Study On The Polymerization Of PBA Resin And The Preparation Of PBA Pulps

Poly p-benzamide(PBA) pulps have excellent compound property besides having kept high performance and excellent heat-resistance of PBA fibers .It can be used widely in the field of heat-resistance and reinforced materials. In this paper, PBA resin and pulps have been prepared directly by solution polycondensation and precipitation, separately.and got excellent heat-resistance PBA pulps.The conditions such as mol ratio of initial monomer concentration,the ratio of NMP and Py, reaction temperature on the molecular weight of PBA resin were studied. It was found that the ratio of NMP and Py, reaction temperature were the two key factors.New nontoxic additive of PVP with low molecular weigh on the properties of the resultant PBA resin was studied too. The polycondensation can be accelerated, the molecular weight of the polymer can be increased by the addition of the PVP. However, PVP hasnot affected the chemical structure of the resultant PBA resin.Got the relationship of η_inh and Wm.Rheology properties, coagulability and stability of the dope were studied. We had obtained some important parameters such as non-Newton exponent, viscous activation energy, structural viscosity index, etc. These research works provided important foundation for the preparation of PBA pulps.A new approach to forming PBA pulps is introduced in this paper — precipitation. That is, a PBA solution was injected into a rapidly stirred coagulant and formed PBA pulps. A mechanism of the process proposed is that when the viscous PBA solution is introduced into a rapidly stirred coagulant, it is dispersed into small drops. The drops of PBA solution become increasingly elongated by action of the extensional flow field with increasing time, then coagulated and solidified when sufficient coagulant has diffused across the boundary between PBA solution and coagulant. At high stirring speed, the solidified PBA fibers are fibrillated into fibrils and become PBA pulps with high specific surface area and certain mean length.The thermal stability and the kinetics of the thermal decomposition of PBA resin and pulps were studied by thermal gravimetric analysis method. It is found that PBA resin and pulps have good thermal stability, and have higher activation energy of thermal decomposition in nitrogenatmosphere. The degradation temperatures rise linearly with the increasing of the speed of rise temperature.New ideas mainly brought forward in this paper are:(1) A new nontoxic macromolecular additive was applied to increase the molecular weight of PPTA in this work.(2 ) A new approach to forming PBA pulps is introduced in this paper — precipitation.ZhaoWei(Material Physics and Chemistry) Supervised by Hu Panpan___________...