【作者】 吕艳娜；

【导师】 何北海；

【作者基本信息】 华南理工大学 ， 制浆造纸工程， 2014， 博士

【摘要】 塑料包装在广泛使用的同时也引起了严重的环境污染问题。由于大多数塑料包装制品来源于不可再生的石油资源，因此寻找一种新的行之有效的方法来处理塑料包装材料造成的污染，同时摆脱对石油基材料的过度依赖成为全球的热点问题。本论文以造纸工业的废弃物蔗髓（BP）为原料，分别将其与淀粉熔融共混制备生物质复合包装材料，与亚硫酸盐制浆废液混合制备生物质缓冲包装材料。研究了蔗髓生物质包装材料的增强机理及制备工艺，对所制备材料的力学性能、流变性、热稳定性和吸湿性进行了分析，为蔗髓在新型包装材料领域中的应用提供了依据。采用甘油和尿素混合增塑剂制备热塑性淀粉（TPS），TPS的X-射线衍射说明尿素和甘油的质量比大于1:1时，混合增塑剂能够抑制淀粉的老化回生。扫描电镜（SEM）和转矩流变仪流变曲线显示增塑剂中尿素含量增加，其对淀粉的塑化效果变好。综合力学性能和包装材料加工特性要求，甘油和尿素混合增塑热塑性淀粉的适宜质量比为1:1。以TPS为基体，蔗髓作为增强相通过熔融共混法制备蔗髓/热塑性淀粉复合包装材料（BP/TPS）。研究了混合增塑剂用量、蔗髓用量、转速、加工温度对材料拉伸性能和弯曲性能的影响，同时优化得到最佳的制备工艺为蔗髓用量10wt%（以绝干淀粉质量计），混合增塑剂用量45wt%（以绝干淀粉质量计），m（甘油）：m（尿素）=1:1，转速40r/min，加工温度140°C。此时得到的包装材料的拉伸强度和断裂伸长率分别为16.71MPa和15.18%，弯曲强度和弯曲模量分别为21.91MPa和1267.55MPa，具有较好的力学性能。研究了40～60目间蔗髓的含量对BP/TPS流变性、力学性能、热稳定性和吸湿性的影响。结果表明，蔗髓含量增加，混合物料塑化时间延长，平衡转矩增大；BP/TPS的拉伸强度和弯曲强度增大，热稳定性提高；在低相对湿度（RH=43%）下，蔗髓加入导致TPS吸湿率上升；在高相对湿度（RH﹥75%）下，蔗髓加入降低了TPS吸湿率。而在RH=75%时，蔗髓对TPS吸湿率的影响取决于其加入量的多少。红外光谱（FT-IR）和扫描电镜（SEM）显示，蔗髓和TPS基体之间形成的分子间氢键以及二者之间良好的界面结合是蔗髓作为增强相的根本原因。研究了蔗髓粒径对BP/TPS的流变性、力学性能和吸湿性的影响，并建立了最大转矩和蔗髓粒径的关系函数。结果表明，随着蔗髓粒径变小，材料的拉伸强度和断裂伸长率都呈现先增大后减小的趋势，其中60～100目间的蔗髓增强热塑性淀粉材料的拉伸性能最好；随着蔗髓粒径变小，BP/TPS包装材料的弯曲强度增加，而弯曲模量降低；当蔗髓含量为10wt%时，在低相对湿度（RH=43%）下，实验中所用四种粒径的蔗髓都不能够抑制TPS的吸湿；而在高相对湿度（RH﹥75%）下，实验中所用四种粒径的蔗髓都能够抑制TPS的吸水。通过对蔗髓进行不同浓度、温度下的碱处理和酸碱混合处理，研究了蔗髓中木素含量对BP/TPS力学性能的影响。结果表明，随着木素含量的降低，BP/TPS材料的拉伸强度逐渐增大，而断裂伸长率呈现先增大后减小的趋势。当在30°C下脱出蔗髓中的木素时，随着木素含量降低，BP/TPS材料的弯曲强度和弯曲模量表现出先减小后增大的趋势，木素含量为12.70%的蔗髓填充的材料的弯曲强度和弯曲模量最大，分别比未处理蔗髓材料增加14%和34%。以蔗髓为基材，蔗渣亚硫酸氢镁制浆废液为胶黏剂，气相法白炭黑为补强填料，通过常温模压工艺制备蔗髓缓冲包装材料（BPCPMs）。研究了蔗髓用量、白炭黑用量、以及白炭黑比表面积对BPCPMs表观密度和力学性能的影响。BPCPMs的微观形态分析表明，气相法白炭黑对于材料的增强是白炭黑填料-聚合物基体间以及白炭黑填料-填料间相互作用的综合结果，白炭黑与基体间的氢键结合以及其在基体中的分散情况均是影响BPCPMs性能的重要因素。BPCPMs具备良好的缓冲性能，可以代替高密度EPS（硬质泡沫塑料）包装脆值较高、质量较大的产品。BP/TPS和BPCPMs的微生物降解实验结果表明，经过15d处理，前者的降解率都大于80%，后者的降解率最高达到52.5%，说明蔗髓生物质包装材料在霉菌作用下具有良好的降解性能。更多还原

