Preparation And Property Of NBR/PP Thermoplastic Vulcanizates

First the property with different ratio of oil rubber and non-oil rubber was investigated.The result showed that, with the blend of oil rubber and non-oil rubber,the molecule of plasticizer DOP was not easily volatilized and drawn out. Second, the effect on property of NBR/PP TPV with different dosage of the vulcanizing agent was studied. The investigation showed that without any plasticizer, the amount of the vulcanizing agent had little effect on the property and the size of dispersed particle of NBR/PP TPV observed by TEM.The third, the sort and the amount of the plasticizers were studied systemly and the effect on the microcosmic conformation and the relative degree of crystallinity was also analyzed by TEM and DSC. When the plasticizer contained rigidity structure such as enzene ring, the hardness of NBR/PP TPV can be reduced effectively. While to the straight chain structure, although the chain moved difficultly, the platicizer also had a good role on the hardness. Contract four plasticizers, the best one is TOTM. While when TOTM was used solely, the solubility is not high and the effect is common. To improve the solubility of plasticizer in NBR/PP TPV, two plasticizers were mixed together including TOTM/7040and TOTM/DEDB. With TEM、DSC and rheological behavior curve, we found mixing plasticizers can improve the properties of NBR/PP TPV including hardness and oil resistant property, but the tensile strain descented. The reason was that the plasticizer not only diluted the concentration of the sulfuration but also reduced the viscidity of the resin. So when the velocity of linking was larger than that of shearing, the rubber was vulcanized before being sheared to small particles.Lastly, with DSC the relative degree of crystallinity of PP was investigated. The result showed that the plasticizers limited the movement of PP chain so that the degree of crystallinity was declined. It was presented mainly in two sides, first the velocity of plasticzer being extruded decided the amount of PP molecule chain which participated in crystallinity. Second, in the process of PP crystallinity, heterogeneous nucleation was the main factor. The result showed that although plasticizers was mostly extruded from the PP matrix, there was also a little plasticizers that increased the velocity of crystallinity of PP and improved the PP chain to form perfect structure of crystal.But because the link force between plasticizer and NBR was larger than the force between plasticizer and PP, the second factor was not significant, so the first one became the main factor of the crystallinity of PP.