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Barranco-García R, García-Peñas A, Blázquez-Blázquez E, Ressia JA, Quinzani LM, Vallés EM, Gómez-Elvira JM, Pérez E, Cerrada ML. Polypropylene Nanocomposites Attained by In Situ Polymerization Using SBA-15 Particles as Support for Metallocene Catalysts: Effect of Molecular Weight and Tacticity on Crystalline Details, Phase Transitions and Rheological Behavior. Molecules 2023; 28:molecules28114261. [PMID: 37298738 DOI: 10.3390/molecules28114261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 05/12/2023] [Accepted: 05/18/2023] [Indexed: 06/12/2023] Open
Abstract
In this study, nanocomposites based on polypropylene are synthesized by the in situ polymerization of propene in the presence of mesoporous SBA-15 silica, which acts as a carrier of the catalytic system (zirconocene as catalyst and methylaluminoxane as cocatalyst). The protocol for the immobilization and attainment of hybrid SBA-15 particles involves a pre-stage of contact between the catalyst with cocatalyst before their final functionalization. Two zirconocene catalysts are tested in order to attain materials with different microstructural characteristics, molar masses and regioregularities of chains. Some polypropylene chains are able to be accommodated within the silica mesostructure of these composites. Thus, an endothermic event of small intensity appears during heating calorimetric experiments at approximately 105 °C. The existence of these polypropylene crystals, confined within the nanometric channels of silica, is corroborated by SAXS measurements obtained via the change in the intensity and position of the first-order diffraction of SBA-15. The incorporation of silica also has a very significant effect on the rheological response of the resultant materials, leading to important variations in various magnitudes, such as the shear storage modulus, viscosity and δ angle, when a comparison is established with the corresponding neat iPP matrices. Rheological percolation is reached, thus demonstrating the role of SBA-15 particles as filler, in addition to the supporting role that they exert during the polymerizations.
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Affiliation(s)
- Rosa Barranco-García
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
- Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Avenida Complutense s/n, Ciudad Universitaria, 28040 Madrid, Spain
| | - Alberto García-Peñas
- Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911 Leganés, Spain
| | - Enrique Blázquez-Blázquez
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
| | - Jorge A Ressia
- Planta Piloto de Ingeniería Química (PLAPIQUI), UNS-CONICET, Camino La Carrindanga km. 7, Bahía Blanca 8000, Argentina
- Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), La Plata 1900, Argentina
| | - Lidia M Quinzani
- Planta Piloto de Ingeniería Química (PLAPIQUI), UNS-CONICET, Camino La Carrindanga km. 7, Bahía Blanca 8000, Argentina
| | - Enrique M Vallés
- Planta Piloto de Ingeniería Química (PLAPIQUI), UNS-CONICET, Camino La Carrindanga km. 7, Bahía Blanca 8000, Argentina
| | - José M Gómez-Elvira
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
| | - Ernesto Pérez
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
| | - María L Cerrada
- Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
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2
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Mihelčič M, Oseli A, Huskić M, Slemenik Perše L. Influence of Stabilization Additive on Rheological, Thermal and Mechanical Properties of Recycled Polypropylene. Polymers (Basel) 2022; 14:polym14245438. [PMID: 36559809 PMCID: PMC9785811 DOI: 10.3390/polym14245438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/05/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
To decrease the amount of plastic waste, the use of recycling techniques become a necessity. However, numerous recycling cycles result in the mechanical, thermal, and chemical degradation of the polymer, which leads to an inefficient use of recycled polymers for the production of plastic products. In this study, the effects of recycling and the improvement of polymer performance with the incorporation of an additive into recycled polypropylene was studied by spectroscopic, rheological, optical, and mechanical characterization techniques. The results showed that after 20 recycling steps of mechanical processing of polypropylene, the main degradation processes of polypropylene are chain scission of polymer chains and oxidation, which can be improved by the addition of a stabilizing additive. It was shown that a small amount of an additive significantly improves the properties of the recycled polypropylene up to the 20th reprocessing cycle. The use of an additive improves the rheological properties of the recycled melt, surface properties, and time-dependent mechanical properties of solid polypropylene since it was shown that the additive acts as a hardener and additionally crosslinks the recycled polymer chains.