【Abstract】 The serious pollution originated by disposal of large volume of plastic packages,together with the depletion of petroleum stocks, have prompted to an increasing interest innew natural-based biomass packaging materials design. In this paper, a new biomasscomposite material was prepared based on bagasse pith and corn starch by melting blendmethod, and a new biomass cushion packaging material was prepared based on bagasse pith,magnesium bisulfite spent liquor, and reinforcing silica filler by press-molding process. Thebiomass packaging materials were evaluated in terms of mechanical properties, rheologicalproperties, thermal stability and water absorption. The reinforcement mechanism of bagassepith and fumed silica particles were also analyzed, respectively.Thermoplastic starch (TPS) was prepared with glycerol and urea as mixed plasticizer.X-ray diffractometry demonstrated that TPS could restrain starch retro gradation when themass ratio of glycerol to urea was above1:1. SEM micrographs and rheological curves ofstarch plasticization processing showed good plasticizing effect with increasing urea content.According to the mechanical and processing properties of TPS, the optimum mass ratio ofglycerol to urea was1:1.Bagasse pith/thermoplastic starch (BP/TPS) packaging materials were prepared fromthe matrix of TPS and the reinforcement of bagasse pith by melt processing. The influencesof mixing plasticizers contents, bagasse pith loadings, roller speeds and processingtemperature on the tensile properties and flexural properties were investigated. The optimumprocess conditions were demonstrated as follows: the bagasse pith content of10wt%, themixed plasticizers content of45wt%, the mass ratio of glycerol to urea of1:1, roller speeds of40r/min, and processing temperature of140°C, which achieved that the tensile strength was16.71MPa, the flexural strength was15.18%, elastic modulus was21.91MPa, and flexuralmodulus was1267.55MPa.The influences of bagasse pith (40～60mesh) content on the rheological properties,mechanical properties, thermal stability and water absorption of BP/TPS were analyzed. Theplasticization time and constant torque of mixed blends increased with increasing bagassepith content. Moreover, the tensile strength and flexural strength increased, and the thermal stability improved. Water absorption of TPS increased with the addition of bagasse pith at43%RH, while decreased as RH＞75%. The water absorption of TPS were determined bybagasse pith contents at75%RH. FT-IR and SEM illustrated that the intermolecularhydrogen bondings and strong interfacial interactions were formed in the bagasse pith andTPS, which led to reinforcing effect of bagasse pith.The effects of particle size of bagasse pith on the rheological properties, mechanicalproperties and water absorption of BP/TPS were studied, and a relationship function betweenmaximum torque and particle size was established. The results showed that tensile strengthand elongation at break increased at first and then decreased with decreasing particle size.The maximum value of tensile properties of TPS reinforced by pith (60～100mesh) wereobserved. Flexural strength of BP/TPS increased, while the flexural modulus decreased withdecreasing particle size. With the same bagasse pith loading of10wt%, the water absorptionof TPS increased with the addition of bagasse pith (＞60mesh) at43%RH, while decreasedas RH＞75%.Bagasse pith was pre-treated by different concentrations of NaOH solution at differenttemperatures. The effects of lignin content of bagasse pith on the mechanical properties ofBP/TPS were investigated. The results showed that tensile strength of BP/TPS increased withdecreasing lignin content, and the minimum tensile strength was achieved by BP/TPS with5.38%lignin content. The elongation at break of BP/TPS increased at first and then decreasedwith decreasing lignin content. When the lignin extraction was carried out at30°C, theflexural strength and flexural modulus decreased at first and then increased with decreasinglignin content, and the maximum values were achieved by BP/TPS with12.70%lignincontent, up14%and34%on the values of the untreated bagasse pith/TPS, respectively.A new biodegradable cushion packaging material was prepared based on bagasse pith,magnesium bisulfite spent liquor, and reinforcing silica filler. The effects of bagasse pithcontent, fumed silica loading and BET Surface Area of fumed silica on the apparent densityand static compressive strength of the bagasse pith cushion packaging materials (BPCPMs)were investigated. The SEM image of the BPCPMs revealed that the reinforcement effect offumed silica was the consequence of silica filler-matrix interaction and silica filler-fillerinteractions. The most important factors to affect the properties of BPCPMs were the hydrogen bonds between the molecules of lignosulfonate and silanol groups on the silicasurface and dispersion state of silica particles in the matrix. BPCPMs had good cushioningproperties within a large stress range and can be used for packaging heavy delicate articles.The bio-degradation performance of BP/TPS and BPCPMs were investigated by mouldsdegradation. The results indicated that the degradability rates of BP/TPS were above80%,and the maximum degradability rate of BPCPMS was52%after15days of incubation in amedium of liquid nutrients. These results indicated the biomass packaging materials based onbagasse pith had good bio-degradation performance.更多还原