【作者】 张杨；

【导师】 杨飞；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2017， 硕士

【摘要】 纸张的耐热性是指纸张在低于其燃点温度下使用时,表现出的物理化学性能的稳定性。植物纤维是纸张的主要组成部分,其耐热性能直接决定了纸张的耐热性能。研究并改善植物纤维的耐热性能,将深化对植物纤维耐热性的认识,为扩大纤维及纸张的应用范围奠定理论基础,具有重要的社会意义和经济价值。本研究挑选了造纸中较常用的10种植物纤维原料,通过热重分析和纸张热处理的方法分析比较了植物纤维的耐热性,研究了造成植物纤维耐热性差异的原因,并通过原位沉淀氢氧化铝的方法改善了植物纤维的耐热性能,具体研究内容及结论如下:分别以空气和氮气为载气,通过热重分析法探究了植物纤维在有氧和无氧状态下的起始分解温度T0、开始大量分解温度Te和分解速率最快时的温度Tm。通过关键温度T0、Te和Tm的对比,发现不同植物纤维耐热性能不同,麻浆的热稳定性最好,针叶木的热稳定性整体表现优于阔叶木,此外植物纤维在有氧状态下更容易分解,热稳定性更差。以所选植物纤维为纸浆原料抄造纸样,研究发现纸张受热后的白度稳定性和强度稳定性呈现不同的规律,白度稳定性好的纸样强度稳定性不一定好,反之亦然。通过对所选原料的组分和结构进行研究,结合原料的耐热性差异,发现半纤维素对纸张受热后的白度稳定性影响较大,半纤维素含量越高,纸张受热后的白度稳定性越差。而结晶度和聚合度高的原料抄造出来的纸样则表现出较好的强度稳定性。从所选原料中挑选出有代表性的浆料P1、P2、P7、P9进行打浆研究,发现打浆能提高纸张受热后的白度稳定性,降低纸张受热后的强度稳定性,但是打浆会提高纸张的强度,提高的强度足以弥补纸张受热后强度稳定性降低造成的强度损失。本论文对植物纤维进行原位沉淀氢氧化铝的改性,不仅使OH-和Al3+在纤维表面结合沉淀出氢氧化铝,还会使OH-和Al3+穿过细胞壁在纤维内沉淀出氢氧化铝,使得氢氧化铝均匀的分布在纤维的表面和内部,降低了氢氧化铝的加入对纸张强度的负面影响,使纸张中氢氧化铝的加入量提高,从而提高了纤维及纸张的耐热性能。更多还原

【Abstract】 The heat resistance of paper refers to the stability of the physical and chemical properties of the paper when it is used below its ignition point.Plant fiber is the main component of paper and its heat resistance directly determines the heat resistance of paper.Researching systematically and improving the heat resistance of plant fiber system will deepen the understanding of the heat resistance of plant fiber,lay a theoretical foundation for expanding the application scope of fiber and paper,and have important social significance and economic value.In this study,10 kinds of plant fiber raw materials,which were commonly used in papermaking,were selected,the heat resistance of the selected plant fibers was compared by thermogravimetric analysis and paper heat treatment,the reason of difference of heat resistance of the selected plant fibers was analyzed and heat resistance of plant fibers has been improved by the way of adding Aluminum Hydroxide to plant fibers using in situ precipitation.The specific research contents and conclusions are as follows:The initial decomposition temperature(T0),the temperature at which a large amount of decomposition is started(Te)and the temperature at which the decomposition rate is the fastest(Tm)of plant fiber under aerobic and anaerobic conditions was investigated by thermogravimetric analysis using air and nitrogen as carrier gas respectively.Through the comparison of the critical temperatures T0,Te and Tm,it was found that heat resistance of different plant fiber was different,the thermal stability of the jute pulp is the best,and the thermal stability of the softwood is better than that of the hardwood.In addition,in the aerobic state plant fibers are more easily decomposed and the thermal stability is worse.The selected plant fiber is used as paper raw material for making paper,it was found that the brightness stability and the strength stability of the paper were different after heat treatment,some papers have good brightness stability,but their strength stability is poor,and vice versa.Based on the study of the composition and structure of the selected plant fiber and the difference in heat resistance of the paper,it was found that hemicellulose had a great effect on the brightness stability of the paper after heating,the higher the hemicellulose content,the worse the brightness stability.While the paper made by the fiber with high crystallinity and high degree of polymerization showed good strength stability.The representative fiber materials P1,P2,P7 and P9 from the selected materials were selected for beating research.It was found that beating can improve the brightness stability of paper after heating and reduce the strength stability of paper.But the beating will increase the strength of the paper,the increased strength is sufficient to compensate for the strength loss caused by the reduced strength stability of the paper after heating.In this paper,adding aluminum hydroxide to plant fibers using in situ precipitation to not only make OH-and Al3+ form aluminum hydroxide on the surface of fiber,but also make OHand Al3+ through the cell wall and form aluminum hydroxide inside of the fiber,enables aluminum hydroxide to be distributed uniformly on the surface and interior of plant fiber.Through this modification,the negative effect of the addition of aluminum hydroxide on the strength of the paper is reduced,the addition amount of aluminum hydroxide in the paper is improved,and the heat resistance of the fiber and the paper is improved.更多还原