Study On The Dynamic Vulcanization EPDM/PP Elastomers

Different EPDM/PP thermoplastic elastomers (EPDM/PP TPVs) were prepared by dynamic vulcanization. We studied the mechanical properties, crystallization behavior, dynamic mechanical behaviors and morphology respectively and got the following conclusions:1. Mechanical analysis shows that TPV has good mechanical properties when the phenolic resin/SnCl2 ? 2H2O is 3/0.3, the ratio of rubber and plastic is 60/40, dynamic vulcanization times are 10min, and the mixer rotor speed is 80r/min.2. The research on crystallization behaviors of TPV shows that with the decrease of the ratio of rubber and plastic, crystal enthalpy increases. The crystallization degree of PP in TPV is higher than the pure PP when the content of PP is 40 phr in EPDM/PP TPV. Contrast to pure PP, the crystallization temperature of EPDM/PP TPV is tend to lower temperature. With the increase of dynamic vulcanization time, the crystallinity and crystallization temperature of PP in TPV decreased firstly and then increased. As the shear rate increases, the crystallinity and crystallization temperature decreased gradually. Analysis showed that the behaviors of isothermal crystallization of PP, TPV and EPDM/PP blends are consistent with Avrami equation. Under the same temperature, the Value of n (Avrami index) is: blends>PP>TPV while the value of k (crystallization rate constant) is: TPV>PP>blends.3. Study on the dynamic mechanical behavior of EPDM/PP TPV by DMA shows that with the increasing dosage of curing agent, Tg of EPDM increased and the storage modulus (E') and loss modulus (E'') has increased to some extent. With lowering the ratio of rubber and plastic, the shape of the Tg peaks of EPDM become more and more wide and tanδget reduced. Tg peak of EPDM moves to higher temperature region while Tg peak of PP is almost unchanged. The storage modulus (E') and loss modulus (E'') have shown an increasing trend. With the increase of dynamic vulcanization time, the Tg peak of EPDM moves to high temperature region. Contrast to the blending time is 2min, Tg is 10℃higher than the blending time is 20 min. Tg peak of PP is almost no change, but the tanδchanges significantly, and when the blending time is 20min, tanδis maximum. The storage modulus (E') and loss modulus (E'') gradually increases. Compared with EPDM/PP blends, Tg of EPDM/PP TPV is lower and is moving towards higher temperature region. The value of E'of EPDM/PP TPV is higher than EPDM/PP blends.4. Analysis by scanning electron microscopy (SEM) shows that the morphology of EPDM/PP blend is a double continuous phase while the morphology of EPDM/PP TPV is a "sea - island " phase with vulcanized rubber particles dispersed in PP, and the size of rubber particles is about 0.5μm.