Research On Preparation, Structure And Properties Of In-situ Compatibilized PA6/HDPE Blends

Polyamide 6(nylon 6)is one of the most used thermoplastic due to its easy processing,wear resistance,and high melting temperature.The broader application of PA 6,however,is limited by its brittleness and high water absorption. In order to improve its toughness,PA6/HDPE blends were prepared by in-situ compatibilization technology in the present of L-101 and MAH,and the mechanical properties,morphology structure,rheological behavior and crystallization properties were investigated by tensile/impact strength testing,scanning electron microscopy(SEM),capillary rheometer,differential scanning calorimeter(DSC)and polarizing microscopy(POM).The experimental results demonstrated that the toughness of PA 6 were improved significantly by in-situ compatibilization technology.When the composition PA6/HDPE/MAH/L-101 was 70/30/0.5/0.1,it gave 11.10kJ/m~2 of impact strength,which was increased by 1.64 times as compared to that of neat PA6(4.2 kJ/m~2).And the Elongation at break of it was increased by 1.33 times.SEM analysis showed that the HDPE dispersed uniformly in PA6 matrix in the form of smaller dimension,which played a key role in the improvement of the toughness.The rheological behaviours of nylon6/HDPE blends were studied by using XLY-Ⅱrheometer.The curves of lgτ_ω-lgγ_ω,lgη_a-lgγ_ω,lgη_a-1/T were obtained.The experimental results showed that PA6/HDPE blends were pseudoplastic fluid.The apparent viscosity of the blends reduced with the increase of the shearing rate. Compared with PA6, the addition HDPE,MAH and L-101 increased the apparent viscosity.And in the same shearing stress the reducing viscous activation energy of the blends indicates that the processing temperature has less influence on their rheological behaviour. The results of polarized optical microscopy (POM) show that PA6 can generate global tridimensional crystals under the experimental conditions. And the addition of HDPE,the size of global tridimensional crystals becomes small obviously.It shows the addition of HDPE plays a role in heterogeneous nucleation.It promots the crystallization of PA6.PA6 and PA6/HDPE which were observed by X-ray diffraction can be found in the experiments: in the addition of MAH and L-101, diffraction peak position of PA6 has not be changed,and it doesn't appearance new diffraction peaks.It shows that the addition of MAH and L-101 doesn't change the crystal of PA6.The isothermal crystallization behavior of in-situ compatibilized PA6/HDPE blends was studied by means of differential scanning calorimetry (DSC).The crystallization kinetics under isothermal conditions was analysized by the Avrami equation.It is shown that the Avrami equation is applicable for isothermal crystallization very well , and the calculated Avrami index n is from 2.19 to 3.70,which demonstrates that the crystallization of nylon 6/HDPE blends is growing with global tridimensional crystals in this situation.The equilibrium melting temperature was obtained from Hoffman-Weeks theory.The non-isothermal crystallization kinetics of in-situ compatibilized PA6/HDPE blends was studied by means of differential scanning calorimetry(DSC).And its nonisothermal crystallization kinetics was studied by the Avrami equations modified by Jeziorny and Mo method.And some important parameters were calculated.The results show that the above equation and method can describe the nonisothermal crystallization of nylon 6 and nylon 6/HDPE blends well.At primary crystallization stage, there are heterogeneous and homogeneous nucleations during the nonisothermal crystallization of nylon 6/HDPE blends. In the secondary crystallization stage, the growth is one-dimensional mode.And the addition of HDPE plays a role in heterogeneous nucleation.It promots the growth of the nuclei.Additionally,the relationship between the activation energy of nonisothermal crystallization (E_a) for nylon 6/HDPE blends and temperature (T) is obtained from Vyazovkin method.