID: PMC11284911 DOI: 10.1039/d4ra04825c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 07/20/2024] [Indexed: 07/31/2024] Open
Abstract
This study explores the temperature-dependent dynamic yield stress of a triblock thermoresponsive polymer, Pluronic F127, with chemical structure (PEO)100(PPO)65(PEO)100, during the sol-gel transition. The yield stress can be defined as static, dynamic, or elastic, depending on the experimental protocol. We examine the dynamic yield stress estimation for this study, which usually entails utilizing non-Newtonian models like the Herschel-Bulkley (HB) or Bingham models to extrapolate the flow curve (shear rate against shear stress). Initially, we determine the yield stress using the HB model. However, apparent wall slip makes it difficult to calculate yield stress using conventional methods, which could lead to underestimates. To validate the existence of apparent wall slip in our trials, we carry out meticulous experiments in a range of rheometric geometries. To determine the true yield stress corrected for slip, we first use the traditional Mooney method, which requires labor-intensive steps and large sample sizes over various gaps in the parallel plate (PP) design. To overcome these drawbacks, we use a different strategy. We modify the Windhab model equation by adding slip boundary conditions to the HB equation, which allowed us to calculate the slip yield stress in addition to the true yield stress. In contrast to other typical thermoresponsive polymers like poly(N-isopropyl acrylamide) (PNIPAM), our findings demonstrate that PF127's yield stress obeys the Boltzmann equation and increases with temperature.
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Affiliation(s)
- Surya Narayana Sangitra
- Soft and Active Matter Group, Department of Physics and Center for Atomic, Molecular and Optical Sciences & Technologies (CAMOST), Indian Institute of Science Education and Research (IISER) Tirupati Yerpedu Tirupati 517619 Andhra Pradesh India
| | - Ravi Kumar Pujala
- Soft and Active Matter Group, Department of Physics and Center for Atomic, Molecular and Optical Sciences & Technologies (CAMOST), Indian Institute of Science Education and Research (IISER) Tirupati Yerpedu Tirupati 517619 Andhra Pradesh India
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2
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Liu H, An L, Ruan Y, Lu Y. Flow Behavior of Entangled Polymer Nanoparticle Composites in a Nanotube: Insights into Jamming State. Macromol Rapid Commun 2024; 45:e2400019. [PMID: 38544358 DOI: 10.1002/marc.202400019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/28/2024] [Indexed: 04/06/2024]
Abstract
Using molecular dynamics simulations, this study investigates the equilibrium properties and flow behaviors of entangled polymer nanoparticle composites (PNCs) within a nanotube. The results show that the density distribution of nanoparticles (NPs), displacement of polymer chains and NPs, and the moduli of PNCs remain relatively unaffected when NP volume fractions (ΦN) ≤0.10. However, the flow behavior of entangled PNCs deviates from the ideal parabolic profile seen in unentangled PNCs, displaying plug-like flow characteristics with a significant platform region, indicating the presence of shear bands. Interestingly, entangled PNCs at intermediate ΦN values undergo a significant alteration in NP distribution under steady flow, resulting in notable NP aggregation. At ΦN = 0.30, a distinct change in the static structure of PNCs occurs, reducing the equilibrium distance between neighboring NPs. Consequently, the motion of both polymer chains and NPs becomes restricted, leading to an increase in the moduli of PNCs resembling solid-like behavior. Additionally, the entangled PNCs experience a complete absence of flow, indicating the entry into a jamming state. This study contributes to the understanding of PNCs flow behavior and provides insights into fundamental aspects and practical implications of PNCs.
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Affiliation(s)
- Hu Liu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Lijia An
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Yongjin Ruan
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Yuyuan Lu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, 230026, P. R. China
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3
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Peng C, Gao H, Wang X. On Characterization of Shear Viscosity and Wall Slip for Concentrated Suspension Flows in Abrasive Flow Machining. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6803. [PMID: 37895784 PMCID: PMC10608499 DOI: 10.3390/ma16206803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 10/13/2023] [Accepted: 10/17/2023] [Indexed: 10/29/2023]
Abstract
In the realm of abrasive flow machining (AFM), precise finishing and maintaining dimensional accuracy have remained challenging due to non-uniformities in the AFM process and complexities associated with the abrasive media's shear viscosity and wall slip behavior. By addressing these challenges, this study introduces a comprehensive framework, combining theoretical foundations, measurement techniques, and experimental setups. Utilizing capillary flow, a novel compensation strategy is incorporated within the Mooney method to counter entrance pressure drop effects. This enhanced capillary flow method emerges as a promising alternative to the conventional Cox-Merz empirical rule, enabling precise characterization of wall slip behavior and shear viscosity, particularly at elevated shear rates. The abrasive media exhibit a Navier nonlinear wall slip, as highlighted by the Mooney method. Rigorous verification of the proposed methodologies and models against supplemental experiments showcases a high degree of congruence between predicted and observed results, emphasizing their accuracy and broad application potential in AFM. This research illuminates the intricacies of the abrasive media's behavior, accentuating the need for meticulous characterization, and provides a robust foundation for genuine modeling and predictions in material removal within AFM.
