Chemical Modification Of Polyvinyl Chloride And Chlorinated Polypropylene

Chlorinated polymer is an important branch of polymer,mainly including chlorinated rubber,polyvinyl chloride,chlorinated polypropylene,etc.,which has been rapidly developed at home and abroad.However,these products need to be modified to expand their applications and even develop new uses.This paper mainly studies the chemical modification of polyvinyl chloride（PVC）and chlorinated polypropylene（CPP）to develop new uses of PVC or improve the ester solubility of CPP,enhance the value of the product.First,PVC is a widely used plastic,with high chlorine content,and improper disposal will cause serious harm to the ecology.Secondly,PVC has poor thermal stability,and thermal decomposition is related to dehydrochlorination.Therefore,it is of great practical significance to study its dehydrochlorination and modification to develop new plastic heat stabilizers and improve the utilization of waste PVC.The main contents and results of PVC modification research are as follows.1)The dechlorination of PVC in the alcohol（aqueous）solution of alkali under different conditions was studied to generate dechlorinated PVC（DPVC）.The dechlorination efficiency increases with reaction temperature,reaction time and Na OH dosage,and first increases and then decreases with the increase of ethanol fraction.DPVC suspension reacts with chlorine gas to generate CDPVC,and its chlorine content increases with reaction temperature,and chloroform is the best solvent,and the chlorine content of CDPVC is up to 58%.The glass transition temperature of CDPVC was increased to 97°C,but the thermal stability was not significantly improved.2)With formic acid and hydrogen peroxide as oxidant,DPVC can be oxidized to epoxy PVC（EPVC）.Its epoxy value first increases and then decreases with the increase of reaction time and temperature.The optimal reaction time and temperature are 5h,70°C,and the epoxy value is up to 4.7%.3)As a stabilizer,EPVC can improve the thermal stability of PVC,the higher the epoxy value,the better the effect.However,when the epoxy value is lower than 1.1%,it will have a negative effect.When 4 phr EPVC with epoxy value of 4.7%was added to PVC,the initial degradation temperature was increased to 226°C.CPP is mainly used in the ink industry,however,with the restriction and elimination of benzene solvents at home and abroad,it is urgent to develop ester-soluble CPP.In this paper,CPP was modified by amination to improve its solubility in ester solubility.The main research contents and results are as follows:1)Under mild reaction conditions,the modification of CPP with five amination agents was studied,and the solubility of the resulting products in ester solvents was compared.The results showed that diethanolamine had the best effect.The grafting degree and efficiency increased with reaction time.When the temperature increases,the grafting degree and grafting efficiency increase,but dehydrochlorination of CPP will occur above 70℃.The grafting rate increases with the increase of the material ratio(m _DEA:m _CPP),while the grafting efficiency is the opposite.2)Infrared spectroscopy,thermogravimetric analysis and gel chromatography were used to characterize the changes of CPP molecular structure and properties after grafting.The results showed that DEA was successfully grafted to the CPP molecular chain,and the thermal stability of CPP remained basically unchanged.3)CPP-DEA has a good linear relationship between solubility（y）and grafting rate（x）in the mixed solvent of butyl acetate-methylcyclohexane（15%）,and the fitting equation is y=1.294x+9.505.