1
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Melzer F, Breuer R, Dahlmann R, Hopmann C. Calculating diffusion coefficients from molecular dynamics simulations for foam extrusion modelling of polypropylene with CO 2, N 2 and ethanol. J CELL PLAST 2022. [DOI: 10.1177/0021955x221087598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In foaming processes, the blowing agent has a significant influence on the material behaviour and the necessary processing parameters. Low-density polypropylene foam sheets are usually produced with aliphatic hydrocarbons or alkanes as physical blowing agent. Due to the necessary safety precautions and the environmental impact, there is great interest in using alternative blowing agents such as CO2. The sole use of CO2 often leads to corrugation, open cells or surface defects on the foam sheet and therefore requires modifications to the process technology. For this reason, blowing agent mixtures based on CO2 and organic solvents are used for the production of foam sheets. For developing a process model describing the melt flow in the extrusion die and the formation of cells, specific material data like diffusion coefficients are necessary. For CO2 and N2 as sole blowing agent, experimental data exist in the literature. Since no experimental data are available for co-blowing agents such as ethanol at elevated temperatures as they occur in the foam process, these data were calculated using molecular dynamics (MD) simulations. The benefit of MD simulations lies in their ability to reduce the experimental effort and, in particular, to provide data in cases where this data is not available through experimental measurements. The calculated diffusion coefficient values are compared to experimental data from the literature and presented for CO2, N2 and ethanol in polypropylene. The calculated diffusion coefficients of CO2 and N2 are compared with literature results and agree well with them. For the ethanol molecules, the diffusion coefficient is compared relative to the both aforementioned ones considered the larger size of the ethanol molecule compared to N2 and CO2. The results of the diffusion coefficients for ethanol are reasonable compared to the values found for the other two molecules.
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Affiliation(s)
- Felix Melzer
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University, Germany
| | - Robert Breuer
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University, Germany
| | - Rainer Dahlmann
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University, Germany
| | - Christian Hopmann
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University, Germany
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2
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Extensional rheology and CO 2 foaming of thermoplastics vulcanizates: Influence of the crosslinking chemistry. J CELL PLAST 2022. [DOI: 10.1177/0021955x221080677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The objective of this study is to investigate the ability of thermoplastic vulcanizates (TPVs) (materials based on PP/EPDM blend) to foam under CO2 batch conditions. The EPDM phase, which is dispersed into the PP phase, was dynamically crosslinked either by a phenolic resin (Resol) or by a radical peroxide (dicumyl peroxide). The results show an influence of the crosslinking chemistry on the extensional viscosity of the TPV. Regarding radical chemistry, the peroxide induces polypropylene degradation by β-scission reaction during the dynamic crosslinking process. As a result, the ability of the TPV to deform under extensional flow (Hencky deformation at break <0.5) is greatly reduced. On the contrary, the Resol-based TPV has demonstrated a non-linear viscosity behaviour (strain hardening) and a great ability to deform (Hencky deformation at break >1.5). This unexpected result for a non-homogeneous system can be explained by the confinement of the PP phase between EPDM nodules which gives to the PP chains a gel rheological behaviour. In addition, the influence of the addition of carbon black filler has also been studied. Finally, the relationship between extensional viscosity and physical foaming has been investigated. As for a homogeneous polymer, the extensional viscosity has been proved to be a key factor to estimate the foaming behaviour of complex systems like TPV. Hence, the importance of non-linear viscosity for a multi-phasic polymer to ensure foaming ability has been demonstrated.