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Affiliation(s)
- Can Peng
- State Key Laboratory of High-Performance Precision Manufacturing, Dalian University of Technology, Dalian 116024, China; (C.P.); (H.G.)
- School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Hang Gao
- State Key Laboratory of High-Performance Precision Manufacturing, Dalian University of Technology, Dalian 116024, China; (C.P.); (H.G.)
- School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China
| | - Xuanping Wang
- State Key Laboratory of High-Performance Precision Manufacturing, Dalian University of Technology, Dalian 116024, China; (C.P.); (H.G.)
- School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China
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4
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Şahin E. Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing. J Mech Behav Biomed Mater 2023; 145:106026. [PMID: 37467554 DOI: 10.1016/j.jmbbm.2023.106026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 07/10/2023] [Accepted: 07/13/2023] [Indexed: 07/21/2023]
Abstract
The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.
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Affiliation(s)
- Erdem Şahin
- Department of Metallurgical and Materials Engineering, Muğla Sıtkı Koçman University, Turkey.
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5
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Şahin E. Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing. J Mech Behav Biomed Mater 2023; 145:106026. [DOI: https:/doi.org/10.1016/j.jmbbm.2023.106026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
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6
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Liu L, Bai J, Su Z, Yao Y, Zhou Z, Xia Y, Zhang Y. 1-Methyl-4-R-1,2,4-triazolium (R = -CH 2CH 2OCH 3, -CH 2COOCH 2CH 3)-Based Ionic Liquids as Plasticizers for Solid Propellants. ACS OMEGA 2023; 8:16738-16747. [PMID: 37214713 PMCID: PMC10193569 DOI: 10.1021/acsomega.3c00256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/27/2023] [Indexed: 05/24/2023]
Abstract
In this paper, a series of energetic ionic liquid plasticizers of 1-methyl-4-methoxyethyl-1,2,4-triazolium chloride (1), 1-methyl-4-methoxyethyl-1,2,4-triazolium bis(trifluoromethylsulfonyl)imide (1a), 1-methyl-4-methoxyethyl-1,2,4-triazolium nitrate (1b), 1-methyl-4-ethyl acetate-1,2,4-triazolium chloride (2), 1-methyl-4-ethyl acetate-1,2,4-triazolium bis(trifluoromethylsulfonyl)imide (2a), and 1-methyl-4-ethyl acetate-1,2,4-triazolium nitrate (2b) were synthesized and characterized. The results show that compounds 1a, 1b, 2a, and 2b have lower melting points (Tm, -72.60 to -32.67 °C) and good thermal stability (Td, 161-348 °C) and are suitable as plasticizers for hydroxyl-terminated polybutadiene (HTPB) curing systems. Among these four ionic liquids, ester-functionalized cations can help to improve the tensile strength (2a, 0.943 MPa; 2b, 1.113 MPa) of the cured system, while ether-functionalized cations are more beneficial to improve elongation at break (1a, 522.90%; 1b, 484.45%). Ester-functionalized ionic liquids are more beneficial to reduce the glass transition temperature of HTPB elastomers. The storage modulus of HTPB elastomers containing NO3- is higher, while that of HTPB elastomers containing NTf2- is lower. The crosslink densities of HTPB/TDI/2a and HTPB/TDI/2b plasticized by ester-functionalized ionic liquids are larger, which are 9369 and 9616 mol/m3, respectively. There are hydrogen bond interactions between the ionic liquid and the HTPB elastomer, and these interactions changed the distribution of the hard and soft segments in the polymer molecules.
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Affiliation(s)
- Long Liu
- Key
Laboratory of Science and Technology on Particle Materials, Beijing
Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100049, China
| | - Jinhu Bai
- Key
Laboratory of Science and Technology on Particle Materials, Beijing
Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100049, China
| | - Ze Su
- Zhengzhou
Institute of Emerging Industrial Technology, Zhengzhou 450000, China
- Institute
of Advanced Technology, Zhengzhou University, Zhengzhou 450002, China
| | - Yuan Yao
- Zhengzhou
Institute of Emerging Industrial Technology, Zhengzhou 450000, China
| | - Zhixiang Zhou
- Zhengzhou
Institute of Emerging Industrial Technology, Zhengzhou 450000, China
- Institute
of Advanced Technology, Zhengzhou University, Zhengzhou 450002, China
| | - Yangfeng Xia
- Institute
of Systems Engineering, Academy of Military Science, Beijing 100071, China
| | - Yanqiang Zhang
- Key
Laboratory of Science and Technology on Particle Materials, Beijing
Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100049, China
- Zhengzhou
Institute of Emerging Industrial Technology, Zhengzhou 450000, China
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7
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Marnot A, Dobbs A, Brettmann B. Material extrusion additive manufacturing of dense pastes consisting of macroscopic particles. MRS COMMUNICATIONS 2022; 12:483-494. [PMID: 36312900 PMCID: PMC9596591 DOI: 10.1557/s43579-022-00209-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/13/2022] [Indexed: 06/16/2023]
Abstract
Additive manufacturing of dense pastes, those with greater than 50 vol% particles, via material extrusion direct ink write is a promising method to produce customized structures for high-performance materials, such as energetic materials and pharmaceuticals, as well as to enable the use of waste or other locally available particles. However, the high volume fraction and the large sizes of the particles for these applications lead to significant challenges in developing inks and processing methods to prepare quality parts. In this prospective, we analyze challenges in managing particle characteristics, stabilizing the suspensions, mixing the particles and binder, and 3D printing the pastes.
