A Study Of Rubber Reinforcement By Modified Pyrolytic Carbon Black From Waste Tires

With the developing of polymer industrial, how to eliminate the waste polymer pollution, reclaim the resource and obtain high extra value of product, are significant in achieving satisfying industry zoology and repetition economic. Waste tires are the one of the biggest source of waste polymer. More attention was focused on the utilization of waste tires. Pyrolytic carbon black (PCB) is one of the key products of the waste tires pyrolysis. The economy of the tire pyrolysis process strongly depends on the quality of the PCB, especially its ability to be used in high value commercial applications. How to improve the properties of recovered PCB from the waste tires obtained by atmospheric pyrolysis, increase its value and characterize its application performance, are the main subject for waste tires pyrolysis. The creative works can be summarized as following:1. Atomic force microscopy (AFM) was applied to investigate the micro-structure properties of PCB. The surface of PCB consists of plentiful poorly organized amorphous structure with distinct imperfections and distortions and a small quantity of graphite-like layers with ordered six-angle rings. The configuration of the rings corresponds to the benzene structure which seems to arrange regularly in a well defined way. Crystallite layers on the surface of PCB are stagger and of cohesion each other. The residual active sites uncovered by ash and carbonaceous deposits on the surface of PCB might exist at the edges of the layers.A "Core-shell model" of PCB was presented firstly. It shows that the main body of the PCB is the same as the original carbon black filled. The surface of PCB is inhomogeneous shell comprised of inorganic ash and carbonaceous deposits. Its polarity is low. And the shell has covered the mostly active sites. The appropriate graft with long chain on the surface of PCB was designed to intensify the interactions between the recycled PCB and natural rubber.2. The rubber reinforcement properties of pyrolytic and modified carbon blacks were investigated and compared with those of commercial carbon black by means of solid-state high resolution nuclear magnetic resonance (NMR). Four aspects(chemical crosslink structure, relaxation and diffusion, dipolar correlation effect and self-diffusion) were examined by NMR. The chemical crosslink structures of the vulcanized rubbers with different carbon blacks are similar. Surface grafting intensified the interactions between the carbon blacks and the neighboring polyisoprene chains. The density of chemical cross-links of the vulcanized rubber with modified PCB was greatly improved. After titanate coupling agent modification, the penetrability of the rubber samples was improved.3. The mechanical testing of the vulcanized rubbers with different kinds of carbon blacks showed the strain of the rubber with modified PCB was improved greatly. The mechanical testing results confirmed the conclusion of the NMR. The PCB modified by the demineralization and NDZ-105 titanate coupling agent could be used to replace the commercial semi-reinforcing carbon black. The heterogeneous multi-shell model was proposed to elucidate the reinforcing mechanism of PCB in rubber matrix. The mechanism considers the heterogeneous multi-shell on the surface of PCB in rubber as backbone connects the cross linked polyisoprene agglomeration and poryisoprene chains in micro-Brown movement, which constitutes a whole network of polymer and PCB.