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3
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Breuer R, Hendriks S, Reinhardt N, Facklam M, Hopmann C. Modeling flow and cell formation in foam sheet extrusion of polystyrene with
CO
2
and co‐blowing agents. Part I: Material model. POLYM ENG SCI 2021. [DOI: 10.1002/pen.25800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Robert Breuer
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Sven Hendriks
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Nicolas Reinhardt
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Martin Facklam
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Christian Hopmann
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
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4
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Breuer R, Hendriks S, Reinhardt N, Facklam M, Hopmann C. Modeling flow and cell formation in foam sheet extrusion of polystyrene with
CO
2
and co‐blowing agents. Part
II
: Process model. POLYM ENG SCI 2021. [DOI: 10.1002/pen.25797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Robert Breuer
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Sven Hendriks
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
- Armacell Benelux S.C.S. Thimister‐Clermont Belgium
| | - Nicolas Reinhardt
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Martin Facklam
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
| | - Christian Hopmann
- Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University Aachen Germany
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5
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Liu B, Jiang T, Zeng X, Deng R, Gu J, Gong W, He L. Polypropylene/thermoplastic polyester elastomer blend: Crystallization properties, rheological behavior, and foaming performance. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5240] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Bujin Liu
- The Institute of Materials and Metallurgy of Guizhou University Guiyang China
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
| | - Tuanhui Jiang
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
| | - Xiangbu Zeng
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
| | - Rong Deng
- The Institute of Materials and Metallurgy of Guizhou University Guiyang China
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
| | - Jun Gu
- The Institute of Materials and Metallurgy of Guizhou University Guiyang China
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
| | - Wei Gong
- The Institute of Materials and Construction of Guizhou Normal University Guiyang China
| | - Li He
- The Institute of Materials and Metallurgy of Guizhou University Guiyang China
- National Engineering Research Center for Compounding and Modification of Polymer Materials Guiyang China
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6
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Bianchin OS, Melo GHF, Bretas RES. Effect of MWCNT carboxyl functionalization on the shear rheological and electrical properties of HMS-PP/MWCNT foams. J CELL PLAST 2020. [DOI: 10.1177/0021955x20943096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Different concentrations of multiwall carbon nanotubes (MWCNT) and carboxyl functionalized MWCNT (MWCNT-COOH) were added to a high melt strength polypropylene (HMS-PP) to produce foams with high dielectric constants, using azodicarbonamide (AZO) as blowing agent. The AZO foaming behavior and the crystallization, thermal properties, steady state and oscillatory shear rheological properties of the nanocomposites were analyzed by polarized light optical microscopy (PLOM), differential scanning calorimetry (DSC), thermogravimetry analyses (TGA) and parallel plate rheometry. The morphology, the dielectric and dynamic mechanical properties (DMTA) of the foams were also studied by scanning electron microscopy (SEM), impedance spectroscopy and bending method, respectively. A decrease in crystallite size and an increase in the HMS-PP overall crystallinity promoted by the presence of both types of MWCNTs was observed, as well as an increase in the crystallization temperatures. From these results and from the analyses of the rheological properties, it was possible to predict that the 5 wt.% MWCNT foam would have the lowest bubble growth rate, the 1.5 wt.% MWCNT-COOH the highest, while the 3 wt.% MWCNT-COOH composition would have the slowest bubble stability (and consequently the highest cellular density) and the 1.5 wt.% MWCNT-COOH the fastest. Also, it was possible to predict that only the 5 wt.% MWCNT-COOH foam would have a percolated and electrically conductive structure. All these predictions were confirmed by the resultant morphology and impedance spectroscopy results. The highest mechanical damping was displayed by the 3 wt.% MWCNT-COOH foam, while the lowest by the 5 wt.% MWCNT-COOH foam. Regarding the dielectric properties, the 1.5 wt% MWCNT-COOH foam was found to be the most suitable to be used as a capacitor material; this foam was also the less dense of all the samples.
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Affiliation(s)
- Olavo S Bianchin
- Department of Materials Engineering, Universidade Federal de São Carlos, São Paulo, Brazil
| | - Guilherme HF Melo
- Department of Materials Engineering, Universidade Federal de São Carlos, São Paulo, Brazil
| | - Rosario ES Bretas
- Department of Materials Engineering, Universidade Federal de São Carlos, São Paulo, Brazil
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7
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Rheology and foaming behaviour of styrene–ethylene–butylene–styrene nanocomposites. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04677-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Qu Z, Yin D, Zhou H, Wang X, Zhao S. Cellular morphology evolution in nanocellular poly (lactic acid)/thermoplastic polyurethane blending foams in the presence of supercritical N2. Eur Polym J 2019. [DOI: 10.1016/j.eurpolymj.2019.03.046] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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9
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Wang G, Li W, Bai S, Wang Q. Synergistic Effects of Flame Retardants on the Flammability and Foamability of PS Foams Prepared by Supercritical Carbon Dioxide Foaming. ACS OMEGA 2019; 4:9306-9315. [PMID: 31460020 PMCID: PMC6648846 DOI: 10.1021/acsomega.9b00321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/17/2019] [Indexed: 05/24/2023]
Abstract
Halogen-free flame-retardant polystyrene (PS) foams prepared by supercritical carbon dioxide (SC-CO2) foaming have been achieved. The flame-retardants include expandable graphite (EG) and melamine phosphate (MP), and their influence on the foamability, decomposition behavior, fire performance, and mechanical properties of PS foams were investigated. It has been shown that flame retardants can generate inert gases and catalyze the char formation from PS, and the formed thick char layer with a notable barrier property can greatly decrease the heat release of PS foams. The addition of triphenyl phosphate (TPP) or hexaphenoxycyclotriphosphazene (HPCTP), which acts as a flame-retardant plasticizer, can obviously improve the foamability and fire performance of the foams. TPP or HPCTP can generate active phosphorous species and phenoxyl radicals to enhance the gas phase flame-retardant effect; therefore, the flame-retarded PS foams (with 25 wt % MP/EG) achieve HF1 and V-0 ratings, with limiting oxygen index (LOI) values of 30.1 or 29.6%, respectively. The numerical assessment of synergistic effects of TPP and HPCTP on further enhancing flame retardancy of PS foams has been provided by the microcalorimeter (MCC) test. Further X-ray photoelectron spectroscopy (XPS) investigation on char residues of PS foams demonstrates the formation of the P-O-C and other stable structures.
