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Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive ProcessingMondal, Manas 28 October 2013 (has links) (PDF)
Thermoplastic Vulcanizates (TPVs) are itself a commercially high valued group of polymer blend. They render technological properties of conventional vulcanized elastomers with the ease of thermoplastic melt (re)processability. With ever growing market, TPVs have got plenty of applications among various fields. Here, the technological properties of these TPVs were tailored according to the purpose by interplaying physical parameters of polymers and advanced high energy electron technology. Electron irradiation, though a well-known technique for cross-linking in polymer industry, is only restricted to final product treatment. We take it to the next level by coupling a conventional internal mixer and a high energy electron accelerator. Polypropylene (PP) and natural rubber (NR) based TPVs have been prepared using this new reactive processing technology, named Electron Induced Reactive Processing (EIReP). Various electron treatment parameters were explored to maximize technological properties of TPVs.
Effects of various polyfunctional monomers (PFM) were also studied. In an endeavor to develop a potential method for customization, deep insights of macroscopic and microscopic structure of these TPVs were presented with the help of various advanced scientific characterization techniques. Commonly faced difficulties like viscosity mismatch, cure rate mismatch, and incompatibility due to different molecular structures were furnished along with plausible solutions. Investigation of phase inversion from co-continuous matrix to thermoplastic matrix was dealt with special care as it helps to understand structure property correlation for all TPVs. To make the whole effort relevant, at the end of this thesis a summary of various technological properties has been given for the newly processed and commercially available TPVs.
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Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive Processing: Polypropylene and Natural Rubber based Thermoplastic Vulcanizates by Electron Induced Reactive ProcessingMondal, Manas 26 September 2013 (has links)
Thermoplastic Vulcanizates (TPVs) are itself a commercially high valued group of polymer blend. They render technological properties of conventional vulcanized elastomers with the ease of thermoplastic melt (re)processability. With ever growing market, TPVs have got plenty of applications among various fields. Here, the technological properties of these TPVs were tailored according to the purpose by interplaying physical parameters of polymers and advanced high energy electron technology. Electron irradiation, though a well-known technique for cross-linking in polymer industry, is only restricted to final product treatment. We take it to the next level by coupling a conventional internal mixer and a high energy electron accelerator. Polypropylene (PP) and natural rubber (NR) based TPVs have been prepared using this new reactive processing technology, named Electron Induced Reactive Processing (EIReP). Various electron treatment parameters were explored to maximize technological properties of TPVs.
Effects of various polyfunctional monomers (PFM) were also studied. In an endeavor to develop a potential method for customization, deep insights of macroscopic and microscopic structure of these TPVs were presented with the help of various advanced scientific characterization techniques. Commonly faced difficulties like viscosity mismatch, cure rate mismatch, and incompatibility due to different molecular structures were furnished along with plausible solutions. Investigation of phase inversion from co-continuous matrix to thermoplastic matrix was dealt with special care as it helps to understand structure property correlation for all TPVs. To make the whole effort relevant, at the end of this thesis a summary of various technological properties has been given for the newly processed and commercially available TPVs.
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Hemocompatibility tuning of an innovative glutaraldehyde-free preparation strategy using riboflavin/UV crosslinking and electron irradiation of bovine pericardium for cardiac substitutesDittfeld, Claudia, Welzel, Cindy, König, Ulla, Jannasch, Anett, Alexiou, Konstantin, Blum, Ekaterina, Bronder, Saskia, Sperling, Claudia, Maitz, Manfred F., Tugtekin, Sems-Malte 07 June 2024 (has links)
Hemocompatibility tuning was adopted to explore and refine an innovative, GA-free preparation strategy combining decellularization, riboflavin/UV crosslinking, and low-energy electron irradiation (SULEEI) procedure. A SULEEI-protocol was established to avoid GA-dependent deterioration that results in insufficient long-term aortic valve bioprosthesis durability. Final SULEEI-pericardium, intermediate steps and GA-fixed reference pericardium were exposed in vitro to fresh human whole blood to elucidate effects of preparation parameters on coagulation and inflammation activation and tissue histology. The riboflavin/UV crosslinking step showed to be less efficient in inactivating extracellular matrix (ECM) protein activity than the GA fixation, leading to tissue-factor mediated blood clotting. Intensifying the riboflavin/UV crosslinking with elevated riboflavin concentration and dextran caused an enhanced activation of the complement system. Yet activation processes induced by the previous protocol steps were quenched with the final electron beam treatment step. An optimized SULEEI protocol was developed using an intense and extended, trypsin-containing decellularization step to inactivate tissue factor and a dextran-free, low riboflavin, high UV crosslinking step. The innovative and improved GA-free SULEEI-preparation protocol results in low coagulant and low inflammatory bovine pericardium for surgical application.
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