【作者】 陈港；

【导师】 何北海；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2013， 博士

【摘要】 纸张作为可书写、印刷、包装的材料,具有原料来源丰富、可生物降解、可回收再利用、良好的机械性能和后加工性能，成本较低、容易卷曲等特点，随着社会经济的快速发展和人类文明的进步，用途越来越广泛。在纸张应用过程中，其性能会因环境条件的变化发生变化，其中温度的影响是最常见因素之一。纸张在热作用下性能的变化严重影响了纸张的使用。本论文针对纸浆、纸张的热性能及其评价方法进行系统研究，旨在弄清影响纸张热性能的各种因素，纸张在热作用下热降解、热老化、光热返黄等内在规律，建立科学评价纸浆纸张热性能的方法，为提高纸张在热环境下的使用效率和研究开发具有良好热性能的新型纸张提供理论支持。TG分析表明，浆料热降解主要经历吸附水解吸，开始脱水热降解，主要热降解阶段和残余热解阶段四个阶段。 TG分析的关键温度Tw、T0.5、TMax可作为浆料热稳定性评价的参数。纸浆热降解机理可用模型方程G() ln(1)来描述，动力学方程为：其中活化能E可用于纸浆热稳定性评价，纸浆的活化能越高，热稳定性越好。漂白针叶木纸浆热稳定性大于漂白阔叶木纸浆；非木材类纸浆中，以棉浆、麻浆的热稳定性为最佳；脱墨浆劣于原生漂白化学浆；未漂浆的热稳定性较漂白浆差。BCTMP热稳定性较差。在给定的光诱导条件下，随光照时间的延长，BCTMP白度呈下降趋势，PC值则不断增大，杉木BCTMP白度稳定性最差，返黄最为严重；BCTMP的R、PC值与lgt呈分段线性关系；通过回归分析得到的R、PC值随光照时间的变化模型利用红外光谱和拉曼光谱相结合分析揭示光诱导条件下BCTMP浆料中官能团结构的变化和光诱导返黄机理，光诱导过程中羰基和碳-碳双键基团的产生是引起BCTMP返黄的重要原因。研究了纸张老化过程纸张强度、白度、聚合度、结晶度、活化能的变化。纸页强度和白度随老化程度的加剧总体呈下降趋势。老化前后纸张的SEM观察表明，纸样随老化程度的增加，纸张纤维表面出现裂纹、裂痕增多甚至龟裂和空洞的现象愈加严重，导致纤维之间的结合力的降低；老化前后XRD分析结果表明，在150℃以下老化纤维素晶体类型和结晶度并没有发生变化。纸张的热解主要经历纸张失水失重、纸张纤维热分解失重和残余失重三个阶段。填料等其他物质的加入导致残余阶段热解与纯纸浆的有差异。浆内加填对纸张的热稳定性有利，使用机械浆和回收浆对纸张稳定性有负面影响。纸张DMA分析表明，纸张损耗模量和损耗因子随温度增加而逐步提高，但没有出现拐点。纸张储能模量因纸张浆料配比和定量的不同有所变化。随着老化时间的增加，纸张的聚合度总体呈下降趋势，而活化能随着老化程度的加剧，纸张的活化能先增大后减小。纸张聚合度相对值(DP/DP0)与Δθ0.5存在指数量化关系，Δθ0.5可作为衡量纸张老化程度的一个参量；根据得到的指数模型方程可对应计算出聚合度相对值，所得的评价模型与实验数据吻合很好，模型具有较好的预测性。以常见的纸杯为研究对象，定义某一温度区间内冷热面温度曲线偏离标准线的积分面积为温度因子ω，ω与温度t之间的关系可用方程：进行描述。某温度区间的温度因子ω可用于纸张材料整体隔热性能的定量评价，以此首次提出了纸张材料整体隔热性能评价的新方法。更多还原

