Effects Of Nucleating Agents On Crystallization And Mechanical Properties Of PET

Polyethylene terephthalate(PET)is an excellent engineering plastic with good comprehensive properties and wide application.But there are some problems for pure PET such as slow rate of crystallization,unperfect crystallization and so on,which limit its development.Aimed at these problems of PET,this paper has done some researches as the follow:1.Montmorillonite(MMT)and several organic modified montmorillonites were used as nucleating agents to study their effects on the crystallization properties of PET.Compared with pure PET,the melting crystallization peak temperature(Tmc)of PET/MMT increases 0.80~6.42℃,the cold crystallization peak temperature(Tcc)decreases 0.33~4.92℃,and 1/t1/2 value increases nearly doubled.Moreover,the crystallization is more perfect owing to the acceleration of crystallization rate with the grain size decreases.2.The binary hybrid nucleating agent,modified MMT(DK2)/TA-401 A,was designed to explore its effect on the crystallization properties of PET.The results show that the introduction of TA-401 A improves the dispersion of DK2 in PET to some extent,and makes DK2 play a more obvious heterogeneous nucleation effect.Compared with pure PET,the Tmc of the composite system rise up to 213.00℃,and the Tcc decreases 3.78~9.11℃,while the cold crystallization peak is obviously weakened.Besides,the crystallization rate is also accelerated,along with the crystal density and crystal uniformity of the composite system are improved.Otherwise,the effects of DK2/TA-401A/ionic compound ternary hybrid nucleating agent on the crystallinity and morphology of PET were also investigated.The results show that the Tmc of PET/DK2/TA-401A/ionic compound composite system increased to 216.75~220.18℃,and the Tcc decreases 5.71~11.85℃,while the cold crystallization peak is further weakened and the half-peak width becomes narrower with 1/t1/2 value nearly twice as high,resulting in the acceleration of crystallization rate.Finally the crystallinity of the composite system is improved,and the grain size is reduced.3.Two composite materials of PET/glass fiber/nucleating agent and PET/glass fiber/toughener/nucleating agent were prepared.It is found that the Tcc of two composite materials are shifted to the lower temperature and the cold crystallization peaks is weakened after adding nucleating agent into the system.The Tmc of the PET/glass fiber composite materials increase and the crystallization peak become narrower.But the crystallization peak temperature of PET/glass fiber/toughener /nucleating agent composite materials are slightly lower after the addition of the toughening agent AX8900,and the crystallization peak is also widened to some extent.Tensile and bending properties of two kinds of composite materials are slightly lower than before.In addition,the introduction of the toughening agent AX8900 enhances the interfacial bonding strength between glass fiber and resin,which could enhance the tensile strength of the composite materials to some extent,and significantly improve the toughness of the resin.