The Preparation And Rheological Properties Of PA66/glass Fiber Composite

In this paper,PA66/glass fiber composites were prepared by melting blending.The effects of glass fiber content and the presence of silane coupling agent KH550 on the mechanical properties,thermal properties,dimensional stability and apparent morphology of PA66/glass fiber composites were studied.The advanced capillary rheometers and rotational rheometers were used to determine the stead-state rheological properties and dynamic rheological properties of the composites.And the effect of glass fiber content and temperature on the rheological behavior of PA66/glass fiber composites was studied.Based on rheological measurement,a model that can accurately describe the rheological behavior of PA66/glass fiber composites was established.The specific research results were as follows:The silane coupling agent KH550 could effectively improve the interface compatibility between glass fiber and PA66,and then improve the mechanical properties of PA/glass fiber composites.When the glass fiber mass fraction was 25wt%,the tensile strength,flexural strength,flexural modulus and notched impact strength of the G5 sample were 185 MPa,192 MPa,8240 MPa and 17.3 kJ·m-2,respectively,which were 2.64,2.95,3.3 and 1.68 times higher than those of pure PA66(P0).The thermal stability of composites with different mass fractions of glass fiber was P0<G1<G2<G5<G3<G4,which was because that a small amount of glass fiber can be uniformly dispersed in the PA66 composites and the two phases have good compatibility,so that heat resistance of PA66/glass fiber composite was improved.When the environmental humidity was higher and the storage time was longer,the hygroscopic of PA66 composites material became more obvious and the size became larger.As the shear rate increased,the shear viscosity of PA66/glass fiber composites decreased and the shear stress increased.with the increase of glass fiber content,the shear viscosity,shear stress and the storage modulus of PA66/glass fiber composites increased.The linear viscoelastic region of PA66/glass fiber composite became narrower,and the Payne effect became more and more obvious.Regardless of the amount of glass fiber added,the storage modulus and energy dissipation modulus of PA66/glass fiber composites increased with the increase of angular frequency.The slope of the storage modulus and angular frequency curve of PA66/glass fiber composites material at lower frequency is small,and the second plateau phenomenon could be observed.And with the increase of glass fiber content,the characteristics of the second platform became more obvious.Based on the measurement of advanced capillary rheometer and rotational rheometer,a rheological model of PA66/glass fiber composites was established,which included shear viscosity,glass fiber content,temperature and shear rate.The established models were verified one by one and the verification results showed that the established rheological model was accurate.