Modification Of The Waste Rubber Powder And Their Blending Performance With Chlorinated Polymers

Waste rubber is a solid waste, and its amount ranks second in all of the waste polymer materials. Production of fine powder of ground rubber tire (GRT) has been the main recycling approache. GRT can be widely used for the production of thermoplastic elastomerors, however, the mechanical properties of the GRT/resin blends are generally poor due to the bad cpmpatability between GRT and polymer resin. Therefore, in this paper, a variety of modification methods were attampted to modify the surface polarity of GRT, and the modified GRT (mGRT) was blent with some resins such as PVC, CPE, and campared with GRT/resin blends.The major work and innovative results of this paper are as follows:1. Preparation of CSM by solution method.In usual atmospheric pressure, CSM (S content of CSM is about 1%) is prepared by soultion method using CPE as raw material, sulfur chloride as chlorosulfonating agent, chloroform as solvent, and pyridine as cocatalyst. The effects of pyridine and the amount of sulfur chloride on the sulfur content of CSM were investigated experimentally. The -SO2C1 group in CSM is confirmed by infrared spectrum analysis.2. Study on chlorinated GRT (CGRT)/PVC blendsCGRT/PVC blends are prepared using PVC and CGRT with its chlorine content ranging from 0% to 14%. The effects of some factors on the mechanical properties of CGRT/PVC blends are investigated experimentally, including the chlorine content of CGRT, the amount of CGRT and plasticizer (DOP), as well as the adding of the third component. The optimal formula of CGRT/PVC blends is as follow:the chlorine content of CGRT is about 8%, the added amount of CGRT is 20 phr, and the amount of DOP is 30-40 phr. The adding of CGRT in the PVC material can increase the swelling resistance of CGRT/PVC blends. Finally, the addition of 5 phr CPE in the optimal CGRT/PVC blends is helpful for the improvement of the mechanical properties of the blends.3. Study on the other modified GRT/PVC blendsThe property of GRT and CGRT was modified via three different methods, namely 1) Chlorination of GRT using SO2Cl2 as chlorinating agent; 2) CGRT with chlorine content of 14% is partially hydrolyzed by alkaline solution; and 3) GRT and CGRT with 7.9% chlorine are coated with different polymer solutions. The effects of these modification methods on mechanical properties of the mGRT/PVC blends are investigated experimentally. The results indicate that 1) The chlorination modification is merely helpful for the improvement of tensile and tear strength of the CGRT/PVC blends; 2) After alkaline hydrolysis of 14%CGRT, the mechanical properties of mGRT/PVC blends is worse than that of 14%CGRT/PVC blends; 3) After surface coating of 7.9%CGRT with polymer solutions, the mechanical properties of the CGRT/PVC blends are improved to some extents, while the impact strength has a certain decrease.4. Preparation of chlorinated/chlorosulfonated GRT and the performance of the resulting mGRT/PVC blendsChlorinated/chlorosulfonated GRT was prepared by solid-state method using sulfur chloride as chlorosulfonating agent. The chlorine and sulfur content of chlorinated/chlorosulfonated GRT is from 4% to 17.4% and from 0.1% to 0.7%. The optimum production condition was found as follows, reaction temperature at 70℃,0.8% of radical initiator, reaction time about 8 h. The chlorine and sulfur content of modified GRT can be controled by the amount of sulfur chloride. Infrared spectra analysis indicates that C-Cl bond and-SO2C1 group exist in the structure of chlorinated/chlorosulfonated GRT. When this modified GRT is blent with PVC, the tensile strength of mGRT/PVC blends is improved to some extent, and tear strength of the blends increased more significantly.5. Preparation of brominated GRT (BrGRT) and the performance of BrGRT/CPE blendsBrominated GRT with varying bromine contents was prepared by aqueous suspension method using the the mixture of (HBr and H2O2) as brominating agent. The properties and polarity of GRT and BrGRT were characterized by ATR-FIIR, TQ and contact angle to water. The results indicate that 1) The present preparation method of BrGRT is feasible; 2) The higher the bromine content of BrGRT is, the worse its thermal stability becomes; 3) The bromination modification enhances the hydrophilicity and polarity of BrGRT to some extent. The BrGRT can be used as a substitute of inorganic fillers as well as polymers for the BrGRT/CPE blends, and the overall mechanical performance kept well when the added amount of BrGRT is controlled in a reasonable range. The mechanical properties, surface wetting properties and morphology of BrGRT/CPE blends show a certain improvements over GRT/CPE blends.