Preparation And Stress Cracking Resistance Of PBT/ABS And TPU/ABS Blends

Acrylonitrile-butadiene-styrene(ABS)is a kind of copolymer,which has excellent mechanical properties,high surface gloss,excellent toughness.But its products often appeared the phenomenon of cracking in the process of long-term use.In order to improve the stress cracking resistance of ABS,this article blended modification ABS by uesing PBT and TPU two polymers respectively.Improve the yield of products and broaden the application of ABSIn this paper,PBT/ABS alloy and TPU/ABS alloy were prepared by twin screw extrusion mechanism.Mechanical properties,section morphology,surface energy,crystallinity and compatibility of PBT/ABS alloy and TPU/ABS alloy were studied by electronic universal testing machine,scanning electron microscope,contact angle,differential scanning calorimetry,respectively.The solvent stress cracking resistance of blend materials was tested by the prefabricated stress-solvent stress release method.The cyclic stress cracking resistance of materials was studied by cyclic stress cracking experiment.Finally,the stress intensity factor(Kic)of the materials was calculated by Griffith theory,and Kic was used to measure the degree of resistance to stress cracking.The results show that the type of PBT makes a great influence on the mechanical properties of PBT/ABS blends materials.With addition of PBT,ABS resin strength increased.Its tensile properties increased,impact strength decreased.The impact section changes from ductile fracture to brittle fracture.When the content of PBT is 4 phr,the composite properties of blends are better.The tensile strength and melt flow rate increased 15.2%and 24.4%respectively,and the impact strength is slightly lower.With the addition of PBT,ABS glass transition temperature moves to low temperature.When PBT content is five copies,glass transition temperature of ABS changed from 105.5? to 100?.With the increase of TPU content,the tensile strength of TPU/ABS blends remain unchanged.With the increase of TPU content,the impact strength and melt fluidity both increased.When the TPU content is 5 phr,the impact strength and melt flow rate of blends increased by 11.4%and 49.67%respectively,besides the tensile strength decreases by 2.5%.Both PBT and TPU can improve the solvent cracking resistance of ABS.When the content of PBT is 5 phr,the stress cracking resistance time of PBT/ABS increases by 162.5%.When the content of TPU is 5 parts,the stress cracking resistance time of TPU/ABS increases by 250%.When the content of PBT was 6,the stress failure cycle times of PBT/ABS increased by 17.0%,and when the content of TPU was 6,the stress failure cycle times of TPU/ABS increased by 22.2%.Griffith theory was used to calculate the Kic of the blend alloy.The addition of PBT increased the Kic of ABS,while the addition of TPU had little effect on the Kic of ABS.Compared with the experimental results,it is found that Kic can better describe the initiation conditions of cracks in ductile and brittle polymers,but can't describe the fracture behavior of ductile polymers.