| There exists strong hydrogen bonds between the amido group of crystalline polymer nylon 66 (PA66), which PA66 has high crystallinity and melting point, pretty mechanical properties, excellent resistant performance to corrosion, wear and heat, self lubrication, etc. However, there are disadvantages in pure PA66, such as poor impact resistance and high water absorption when it is at a dry state and low temperature, which narrows the application fields of nylon. Blending nylon and polyolefin can overcome the shortcomings of PA66. Ethylene-1-octene copolymer (POE) is one of the most effective flexibilizer of thermoplastic elastomers for nylon for the cold resistance and toughening modification. But the key point is poor compatibility between the non-polar POE and the polar nylon. The approach in this paper is that grafting polar small molecule of itaconic acid (ITA) in the molecular chain of POE, which could react with amido group in the molecular chain of PA66. Then the compatibility of in-situ reaction occures during the process of melt extrusion reaction of the graft polymer and PA66. Finally, it generates one kind of graft or block copolymer, which strengthens the adhesive force between the interface of two phases, and minimizes the size of the disperse phase while widens the distribution range of dispersed phase in the continuous phase. These led to the remarkable improvement in the performance of toughness of the nylon blends.In this paper, the ITA grafted POE (POE-g-ITA) was prepared by melt extrusion in twin-screw extruder. Infrared spectroscopy and chemical titration method show that ITA has been grafted to the POE molecular chains by chemical reaction. The processing conditions on the grafting reaction, such as the content of the monomer ITA, the content of initiator dicumyl peroxide (DCP) and screw speed have been explored. The optimum conditions were determined as POE/ITA/DCP=100/2/0.25, screw speed of 200r/min and reaction temperature of 180℃.In order to compare with PA66/POE-g-ITA blends, PA66/POE-g-MAH blends were prepared. In PA66/POE-g-MAH blends, the brittle-ductile transition occurred when the content of POE-g-MAH was 10wt%-15wt%. The Izod notched impact strength of the blends came up to 83.3kJ/m2when the content of POE-g-MAH was 20wt%,18.5 times than that of pure PA66, which reached to the super toughening purpose. SEM photographs showed that POE-g-MAH had a significant effect both on the compatibilization and toughness to PA66. With increase of the content of POE-g-MAH, the notched impact strength of the blends increased significantly, while the tensile strength, bending strength and modulus declined, the elongation at break increased, the melt flow rate and the water absorption decreased. The brittle-ductile transition occurred when the graft rate of POE-g-MAH was 0.05%-0.2%. With the increase of graft rate of POE-g-MAH, the notched impact strength of blends increased, while the tensile strength, bending strength and modulus declined little, the elongation at break increased, the melt flow rate decreased, and the water absorption didn't change obviously.The content of ITA, the content of DCP and the screw speed when POE-g-ITA were prepared, which affected the mechanical properties, melt index, water absorption in the PA66/POE-g-ITA blends. The optimum range of each factor was as determined as the content of ITA and DCP of 1-2wt% and 0.1-0.25wt% respectively, and the screw speed of 200-300r/min. In PA66/POE-g-ITA blends, the brittle-ductile transition occurred when the content of POE-g-ITA was 15wt%-20wt%. The Izod notched impact strength of the blends came up to 84.8kJ/m2 when the content of POE-g-ITA was 20wt%,18.8 times than that of pure PA66. With increase of the content of POE-g-ITA, the notched impact strength of the blends increased significantly, while the tensile strength, bending strength and modulus declined, the elongation at break increased, the melt flow rate decreases, and the water absorption decreased obviously. There was comprehensive high performance in PA66/POE-g-ITA blends than PA66/POE-g-MAH blends, and PA66/POE-g-ITA blends could be compared with the mechanical properties such as the super toughing of Du Pont Zytel ST 801. SEM photographs and Molau compatibility experiment showed that, POE-g-ITA had a significant effect both on the compatibilization and toughness to PA66. With the increase of the content of POE-g-ITA in PA66/POE-g-ITA blends, the impact toughness increased, the particle size of dispersed phase decreased, the compatibility of the two phases improved. The compatibility of in-situ reaction occurred in the blends, and then generated PA66-ITA-g-POE graft or block copolymer, which acted as emulsifier in the blends interface, inhibited the aggregation of dispersed particles, reduced the interfacial tension, diminished the particle size of dispersed phase. Therefore, the compatibility and cohesive force between the interface of two phases were enhanced, and the dispersity of the dispersed phase was also improved in the matrix.In this paper, the non-isothermal crosslinking of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) in present of benzoyl peroxide (BPO) also was studied by differential scanning calorimetry (DSC) analysis. The thermal kinetics of the reaction was analyzed using model-free methods including Friedman, Ozawa-Flynn-Wall, and Kissinger methods and the initial kinetic parameters were calculated. The precise parameters were also obtained by using model-fitting method via multivariate nonlinear regression analysis. Three steps in the crosslinking reaction of SEBS were identified with the activation energies becoming smaller. It showed that the crosslinking degree of SEBS could be controlled by varying the reaction temperature and time.
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