The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Jun Zhang - One of the best experts on this subject based on the ideXlab platform.
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uv aging behaviour of ethylene Vinyl Acetate copolymers eva with different Vinyl Acetate contents
Polymer Degradation and Stability, 2010Co-Authors: Shuangjun Chen, Jun ZhangAbstract:Abstract The mild UV aging of ethylene-Vinyl Acetate copolymer (EVA) with two Vinyl Acetate (VAc) contents (14, 18 wt%) was performed in a xenon arc source chamber. The degradation mechanism was analyzed via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel content and high temperature gel permeation chromatography (HTGPC). Photo-chemically induced deterioration was first initiated from vulnerable VAc units. Ketone formation preceded lactone generation, especially in EVA with high VAc content. Un-stable structures induced further degradation in the main chain. Competition between radiation induced cross-linking and chain scission in EVA was observed, and the later was confirmed to be dominant. Higher VAc content resulted in remarkable drop in molecular weight and growth in polydispersity. Apparent re-arrangement in crystallisation and consequent decrease in thermal stability are discussed through differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), which accorded well with the chain scission tendency. Interaction between photo-chemical degradation and physical annealing accounted for the first increasing then decreasing tendency in the mechanical properties of both EVAs.
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UV aging behaviour of ethylene-Vinyl Acetate copolymers (EVA) with different Vinyl Acetate contents
Polymer Degradation and Stability, 2010Co-Authors: Jing Jin, Shuangjun Chen, Jun ZhangAbstract:The mild UV aging of ethylene-Vinyl Acetate copolymer (EVA) with two Vinyl Acetate (VAc) contents (14, 18 wt%) was performed in a xenon arc source chamber. The degradation mechanism was analyzed via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel content and high temperature gel permeation chromatography (HTGPC). Photo-chemically induced deterioration was first initiated from vulnerable VAc units. Ketone formation preceded lactone generation, especially in EVA with high VAc content. Un-stable structures induced further degradation in the main chain. Competition between radiation induced cross-linking and chain scission in EVA was observed, and the later was confirmed to be dominant. Higher VAc content resulted in remarkable drop in molecular weight and growth in polydispersity. Apparent re-arrangement in crystallisation and consequent decrease in thermal stability are discussed through differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), which accorded well with the chain scission tendency. Interaction between photo-chemical degradation and physical annealing accounted for the first increasing then decreasing tendency in the mechanical properties of both EVAs. © 2010 Elsevier Ltd. All rights reserved.
Shuangjun Chen - One of the best experts on this subject based on the ideXlab platform.
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uv aging behaviour of ethylene Vinyl Acetate copolymers eva with different Vinyl Acetate contents
Polymer Degradation and Stability, 2010Co-Authors: Shuangjun Chen, Jun ZhangAbstract:Abstract The mild UV aging of ethylene-Vinyl Acetate copolymer (EVA) with two Vinyl Acetate (VAc) contents (14, 18 wt%) was performed in a xenon arc source chamber. The degradation mechanism was analyzed via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel content and high temperature gel permeation chromatography (HTGPC). Photo-chemically induced deterioration was first initiated from vulnerable VAc units. Ketone formation preceded lactone generation, especially in EVA with high VAc content. Un-stable structures induced further degradation in the main chain. Competition between radiation induced cross-linking and chain scission in EVA was observed, and the later was confirmed to be dominant. Higher VAc content resulted in remarkable drop in molecular weight and growth in polydispersity. Apparent re-arrangement in crystallisation and consequent decrease in thermal stability are discussed through differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), which accorded well with the chain scission tendency. Interaction between photo-chemical degradation and physical annealing accounted for the first increasing then decreasing tendency in the mechanical properties of both EVAs.