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Affiliation(s)
- Alexandra Marnot
- Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Alexandra Dobbs
- Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Blair Brettmann
- Chemical and Biomolecular Engineering, Materials Science and Engineering, Georgia Institute of Technology, Atlanta, USA
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8
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Haghgoo M. An experimental approach to investigate the viscoelastic and rheological behavior of polydisperse glass suspensions. CHEM ENG COMMUN 2022. [DOI: 10.1080/00986445.2022.2095266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Parallel-Disk Viscometry of a Viscoplastic Hydrogel: Yield Stress and Other Parameters of Shear Viscosity and Wall Slip. Gels 2022; 8:gels8040230. [PMID: 35448131 PMCID: PMC9027982 DOI: 10.3390/gels8040230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/16/2022] [Accepted: 03/28/2022] [Indexed: 11/26/2022] Open
Abstract
The rheology, i.e., the flow and deformation properties, of hydrogels is generally a very important consideration for their functionality. However, the accurate characterization of their rheological material functions is handicapped by their ubiquitous viscoplasticity and associated wall slip behavior. Here a parallel-disk viscometer was used to characterize the shear viscosity and wall slip behavior of a crosslinked poly(acrylic acid) (PAA) carbomer hydrogel (specifically Carbopol® at 0.12% by weight in water). It was demonstrated that parallel-disk viscometry, i.e., the steady torsional flow in between two parallel disks, can be used to unambiguously determine the yield stress and other parameters of viscoplastic constitutive equations and wall slip behavior. It was specifically shown that torque versus rotational speed information, obtained from parallel-disk viscometry, was sufficient to determine the yield stress of a viscoplastic hydrogel. Additional gap-dependent data from parallel-disk viscometry could then be used to characterize the other parameters of the shear viscosity and wall slip behavior of the hydrogel. To investigate the accuracy of the parameters of shear viscosity and apparent wall slip that were determined, the data were used to calculate the torque values and the velocity distributions (using the lubrication assumption and parallel plate analogy) under different flow conditions. The calculated torques and velocity distributions of the hydrogel agreed very well with experimental data collected by Medina-Bañuelos et al., 2021, suggesting that the methodologies demonstrated here provide the means necessary to understand in detail the steady flow and deformation behavior of hydrogels. Such a detailed understanding of the viscoplastic nature and wall slip behavior of hydrogels can then be used to design and develop novel hydrogels with a wider range of applications in the medical and other industrial areas, and for finding optimum conditions for their processing and manufacturing.
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10
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11
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Wright CJ, Wilkinson PJ, Gaulter SE, Fossey D, Burn AO, Gill PP. Is ResonantAcoustic Mixing® (RAM) a Game Changer for Manufacturing Solid Composite Rocket Propellants? PROPELLANTS EXPLOSIVES PYROTECHNICS 2022. [DOI: 10.1002/prep.202100146] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Peter J. Wilkinson
- Centre for Defence Chemistry Cranfield University Defence Academy of the United Kingdom Shrivenham SN6 8LA UK
| | - Sally E. Gaulter
- Centre for Defence Chemistry Cranfield University Defence Academy of the United Kingdom Shrivenham SN6 8LA UK
| | - Donald Fossey
- The Falcon Project Ltd Westcott, Aylesbury HP18 0XB UK
| | | | - Philip P. Gill
- ROXEL (UK Rocket Motors) Ltd Summerfield Ln Kidderminster DY11 7RZ UK
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12
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Yan G, Cao Z, Devine D, Penning M, Gately NM. Physical Properties of Shellac Material Used for Hot Melt Extrusion with Potential Application in the Pharmaceutical Industry. Polymers (Basel) 2021; 13:polym13213723. [PMID: 34771279 PMCID: PMC8587309 DOI: 10.3390/polym13213723] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/18/2021] [Accepted: 10/26/2021] [Indexed: 11/29/2022] Open
Abstract
Hot melt extrusion offers an efficient way of increasing the solubility of a poorly soluble drug. Shellac has potential as a pharmaceutical matrix polymer that can be used in this extrusion process, with further advantages for use in enteric drug delivery systems. The rheological property of a material affects the extrusion process conditions. However, the literature does not refer to any published work that investigates the processability of various shellac materials. This work explores various types of shellac and explores their physicochemical and thermal properties along with their processability in the hot melt extrusion application. Physicochemical characterization of the materials was achieved using differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Additional processability characterization was achieved using melt flow index and rheology analysis. The results indicated that there was no chemical difference between the various shellac types compared in this study. However, the extrudable temperature ranges and rheological properties of different shellac types varied; SSB 55 Pharma FL had the lowest processing temperature and glass transition temperatures. Due to the shear-thinning behaviours, shellac can be extruded at lower temperatures. This study provides necessary data to determine the processing conditions in hot melt extrusion applications for the range of shellac materials.
