Study On The Preparation And Properties Of Silane Grafting Polyphenylene Sulfide (PPS)

This research developed a new method of toughening Polyphenylene sulfide (PPS) by silane grafting. Siloxane flexible group was grafted onto PPS by suspension grafting and silane crosslinking technique. The influences of silicone content, reaction time, reaction temperature and solvents on the graft reaction were investigated. The kinetics of thermal decomposition and crystallization of silane modified PPS were also investigated, and finally its rheological properties and impact toughness were studied.It was found that grafting degree increased with the increasing of silicone content, reaction time, reaction temperature. The degree of grafting and crosslinking of silane modified PPS could be controlled by adjusting these reaction conditions. Thermogravimetric analysis (TGA) result showed that the thermal decomposition of silane modified PPS was divided into two steps. First was the silane which was grafted onto PPS, follow by PPS main chain. The initial thermal decomposition temperature was much higher than processing temperature. The studies of thermal decomposition kinetics indicated that thermal decomposition reaction of silane modified PPS was first-order reaction and the activation energy of thermal decomposition reduced compared to pure PPS, but it was still a good thermal stable material. WXRD and PLM directly reflected that the crystallization degree of modified PPS decreased and grain size reduced. Differential scanning calorimetry (DSC) testing results and the studies of crystallization kinetics of silane modified PPS showed that its crystallization temperature reduced and crystallization rate decreased. The nonisothermal crystallization mechanism of silane modified PPS is predominately two-dimensional growth with heterogeneous nucleation mode. The effects of grafting ratio and content of silane modified PPS on modified PPS/pure PPS blends were investigated by using a haake torsion rheometer. Melt viscosity of PPS was not sensitive to shear rate. Although the melt viscosity of modified PPS increased with increasing of grafting ratio, it was still lower than that of pure PPS. The impact toughness of the blends increased with the increasing of grafting ratio and content of silane modified PPS. As the grafting ratio of modified PPS was 12.7% and its content in the blends was 35%, the impact strength was increased 26.7% compared to pure PPS.