Mechanical Reinforcement Of Poly(Ethylene Terephthalate) By Coupling Of Ionization And Liquid-crystalline Polymer Incorporation

The purpose of this research is not only to speed up the crystallization and improve the crystallinity of poly(ethylene terephthalate)(PET),and further strengthen the effect of PET to meet the engineering requirements of the harsh material performance,and can not result in reduced processing performance,but also repeat the performance of recycling low attenuation,making the material recovery efficiency is high,to avoid pollution of the environment.Based on the above requirements,the introduction of liquid-crystalline polymer(LCP)in thermoplastic matrix PET can not only improve the crystallinity of PET matrix by using LCP as heterogeneous nucleating agent of PET matrix,but also can use the liquid crystal in the process of cutting or stretching flow field Under the action of oriented fiber to further strengthen the PET matrix,to achieve synergistic effect;Moreover,this composite material due to enhance the micro-fiber renewable properties,making its recycling value greatly enhanced.Through one-pot method,with the high rigidity LCP of 4-hydroxybenzoic acid-2-hydroxynaphthalene-6-carboxylic acid(HBA-HNA)to enhanced PET.Blending HBA-HNA with PET melting by in situ adding chain extender pyromellitic dianhydride(PMDA)ionization system with zinc hydroxide composition.The chain extension of PET matrix and introducing covalent ionic groups,then using the ion of PET ionomer between the dipole of HBA-HNA ester interaction to achieve significant expansion and enhancement.The modified PET was prepared by melt blending of PET with different mass fraction of PMDA and zinc hydroxide.The synthesis of PET ionomer was confirmed by atomic absorption spectrometry.The intrinsic viscosity,complex viscosity and crystallization properties of pure PET,PET and PET were analyzed and the results show that:(1)the molecular chain of the PET is caused by the introduction of the ionic group,which makes the molecular chain a certain degree of curling,so that it has some properties in the case of no change in the molar mass but reduce in intrinsic viscosity;(2)The introduction of ionic groups in the PET molecular chain leads to an increasing tendency of the complex viscosity of the polymer due to the interaction between ions in the chain or between the ionic–dipole;(3)Although a small amount of ionic groups introduced in the PET molecule is not sufficient to cause a significant change in the glass transition temperature,it may inhibit the movement of the PET molecular chain and may impede the regular arrangement of the PET molecular chains to a certain extent reduce.The microstructures of the composites prepared by blending PET with different mass fraction of PMDA,zinc hydroxide and HBA-HNA were investigated by optical microscopy combined and scanning electron microscopy.The results showed that,the compatibility of pure PET,extended-chain PET and ionized PET with HBA-HNA increased successively.The compatibility of ionized PET and HBA-HNA was the best in the study of the complex viscosity of the three composite materials.The extended chain PET and HBA-HNA secondly.The results of tensile and impact tests show that the compatibility of pure PET and HBA-HNA is poor and the interfacial adhesion is poor.With the increasement of HBA-HNA fraction,the mechanical properties are gradually deteriorated.In contrast,the extended chain PET/HBA-HNA composites with improved carboxyl group concentration after chain extension can help improve the compatibility of both phases,and due to the hydrogen bonding reaction between carboxyl groups of PET molecular chains and HBA-HNA ester oxygen,or as a reactive compatibilizer.The mechanical properties of the extended chain PET/HBA-HNA composites increased with the increase of HBA-HNA content,which resulted by the improvement of the two phases compatibility.And the strong ion-dipole between the ionic groups on the molecular chain of the PET ionomer and the ester oxygen of HBA-HNA are in place of the weak hydrogen bond,and the compatibility between PET and HBA-HNA is further improved.Performance is further optimized.