Preparation And Properties Of Short Glass Fiber Reinforced PA12T Composites

Nylon 12T(PA12T)is a novel heat-resisting material developed in recent years.Compared with the aliphatic nylon,it has higher mechanical strength,better heat resistance and lower hygroscopicity,widely used in automobile and electronic industries.Glass fiber is cheap and easy to obtain,and glass fiber reinforced nylon thermoplastic resin has rich theoretical foundation and technical support.With the improvement of PA12T industrialization,the research on preparation and properties of glass fiber reinforced PA12T composites has important research value.In this dissertation,PA 12T was used as matrix resin and the commercially available glass fiber was used as reinforced fiber.The nylon 12T/short glass fiber composites(PA12T/SGF)with different glass fiber varieties and glass fiber content were prepared by melt extrusion.The mechanical properties,thermal properties,dynamic mechanical properties,thermal-oxygen aging properties and glass fiber in the matrix were also studied.The dispersion and the interface between glass fiber and resin were analyzed.The main contents and results are as follows:(1)The effect of glass fiber addition on mechanical properties,processability and thermal properties of PA12T/SGF composites was studied.The results showed that the mechanical strength of composites increased with the increase of glass fiber content.When the glass fiber content is 30%,the tensile strength is increased by 2.17 times,the bending strength is increased by 3.12 times,the notch impact strength is increased by 2.02 times,and the shore hardness is slightly improved.The dynamic mechanics study shows that the increase of the glass fiber content,the increase of the modulus of the energy storage of the composites,the increase of the rigidity and the peak of the alpha change to the high temperature.With the increase of glass fiber content and the decrease of melt flow rate,the processing performance of high glass fiber content decreased;glass fiber added heat deformation temperature.When glass fiber content was 30%,the thermal deformation temperature was raised to 249 ℃,and 113 ℃ was increased compared with the PA12T matrix resin.(2)TG and DSC were used to analyze and characterize the thermal properties,crystallization ability and interfacial adhesion of composites.The results show that the thermal decomposition temperature rises with the increase of glass fiber content.When the glass fiber content is 40%,the initial decomposition temperature is increased from 384 ℃ to 396.Glass fiber is added to increase the crystallization temperature of PA12T from 271.1 ℃ to 274.6 ℃,and the glass fiber has the effect of inducing PA12T crystallization.(3)The hydrothermal resistance and heat resistance of composites were studied.The results show that with the increase of glass fiber content,the tensile strength of the composite after water absorption is decreased,but it is kept above 83%.After drying,the strength of the hygroscopic specimen is recovered and the retention rate is above 89%.The results of aging test at 160℃ under the standard heat and oxygen aging test showed that the strength of the material decreased with the prolongation of aging time,and the tensile strength was increased first and then decreased with the increase of fiber content.(4)The effects of dispersing lubricants(TAF)and toughening agent POE-g-MAH on the mechanical properties of composites were investigated.The results show that the tensile strength,bending strength and impact strength of the composites increase with the increase of the amount of POE-g-MAH,and the tensile strength,impact strength and bending strength of the composites increase first and then decrease with the addition of TAF.Scanning electron microscopy(SEM)was used to observe the notch impact profile of the composites.It was found that the addition of TAF and POE-g-MAH could improve the interfacial bonding between the PA12T matrix resin and the glass fiber in the composite.(5)The effects of PA12T molecular weight and glass fiber type on the properties of the composites were investigated.The results showed that the tensile strength of the composite first increased and then decreased with the increase of the relative viscosity of the resin,and the bending strength,notched impact strength and hardness increased.When the glass fiber length is longer,the forming difficulty is increased,and the material performance is poor.The mechanical strength and water resistance of glass fiber composite surface treated with-NH2 surface treatment agent are better than those of other treatment agents.