Preparation Of Pet-base Materials With Weather-aging Resistance

Polyethylene terephthalate is one kind of general polymer widely used as fiber,film and engineering plastics in many fields.However,PET has some shortages including oxidative degradation with oxygen under high temperature,shorter life with UV-irradiation,obvious hydrolysis in damp environment,which largely limits the PET application scope.This study is about a project conducted by the cooperation between DHU and enterprise,aiming to provide the theoretical basis and technology support for industrialization of PET-base materials with weather-aging resistance.Therefore,two main works have been done.Firstly,various additives,including a kind of Poly carbodiimide hydrolysis resistance agent UN-03,antioxidant agent P262 containing hindered phenol and phosphite ester,UV stabilizer UV-1577,were introduced into the PET matrix by melt blending to improve PET properties.The thermal degradation,melting crystallization,rheological property and processibility of the resulted PET resin and its fiber's weather-aging resistance properties were studied.Furthermore,PET nanocomposite containing sheet-like Titanium organic compound is a new type of nanocomposite prepared by our research group.Its thermal degradation,melting crystallization,rheological property and its film's UV stability were also studied.And the PET base nanocomposites were further modified by solid-state polycondensation.The main results are as follows:1)The thermal degradation,crystallization under melting,rheological properties as well as processing ability of PET/UV-1577 resin prepared by blending were studied,and UV stability of the resulted fibers were compared to pure PET fiber,semi-dull PET fiber(with 0.8%TiO2),full extinction PET fiber(with 2.5%TiO2).The results show that the introduction of UV-1577 has almost no effect on thermal degradation performance,increases Tm and decrease Tg and Tcc with UV-1577 content increasing.For the melt of modified PET,shear viscosity of PET/UV-1577decreased with UV-1577content for its rool of plasticization.The same principle would be got in logy-log o analysis graphic.The PET/UV-1577 resins show good spinnability and the resulted fibers show better mechanical properties than pure PET fiber.After ten days of UV irradiation,the tensile maintanence of PET/UV-1577fibers was bigger than 90%.The tensile strength maintanence is 98%and breaking elongation maintanence is almost 100%while the UV-1577 content is 5wt%,which is largely bigger than those of the full extinction PET fiber,40%and 40%.2)For improving mechanical properties of PET materials under wetty and hot atmosphere,the hydrolysis resistant agent UN-03 and the oxidation resistant agent P262 were introduced into PET resin by melt blending.And thennal degradation,crystallization,rheology as well as processing ability of the resulted resins were studied and hydrolysis resistant properties of its fibers were examined.The results show that,Td and Tm of PETA/UN-03 resin almost have no change while Tmc increased as UN-03 content increase.The PET/UN-03 resins have good spinnability at UN-03 content 4wt%,5wt%and 6wt%.The PET/UN-03 spline by melt injection and fiber both contribute to a good hydrolysis resistant perfonnance after 10d treatment under the test environment of 85 ? and 85%RH,and their mechanical properties maintanence are 80%for spline and 105%for fiber when UN-03 content is 5%,which are bigger than those of the blank sample,50%for spline and 60%for fiber.On this basis,the thermal degradation,melt crystallization,rheological properties,spinnability and its fiber's hydrolysis resistance performance of PET resin with 5 wt%UN-03 and 0.3 wt%P262.It was found that the mechanical properties maintanence of the fiber keeps at 75%after 10d treatment.3)Based on the previous research results,the PET resin with 5 wt%UN-03,0.3 wt%P262,5 wt%UV-1577content was prepared and its thermal degradation,melt crystallization,rheological properties and spinnability were studied and its fiber's weather-aging resistance was examined.The results show that the modified resin has good spinnability.The mechanical properties maintanence of the resulted fiber keeps at 85%after 10d treatment in xenon lamp aging box(290?800nm,85?,85%RH).4)PET nanocomposite containing sheet-like Titanium organic compound is a new type of nanocomposite prepared by our research group.Its thermal degradation,melting crystallization,rheological property and its film's UV stability were also studied.And the PET base nanocomposites were further modified by solid-state polycondensation.The results show that the introduction of titanium organic compound(TOC)to PET has no obvious effect on the thermal degradation performance,and its Tm and degree of crystallinity show a little decrease as titanium organic compound content increasing.The nanocomposite resin shows interesting rheological behavior:Under lower shear rate(smaller than 10Hz),the PET/TOC resin melt show higher apparent viscosity than that of pure PET and as temperature increase.It may cause by that there exists stronger interactions between PET and TOC phase,and the tablet bedded TOC network formed by Brownian motion restricts movement of PET molecular chain.Under high shear rate(bigger than 100 Hz),the PET/TOC resin melts contribute to lower apparent viscosity than that of pure PET resin melt.It was resulted from orientation of the PET molecular chain induced by oriented pieces of sheet-like TOC under shearing action as the 2D-WAXD patterns show.This series of composite resin have excellent BOPET processibility.The as-spun films can be stretched 4 times in two-way and the resulted film has good mechanical properties with breaking strength 86.2 MPa and breaking elongation 130%.The as-spun film with 0.5 wt%TOC content has 99%UV shielding rate(380 nm)and its maintanence of tensile strength and elongation at break both keep at about 80%after 10d treatment by 340nm UV irradiation.It suggests that UV radiation resistance of PET can be effectively improved by introduction of TOC.The influence of solid-state polycondensation process on PET molecular weight was preliminary studied.The modified PET resin with 30000 molecular weight,1.6 PDI,and less than 30mol·t-1 end carboxyl content can be prepared under 150? 6h for preliminary crystallization,180?220?8h for crystallization,255? 20h for solid polycondensation by using vacuum oven.It give necessary foundation for further research in polyester industrial yarn field.