Plastics,Rubber and Composites: Macromolecular Engineering

Flame retardant ethylene vinyl acetate (EVA) composites were prepared based on different contents of hollow glass beads (HGBs) and aluminium hydroxide (ATH) in this paper, and the flame retardant properties were studied using limiting oxygen index, UL-94 test and cone calorimeter test respectively. The results showed that EVA-4 with 1·0 wt-%HGBs has the lowest heat release rate, total heat release and smoke production rate among all samples, and HGBs could promote to form a compact char layer on the surface of the sample. It indicates that there is an obvious synergistic flame retardant effect between HGBs and ATH in this composite.

Recent concern over the harmful effects on the ecology of long lasting plastics has led to heightened interest in the development of more environmentally sustainable materials. Attention has been paid to biodegradable thermoplastic polymers, polylactic acid (PLA) and polybutylene succinate (PBS). However, although these materials have been widely used as matrix in a composite, the potential of biopolymers as reinforcement in a composite structural system has been examined less. Two types of unidirectional biodegradable composites, PLA self-reinforced and PLA reinforced PBS matrix composites, were produced. The composites were tested for Young's modulus, tensile strength and strain at break. Cross-section and fracture surface characteristics of the composites were also examined by scanning electron microscopy to identify damage modes. It is found that the tensile strength of both PLA self-reinforced and PLA–PBS composites is increased by 10–40%, while their initial modulus is 2–6 times higher than that measured for PLA and PBS films.

In order to obtain epoxy based composite with low coefficient of thermal expansion (CTE) and good mechanical properties at cryogenic temperature (77 K), core–shell rubber (CSR) particles were integrated into epoxy. Fourier transform infrared spectroscopy results showed the occurrence of intermolecular hydrogen bond between the CSR particles and the epoxy matrix. The results of thermomechanical analysis indicate that the CTE of CSR–epoxy composites below T_g reached the minimum of the CSR content of 0·5 wt-%, then followed by an increase when the CSR content was higher than 0·5 wt-%. The CTE value under T_g was decreased 18·89% with 0·5 wt-% CSR content. The tensile strength, Young's modulus and impact strength of CSR–epoxy composites at 77 K all reached a maximum with the CSR content of 0·5 wt-%, followed by a decrease when the CSR content was higher than 0·5 wt-%. The storage modulus of CSR modified epoxy resin in glassy region was higher than that of the neat epoxy resin.

Integrating rechargeable battery cells with fibre reinforced polymer matrix composites is a promising technology to enable composite structures to concurrently carry load and store electric energy, thus significantly reducing weight at the system level. To develop a design criterion for structural battery composites, rechargeable lithium polymer battery cells were embedded into carbon fibre/epoxy matrix composite laminates, which were then subjected to tensile, flexural and compressive loading. The electric charging/discharging properties were measured at varying levels of applied loads. The results showed that degradation in battery performance, such as voltage and energy storage capacity, correlated well with the applied strain under three different loading conditions. Under compressive loading, battery cells, due to their multilayer construction, were unable to prevent buckling of composite face sheets due to the low lateral stiffness, leading to lower compressive strength than sandwich panels with foam core.

A series of flame retardant epoxy composites were prepared based on bisphenol A epoxy resin, T31 curing agent, intumescent flame retardant and CYH-277 toughener. The combustion and thermal degradation properties of the epoxy composites were evaluated by cone calorimeter test (CCT), thermogravimetric analysis (TGA), scanning electron microscopy and smoke density test (SDT) respectively. The CCT results showed that the addition of CYH-277 can decrease heat release rate, total heat release and smoke production rate, reduce the char residue, and delay the ignition time of flame retardant epoxy composites. EP-3 with 14 wt-% CYH-277 toughener comparatively showed the best flame retardancy among all samples. The TGA results showed that CYH-277 toughener had an influence on the initial decomposition temperature rather than on the char residues. In addition, the SDT results showed that EP-1 had the best smoke suppression ability.