Synthesis And Application Of Maleic Acid-sorbitol Ester And Its Zinc Complexe

Polyvinyl chloride?PVC?has many excellent performance,such as easy processing,high strength,electrical insulation and chemical corrosion resistance.It is widely used in wire,pipe,aerospace and automotive fields.However,due to its poor thermal stability,thermal stabilizer must be added to the PVC during the processing.With the increasing focus on environmental protection and the rapid development of the PVC industry,environmentally-friendly thermal stabilizers with excellent performance have become an important research objects.Environmentally-friendly thermal stabilizers was synthesized in this paper.The main research works are as follow:?1?Maleic acid-sorbitol ester?SM?was synthesized by using maleic acid and sorbitol,and the synthesized ester compound was reacted with zinc oxide to form a zinc complexe?SM-Zn?.The composition and structure of the sorbitol-maleic acid compound and its zinc complexe were characterized by FT-IR,TGA,SEM,DSC and XRD.The results indicated that sorbitol was esterified with maleic acid,and the optimal reaction conditions were 170?and 2h.The esterified compound could react with zinc oxide to form zinc complexe.Both products were stable during the whole processing of PVC,and have good fluidity in low temperature or high temperature.?2?These two products were added to PVC as thermal stabilizers,and the effects of maleic acid-sorbitol and their zinc complexe on the initial thermal stability,long-term thermal stability,dynamic thermal stability,lubricating properties,thermal decomposition temperature,dispersion effect and mechanical properties of PVC were characterized by static oven test,Congo red test,torque rheology test,TGA test,scanning electron microscope,impact strength test,tensile strength test and flexural strength.The results showed that SM ester could improve the long-term thermal stability,lubrication performance and mechanical properties of PVC and the dispersion effect in PVC was better than that of SM-Zn.But SM-Zn could improve the early thermal stability of PVC.?3?The maleic acid-sorbitol ester was used as an auxiliary organic thermal stabilizer to compound with CaSt₂/ZnSt₂ and its thermal stability mechanism was discussed.The maleic acid-sorbitol zinc complexe was used as the main stabilizer to compound with CaSt₂ and its thermal stability mechanism was discussed.The results showed that the SM ester could adhere to the surface of PVC particles at the initial stage of processing and the plasticizing time is prolonged,which could be used as an external lubricant in the formulation system.The SM ester gradually migrated to the PVC chains,weaken the interaction between PVC chains during the processing.In addition to improving the initial thermal stability of PVC,SM-Zn had a certain degree of lubricity,lowering the balance torque and prolonging the plasticizing time.The maleic acid-sorbitol ester contained carbon-carbon double bonds and hydroxyl groups which could interact non-covalently with hydrogen and chlorine in the PVC chain,for which its long-term thermal stability could be improved.The maleic acid-sorbitol zinc complexe,a compound with basic and nucleophilic properties,could react with hydrogen chloride,which could improve the initial thermal stability.