Functionalization Of Thermoplastic Elastomer By Cracking Initiation And Research Of Their Toughening PA66

In this paper, the maleic anhydride (MAH) grafted SBS (SBS-g-MAH), grafted LDPE (LDPE-g-MAH) and grafted POE (POE-g-MAH) were prepared through thermal cracking initiation by a laboratory-seal twin-screw extruder. The effects of MAH content, grafting temperature and additives amount on grafting level, melt-flow property and gel content of the grafted products were investigated by means of chemical titration, FT-IR and melt-flow index, et al. The results show that the cross-linking reaction in the grafting process can be restrained. The grafting level of the grafted products, which is over 0.4%, the melt-flow index, which is between 3.0 and 8.0 g/10min, and the gel content, which is less than 1.0%, are depended upon the grafting temperature, the MAH content and the additives amount.The effects of the weight fraction of the grafted products on the mechanical properties of the PA66/SBS-g-MAH, PA667LDPE-g-MAH and PA66/POE-g-MAHblends, and on their morphology structure were studied by means of mechanical testing, SEM and TEM. The results show that the grafted products can obviously improved the miscibility between PA66 and SBS and between PA66 and POE, and obviously increased the charpy notched impact strength of these blends, in which the charpy notched impact strength of PA66/LDPE-g-MAH blend is 2 times higher than that of PA66, the charpy notched impact strength of PA66/SBS-g-MAH blend is 7 times higher than that of PA66, and the charpy notched impact strength of PA66/POE-g-MAH blend is 14 times higher than that of PA66. Meanwhile, it was found that there are more regular structures in the dispersion phase of PA66/POE-g-MAH blend than in that of PA66/POE blend.The effects of cooling shrinkage stress on the matrix crystallization behavior of the PA66/POE-g-MAH blend were investigated by means of DSC and a kinetic method for characterizing the effect of cooling shrinkage stress on crystallization of polymer. The results show that the cooling shrinkage stress coming from the matrix shrinkage during cooling process can accelerate crystallization of the matrix, and obviously increase the crystallization growth index n, the crystallization temperature Tcd and the crystallization enthalpy Hc, Under a higher cooling rate condition, thedispersion particles and then- block copolymer with PA66 chains have two influencesof hindrance and strain-induce on crystallization of matrix, when the POE-g-MAHcontent is between 15% and 20%, in the case the brittle-ductile transition of the blendoccurs, the strain-induced crystallization action reaches to strongest, the change rateof growth rate constant over cooling rate. k/ a, Tcd and Hc reach to maximum.