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Affiliation(s)
- Guangming Yan
- Materials Research Institute, Technological University of the Shannon, Midlands Midwest, N37 HD68 Co. Westmeath, Ireland; (G.Y.); (Z.C.); (D.D.)
| | - Zhi Cao
- Materials Research Institute, Technological University of the Shannon, Midlands Midwest, N37 HD68 Co. Westmeath, Ireland; (G.Y.); (Z.C.); (D.D.)
| | - Declan Devine
- Materials Research Institute, Technological University of the Shannon, Midlands Midwest, N37 HD68 Co. Westmeath, Ireland; (G.Y.); (Z.C.); (D.D.)
| | - Manfred Penning
- Shellac Consultant, Wormser Strasse 28, D-55277 Oppenheim, Germany;
| | - Noel M. Gately
- Materials Research Institute, Technological University of the Shannon, Midlands Midwest, N37 HD68 Co. Westmeath, Ireland; (G.Y.); (Z.C.); (D.D.)
- Correspondence: ; Tel.: +35-387-621-7186
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13
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Benz J, Bonten C. Rigid Amorphous Fraction as an Indicator for Polymer-Polymer Interactions in Highly Filled Plastics. Polymers (Basel) 2021; 13:polym13193349. [PMID: 34641165 PMCID: PMC8512654 DOI: 10.3390/polym13193349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/27/2021] [Accepted: 09/27/2021] [Indexed: 11/16/2022] Open
Abstract
Above a percolation threshold a flow restriction has to be overcome by higher pressure in plastic processing. Besides amount and geometry of fillers, the interactions of polymer and filler are important. By differing the amorphous phase of polymers into a rigid amorphous and a mobile amorphous fraction, predictions about interactions are possible. The objective is the generation of a flow restriction and the combined investigation of polymer-particle interaction. SiO2 was used up to 50 vol.% in different spherical sizes in PLA and PP. A capillary-rheometer was used as a tool to create a yield point and by that investigations into the state of the flow restriction were possible. All produced compounds showed, in plate-plate rheometry, an increase in viscosity for lower shear rates and a significant change in the storage modulus. In DSC, hardly any specific rigid amorphous fraction was detectable, which suggests that there is a minor interaction between macromolecules and filler. This leads to the conclusion that the change in flow behavior is mainly caused by a direct interaction between the particles, even though they are theoretically too far away from each other. First images in the state of the yield point show a displacement of the particles against each other.
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14
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Formulation engineering of food systems for 3D-printing applications - A review. Food Res Int 2021; 148:110585. [PMID: 34507730 DOI: 10.1016/j.foodres.2021.110585] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/21/2021] [Accepted: 07/01/2021] [Indexed: 11/23/2022]
Abstract
The efficient development of extrusion-based 3D-printing requires flexibility in both formulation- and process design. This task requires a fundamental understanding of the influence of material rheological properties on the extrusion process. Within this review, a qualitative toolbox for food extrusion is presented which provides guidelines for the formulation and engineering of extrusion processes in general and 3D-printing in particular. The toolbox is based on current knowledge of highly viscous food systems and the influence of individual components on the overall rheology. It includes the efficiency of particle packing, microstructure and the influence of shear rate, as well as the formation of self-supporting structures by gelation of the liquid phase and crowding of particles. Physical laws and semi-empirical equations are discussed to describe the rheology and relate relevant theory to the extrusion process. Practical information is presented, including examples of extrusion and 3D-printing of food and non-food systems. The qualitative extrusion toolbox provides a general framework for the emerging field of extrusion-based 3D-printing of food products. It can be used to identify which specific material and process parameters can be changed and how they may be altered to optimize the 3D-printing process. The general framework will assist researchers, as well as industry.
