Study On High Thermal Stability Chlorinated Paraffin-70

Currently,there are frequent fires caused by polymer materials,and their flammability and release of toxic gases at high temperatures pose a significant threat to human safety and the environment.Flame retardants are used to improve the flame resistance of polymer materials and can be classified into additive and reactive types according to their mechanism of action.Halogen flame retardants are a type of additive flame retardant that have the characteristics of high cost-effectiveness,low addition amount,and good flame retardancy.Chlorinated paraffin is the most widely used halogen flame retardant,which can effectively improve the flame retardancy of polymer materials and is often used for flame retardancy of polyvinyl chloride(PVC)materials.However,due to its poor stability at high temperatures,it easily releases toxic gases,and the use of chlorinated paraffin flame retardants is greatly restricted.Therefore,it is of great significance to improve the flame retardancy of chlorinated paraffin while reducing its impact on the environment.This article discusses the current development of chlorinated paraffin-70 and its flame-retardant effect in PVC.Molecular design was used,and nucleophilic substitution was employed to modify chlorinated paraffin-70 with sodium dibutyl dithiocarbamate and thiosalicylic acid.An orthogonal experiment method was used to design a synergistic flame retardant of ethylenediaminetetraacetic acid disodium salt(EDTA disodium)and chlorinated paraffin-70.Ultimately,the modified product and synergistic flame retardant were added to PVC to produce PVC plastic products.The flame-retardant and mechanical properties were studied through methods such as infrared testing,thermogravimetric analysis,limiting oxygen index testing,and mechanical property testing.The following conclusions were drawn:(1)Sodium dibutyl dithiocarbamate was generated through the reaction of dibutylamine,carbon disulfide,and sodium hydroxide.This product was then used in a nucleophilic substitution reaction with chlorinated paraffin-70,resulting in the final product of modified chlorinated paraffin-70.The thermogravimetric analysis of the modified chlorinated paraffin-70 showed an increase of 52 ℃ in its thermal decomposition temperature co MPared to that of chlorinated paraffin-70.Tensile testing revealed that the addition of modified chlorinated paraffin-70 to PVC materials led to an increase in both the tensile strength and elongation at break co MPared to the addition of unmodified chlorinated paraffin-70.The limiting oxygen index(LOI)test results demonstrated an 8% increase in the LOI value of the modified chlorinated paraffin-70/PVC composite material co MPared to that of the chlorinated paraffin-70/PVC composite material.(2)Through a nucleophilic substitution reaction between the mercapto group in the molecular structure of thiosalicylic acid and the unstable Cl in the structure of chlorinated paraffin-70,thiosalicylic acid was grafted onto the long carbon chain of chlorinated paraffin-70.The thermal decomposition temperature of the modified chlorinated paraffin-70 obtained by this method was found to be 39 ℃ higher than that of chlorinated paraffin-70.Tensile test data showed that the tensile strength of PVC materials containing modified chlorinated paraffin-70 was increased by 23.8%co MPared to those containing chlorinated paraffin-70,and the elongation at break was increased by 180%.The results of the Limiting Oxygen Index(LOI)test indicated that the LOI value of PVC materials containing modified chlorinated paraffin-70 was increased by 6.7% co MPared to those containing chlorinated paraffin-70.(3)By using an orthogonal experimental design,the synergistic flame retardant effect of disodium EDTA and chlorinated paraffin-70 was investigated.Four factors were studied,including the raw material ratio of disodium EDTA and chlorinated paraffin-70,the heating temperature of the mixture,the mechanical stirring time,and the amount of the final product added to PVC,to evaluate their i MPacts on the mechanical properties and flame retardancy of PVC products.The results showed that the best mechanical and flame retardant properties of PVC were achieved when the raw material ratio was 1:1,the heating temperature was 175 ℃,the stirring time was8 hours,and the amount of the synergistic flame retardant added to PVC was 8 parts per 100 parts of PVC.(4)Using the Materials Studio simulation software,molecular dynamics were used to explore the various mechanisms of action of PVC mixed with two types of modified chlorinated paraffin,namely,sodium dibutyldithiocarbamate-modified chlorinated paraffin-70 and thiol salicylic acid-modified chlorinated paraffin-70.The simulation results showed that the two modified chlorinated paraffins had better co MPatibility with PVC and a more stable mixing system with PVC co MPared to chlorinated paraffin-70.