【Abstract】 As a material for writing, printing, and packaging, paper has the characteristics ofabundant sources, biodegradability, recyclability, excellent mechanical properties andpost-processing performance, low cost, and flexibility. With the rapid economic developmentand social progress of human civilization, more potential areas will be explored in future.The properties of paper alter as the change of environmental conditions during theapplication of paper, one of significant factors is temperature which will severely affectpaper’s performance that hinders the application of paper. In this thesis, the thermalperformance of pulp&paper and its evaluation method are systematically studied aiming toclarify the factors influencing the thermal performance of paper and explore the intrinsic lawexisting among pyrolysis of paper, thermal aging, yellowing and so on under thermalcondition. More specifically, the research work establishes scientific method to evaluate thethermal properties of paper and provides theoretical support for efficiently utilizing paperunder high temperature atmosphere and developing new paper with excellent thermalstability.Thermogravimetric analysis shows that there are four phases occurring in the course ofthe thermal degradation of paper: loss of adsorbed water, dehydration, the main thermaldegradation and residual pyrolysis. Three primary temperatures (Tw, T0.5, and TWax) are usedto evaluate the thermal stability of pulp.The mechanism for the thermal degradation of pulp is depicted by the model equation. Kinetic equation isln()lnE, the activation energy be used to evaluate the thermal stability of pulp, the higher pulp activation energy representsbetter thermal stability of paper.When it comes to the thermal stability of various pulp, bleached softwood pulp issuperior to bleached hardwood pulp; for the non-wood pulp, cotton and hemp possess highestthermal stability; besides, deinking pulp (DIP) is inferior to virgin bleached chemical pulp, unbleached pulp is worse than bleached pulp; and BCTMP has poor thermal stability.For the given light-induced conditions, the brightness of BCTMP decreases as theincrease of light-induced time, but the PC value shows a downward trend. BCTMP made fromfir demonstrates a worst brightness stability and a serious yellowing phenomenon. R and PCvalues of BCTMP exhibit a linear relationship in a certain range with lgt of BCTMP,respectively, and the model demonstrating the R and PC value of BCTMP vary as theextension of light-induced time was deduced by regression analysis.Light-induced yellowing mechanism of BCTMP is studied by using Infraredspectroscope (IR) and Raman spectroscope to analyze the structure of functional groupswithin BCTMP before and after it exposes to ultraviolet light, and results illustrate that theappearance of double bond and triple bond between two carbons in BCTMP during thelight-induced procedure primarily causes the color reversion of BCTMP.There are three phases occurring in the pyrolysis of paper: dehydration, mass loss ofcellulose, and mass loss of char residue. The addition of fillers or other additives in the paperresults in the pyrolytic difference in the third phase compared with paper made of purecellulose. Filler loading is beneficial to thermal stability of paper, however, mechanical pulpand recyclable pulp have an adverse effect on thermal stability of paper. According toDynamic mechanical analysis (DMA), the loss modulus and damping factor of paper improveas the increase of temperature, but no turning point is observed in the pyrolytic curve. Inaddition, the storage modulus varies as the basic weight of paper and pulp proportion.Tensile strength, brightness, degree of polymerization, crystallinity and activation energyof paper during the aging process are investigated in detail. As the increase of aging time,tensile strength and brightness of paper present a downward trend. SEM images of the paperbefore and after aging indicates the phenomenon of cracking was even more serious and more and more voids appeared on the surface of paper fibers. This led to the binding force betweenfibers decreased; the crystallinity and crystal type of cellulose of paper before and after aginghad not changed under the aging temp.150°C based on XRD results.With the aging time increases, the degree of polymerization of the paper demonstrates adecreasing trend, however, the activation energy of the paper first increases and thendecreases.There is a quantitative relationship between the relative value of paper polymerizationdegree (DP/DP0) and Δθ0.5which can be used to evaluate the aging degree of paper. Therelative value of the polymerization degree can be calculated from the obtained equation, andthe evaluation model fits well with the experimental data, which indicates the good predictionof our model.A novel method for evaluating insulating properties of paper is proposed by taking papercup as the research object. We define temperature factor ω as the integral area of temperaturecurve on hot and cold side that deviates from standard curve in a certain temperature range,The relationship between temperature factor ω and temperature t is described by an equationThe temperature factors ω in a certain temperature range can be used toquantitatively assess the thermal insulation performance of paper material.更多还原