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15
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Luo J, Chen J, Liu M, Min J, Fu Q, Zhang J. Investigating the Influence of Incorporation of Boron Nitride on the Kinetics of Isotactic Polypropylene Entanglement Recovery. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c02003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jiaxu Luo
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Jin Chen
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Mingjin Liu
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Jie Min
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Qiang Fu
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Jie Zhang
- State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, China
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16
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Balani SB, Ghaffar SH, Chougan M, Pei E, Şahin E. Processes and materials used for direct writing technologies: A review. RESULTS IN ENGINEERING 2021; 11:100257. [DOI: https:/doi.org/10.1016/j.rineng.2021.100257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
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17
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Balani SB, Ghaffar SH, Chougan M, Pei E, Şahin E. Processes and materials used for direct writing technologies: A review. RESULTS IN ENGINEERING 2021; 11:100257. [DOI: 10.1016/j.rineng.2021.100257] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
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18
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He J, Lee SS, Colakyan M, Kalyon DM. Viscoelastic properties and flow instabilities of aqueous suspensions of cellulosic fibers: Effects of a gelation agent on dispersion, rheology, and flow stability. POLYM ENG SCI 2021. [DOI: 10.1002/pen.25656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Jing He
- Highly Filled Materials Institute Stevens Institute of Technology Hoboken New Jersey USA
- Chemical Engineering and Materials Science Department Stevens Institute of Technology Hoboken New Jersey USA
| | - Stephanie S. Lee
- Chemical Engineering and Materials Science Department Stevens Institute of Technology Hoboken New Jersey USA
| | | | - Dilhan M. Kalyon
- Highly Filled Materials Institute Stevens Institute of Technology Hoboken New Jersey USA
- Chemical Engineering and Materials Science Department Stevens Institute of Technology Hoboken New Jersey USA
- Biomedical Engineering Department Stevens Institute of Technology Hoboken New Jersey USA
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19
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Quan L, Lee SS, Kalyon DM. Dynamics of the sub-ambient gelation and shearing of solutions of P3HT and P3HT blends towards active layer formation in bulk heterojunction organic solar cells. SOFT MATTER 2021; 17:1642-1654. [PMID: 33367403 DOI: 10.1039/d0sm01759k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic solar cells (OSCs) containing an active layer consisting of a nanostructured blend of a conjugated polymer like poly(3-hexylthiophene) (P3HT) and an electron acceptor have the potential of competing against silicon-based photovoltaic panels. However, this potential is largely unfulfilled first due to interrelated production and stability issues of organic solar cells and second due to the unscalable nature of the generally employed spin coating process used for the fabrication of organic solar cells. Furthermore, alternatives to spin coating, especially relying on continuous polymer processing methods like extrusion and coating, cannot be readily applied due to the typically low shear viscosity and elasticity of polymer solutions making up the active layer. Recently, He et al. have reported that the gelation of P3HT with [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) under sub-ambient conditions can provide a new route to the processing of the active layers of bulk heterojunction solar cells. Furthermore, increases in power conversion efficiencies (PCEs) of the P3HT/PC60BM active layer were determined to be possible under certain shearing and thermal histories of the P3HT/PC60BM gels. Here oscillatory and steady torsional flows were used to investigate the gel formation dynamics of P3HT with a recently proposed non-fullerene acceptor o-IDTBR under sub-ambient conditions and compared with the gelation behavior of P3HT/PC60BM blends. The rheological material functions as well as the gel strengths defined on the basis of linear viscoelastic material functions, characterized via small-amplitude oscillatory shearing, were observed to be functions of the P3HT and o-IDTBR concentrations, the solvent used and the shearing conditions. Overall, the P3HT gels which formed upon quenching to sub-zero temperatures were found to be stable during small-amplitude oscillatory shear (linear viscoelastic range) but broke down even at the relatively low shear rates associated with steady torsional flows, suggesting that the shearing conditions used during the processing of gels of P3HT and blends of P3HT with small molecule acceptors can alter the gel structure, possibly leading to changes in the resulting active layer performance.
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Affiliation(s)
- Li Quan
- Chemical Engineering and Materials Science, Stevens Institute of Technology, Castle Point St., Hoboken, NJ 07030, USA.
| | - Stephanie S Lee
- Chemical Engineering and Materials Science, Stevens Institute of Technology, Castle Point St., Hoboken, NJ 07030, USA.
| | - Dilhan M Kalyon
- Chemical Engineering and Materials Science, Stevens Institute of Technology, Castle Point St., Hoboken, NJ 07030, USA.
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20
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Şahin E, Çiftçioğlu M. Compositional, microstructural and mechanical effects of NaCl porogens in brushite cement scaffolds. J Mech Behav Biomed Mater 2021; 116:104363. [PMID: 33550144 DOI: 10.1016/j.jmbbm.2021.104363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 11/30/2022]
Abstract
Modification of the setting process of brushite cements by varying the concentration of ions that alter calcium phosphate crystallization kinetics, is known to enable control on the monetite conversion extent and the accompanying microporosity. This is useful because monetite serves as a suitable matrix in macroporous scaffolds due to its higher phase stability and finer crystal morphology compared to its hydrous counterpart brushite. In this study the synergistic effect of NaCl and citric acid on the microstructural evolution of brushite cement was demonstrated and microporosity of macroporous monetite-rich cement blocks was minimized by a variable NaCl porogen size distribution approach. Initially, maximum packing ratio of various combinations of NaCl size groups in PEG were determined by their rheological analysis in a range between 57% and 69%. Statistical analysis revealed a positive correlation between the amounts of NaCl particles under 38μm and 212μm and the maximum packing ratio. Further broadening the size distributions of NaCl porogens with fine cement precursors was effective in increasing the solids packing ratio of cement blocks more than the maximum packing ratio for the porogens. This improvement in packing was accompanied by a reduction in microporosity despite the increase in micropore volume with ion induced monetite formation. The detrimental effect of the microporosity introduced to the structure during monetite formation was balanced for some size distributions and not so much for others, thereby resulting in a wide range of porosities and mechanical properties. Thus, the exponential dependence of mechanical properties on porosity and the mechanical properties of monetite-rich macroporous blocks at the theoretical zero-porosity were determined according to Rice's model. Zero-porosity extrapolations were much higher than those predicted for brushite cement, contrary to the common assumption that brushite is mechanically stronger than monetite.