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Affiliation(s)
- Mohor Mihelčič
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva Ulica 6, 1000 Ljubljana, Slovenia
| | - Alen Oseli
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva Ulica 6, 1000 Ljubljana, Slovenia
| | - Miroslav Huskić
- Faculty of Polymer Technology, Ozare 19, 2380 Slovenj Gradec, Slovenia
| | - Lidija Slemenik Perše
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva Ulica 6, 1000 Ljubljana, Slovenia
- Correspondence:
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3
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Radiation, thermo-oxidative and storage induced changes in microstructure, crystallinity and dielectric properties of (un)oriented isotactic polypropylene. Polym Degrad Stab 2021. [DOI: 10.1016/j.polymdegradstab.2021.109564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4
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Liu X, Liu X, Li Y, Zhang Y, Xie X, Li K, Chen Z, Zhang L, Tang Z, Liu Z. Nanoengineering of transparent polypropylene containing sorbitol-based clarifier. JOURNAL OF POLYMER RESEARCH 2020. [DOI: 10.1007/s10965-020-02169-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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5
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Gaska K, Manika GC, Gkourmpis T, Tranchida D, Gitsas A, Kádár R. Mechanical Behavior of Melt-Mixed 3D Hierarchical Graphene/Polypropylene Nanocomposites. Polymers (Basel) 2020; 12:E1309. [PMID: 32521812 PMCID: PMC7361869 DOI: 10.3390/polym12061309] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/02/2020] [Accepted: 06/05/2020] [Indexed: 11/16/2022] Open
Abstract
The mechanical properties of novel low percolation melt-mixed 3D hierarchical graphene/polypropylene nanocomposites are analyzed in this study. The analysis spans a broad range of techniques and time scales, from impact to tensile, dynamic mechanical behavior, and creep. The applicability of the time-temperature superposition principle and its limitations in the construction of the master curve for the isotactic polypropylene (iPP)-based graphene nanocomposites has been verified and presented. The Williams-Landel-Ferry method has been used to evaluate the dynamics and also Cole-Cole curves were presented to verify the thermorheological character of the nanocomposites. Short term (quasi-static) tensile tests, creep, and impact strength measurements were used to evaluate the load transfer efficiency. A significant increase of Young's modulus with increasing filler content indicates reasonably good dispersion and adhesion between the iPP and the filler. The Young's modulus results were compared with predicted modulus values using Halpin-Tsai model. An increase in brittleness resulting in lower impact strength values has also been recorded.
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Affiliation(s)
- Karolina Gaska
- Department of Industrial and Materials Science, Division of Engineering Materials, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; (G.C.M.); (R.K.)
| | - Georgia C. Manika
- Department of Industrial and Materials Science, Division of Engineering Materials, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; (G.C.M.); (R.K.)
| | - Thomas Gkourmpis
- Innovation & Technology, Borealis AB, SE-444 86 Stenungsund, Sweden;
| | - Davide Tranchida
- Innovation & Technology, Borealis Polyolefine GmbH, St.-Peter-Straße 25, 4021 Linz, Austria; (D.T.); (A.G.)
| | - Antonis Gitsas
- Innovation & Technology, Borealis Polyolefine GmbH, St.-Peter-Straße 25, 4021 Linz, Austria; (D.T.); (A.G.)
| | - Roland Kádár
- Department of Industrial and Materials Science, Division of Engineering Materials, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden; (G.C.M.); (R.K.)