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Affiliation(s)
- Gang Wang
- State
Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, China
| | - Wenzhi Li
- State
Key Laboratory of Special Functional Waterproof Materials, Beijing 101300, China
| | - Shibing Bai
- State
Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, China
| | - Qi Wang
- State
Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, Sichuan 610065, China
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10
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Yeh SK, Yang SH, Han L, Liu HY, Liao YS, Chang YC. Foam extrusion of polypropylene–rice husk composites using CO2 as the blowing agent. J CELL PLAST 2019. [DOI: 10.1177/0021955x19839744] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Shu-Kai Yeh
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC
| | - Ssu-Hsuan Yang
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC
| | - Long Han
- Huntsman LLC, The Woodlands, TX, USA
| | - Hung-Yun Liu
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC
| | - Yi-Syun Liao
- Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC
| | - Yi-Chun Chang
- Miniwiz Sustainable Energy Development Co., Ltd, Taipei, Taiwan, ROC
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11
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Kim ES, Park HE, Lopez-Barron CR, Lee PC. Enhanced Foamability with Shrinking Microfibers in Linear Polymer. Polymers (Basel) 2019; 11:E211. [PMID: 30960196 PMCID: PMC6419035 DOI: 10.3390/polym11020211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/14/2019] [Accepted: 01/19/2019] [Indexed: 11/21/2022] Open
Abstract
Strain hardening has important roles in understanding material structures and polymer processing methods, such as foaming, film forming, and fiber extruding. A common method to improve strain hardening behavior is to chemically branch polymer structures, which is costly, thus preventing users from controlling the degree of behavior. A smart microfiber blending technology, however, would allow cost-efficient tuning of the degree of strain hardening. In this study, we investigated the effects of compounding polymers with microfibers for both shear and extensional rheological behaviors and characteristics and thus for the final foam morphologies formed by batch physical foaming with carbon dioxide. Extensional rheometry showed that compounding of in situ shrinking microfibers significantly enhanced strain hardening compared to compounding of nonshrinking microfibers. Shear rheometry with linear viscoelastic data showed a greater increase in both the loss and storage modulus in composites with shrinking microfibers than in those with nonshrinking microfibers at low frequencies. The batch physical foaming results demonstrated a greater increase in the cell population density and expansion ratio with in situ shrinking microfibers than with nonshrinking microfibers. The enhancement due to the shrinkage of compounded microfibers decreasing with temperature implies that the strain hardening can be tailored by changing processing conditions.
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Affiliation(s)
- Eric S Kim
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
| | - Heon E Park
- Department of Mechanical Engineering, University of Vermont, 33 Colchester Avenue, Burlington, VT 05405, USA.
| | - Carlos R Lopez-Barron
- ExxonMobil Chemical Company, Baytown Technology and Engineering Complex, Baytown, TX 77520, USA.
| | - Patrick C Lee
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada.