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Affiliation(s)
- Erdem Şahin
- Department of Metallurgical and Materials Engineering, Muğla Sıtkı Koçman University, Muğla, Turkey.
| | - Muhsin Çiftçioğlu
- Department of Chemical Engineering, İzmir Institute of Technology, İzmir, Turkey.
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21
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Delaroa C, Fulchiron R, Lintingre E, Buniazet Z, Cassagnau P. Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks. Polymers (Basel) 2020; 12:polym12102247. [PMID: 33003629 PMCID: PMC7601610 DOI: 10.3390/polym12102247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 11/16/2022] Open
Abstract
The impact of polypropylene and high-density polyethylene backbone binders on the structure of organic matrix, feedstock, and ceramic parts is investigated in terms of morphology in this paper. The miscibility of wax with polyethylene and polypropylene is investigated in the molten state via a rheological study, revealing wax full miscibility with high-density polyethylene and restricted miscibility with polypropylene. Mercury porosimetry measurements realized after wax extraction allow the characterization of wax dispersion in both neat organic blends and zirconia filled feedstocks. Miscibility differences in the molten state highly impact wax dispersion in backbone polymers after cooling: wax is preferentially located in polyethylene phase, while it is easily segregated from polypropylene phase, leading to the creation of large cracks during solvent debinding. The use of a polyethylene/polypropylene ratio higher than 70/30 hinders wax segregation and favors its homogeneous dispersion in organic binder. As zirconia is added to organic blends containing polyethylene, polypropylene, and wax, the pore size distribution created by wax extraction is shifted towards smaller pores. Above zirconia percolation at 40 vol%, the pore size distribution becomes sharp attesting of wax homogeneous dispersion. As the PP content in the organic binder decreases from 100% to 0%, the pore size distribution is reduced of 30%, leading to higher densification ability. In order to ensure a maximal densification of the final ceramic, polyethylene/polypropylene ratios with a minimum content of 70% of high-density polyethylene should be employed.
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Affiliation(s)
- Claire Delaroa
- Ingénierie des Matériaux Polymères, Univ Lyon, Université Lyon 1, CNRS UMR 5223, 15 Boulevard Latarjet, 69622 Villeurbanne CEDEX, France; (C.D.); (R.F.)
- Saint-Gobain CREE, Grains et Poudres, 550 Avenue Alphonse Jauffret, BP 20224, 84306 Cavaillon, France; (E.L.); (Z.B.)
| | - René Fulchiron
- Ingénierie des Matériaux Polymères, Univ Lyon, Université Lyon 1, CNRS UMR 5223, 15 Boulevard Latarjet, 69622 Villeurbanne CEDEX, France; (C.D.); (R.F.)
| | - Eric Lintingre
- Saint-Gobain CREE, Grains et Poudres, 550 Avenue Alphonse Jauffret, BP 20224, 84306 Cavaillon, France; (E.L.); (Z.B.)
| | - Zoé Buniazet
- Saint-Gobain CREE, Grains et Poudres, 550 Avenue Alphonse Jauffret, BP 20224, 84306 Cavaillon, France; (E.L.); (Z.B.)
| | - Philippe Cassagnau
- Ingénierie des Matériaux Polymères, Univ Lyon, Université Lyon 1, CNRS UMR 5223, 15 Boulevard Latarjet, 69622 Villeurbanne CEDEX, France; (C.D.); (R.F.)