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UV aging behaviour of ethylene-Vinyl Acetate copolymers (EVA) with different Vinyl Acetate contents
Polymer Degradation and Stability, 2010Co-Authors: Jing Jin, Shuangjun Chen, Jun ZhangAbstract:The mild UV aging of ethylene-Vinyl Acetate copolymer (EVA) with two Vinyl Acetate (VAc) contents (14, 18 wt%) was performed in a xenon arc source chamber. The degradation mechanism was analyzed via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel content and high temperature gel permeation chromatography (HTGPC). Photo-chemically induced deterioration was first initiated from vulnerable VAc units. Ketone formation preceded lactone generation, especially in EVA with high VAc content. Un-stable structures induced further degradation in the main chain. Competition between radiation induced cross-linking and chain scission in EVA was observed, and the later was confirmed to be dominant. Higher VAc content resulted in remarkable drop in molecular weight and growth in polydispersity. Apparent re-arrangement in crystallisation and consequent decrease in thermal stability are discussed through differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), which accorded well with the chain scission tendency. Interaction between photo-chemical degradation and physical annealing accounted for the first increasing then decreasing tendency in the mechanical properties of both EVAs. © 2010 Elsevier Ltd. All rights reserved.
E. Fontan - One of the best experts on this subject based on the ideXlab platform.
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Aspects of the thermal oxidation of ethylene Vinyl Acetate copolymer
Polymer Degradation and Stability, 2000Co-Authors: Norman S. Allen, Christopher M. Liauw, Michele Edge, Miguel Rodriguez, E. FontanAbstract:The thermal oxidation of ethylene-Vinyl Acetate copolymer [EVA-17 and 28% w/w VA (Vinyl Acetate) units] is examined by thermo-gravimetric and hydroperoxide analysis, Fourier transform infra-red (FTIR) fluorescence spectroscopy and yellowness index. Thermal analysis indicates the initial loss of acetic acid followed by oxidation and breakdown of the main chain. FTIR spectroscopic analysis of the oxidize EVA shows evidence for de-acetylation followed by the concurrent formation of hydroxyl/hydroperoxide species. The EVA degradation is therefore, different from that of PVC where in the latter case polyconjugated Vinyl groups are evident through conjugated absorption bands in the UV spectrum.
Jing Jin - One of the best experts on this subject based on the ideXlab platform.
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UV aging behaviour of ethylene-Vinyl Acetate copolymers (EVA) with different Vinyl Acetate contents
Polymer Degradation and Stability, 2010Co-Authors: Jing Jin, Shuangjun Chen, Jun ZhangAbstract:The mild UV aging of ethylene-Vinyl Acetate copolymer (EVA) with two Vinyl Acetate (VAc) contents (14, 18 wt%) was performed in a xenon arc source chamber. The degradation mechanism was analyzed via attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), gel content and high temperature gel permeation chromatography (HTGPC). Photo-chemically induced deterioration was first initiated from vulnerable VAc units. Ketone formation preceded lactone generation, especially in EVA with high VAc content. Un-stable structures induced further degradation in the main chain. Competition between radiation induced cross-linking and chain scission in EVA was observed, and the later was confirmed to be dominant. Higher VAc content resulted in remarkable drop in molecular weight and growth in polydispersity. Apparent re-arrangement in crystallisation and consequent decrease in thermal stability are discussed through differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), which accorded well with the chain scission tendency. Interaction between photo-chemical degradation and physical annealing accounted for the first increasing then decreasing tendency in the mechanical properties of both EVAs. © 2010 Elsevier Ltd. All rights reserved.
Norman S. Allen - One of the best experts on this subject based on the ideXlab platform.
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Aspects of the thermal oxidation of ethylene Vinyl Acetate copolymer
Polymer Degradation and Stability, 2000Co-Authors: Norman S. Allen, Christopher M. Liauw, Michele Edge, Miguel Rodriguez, E. FontanAbstract:The thermal oxidation of ethylene-Vinyl Acetate copolymer [EVA-17 and 28% w/w VA (Vinyl Acetate) units] is examined by thermo-gravimetric and hydroperoxide analysis, Fourier transform infra-red (FTIR) fluorescence spectroscopy and yellowness index. Thermal analysis indicates the initial loss of acetic acid followed by oxidation and breakdown of the main chain. FTIR spectroscopic analysis of the oxidize EVA shows evidence for de-acetylation followed by the concurrent formation of hydroxyl/hydroperoxide species. The EVA degradation is therefore, different from that of PVC where in the latter case polyconjugated Vinyl groups are evident through conjugated absorption bands in the UV spectrum.
