TY - THES

T1 - Irreversible and reversible crosslinking of carboxylated acrylonitrile butadiene rubber

AU - Fleischmann, Doris Darya

N1 - embargoed until 23-03-2020

PY - 2015

Y1 - 2015

N2 - The present work aims at the development of new crosslinking strategies for carboxylated nitrile butadiene rubber (XNBR) which is used in different fields of applications ranging from seals to gloves. Besides thermal curing approaches with low molecular weight crosslinkers and functional inorganic particles, photochemical routes such as UV induced thiol-ene chemistry were pursued to crosslink XNBR latex. The crosslink kinetics was studied by FTIR spectroscopy whilst the mechanical properties of crosslinked XNBR latex films were characterized by means of tensile testing. The corresponding crosslink densities were determined by equilibrium swelling measurements. The influence of selected key parameters such as crosslinker concentration, reaction time, reaction temperature and UV exposure dose on the tensile strength and elongation at break were studied and optimized. Along with the formation of irreversible crosslinks, a new way of reversible crosslinking of XNBR was established by using the reversible [4πs+4πs] photodimerization of anthracenes. Epoxy-functionalized anthracene derivatives were attached to the XNBR by ring-opening reaction of epoxy-groups with carboxylate moieties of the polymer chains. Anthracene groups undergo a photocycloaddition reaction upon irradiation with UV light (λ > 300 nm) which can be reverted thermally or upon UV irradiation (λ <300 nm). The crosslinking kinetics and reversibility of the photoreaction were studied by means of UV-Vis measurements, light microscopy and confocal microscopy. Based on these studies, the reversibility of the photodimerization could be enhanced considerably by employing hydrogenated XNBR (H-XNBR) and amounted up to 30%.

AB - The present work aims at the development of new crosslinking strategies for carboxylated nitrile butadiene rubber (XNBR) which is used in different fields of applications ranging from seals to gloves. Besides thermal curing approaches with low molecular weight crosslinkers and functional inorganic particles, photochemical routes such as UV induced thiol-ene chemistry were pursued to crosslink XNBR latex. The crosslink kinetics was studied by FTIR spectroscopy whilst the mechanical properties of crosslinked XNBR latex films were characterized by means of tensile testing. The corresponding crosslink densities were determined by equilibrium swelling measurements. The influence of selected key parameters such as crosslinker concentration, reaction time, reaction temperature and UV exposure dose on the tensile strength and elongation at break were studied and optimized. Along with the formation of irreversible crosslinks, a new way of reversible crosslinking of XNBR was established by using the reversible [4πs+4πs] photodimerization of anthracenes. Epoxy-functionalized anthracene derivatives were attached to the XNBR by ring-opening reaction of epoxy-groups with carboxylate moieties of the polymer chains. Anthracene groups undergo a photocycloaddition reaction upon irradiation with UV light (λ > 300 nm) which can be reverted thermally or upon UV irradiation (λ <300 nm). The crosslinking kinetics and reversibility of the photoreaction were studied by means of UV-Vis measurements, light microscopy and confocal microscopy. Based on these studies, the reversibility of the photodimerization could be enhanced considerably by employing hydrogenated XNBR (H-XNBR) and amounted up to 30%.

KW - elastomer

KW - carboxylated acrylonitrile butadiene rubber

KW - XNBR

KW - crosslinking

KW - thiol-ene reaction

KW - [4πs+4πs] photodimerization

KW - Elastomer

KW - Carboxylierter Acrylnitril-Butadien-Kautschuk

KW - XNBR

KW - Vernetzung

KW - Thiol-En-Reaktion

KW - [4πs+4πs]-Photodimerisierung

M3 - Master's Thesis

ER -