- Correspondence:
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22
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Modulating water mobility in comminuted meat protein gels using model hydrophilic filler particles. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109376] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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McGlasson A, Rishi K, Beaucage G, Narayanan V, Chauby M, Mulderig A, Kuppa VK, Ilavsky J, Rackaitis M. The effects of staged mixing on the dispersion of reinforcing fillers in elastomer compounds. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.121765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Online Rheometry Investigation of Flow/Slip Behavior of Powder Injection Molding Feedstocks. Polymers (Basel) 2019; 11:polym11030432. [PMID: 30960416 PMCID: PMC6473305 DOI: 10.3390/polym11030432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/24/2019] [Accepted: 02/27/2019] [Indexed: 11/28/2022] Open
Abstract
Wall slip in the flow of powder injection molding (PIM) compounds can be the cause of unrealistically low viscosity values, and can lead to a failure of flow simulation approaches. Regardless of its importance, it has been considered only scarcely in the rheological models applied to PIM materials. In this paper, an online extrusion rheometer equipped with rectangular slit dies was used to evaluate the slip velocity of commercial as well as in-house-prepared PIM feedstocks based on metallic and ceramic powders at close-to-processing conditions. The tested slit dies varied in their dimensions and surface roughness. The wall-slip effect was quantified using the Mooney analysis of slip velocities. The smaller gap height (1 mm) supported the wall-slip effect. It was shown that both the binder composition and the powder characteristic affect slip velocity. Slip velocity can be reduced by tailoring a powder particle size distribution towards smaller particle fractions. The thickness of the polymer layer formed at the channel wall is higher for water-soluble feedstocks, while in the case of the catalytic polyacetal feedstocks the effect of surface roughness was manifested through lower viscosity at smooth surfaces.
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Campbell GA, Wetzel MD. Investigation of the Effect of Filler Concentration on the Flow Characteristics of Filled Polyethylene Melts. INT POLYM PROC 2018. [DOI: 10.3139/217.3571] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
All polymeric slurries that have a high concentration of filler are shear thinning. Shear thinning is an important characteristic of polymers, filled and unfilled, because it enables an increase in the throughput, shear rate in a die or an injection molding system without having to use substantially more power to increase the flow rate. Newtonian fluid-based slurries show an increase in shear thinning as the concentration of “filler” increases above the percolation threshold. As particle maximum packing concentration is approached the slurries begin to approach a perfect pseudoplastic fluid. In some cases, the shear thinning characteristics of a filled polymer do not increase substantially as the filler loading is increased. This is a quite different response than in Newtonian fluid-based slurry. Therefore, it is important to understand the materials engineering interactions that control shear thinning so that process flow models can better predict the performance of filled polymer systems. Highly filled polymers can have processing issues, including high screw shaft torque, energy consumption, die pressure and melt temperature rise. Previous theoretical developments and experimental evaluations of highly filled polymer melts showed that the rheology can be effectively described with a percolation model. In this work, capillary rheometer measurements using several low-density polyethylene resins, calcium carbonate and titanium dioxide fillers are reported using percolation theory concepts. The theoretical treatment of the rheology as a particulate percolating system with power-law behavior is used to analyze capillary rheometer data. The observed effects of resin molecular weight, filler type and size on rheology are described. Engineers that design and debottleneck polymer processes need to utilize the polymer viscosity at the minimum process shear rate to determine the smallest motor that will allow the process to run; in addition, the shear thinning characteristics of the polymer are used to indicate how much increased production may be possible with a given motor size. Thus, some examples of expected effects on melt processing are also presented.
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Radcliffe AJ, Hilden JL, Nagy ZK, Reklaitis GV. Dropwise Additive Manufacturing of Pharmaceutical Products Using Particle Suspensions. J Pharm Sci 2018; 108:914-928. [PMID: 30308177 DOI: 10.1016/j.xphs.2018.09.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 09/05/2018] [Accepted: 09/14/2018] [Indexed: 11/16/2022]
Abstract
The principal method of drug delivery is by oral solid doses, the production of which often necessitates multiple post-crystallization unit operations to ensure content uniformity or enhance bioavailability. As an alternative to conventional dose production methods, applications of additive manufacturing technologies based on solvent- or melt-based formulations have demonstrated the potential for improvements to process efficiency, flexibility, and dosing precision. Here we explore the use of particulate suspensions in a dropwise additive manufacturing process as a method for dosing active ingredients in crystalline form, which may be difficult to achieve via powder processing due to poor flow properties. By employing a fluid-based method, powder flow issues are alleviated and adaptation of the process to new particles/crystals is facilitated by dimensional analysis. In this work, a feasibility study was conducted using 4 active ingredient powders, each with non-ideal particle properties, and 2 carrier fluids, in which the active ingredient does not dissolve, to formulate suspensions for dose manufacturing; drug products were analyzed to show reproducibility of dosing and to assess preservation of particle size through the process. Performance across particle types is affected by particle size and shape, and is related through effects on the rheological properties of the formulation.
