A Study On Novel Non-halogen Flame Retardant Acrylonitrile-Butadiene-Styrene (ABS) Composites

This work was financially supported by the natural science foundation of Liaoning province (No.20052159) and the youth science and technology foundation of Dalian, China (No.2002114). At present, flame retardant acrylonitrile-butadiene-styrene (ABS) materials containing halogen are restricted in ecological environment because they produce lots of toxic gases and corrosive smokes while burning. In view of existing situation, intumescent flame retardant (IFR) with halogen-free and low toxicity was selected to be the main flame retardant for ABS. The flame retardant effect and mechanism of IFR on ABS was systematically studied. The synergistic effects between IFR and zinc borate (ZB), zeolite, montmorillonite respectively on ABS were investigated. And the influences of different toughening methods on structure and properties of flame retardant ABS composites were comparatively analysed. The main research contents are as the follows.Three kinds of IFR systems were established, of which, ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER), polyamide-6 (PA-6), polycarbonate (PC) as a carbonization agent, respectively. The influences of ratio and amount of these IFR syetems on flame resistance, mechanical properties, processability, behavior of carbonization and microstructure of ABS composites were systematically researched. The results showed that IFR based on APP and PER had a good flame retardant effect on ABS composites. When the ratio of APP and PER was 3:1and the conten was 30%, the flame resistance, impact and tensile strength, and processability of ABS/APP/PER composites were higher than those of ABS/APP/PA-6 composites and ABS/APP/PC composites. However, three kinds of IFR brought bad effects on mechanical properties and processability, of which, the decrease of impact strength was more serious.The synergistic mechanisms of IFR with ZB, zeolite 4A and 13X were investigated. The results demonstrated that adding ZB with 2% content to ABS/APP/PER composites enhanced the flame resistance and modified the flexural strength, flexural modulus and processability. However, ZB produced bad influences on impact and tensile property. Compared with ZB and zeolite 13X, zeolite 4A with lower ratio Si/Al, stronger surface polarity had the best synergistic effect with IFR. When the content of zeolite 4A was 1 wt.%, the flame resistance, mechanical properties and processability of ABS/APP/PER composites were increased and modified on the whole. Montmorillonite was organized by three kinds of intercalating agents such as cetyhrimetheylammonium bromide (C16), octadecyltrimethyl ammonium chloride (C18) and bi-octadecyldimethyl ammonium chloride (2C18), and the effect of amount of different intercalating agents on intercalation of organic montmorillonite (OMMT) was studied. Selecting acrylamide (AM) as a monomer, the functionalized masterbatch of montmorillonite (FMMT) was prepared by grafting in solution. ABS/OMMT/IFR and ABS/FMMT/IFR composites were prepared by adopting one-step method and functionalized masterbatch method, respectively. The synergistic effects of two kinds of montmorillonite with IFR were investigated. The results showed that IFR had a synergistic effect with OMMT and FMMT, of which, synergistic effect between IFR and FMMT was more protruding. When the amount of IFR was 20phr, the flame resistance, mechanical properties of ABS/FMMT/IFR (96/4/20) composites were better than those of ABS/OMMT/IFR composites. Compared with commercial flame retardant ABS containing halogen (PA-766 and PA-769), the tensile and flexural properties of ABS/FMMT/IFR (96/4/20) composites were superior to that of PA-766 and PA-769, and its impact property was equivalent to that of PA-766 and PA-769.In order to make further increase in the toughness of non-halogen flame retardant ABS composites, ABS-g-AA graft was synthesized by melt grafting when acrylic acid (AA) as a monomer. Taking ABS-g-AA graft as a compatibilizer, non-halogen flame retardant ABS composites (T-ABS) toughened by the method of direct adding and non-halogen flame retardant ABS composites (Y-ABS) toughened by the method of in-situ reaction were prepared. The influences of two toughening methods of direct adding and in-situ reaction on structure and properties of ABS/OMMT/IFR composites were analysed comparatively. The results showed that adopting the method of direct adding, althougth ABS-g-AA had a toughening effect on ABS/OMMT/IFR composites, resulted in decreasing in flame resistance and processability of ABS/OMMT/IFR composites. And with the increasing of ABS-g-AA amount, flame resistance and processability of ABS/OMMT/IFR composites continually decreased. Unlike the method of direct adding, compatibilizer synthesized by the method of in-situ reaction could impart excellent mechanical properties to Y-ABS composites, meanwhile it made ABS/OMMT/IFR composites maintain its flame resistance and processability, and made Y-ABS composites have lower production cost and simple machining process. As a result, the comphrehensive properties of non-halogen flame retardant Y-ABS composites were better than those of T-ABS composites, PA-766 and PA-769.