Study On The Thermal Stability Of Coal/Polymer Blends

Coal/polymer blends are synthesized by three kinds of coal (Tongchan Xujiagou Coal, Shenfu3-1 Coal and Huayingshan Lushuidong Coal) and three kinds of polymer matrix(LDPE,LLDPE,HDPE). The thermal stability and thermal oxidation stability of the samples were investigated by means of TG and DSC, respectively. Three kinds of coal have different effect on polymer stability, for thermal stability, the effect degree are in agreement with the aromaticity of coal. The structure, melt index and crystallinity of matrix also have important effect for the blends thermal stability. The effect degree order are: LDPE>LLDPE>HDPE. The coal have same effect on thermal and thermal oxidation stability of LDPE and LLDPE, but contrary on the HDPE. When coal concentration <10wt%, the thermal stability of the blends were decreased, especially when coal concentration was 5wt%. Study shown that different assistants contribute to different effects on the thermal stability of the blends. It was depend on the structure and effect of assistants. So the coal, coal content; the structure and properties of matrix; the structure and effect of assistants are the key factors to affect thermal stability blends. The difference of these factors affect on thermal stability of blends provide base for blends's control degradation. Base on the FTIR of thermal decomposition products and the result of preference, a irregular broken chain initiated free radical chain reaction mechanism was assumed for the thermal degradation and thermal oxidation of the blends. Coal participates in all process of chain initiation, chain communication and chain termination. The effect of coal mainly incarnates through the *H donor function of coal peripheral functional groups and –OH group produced during coal thermal degradation, made the chain reaction end through the chain transfer of active free radical and formed phenol-oxygen free radical which have the conjugate structure. At the same time, the aroma macromolecule free radical of coal made the chain reaction end by combining with polymer macromolecule free radical. The adding of coal in the blends are benefit to the thermal and thermal oxidation stability for the predominate of chain transfer and chain end in blends when high coal content. On the condition of low coal content, the thermal stability of blends decreased, for great deals of free radical exist in coal at room temperature. Thermal degradation dynamic were studied based on TG data. Results further proved that the exist of coal changed the thermal mechanism of polymer.