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Affiliation(s)
- Andrew J Radcliffe
- Department of Chemical Engineering, Purdue University, West Lafayette, Indiana.
| | - Jon L Hilden
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Zoltan K Nagy
- Department of Chemical Engineering, Purdue University, West Lafayette, Indiana
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Wetzel MD, Campbell GA. A Study of Concentrated Suspensions in Polyethylene Melts and the Impact on Viscosity and Polymer Processing Operations. INT POLYM PROC 2018. [DOI: 10.3139/217.3577] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AbstractFilled polymer compounds can present processing challenges, including poor dispersive mixing, high screw shaft torque and energy consumption, flow instabilities, and significant increases in melt pressures and temperatures. Previous theoretical development and experimental evaluations of polymer melts filled with particulate solids showed that the viscosity can be described with a model based on percolation theory concepts. This paper describes a batch mixer characterization method developed to measure the effects of filler concentration and operating conditions on the melt viscosity and process response. Experimental results are compared with capillary rheometer measurements using several low-density polyethylene resins, calcium carbonate and titanium dioxide. The theoretical treatment of the viscosity as a particulate percolating system with power-law behavior was used to analyze and compare rheometer and batch mixer data. The effects of resin molecular weight, filler type and size on viscosity and melt processing were examined and there was good agreement between rheometer and mixer viscosity trends, and percolation model predictions. The laboratory experiments and model estimates provide quantitative information that can be used to develop and troubleshoot extrusion compounding, single screw extrusion and low-shear forming processes.
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Affiliation(s)
| | - G. A. Campbell
- 2Castle Associates, Jonesport, Maine, USA
- 3Clarkson University, Postdam, NY, USA
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29
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Ionic coupling effects in dynamic electrophoresis and electric permittivity of aqueous concentrated suspensions. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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30
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Influence of capillary die geometry on wall slip of highly filled powder injection molding compounds. POWDER TECHNOL 2018. [DOI: 10.1016/j.powtec.2017.11.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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31
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Pěnkavová V, Tihon J, Wein O. Bulk fluidity and apparent wall slip of aqueous kaolin suspensions studied using the cone-cone (KK) sensor: Effect of the sensor surface quality. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.08.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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32
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Şahin E, Kalyon DM. The rheological behavior of a fast-setting calcium phosphate bone cement and its dependence on deformation conditions. J Mech Behav Biomed Mater 2017; 72:252-260. [DOI: https:/doi.org/10.1016/j.jmbbm.2017.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
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33
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Şahin E, Kalyon DM. The rheological behavior of a fast-setting calcium phosphate bone cement and its dependence on deformation conditions. J Mech Behav Biomed Mater 2017; 72:252-260. [PMID: 28505594 DOI: 10.1016/j.jmbbm.2017.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/03/2017] [Accepted: 05/09/2017] [Indexed: 10/19/2022]
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34
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Ding H, Tourlomousis F, Chang RC. Bioprinting multidimensional constructs: a quantitative approach to understanding printed cell density and redistribution phenomena. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa70f0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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35
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Rueda MM, Auscher MC, Fulchiron R, Périé T, Martin G, Sonntag P, Cassagnau P. Rheology and applications of highly filled polymers: A review of current understanding. Prog Polym Sci 2017. [DOI: 10.1016/j.progpolymsci.2016.12.007] [Citation(s) in RCA: 204] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jalaal M, Balmforth NJ, Stoeber B. Slip of Spreading Viscoplastic Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12071-12075. [PMID: 26418827 DOI: 10.1021/acs.langmuir.5b02353] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The spreading of axisymmetric viscoplastic droplets extruded slowly on glass surfaces is studied experimentally using shadowgraphy and swept-field confocal microscopy. The microscopy furnishes vertical profiles of the radial velocity using particle image velocimetry (PIV) with neutrally buoyant tracers seeded in the fluid. Experiments were conducted for two complex fluids: aqueous solutions of Carbopol and xanthan gum. On untreated glass surfaces, PIV demonstrates that both fluids experience a significant amount of effective slip. The experiments were repeated on glass that had been treated to feature positive surface charges, thereby promoting adhesion between the negatively charged polymeric constituents of the fluids and the glass surface. The Carbopol and xanthan gum droplets spread more slowly on the treated surface and to a smaller radial distance. PIV demonstrated that this reduced spreading was associated with a substantial reduction in slip. For Carbopol, the effective slip could be eliminated entirely to within the precision of the PIV measurements; the reduction in slip was less effective for xanthan gum, with a weak slip velocity remaining noticeable.
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Affiliation(s)
- Maziyar Jalaal
- Department of Mechanical Engineering, University of British Columbia , Vancouver, British Columbia V6T 1Z4, Canada
| | - Neil J Balmforth
- Department of Mathematics, University of British Columbia , Vancouver, British Columbia V6T 1Z4, Canada
| | - Boris Stoeber
- Departments of Mechanical and Electrical and Computer Engineering, University of British Columbia , Vancouver, British Columbia V6T 1Z4, Canada
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General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields. J Colloid Interface Sci 2015; 455:46-54. [DOI: 10.1016/j.jcis.2015.05.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/12/2015] [Accepted: 05/12/2015] [Indexed: 11/17/2022]
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Affiliation(s)
- Morton M. Denn
- Benjamin Levich Institute and Department of Chemical Engineering, City College of New York, New York, New York 10031; ,
| | - Jeffrey F. Morris
- Benjamin Levich Institute and Department of Chemical Engineering, City College of New York, New York, New York 10031; ,
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