Regulation Of Crystallization And Mechanical Properties Of Poly(Ethylene 2,6-naphathalate)

Aiming at the problems of slow crystallization rate and poor impact toughness of Poly(ethylene 2,6-naphthalate)(PEN),this paper chooses the method of self-nucleation,the addition of square amide derivatives(TMB-5),phenyl phosphate(TMC-210)and thermoplastic elastomer(TPEE)for the purpose of regulating the crystallization behavior of PEN and modifying its mechanical properties.PEN/TMB-5,PEN/TMC-210,PEN/TPEE,and PEN/TPEE/TMC-210 blended materials were prepared by melt blending methods.The effects of TMB-5,TMC-210,and TPEE on the crystallization behavior of PEN(non-isothermal crystallization and isothermal crystallization kinetics),spherulite morphology,crystal structure,impact fracture surface,and mechanical properties were studied using various test characterization instruments.First,the effect of self-nucleation on the crystallization rate of PEN was examined.It was found that self-nucleation can effectively increase the crystallization rate of PEN.The non-isothermal crystallization process shows that the optimal self-nucleation interval of PEN is 266-273?.When the self-nucleation treatment temperature is 266?,the crystallization temperature is greatly increased,and the crystallization temperature is increased by 43.2?.The isothermal crystallization process shows that the PEN half-crystallization time can be significantly reduced.Because the crystallization temperature is increased to 233? after 266? treatment,when the isothermal crystallization temperature is 224?,226?,228?,and 230?,the semi-crystallization time showed a decreasing trend in turn.In addition,the absolute value of the isothermal crystallization activation energy of PEN is larger than that of PEN after self-nucleation treatment at 266?,which also proves that auto-nucleation treatment can increase the crystallization rate of PEN.Secondly,the effects of two nucleating agents,arylamide derivatives(TMB-5)and phenyl phosphate(TMC-210),on the crystallization behavior of PEN were investigated.The results show that both TMB-5 and TMC-210 can significantly increase the crystallization rate and crystallization temperature of PEN.When the content of TMB-5 is up to 1wt%,the crystallization temperature is increased by 17.8?,while the content of TMC-210 is only 0.6wt%.Compared with pure PEN,the crystallization temperature increased by 31.2?,and the nucleation efficiency reached 73.72%.Through isothermal crystallization kinetic analysis,both TMB-5 and TMC-210 can reduce the semi-crystallization time of PEN,while TMC-210 can reduce the semi-crystallization time of PEN by 95.3%.Both nucleating agents had no effect on the crystalline form of PEN.In terms of mechanics,TMC-210 can slightly increase the impact toughness of PEN.To solve the problem of poor toughness of PEN,a thermoplastic elastomer(TPEE)was selected to modify PEN,and the influence of TPEE on the regulation and performance of PEN crystallization behavior was investigated.The study found that the addition of TPEE had a significant effect on the crystallization behavior of PEN,causing a significant crystallization peak in PEN,but the glass transition temperature decreased.The study found that the addition of TPEE had a significant effect on the crystallization behavior of PEN,causing a significant crystallization peak in PEN,but the glass transition temperature decreased.The non-isothermal crystallization process of PEN and PEN/TPEE blending systems was successfully studied by Jeziomy method and Mo Zhishen method.The results of the two analysis methods are consistent,and the optimal content of TPEE is 10wt%.The addition of TPEE has no effect on the PEN crystal structure.The impact fracture surface of PEN/TPEE composite shows plastic fracture,and the compatibility between TPEE and PEN is good.TPEE does not change the crystal structure of PEN.It was found in mechanical tests that with the increase of TPEE content,the bending strength and flexural modulus of PEN/TPEE composites decreased,but the toughness and ductility of PEN could be improved.When the content of TPEE was 30wt%,the notched impact strength of PEN/TPEE composites is 1.6 times higher than that of pure PEN.In addition,the impact section of the PEN/TPEE blended system showed ductile fracture.According to the comparison in the previous chapters,PEN/TPEE/TMC-210 blended materials with high crystallization rate and high toughness were finally prepared.The study found that the addition of 10wt%TPEE maximized the crystallization temperature of PEN,and that the glass transition temperature of PEN/TMC-210/TPEE blended materials decreased with the increase of TPEE content The non-isothermal crystallization process of the PEN/TPEE/TMC-210 blend system was also successfully studied using the Jeziomy method and the Mo Zhishen method,and the analysis results are consistent.TMC-210 and IPEE were added to PEN together,which did not change the crystal structure of PEN.The addition of TPEE significantly increased the impact toughness of PEN.The impact section of the PEN/TPEE/TMC-210 blend showed tough fracture,but reduced the rigidity of PEN.In the end,the optimal contents of TPEE and TMC-210 modified PEN were confirmed to be 10wt%and 0.6wt%,respectively.