Study On The Preparation Of Chlorinated Polyethylene By Solid Phase Method

In recent years,the suspension method has been unable to meet more and more high environmental protection requirements,and research on the solid phase production process has received increasing attention.The product bonding and high residual crystallinity caused by the reaction exotherm are the key factors that restrict the development of the solid phase process.Therefore,the key to this process is to solve the problem of product bonding and reduce the residual crystallinity of the product.In this paper,the process of chlorinated polyethylene by solid phase method has been studied,using the method of cryogenic chlorination and the addition of anti bonding agent for sieved quartz sand,the problems of reaction exothermic adhesion and nonuniformity of chlorination in the preparation of chlorinated polyethylene was solved,and the residual crystallinity of the product was reduced.The production technology of the solid phase method was investigated to find out the best process reaction conditions.In this paper,the polyethylene raw material used for chlorination was screened out and characterized in terms of DSC,density,particle size,wax content,melt flow rate,BET,infrared spectroscopy,and scanning electron microscopy.The raw material is high-density polyethylene with good crystallization performance,suitable particle size,uniform particle distribution,low wax content,suitable melt flow rate and melt flow ratio,low degree of branching,loose and porous particles on the surface,many filamentous structure connections,a large specific surface area and rich internal pore structure.This article designed a tube furnace temperature programmed experimental equipment,using the method of low-temperature chlorination and adding sieved quartz sand anti binding agent in the chlorination process,solves the problems of bonding and chlorination of products during high temperature chlorination,and the residual crystallinity of products was reduced.The subsequent chlorination reaction temperature was raised to 130?,chlorine content reached to 40%.In this paper,the solid-phase chlorination reaction experiment was conducted through the tube furnace experimental equipment,and then determining the chlorination reaction temperature,chlorination reaction time,initiator dosage,chlorine gas dosage,anti-binding agent dosage,UV lamp irradiation time,and initiation method,the optimal process conditions for the use of anti-binding agent.The chlorinated polyethylene products prepared in this paper were characterized in terms of thermal stabilization time,volatiles(including water)content,combustion residue,DSC,infrared spectroscopy,scanning electron microscopy,thermogravimetry and nuclear magnetic resonance spectroscopy.The product has good thermal stability,low content of volatile matter(including water),very few impurities,low residual crystallinity,good molecular chain flexibility,low brittle temperature,good low-temperature performance,hardly an partial chlorine structure.The surface of the product is tight and smooth,the chlorine distribution is mainly linear and irregular,which is relatively uniform.