Reaearch On The Crystalline And Mechanical Properties Of PET Polyester Blends

Polyethylene terephthalate(PET)has excellent properties on heat resistance,chemical resistance and electrical insulation.It is widely used in the fields of fiber and some non-fiber fields.But the applications in engineering plastics have been limited because of its poor toughness and slow crystallization speed.In order to solve the shortcomings of PET,different PET composite systems were prepared by the blending method.PET and its blended composite system were studied on its crystallization performance and mechanical properties.The main research contents and results include:(1)The effects of talc,sodium benzoate,sodium carbonate,sodium bicarbonate,sodium sulfate and NAV101 on the crystallization performance and intrinsic viscosity of PET were studied.The results show that: sodium sulfate can obstruct the crystallization of PET,sodium carbonate and sodium bicarbonate will impede the crystallization of PET when the content is low.When the content is high,it will promote the crystallization of PET.When the content is 0.5%,NAV101 has the best effect in promoting the crystallization of PET.When the sodium benzoate is 1.5%,the sodium benzoate/PET system has the fastest crystallization rate.It can reduce the half-crystallization time by 65%.Talc/PET has highest intrinsic viscosity,and sodium benzoate/PET has the lowest intrinsic viscosity.In addition to talcum powder,when the content of nucleating agent exceeds 2%,the nucleating agent is excessive at this time,and the intrinsic viscosity of PET/nucleating agent system drop sharply.(2)When using SBS,SEBS-G-MAH and PTW to toughen PET,with the increase of toughening agent content,the impact strength of PTW/PET composite system increase firstly,then decline,and reach to stable finally.For SBS/PET and SEBS-G-MAH/PET,with the increase of toughening,the impact strength drop firstly,then rise,then fall and reach to stable finally.Toughening effect sequence: PTW>SEBS-G-MAH>SBS.When the PTW content is 16%,theimpact strength of the PET/PTW system is 8.75 MPA which is the optimum value,increasing by200%.Through SEM observation,it can be found that the compatibility of PTW and PET is the best and seldom have debonding phenomenon under the DMA test.The glass transition temperature and the storage modulus of the material are found to decrease after the PTW is mixed into PET.DSC tests show that the three tougheners will hinder the crystallization of PET,and the hindrance of PTW is most obvious.(3)The crystallization and mechanical properties of PET/nucleating agent/toughening agent ternary system were analyzed.The results show that the addition of nucleating agent will lead to a serious decline in the mechanical properties of the system.The adverse effect of sodium benzoate on the mechanical properties is more obvious than NAV101.The Jeziomy method is found to be suitable for non-isothermal crystallization of PET/nucleating agent/toughening agent ternary systems.The addition of SEBS-G-MAH can be used to promote nucleating effect of nucleating agent.The half-crystallization time of PET/16%SEBS-G-MAH/1% sodium benzoate system was the lowest,which was 0.23 min.The mechanical properties of the PET/PTW/NAV101 system are the best.