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Digital Document
Description
Our continuing quest to improve the performance of polymer composites under
moist and saltwater environments has gained momentum in recent years with the
reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation
of composites under such environments is to maintain the integrity of the fiber/matrix
(F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been
modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS).
POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having
silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that
the silicon atoms can be linked to a substituent that can be almost any chemical group
known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm
in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further,
cubic structure of POSS remains intact during the polymerization process and therefore
with appropriate functional groups, if installed on the fiber surface, would provide a stable
and strong F/M interface. Two POSS systems with two different functional groups;
namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and
mechanical procedures has been developed to coat carbon fibers with POSS, and to
fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with
respect to control samples made without the POSS coating. Saltwater and hygrothermal
tests at various environmental conditions have revealed that coating with POSS reduces
water absorption by 20–30% and retains the composite properties.
moist and saltwater environments has gained momentum in recent years with the
reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation
of composites under such environments is to maintain the integrity of the fiber/matrix
(F/M) interface. In this study, the F/M interface of carbon/vinyl ester composites has been
modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS).
POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having
silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that
the silicon atoms can be linked to a substituent that can be almost any chemical group
known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm
in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further,
cubic structure of POSS remains intact during the polymerization process and therefore
with appropriate functional groups, if installed on the fiber surface, would provide a stable
and strong F/M interface. Two POSS systems with two different functional groups;
namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and
mechanical procedures has been developed to coat carbon fibers with POSS, and to
fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with
respect to control samples made without the POSS coating. Saltwater and hygrothermal
tests at various environmental conditions have revealed that coating with POSS reduces
water absorption by 20–30% and retains the composite properties.
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