Studyies On Prepatation And Properties Of PVC/Organoclay Nanocomposites

Polymer/Clay nanocomposite, as a kind of novel material, is arousing wide interest among the researchers due to its excellent properties and significance in the scientific research. In this thesis, PVC/Organoclay nanocomposites were synthesized by in-situ intercalation and melt-blending intercaltion. The structure and properties of the composites were investigated. Furthermore, some factors, such as special synthesis method, the different clay surface modifiers and the molecular weight of the polymer matrix which can be affect the intercalation results, were discussed.The structure of the composites was characterized by X-ray diffraction and transmission-electric microscope. The experimental results showed that the in-situ intercalation realized much finer dispersion of the silicate layers in the PVC matrix than the melt-blending intercalation. As for as the properties of the composites, the well-dispersed organoclay in the composites improved the properties of the materials, especially for the Viscat Softing Temperature. Compared with the two kinds of composites, silicate layers gained much finer dispersion in the PVC matrix due to the special process. Besides, based on the GPC results, the organoclay does not have apparent effect on the molecular weight and its distribution.For the melt intercalation system, the clay surface modifiers have great influence on the intercalation effect, while no great effect for the intercalation system. Such a result may be attributed to the different intercalation mechanism and process, at the meanwhile, we can learn that the intercalation and exfoliation can be made in a much wider range of organoclays and at a greater extension by in-situ intercalation than the melt-blending.The intercalation effect can be affected by the matrix molecular weight. Base on our experimental results, a conclusion can be deduced. When the polymer and silicate layers have some capacity, the polymer chains with great molecular weight can exert much greater shear andstress, which is favorable to the exfoliation. While, the huge molecular weight could lead to the loss of fluidity of the polymer melt. So it will hinder the intercalation or exfoliation of the polymer at some extent. In a sum, the final intercalation structure is determined by many factors.The thermo-degradation of PVC/Clay nanocomposites was discussed. The ammonium in the organoclay galleries has bad effect on the properties of the composites. Therefore, some new kinds of modifiers will be meaningful and urgent to wholly improve the properties of the PVC/Clay nanocomposites.