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12
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Hendriks S, Hopmann C, Zepnik S. Extrusion foaming of thermoplastic cellulose acetate sheets with HFO-1234ze and co-blowing agents. POLYM ENG SCI 2018. [DOI: 10.1002/pen.24850] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sven Hendriks
- Institute of Plastics Processing (IKV); RWTH Aachen University; 52074 Aachen Germany
| | - Christian Hopmann
- Institute of Plastics Processing (IKV); RWTH Aachen University; 52074 Aachen Germany
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13
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Kim ES, Park HE, Lee PC. In situ shrinking fibers enhance strain hardening and foamability of linear polymers. POLYMER 2018. [DOI: 10.1016/j.polymer.2017.12.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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Zhao J, Zhao Q, Wang L, Wang C, Guo B, Park CB, Wang G. Development of high thermal insulation and compressive strength BPP foams using mold-opening foam injection molding with in-situ fibrillated PTFE fibers. Eur Polym J 2018. [DOI: 10.1016/j.eurpolymj.2017.11.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Tiwary P, Park CB, Kontopoulou M. Transition from microcellular to nanocellular PLA foams by controlling viscosity, branching and crystallization. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.04.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Bahreini E, Aghamiri SF, Wilhelm M, Abbasi M. Influence of molecular structure on the foamability of polypropylene: Linear and extensional rheological fingerprint. J CELL PLAST 2017. [DOI: 10.1177/0021955x17700097] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The foaming structure and rheological properties of four different isotactic homo-polypropylenes with various molecular weights and an isotactic long chain branched polypropylene were investigated to find a suitable rheological fingerprint for PP foams. The molecular weight distribution and thermal properties were measured using GPC-MALLS and differential scanning calorimetry, respectively. Small amplitude oscillatory shear data and uniaxial extensional experiments were analyzed using the frameworks of van Gurp-Palmen plot (δ vs. | G*|) and the molecular stress function model, respectively. These analyses were used to find a correlation between the molecular structure, rheological properties and foaming structures of linear and long chain branching polypropylenes. Two linear viscoelastic characteristics, | G*| at δ = 60° and | η*| at ω = 5 rad/s were used as criteria for foamability of these polymers, where decreasing of both parameters by increasing the long chain branching content results in smaller cell size and higher cell density. The molecular stress function model was able to quantify the strain hardening properties of long chain branching blends using small amplitude oscillatory shear data and two nonlinear material parameters, 1 ≤ β ≤ 2.2 and 1 ≤ [Formula: see text] ≤ 600, where the minimum and maximum values of these parameters belong to the linear and long chain branched polypropylene, respectively. Increasing the long chain branched polypropylene content of the PP blends increased strain hardening, and therefore improved the foaming characteristics significantly by suppressing the coalescence of cells. Dilution of linear PP with only 10 wt% of long chain branched polypropylene enhanced the cell density from 5.7 × 106 to 2.7 × 107 cell/cm3 and reduced the average cell diameter from 58 to 26 µm, respectively, while their volume expansion ratio remained in the same range of 2–3. Increasing of long chain branching to 50 and 100 wt% enhanced the V.E.R. to 6.2 and 7.8, respectively.
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Affiliation(s)
- Ebrahim Bahreini
- Chemical Engineering Department, Faculty of Engineering, University of Isfahan, Iran
| | - Seyed Foad Aghamiri
- Chemical Engineering Department, Faculty of Engineering, University of Isfahan, Iran
| | - Manfred Wilhelm
- Institute of Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Germany
| | - Mahdi Abbasi
- Chemical Engineering Department, Faculty of Engineering, University of Isfahan, Iran
- Institute of Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Germany
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17
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Wang L, Ishihara S, Ando M, Minato A, Hikima Y, Ohshima M. Fabrication of High Expansion Microcellular Injection-Molded Polypropylene Foams by Adding Long-Chain Branches. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b03641] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Long Wang
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Shota Ishihara
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Megumi Ando
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Atsushi Minato
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Yuta Hikima
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Masahiro Ohshima
- Department
of Chemical Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
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18
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Tiwary P, Gui H, Ferreira PL, Kontopoulou M. Coagent Modified Polypropylene Prepared by Reactive Extrusion: A New Look into the Structure-Property Relations of Injection Molded Parts. INT POLYM PROC 2016. [DOI: 10.3139/217.3209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AbstractPeroxide-mediated reactive extrusion of linear isotactic polypropylene (L-PP) was conducted in the presence of trimethylolpropane trimethacrylate (TMPTMA) and triallyl trimesate (TAM) coagents, using a twin screw extruder. The resulting coagent-modified polypropylenes (CM-PP) had higher viscosities and elasticities, as well as increased crystallization temperature compared to PP reacted only with peroxide (DCP-PP). Additionally, deviations from terminal flow, and strain hardening were observed in PP modified with TAM, signifying the presence of long chain branching (LCB). The CM-PP formulations retained the modulus and tensile strength of the parent L-PP, in spite of their lower molar mass and viscosities, whereas their elongation at break and the impact strength were better. This was attributed to the finer spherulitic structure of these materials, and to the disappearance of the skin-core layer in the injection molded specimens.
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Affiliation(s)
- P. Tiwary
- 1Department of Chemical Engineering, Queen's University, Kingston, Ontario, Canada
| | - H. Gui
- 2Sinopec, Beijing Research Institute of Chemical Industry, Beijing, PRC
| | - P. L. Ferreira
- 1Department of Chemical Engineering, Queen's University, Kingston, Ontario, Canada
| | - M. Kontopoulou
- 1Department of Chemical Engineering, Queen's University, Kingston, Ontario, Canada
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