Study On The Reaction Of In Situ Polymerization And In Situ Compatibilization Of PS-MMA/ε-CL And The Formation Mechanism Of Their Nanoblends

Control of phase morphology of incompatible polymer blend systems is an important subject which has gained increasing attention in the recent years. Reactive compatibilization, or in situ compatibilization can be adopted to efficiently improved the compatibility between the polymer components, reduce the size of the dispersed particles and thus enhance the properties of the materials. However, it is still unable to make the size of dispersed particles below 100nm. More recently, it was successfully prepared the nanoblend with size of dispersed particles about 80nm via a novel process of in situ polymerization and in situ compatibilization. This is an important progress achieved in the field of polymer blend. Therefore, it is no doubt that to further get better understanding of the formation mechanism from thermodynamic and kinetic aspects has important theoretical and practical significances in the development of such new materials.In this dissertation, with the poly(styrene-co-methylmathacrylate)(PS-MMA) as a macroactivator, the process of in situ polymerization and in situ compatibilization of PS-MMA and ε-caprolactam (ε -CL) was systematically studied;the PS-g-PA6/PA6 nanoblends with subtle phase morphology were prepared;the factors which affect the phase morphology of the nanoblends were discussed in detail;in addition, the theoretical simulation of the phase morphology was made for the reactive blends by using a genetic algorithm(GA) method. The main results obtained are as follows:1, The process of in situ polymerization and in situ compatibilization PS-MMA andε -CL was performed by using three different mixing methods. The resultsindicated that with one-step mixing method(method A), the reactants weredifficult uniformly mixed due to the large difference in viscosity betweenPS-MMA and e -CL, thus unable to achieve the nanoblends with uniform particle size. However, with both pre-dissolve methodC method B) and pre-solvent mixing method (method C), PS-MMA and e -CL could be mixed uniformly, consequently, in the presence of macroactivator, microactivator and initiator, more PS-g-PA6 graft copolymer could be generated during the process of in situ polymerization and in situ compatibilization, and thus the uniformly dispersed nanoblends of PS-g-PA6/PA6 could be achieved. With method C, the nanostructured morphology could be remained after annealing, even after melting. The WAXD analysis demonstrated that there still existed some imperfect PA6 crystallites in the nanoblends of PS-g-PA6/PA6. However, there was no distinct melting peak viewed in the DSC curves.2, The important factors which affect the process of in situ polymerization and in situ compatibilization of PS-MMA and e -CL were studied. The results indicated that the amount, the molecular weight of PS-MMA and the content of MMA in PS-MMA had significant effect on the reaction process: as the amount of PS-MMA lower than 30wt%, with increasing the amount of PS-MMA the graft yield increased while the molecular weight of dispersed PA6 decreased;by using low molecular weight of PS-MMA and increasing the content of MMA in the PS-MMA, both were favorable to enhance the graft yield and the amounts of PS-g-PA6 generated meanwhile the content and the molecular weight of PA6 were toward decrease. With increasing the amount of BDI, the amount of PA6 in the reactive blends increased while the amount of PS-g-PA6 and the average degree of the PA6 grafted branches reduced. Elevating the mixing temperature was benefit to increase the amount of PA6 and decrease the amount of PS-g-PA6 in the blends.3 > The kinetics of the process of in situ polymerization and in situ compatibilization of PS-MMA and e-CL was discussed. The results indicated that enhancing both the amount and the content in the PS-MMA were favorable to increase in the graft reaction rate while decrease in the homopolymerization rate of e-CL;Contrarily, enhancing the amount of BDI was favorable to the generation of PA6 and reducing the graft reaction rate;lowering the reaction temperature and increasingthe molecular weight of PS-MMA used both were unfavorable to the homopolymerization of e-CL and graft reaction with PS-MMA. The results further indicated that the lower the amount of e-CL, the more content of MMA in the PS-MMA, and the higher the reaction temperature, the more deviation from the linear reaction of log(l-C)~t was viewed.4> The effect of the blending conditions on the phase morphology of the reactive blends in situ prepared was further analyzed by using a image statistical method. The results revealed that enhancing the amount and the content of MMA in the PS-MMA, using higher molecular weight of PS-MMA, and retarding the addition of microactivator BDI, all these factors were favorable to form fine and uniformly distributed nanostrucured morphology. The effect of temperature on the morphology was complicated, when at 200 °C, it was unfavorable to the formation of the dispersed particles with nanostructure.5, The phase morphology evolution of the blends formed during the process of in situ polymerization and in situ compatibilization was for the first time systematically examined by using small angle light scattering (SALS) method. The results showed that the diffusion of small molecules toward inner part of dispersed phase and aggregation between the dispersed particles were coexisted which could cause an increase in their diameter and the distance between them. With enhancing the molecular weight, the amount of PS-MMA and the content of MMA in the PS-MMA chain, lowering the temperature used, all these factors were possible to reduce the diameter of the dispersed particles and the growth rate of the distance between them. With the amount of BDI in 5.23g/100g e -CL, the diameter of the dispersed particles and the growth rate in the distance between them were highest.6, The theoretical simulation of the phase morphology was for the first time made for the reactive blends formed via the process of in situ polymerization and in situ compatibilization by using a genetic algorithm (GA) method. The predicted patterns of the blends were generally in consistent with the previous experimental results.