Recycling Of Paper Mill Sludge As Filler In Polyvinyl Chloride Composites

With the rapid development of industry, the paper industry has become one of the major industrial pollution in China. On pulp and paper process, large amounts of solid waste paper mill sludge (PMS) are produced with papermaking wastewater processing such as precipitation and concentration. With high moisture content, PMS is mainly made of calcium carbonate, kaolin, cellulose, and so on.By reason of complicated components, it becomes the urgent problem to be solved that effective treatment and recycling of PMS.First, from analyzing physical and chemical properties of PMSbeing used for this study, it was obtained that main components and surface hydrophilicity of PMS.The surface of PMS were modified by single surface modifier including sodium stearate (NaSt), sodium dodecyl benzene sulfonate (SDBS), silane coupling agent KH550 and KH560.It was determined that the process parameters and the high-performance modifier by studying the effect of modifier types and modification conditions on viscosity in slurry and oil-absorbed value of PMS. Remarkable effect, which oil-absorbed valuedecreased to54.97g/100g andviscosity decreased tol 15.8mPa·s, had been obtained with compound modifier of NaSt/KH550. Besides, the influence of drying conditions and surface modification on drying process of PMS was investigated. The results showed that Midilli model was the best one for describing drying process of PMS. The moisture effective diffusivity (Deff) increased from 6.51 × 10-9to 18.64× 10-9m2/s and drying activation energy (Ea) was 22.23 kJ/mol. Finally,modified PMS, which was prepared by surface modification and drying, was filled in PVCcomposite materials. It was studiedthatmechanical properties, thermo-stability and microstructure of PVC/PMS composite materials. The results showed it is feasible that recycling of PMS as filler in thermoplastic composite.