注射交联发泡成型EVA/EPDM高弹性材料的研究

Study on Injection Foamed Cross-linking EVA/EPDM with High Elasticity

乙烯-乙酸乙烯共聚物(EVA)与三元乙丙橡胶(EPDM)共混,加入滑石粉填料(TA),用过氧化二异丙苯(DCP)引发交联,偶氮二碳酰胺(ADC)发泡,得到了一次性注射交联闭孔式发泡成型的高弹性材料。用扫描电子显微镜(SEM)表征了发泡材料剖面气孔的形态结构。研究了DCP、ADC、氧化锌(ZnO)、硬脂酸(St)、硬脂酸锌(ZnSt)和TA对其力学性能的影响。结果表明:DCP量为0.75份、ADC量为2.50份、St量为0.40份、ZnSt量为0.50份和ZnO量为2.30份时,材料具有优异的力学性能。氯化聚乙烯(CPE)对此体系有增容作用,当共混物(EVA/EPDM)的共混比为70/30、CPE为2份时,得到气孔形态结构均匀细密的发泡材料,其弹性达61%,与橡胶的黏合力可提高10%～25%,耐紫外老化达5.0AATCC级。确定了稳定、可靠、重复性好的配方,得出最佳的交联与发泡温度为175℃。

An high elasticity, injection cross-linked, closed-cell foam was prepared based on a polymer blend of ethylene-vinyl acetate copolymer (EVA) and ethylene propylene diene tercopolymer (EPDM) rubber with an inorganic filler (TA). Dicumyl peroxide (DCP) was employed as cross-linker, azodicarbonamide (ADC) as the foaming agent. Scanning electron microscope (SEM) showed that the cells were fine and uniform. When the recipe was DCP 0.75 phr, ADC 2.50 phr, St 0.40 phr, ZnSt 0.50 phr, and ZnO 2.30 phr, a high elasticity (61 %) and excellent mechanical properties were obtained. This material also had an excellent UV-resistant performance that reaches 5.0 AATCC Grade. Chloridized polyethylene (CPE) could be used as compatibilizer of the system, when 2 phr of CPE was introduced into a blend of EVA/EPDM=70/30(w/w), the bonding force of the foam with rubber was increased over 10 %. The optimal molding temperature was found to be 175 ℃.