| Aluminum trihydroxide (ATH) is a traditional inorganic flame retardant and is widely used in plastics and rubbers. The aluminum trihydroxide starts to decompose at about200℃, so it can not be used in the polymer materials with higher processing temperature such as high impact polystyrene(HIPS), poly butylenes terephthalate(PBT), acrylonitrile-butadiene-styrene copolymer(ABS), and poly hexamethylene adipamide(PA66). Nano-CG-ATH is a product which is obtained from aluminum trihydrate by chemical modification. Its decomposition temperature is above330℃, so it can be added to various processing temperature polymer materials.In this paper, the nano-CG-ATH was applied in HIPS after being modified by various surface modifier, then the flame retardant and mechanical properties of the obtained composites were researched, by which titanate coupling agent T1was choosed. After surface modifier was made sure, the effects of modifier content, modification time, and modification temperature on the result of surface modification for the nano-CG-ATH were investigated. The results show that the comprehensive property of CG-ATH/HIPS nano-composite was best when the nano-CG-ATH was modified by1.5wt%coupling agent for20min at85℃. The modified nano-CG-ATH under optimal modification conditions was analyzed by transmission electron microscopy(TEM), thermogravimetry(TG), and fourier transform infrared(FTIR) spectrum. The results show that after being modified by coupling agent T1, the dispersion of the nano-CG-ATH was evidently improved, thermogravimetric ratio of the nano-CG-ATH was increased to some extent, and the surface of the nano-CG-ATH was successfully encapsulated by the coupling agent T1.The nano-CG-ATH was added to HIPS, then the effects of the modified nano-CG-ATH and the unmodified nano-CG-ATH on the flame retardant and mechanical properties of HIPS were studied. The results show that the nano-CG-ATH could improved the flame retardant and flexural properties of HIPS whether or not it was modified by coupling agent T1, but the impact property of HIPS was seriously harmed, and its tensile property was also decreased to some extent when the content of the nano-CG-ATH was too high. In addition, when the content of the nano-CG-ATH was less than12wt%, the flame retardant and mechanical properties of HIPS/CG-ATH nano-composites were basically not influenced whether or not the nano-CG-ATH was modified by coupling agent11. Alter the nano-CCi-ATH content was above12wt%, the flame retardant and mechanical properties of the HIPS/CG-ATH nano-composites with the modified nano-CG-ATH were better than those of the HIPS/CG-ATH nano-composites with the modified nano-CG-ATH. The HIPS composites with the modified nano-CG-ATH and the HIPS composites with the unmodified nano-CG-ATH was analyzed by scanning electron microscope(SEM) and transmission electron microscopy. The results show that the nano-CG-ATH could be well dispersed in HIPS matrix at low loadings whether or not it was modified by coupling agent T1. At high loadings, the unmodified nano-CG-ATH severely aggregated in HIPS matrix, and the interfacial adhesion between the nano-CG-ATH and HIPS matrix was very bad. However, the dispersion of the nano-CG-ATH in HIPS matrix and the interfacial adhesion between the nano-CG-ATH and HIPS matrix were evidently improved after the nano-CG-ATH was modified by the coupling agent T1. The HIPS, nano-CG-ATH, and HIPS/CG-ATH nano-composites were analyzed by TG. The results show that the addition of the nano-CG-ATH was beneficial to the thermal stability of HIPS.In order to improve the flame retardant and mechanical properties of he HIPS/CG-ATH nano-composite, the effects of SMA and MHIPS on he flame retardant and mechanical properties of the HIPS/CG-ATH lano-composite were researched. The results show that the addition of SMA could improve the flame retardant, tensile, and flexural properties of the HIPS/CG-ATH nano-composite, but its impact property was hardly increased. However, to HIPS composites, the impact property is very important property. When a certain quantity of MHIPS was added to the HIPS/CG-ATH nano-composite, its flame retardant and mechanical properties were both evidently improved. In addition, the flame retardant and mechanical properties of the HIPS/CG-ATH nano-composite with the modified nano-CG-ATH were better than those of the HIPS/CG-ATH nano-composite with the unmodified nano-CG-ATH. The HIPS/CG-ATH nano-composite with MHIPS or without MHIPS was characterized by SEM and TEM. The results show that the addition of MHIPS evidently improved the dispersion of the nano-CG-ATH in HIPS matrix and the interfacial adhesion between the nano-CG-ATH and HIPS matrix.In order to reduce the content of flame retardants and the disadvantageous influence brought due to the addition of flame retardants on the mechanical properties of HIPS, the effects of the incorporation of the nano-CG-ATH and other flame retardants on the flame retardant and mechanical properties of HIPS were researched. In addition, the effects of MHIPS and SBS on the flame retardant and mechanical properties of the HIPS composites were researched. The results show that the intumescent flame retardant system consisting of pentaerythritol, ammounium polyphosphate, and melamine did not befit to be applied in HIPS. If only the nano-CG-ATH and ammounium polyphosphate were added to HIPS, when the impact strength of the HIPS composite decreased to1.49kJ/m2, its flame retardant property could not meet the demand for UL94vertical flame rating yet. The nano-CG-ATH showed a good synergistic effect of flame retardancy with encapsulated red phosphorus(ERP). When the content of the nano-CG-ATH and ERP was32wt%, the UL-94rating of the HIPS composite reached V-0, but its impact strength was only2.37kJ/m2. However, after a certain quantity of MHIPS was added to the HIPS composite, When the content of the nano-CG-ATH and ERP was30wt%, the UL-94rating of the HIPS composite reached V-0, and its impact strength was increased to4.13kJ/m2. The nano-CG-ATH showed a good synergistic effect of flame retardancy with ERP and organic silicone polymer or with ERP and organophilic montmorillonite. In comparison with the flame retardant system adding the nano-CG-ATH and ERP, when the UL-94rating of HIPS reached V-0, the content of flame retardants in the system adding the nano-CG-ATH, ERP, and organic silicone polymer or adding the nano-CG-ATH, ERP, and organophilic montmorillonite was reduced to a certain extent, and the impact property of the HIPS composites was better, but the mechanical property of the HIPS composites could not meet using demand yet. If the nano-CG-ATH, ERP, and modified polyphenyl ether(MPPO) were together added to HIPS, when the UL-94rating of the HIPS composite reached V-0, its impact strength was4.78kJ/m2. In addition, SBS could evidently increase the toughness of HIPS composites. When a certain quantity of SBS was added to the HIPS composites, their impact strength could be increased about one time, and their flame retardant property was not influenced, and their tensile and flexural properties were also not too bad. The financial support of this research was provided by National "863" Program of China (No.2002AA302605). |
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