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6
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Eichelter J, Wilhelm H, Eder A, Mautner A, Bismarck A. Influence of the α-relaxation on the high-velocity stretchability of isotactic polypropylene. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Melt-Mixed 3D Hierarchical Graphene/Polypropylene Nanocomposites with Low Electrical Percolation Threshold. NANOMATERIALS 2019; 9:nano9121766. [PMID: 31835842 PMCID: PMC6956219 DOI: 10.3390/nano9121766] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 11/27/2019] [Accepted: 12/04/2019] [Indexed: 11/16/2022]
Abstract
Graphene-based materials are a family of carbonaceous structures that can be produced using a variety of processes either from graphite or other precursors. These materials are typically a few layered sheets of graphene in the form of platelets and maintain some of the properties of pristine graphene (such as two-dimensional platelet shape, aspect ratio, and graphitic bonding). In this work we present melt mixed graphene-based polypropylene systems with significantly reduced percolation threshold. Traditionally melt-mixed systems suffer from poor dispersion that leads to high electrical percolation values. In contrast in our work, graphene was added into an isotactic polypropylene matrix, achieving an electrical percolation threshold of ~1 wt.%. This indicates that the filler dispersion process has been highly efficient, something that leads to the suppression of the β phase that have a strong influence on the crystallization behavior and subsequent thermal and mechanical performance. The electrical percolation values obtained are comparable with reported solution mixed systems, despite the use of simple melt mixing protocols and the lack of any pre or post-treatment of the final compositions. The latter is of particular importance as the preparation method used in this work is industrially relevant and is readily scalable.
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8
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Ge Q, Ding L, Zhang C, Wu T, Yang F, Xiang M. The effect of microstructure on the toughness of polypropylene random copolymer. POLYM-PLAST TECH MAT 2019. [DOI: 10.1080/25740881.2018.1563128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Qian Ge
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
| | - Lei Ding
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
| | - Chao Zhang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
| | - Tong Wu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
| | - Feng Yang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
| | - Ming Xiang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu, People’s Republic of China
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9
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Basu D, Agasty A, Das A, Chattopadhyay S, Sahu P, Heinrich G. Phase changing stearate ions as active fillers in multifunctional carboxylated acrylonitrile–butadiene composite: Exploring the role of zinc stearate. J Appl Polym Sci 2019. [DOI: 10.1002/app.48271] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Debdipta Basu
- East Centre, Indian Rubber Manufacturers Research Association Thane 400604 Maharashtra India
| | - Airit Agasty
- Department of Elastomers, Leibniz‐Institut für Polymerforschung Dresden e.V., Hohe Straße 6 Dresden 01069 Germany
- Rubber Technology CentreIndian Institute of Technology Kharagpur West Bengal 721302 India
| | - Amit Das
- Department of Elastomers, Leibniz‐Institut für Polymerforschung Dresden e.V., Hohe Straße 6 Dresden 01069 Germany
| | - Santanu Chattopadhyay
- Rubber Technology CentreIndian Institute of Technology Kharagpur West Bengal 721302 India
| | - Puspendu Sahu
- Department of PhysicsJadavpur University Kolkata 700032 India
| | - Gert Heinrich
- Department of Elastomers, Leibniz‐Institut für Polymerforschung Dresden e.V., Hohe Straße 6 Dresden 01069 Germany
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10
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Barranco-García R, Ferreira AE, Ribeiro MR, Lorenzo V, García-Peñas A, Gómez-Elvira JM, Pérez E, Cerrada ML. Hybrid materials obtained by in situ polymerization based on polypropylene and mesoporous SBA-15 silica particles: Catalytic aspects, crystalline details and mechanical behavior. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.07.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Spieckermann F, Polt G, Wilhelm H, Kerber MB, Schafler E, Reinecker M, Soprunyuk V, Bernstorff S, Zehetbauer M. Dislocation Movement Induced by Molecular Relaxations in Isotactic Polypropylene. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00931] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Florian Spieckermann
- Department
for Material Physics, Montanuniversität Leoben, Jahnstrasse 12, 8700 Leoben, Austria
| | | | - Harald Wilhelm
- Laboratory
of Polymer Engineering, LKT-TGM, Wexstrasse 19-23, 1200 Wien, Austria
| | | | | | | | | | - Sigrid Bernstorff
- Elettra
−
Sincrotrone Trieste, Strada Statale
14 km 163.5 in AREA Science Park, 34149 Basovizza, Trieste, Italy
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12
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Chen X, Lv F, Su F, Ji Y, Meng L, Wan C, Lin Y, Li X, Li L. Deformation mechanism of iPP under uniaxial stretching over a wide temperature range: An in-situ synchrotron radiation SAXS/WAXS study. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.04.054] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Qiu B, Chen F, Shangguan Y, Lin Y, Zheng Q, Wang X. Toughening mechanism in impact polypropylene copolymer containing a β-nucleating agent. RSC Adv 2016. [DOI: 10.1039/c6ra01046f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The voids in β-nucleated IPC could help to ease craze formation and multiply shear yielding while extensive stress whitening phenomenon appears in neat IPC.
