【作者】 胡立华；

【导师】 周安宁；

【作者基本信息】 西安科技大学 ， 矿物加工工程， 2004， 硕士

【摘要】 选用铜川徐家沟煤、神府3－1煤和华蓥山绿水洞煤三种超细粉，低密度聚乙烯、线性低密度聚乙烯和高密度聚乙烯三种基体。用热重分析（TG）对煤/聚合物共混材料的热稳定性进行了研究，用差示扫描量热分析（DSC）对共混材料的热氧稳定性进行了研究，结果表明当煤组分含量大于10％时，有助于提高聚合物的热稳定性，且随着煤组分含量的增加，热稳定性逐渐增加。并且，煤种不同对聚合物基体的热稳定性影响不同，煤种使聚合物基体热稳性增加程度与煤的芳香度大小顺序一致。基体树脂的化学结构、熔融指数和结晶程度对煤/聚合物共混材料的热稳定性也有重要影响，其影响程度为：LDPE>LLDPE>HDPE。同一煤种对LDPE和LLDPE的稳定性影响一致，即热及热氧化稳定性均增加，而对于高密度聚乙烯却是增加了聚合物热稳定性而降低了聚合物的热氧稳定性。当煤组分含量小于10％时，煤/聚合物共混体系的热及热氧稳定性均降低，且当煤组分含量在5％时，对聚合物的热稳定性降低程度最为显著。助剂对煤/聚合物共混材料热稳定性影响研究表明，不同助剂对其有不同的影响作用，其影响取决于助剂的结构与作用。综上所述，影响煤的热稳定性、热氧化稳定性因素主要有：煤种、煤作为大分子聚合物在共混物中的比例，共混物基体树脂的结构与特性、助剂的结构与作用等。这些因素对煤/聚合物共混材料热稳定性影响的差异性为实现对煤/聚合物共混材料的热降解控制奠定了基础。煤种、煤含量以及功能性金属离子、抗氧剂是控制煤基共混物材料热降解和热氧化降解的关键因素。为此基于热解产物的FTIR及相关文献，推测煤基聚合物共混材料降解过程遵循无规断链引发自由基链式反应机理，煤参与了链引发、链传递、链终止全过程。对聚合物热稳定性影响主要体现在煤酚羟基官能团和煤热解生成产物中的酚羟基官能团的供氢作用，使其活性自由基发生链转移，形成具有高度共轭结构的煤基芳香大分子酚氧基稳定自由基，从而造成链反应的终止。同时，煤中固有的芳香大分子自由基也可与聚合物大分子自由基结合发生自由基链终止反应。因此，煤基聚合物共混体系中，煤的含量较高时，由于煤芳香大分子的链转移和链终止占优势，煤的加入有助于提高聚合物的热稳定性和热氧稳定性。但当煤的含量低于一定程度时，由于煤在室温下就存在大量自由基，因此煤的大分子自由基就可能起到自由基诱导和引发的作用，从而促进聚合物的降解，降低<WP=3>其热稳定性。通过TG分析，获得了相应的动力学参数。由动力学参数的变化进一步证明了煤的存在改变了聚合物的热降解机理。更多还原

【Abstract】 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 <WP=5>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.更多还原