Study Of The Impact Of Thermal Stability To UPR With Complex Inhibitors

The radical polymerization almost belongs to the chain polymerization.The elementary reactions of chain polymerization are chain initiation, chain growth and chain termination. In the chain initiation,because of containing unsaturated bonds in all the reactants,their activity are higher and often reacted by light, heat and other factors. In order to control the stability of products in the preparation, distillation, transport and storage, appropriate to reduce the initiation activity of the chain initiation reaction,and extend the induction period,the system of resin is often added some chemicals to scaveng free radicals.This kind of chemicals are named as inhibitors.This paper is the study of the effect of the different inhibitor of unsaturated polyester resins (UPR).The UPR crosslinking reaction is a typical free radical polymerization.UPR is a mixture of crosslinking monomer and unsaturated polyester, and crosslinking monomer is usually about30%to40%part of system.In this paper UPR is selected the modified UPR,to be made by our laboratory,which active functional group of carbon-carbon double bond is located in the molecular chain ends. Compared to the common UPR,the modified UPR is higher in response activity, lower viscosity, better bonding properties of the fiber strength and modulus of the products. So as to discuss the inhibitor effect of the inhibitor of modified UPR,this paper are studied the influence of styrene monomer and modified UPR by added the different kinds of inhibitors.There are two systems to be studied,one is the most commonly used crosslinking styrene monomer, another is the modified UPR.In the system of styrene, the main inhibitor type is used the traditional HQ alone, and HQ mixed with MEHQ, TH701, phenothiazine or AI-61R.In the system of modified UPR,the main inhibitor tyre is used the TH701alone,and TH701mixed with HQ,MEHQ,AI-61R or phenothiazine.There are studied from two aspects to analyze the effect of different system of inhibitor, the first part is the chain polymerization reaction, the other part is the impact on the mechanical properties after the resin cured. The result shows that the inhibitor obviously effect on chain initiation reaction, while the mechanical properties of the resin curing basically did not change. In chain initiation reaction,the inhibitor primarily effects the length of the induction period and the level of difficulty to react. The specific performance are the thermal stability and reaction kinetics of the system. Therefore, in order to evaluate the thermal stability of the system, the way is method of80℃storage stability measurement, method of100℃reacted time measurement and method of25℃gelation time measurement,thus comprehensive evaluation of the thermal stability of the system. According to the theory of the resin reaction kinetics, with the DSC method,project resin reaction activation energy,and further analyze the curing behavior.The results show that the inhibitor system of TH701mixed with HQ is better inhibitor effect to styrene than used HQ alone,which the system of300ppm HQ mixed with300ppm TH701is best.The storage time of80℃is more than200hours,and the the gel time of100℃is37minutes.In the system of modified UPR,the result shows that the inhibition effect of TH701mixed with phenothiazine is better than other. Among all the system,the inhibitor system of700ppm TH701mixed with50ppm phenothiazine is best. The storage time of80℃is74hours,while the the gel time of25℃is50minutes.The activation energy is80.8kJmol-1.From analyzed on the kinetics,the results are the same as the previous analysis of the initiation activity.