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Affiliation(s)
- Biwei Qiu
- School of Materials Science and Engineering
- University of Shanghai for Science and Technology
- Shanghai 200093
- People's Republic of China
| | - Feng Chen
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- People's Republic of China
| | - Yonggang Shangguan
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- People's Republic of China
| | - Yu Lin
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- People's Republic of China
| | - Qiang Zheng
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- People's Republic of China
| | - Xia Wang
- School of Materials Science and Engineering
- University of Shanghai for Science and Technology
- Shanghai 200093
- People's Republic of China
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14
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Radiation-induced modification of dielectric relaxation spectra of polyolefins: polyethylenes vs. polypropylene. Polym Bull (Berl) 2014. [DOI: 10.1007/s00289-014-1190-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Towards high-performance polypropylene and its random copolymer: Insight into toughening mechanism of supercritical carbon dioxide assisted annealing. J Supercrit Fluids 2014. [DOI: 10.1016/j.supflu.2014.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Sarlin J, Immonen K. Poly(propylene) composite with hybrid nanofiller: Dynamic properties. J Appl Polym Sci 2013. [DOI: 10.1002/app.38532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Solid and melt-state 1H NMR studies of relaxation processes in isotactic polypropylenes. JOURNAL OF POLYMER RESEARCH 2013. [DOI: 10.1007/s10965-013-0117-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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Suljovrujic E. Complete relaxation map of polypropylene: radiation-induced modification as dielectric probe. Polym Bull (Berl) 2012. [DOI: 10.1007/s00289-012-0714-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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19
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Na B, Li Z, Lv R, Zou S. Annealing-induced structural rearrangement and its toughening effect in injection-molded isotactic polypropylene. POLYM ENG SCI 2011. [DOI: 10.1002/pen.22156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Bai H, Luo F, Zhou T, Deng H, Wang K, Fu Q. New insight on the annealing induced microstructural changes and their roles in the toughening of β-form polypropylene. POLYMER 2011. [DOI: 10.1016/j.polymer.2011.03.017] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Suljovrujic E, Trifunovic S, Milicevic D. The influence of gamma radiation on the dielectric relaxation behaviour of isotactic polypropylene: The α relaxation. Polym Degrad Stab 2010. [DOI: 10.1016/j.polymdegradstab.2009.11.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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22
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Properties of isotactic polypropylene irradiated in various atmospheres. HEMIJSKA INDUSTRIJA 2010. [DOI: 10.2298/hemind091221029m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this paper, changes in structure and physical properties of stabilized isotactic polypropylene (iPP) were created by gamma irradiation, up to a dose of 700 kGy, in different media: air, deionized distilled (DD) water and acetylene. Two main effects occur when polyolefins, such as iPP, are subjected to ionizing radiation: crosslinking and scission of macromolecules. The domination of one or the other of these competitive processes is determined by both the structural peculiarities of the polymers and the experimental irradiation conditions. Gel and infrared (IR) spectroscopy measurements were used to determine the changes in the degree of network formation and oxidative degradation, respectively. Sol-gel analysis was studied in detail using the Charlesby-Pinner (C-P) equation. The radiation-induced changes in the structure and evolution of oxygen-containing species were also studied through dielectric loss (tan ?) analysis in a wide temperature and/or frequency range. Evolution