Preparation And Study Of CIIR/PA12 Thermoplastic Vulcanizaes

A series of chlorinated butyl rubber (CIIR)/nylonl2 thermoplastic vulcanizates (TPV) are prepared by dynamic vulcanization. CIIR/PA12 TPV not only has fine gas impermeability and resistance to heat coming from CIIR, but also have exceptional processing and mechanical properties as a result of PA. Based on its excellent properties, it can be widely used as soft tubes in refrigerator, gas seal in tire and so on.The effects of different curing systems including ZnO,HVA-2/ZnO and PK900/ZnO on properties of TPV are investigated. The results show that curing speed and cross-linked degree with ZnO system is the lowest. Comparing with other two curing systerms, although physical property of TPV prepared with PK900/ZnO system is the best, the external appearance is not smooth. Using HVA-2/ZnO as curing system, the diameter of rubber phase are about 2～6μm which dispersed unevenly in the plastic phase. Although physical property of TPV prepared with HVA-2/ZnO system is relatively poor than TPV producted by PK900/ZnO system, the external appearance is very smooth yet. The ratio of curing agent PK900 and ZnO are studied. The results show that when the weight ratio of PK900/ZnO is 3/5, the physical property of TPV is quite well and the rubber phase particles are about 2μm and dispersed uniformly in the plastic phase. The rotation rate and temperature of twin screw extruder are also studied. The results showed that the optimal screw rotation speed and vulcanize temperature was 300r/min and 210℃respectively.Different kinds of compatibilizers (SEBS-g-MAH, SEPS and PP-g-MAH) have been discussed, which may influence the physical property, morphology, crystallization characteristics and air permeability performan-ce of the CIIR/PA12 TPV. The results show that PP-g-MAH is the effective compatibilizer of CIIR/PA12 TPV. When using 10～15 phr PP-g-MAH, the TEM show that the phase interface become ambiguous, the diameter of rubber phase are decreased from 6μm to 2μm and disperse uniformly in the plastic phase. Meanwhile, the compatibilizer could influence the crystalli-zation characteristics of the plastic phase to a certain extent.In this paper, in order to reduce high stiffness of TPV as well as obtain good elasticity, different kinds of plastizer (naphthenic oil, poluisobutene and n-buty benzenesulfonamide) have been studied. The results show that n-buty benzenesulfonamide was the effective plastizer of CIIR/PA12 TPV. It was found that 25 phr n-buty benzenesulfonamide could decrease the hardness of TPV from 95A to 85 A, and do not have influence on the crystalline of plastic phase, while a 40℃fall in glass transition will occur.