of low temperature dielectric relaxations with gamma irradiation was investigated. The results showed that degradation was the major reaction in the initial step of irradiation, no matter what the atmosphere was. The C-P equation seemed applicable when stabilized iPP was irradiated within a certain dose range in various atmospheres. The iPP irradiated in acetylene/air had the lowest/highest values for oxidation level, dielectric losses, Dg and G(s)/G(x) values. The calculated Dg values are 1.5 and 5 times larger for the irradiation in DD water and air than for the acetylene. Furthermore, our data confirm that oxidation strongly affects the gel point but has a much lower effect on the G(S)/G(X) ratio. In the case of dielectric relaxation measurements, the connection between the oxidative degradation and dielectric properties is well established and is in good agreement with IR spectroscopy measurements. The amount of carbonyl, hydroperoxide and other polar groups is much higher for the irradiation in air than in other media, leading to higher dielectric losses. Disappearance of low temperature (? and ?) relaxations with gamma radiation confirmed great sensitivity of iPP structure to radiation-induced changes. Complete ?vanishing? of the ? relaxation in iPP samples irradiated in air is connected with a large radiation-induced oxidative degradation in this medium. Similar crosslinking, oxidation and dielectric behaviour was observed for the samples irradiated in water and acetylene, indicating DD water as a good crosslinking medium.
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23
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Correlation between regioselectivity and site charge in propene polymerisation catalysed by metallocene. Struct Chem 2009. [DOI: 10.1007/s11224-009-9519-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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24
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Joseph A, Lüftl S, Seidler S, Thomas S, Joseph K. Nonisothermal thermophysical evaluation of polypropylene/natural rubber based TPEs: Effect of blend ratio and dynamic vulcanization. POLYM ENG SCI 2009. [DOI: 10.1002/pen.21219] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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Suljovrujic E. Gel production, oxidative degradation and dielectric properties of isotactic polypropylene irradiated under various atmospheres. Polym Degrad Stab 2009. [DOI: 10.1016/j.polymdegradstab.2009.01.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Hoyos M, Tiemblo P, Gómez-Elvira JM. Influence of microstructure and semi-crystalline morphology on the β and γ mechanical relaxations of the metallocene isotactic polypropylene. Eur Polym J 2009. [DOI: 10.1016/j.eurpolymj.2009.01.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Hoyos M, Tiemblo P, Gómez-Elvira JM. Effect of microstructure on the thermo-oxidation of solid isotactic polypropylene-based polyolefins. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2008; 9:024404. [PMID: 27877971 PMCID: PMC5099728 DOI: 10.1088/1468-6996/9/2/024404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 07/10/2008] [Accepted: 05/18/2008] [Indexed: 06/06/2023]
Abstract
In the present work we aim to clarify the role of the microstructure and the crystalline distribution from the thermo-oxidation of solid isotactic PP (iPP) and ethylene-propylene (EP) copolymers. The effects of the content and quality of the isotacticity interruptions, together with the associated average isotactic length, on the induction time (ti) as well as on the activation energy (Eact) of the thermo-oxidation are analysed. Both parameters have been found to change markedly at an average isotactic length (n1) of 30 propylene units. While ti reaches a minimum when n1 is approximately 30 units, Eact increases quasi-exponentially as the number of units decreases from 30. This variation can be explained in terms of changes induced in the crystalline interphase, i.e. local molecular dynamics, which are closely linked to the initiation of the thermo-oxidation of isotactic PP-based polyolefins.
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