【作者】 王娟；

【导师】 黄崇杏；

【作者基本信息】 广西大学 ， 制浆造纸工程， 2013， 硕士

【摘要】 纳米纤维素(NCC)因其质轻、价廉、优良的可生物降解性和可再生性、优异的机械性能使之成为复合高分子材料理想的填充增强材料。本文通过浓硫酸水解微晶纤维素的方法制备纳米纤维素,并通过接枝改性及偶联剂改性使之达到较好的分散性及与聚乳酸(PLA)的相容性。利用混炼机及平板硫化机压制复合薄膜,通过各个工艺对薄膜力学性能、阻隔性能及热学性能的影响分析优化出薄膜的制备工艺参数。并分别对PLA薄膜和NCC/PLA薄膜在酸、碱溶液及紫外光照射条件下进行降解实验,通过研究二者在降解过程中的失重分析、扫描电镜(SEM)观察以及X射线光电子能谱(XPS)分析对薄膜的降解机理进行研究。结果如下：(1)酸水解微晶纤维素得到的纳米纤维素粒径大部分低于100nm,符合纳米级单位要求；红外光谱图结果显示接枝改性纳米纤维素和偶联剂改性纳米纤维素的各分子结构中的各个基团对应红外光谱谱带位置均有吸收峰出现,表明两种改性方法均成功。(2)通过研究NCC含量、混炼温度、压板时间及NCC改性方法这四项参数对薄膜性能的影响,结果表明薄膜制备的最优工艺参数为：NCC含量5%、混炼温度190℃、平板硫化机压板时间4分钟、NCC改性方法为添加硅烷偶联剂kh560。在此条件下,薄膜的综合性能达到最优。(3)失重分析表明薄膜在碱性环境下降解速率最快,酸性条件下次之,紫外光照射降解的速率较慢；NCC/PLA薄膜比PLA薄膜降解速率稍大,说明NCC对复合薄膜的降解性能有增强作用。XPS分析结果表明PLA薄膜在酸性条件降解过程中—CO—、—C=O首先降解导致O/C减小,而在其他降解条件下—CC—的降解速率相对较快导致O/C变大；NCC/PLA薄膜在三种降解条件下均是—C—的降解速率相对较快造成O/C增大。更多还原

【Abstract】 Nanocellulose crystal (NCC) becomes an ideal filling reinforcing material of composite polymer materials because of the light weight, low price, and the properties of its excellent biodegradability, renewability and excellent mechanical properties. Nanocellulose crystal is prepared by acid hydrolysis microcrystalline cellulose. NCC modified by grafting and coupling agent to achieve better dispersion and compatibility of poly (lactic acid)(PLA). The composite film is preformed by the mixing mill and the vulcanizing machine, and the best film preparation process parameters was optimized through comparing the film mechanical properties, barrier properties, and thermal properties. The PLA film and NCC/PLA film were degraded by the acid solution, alkali solution, and ultraviolet light irradiation. The degradation mechanism was researched by gravimetric analysis, scanning electron microscopy (SEM) observation and X-ray photoelectron spectroscopy (XPS) analysis of the degraded film. The results as follows:(1) Acid hydrolysis microcrystalline cellulose to get the nano-cellulose, the particle size of which are most less than100nm, which fits the nanoscale requests; the infrared spectra results showed that the graft modification of nano-cellulose and coupling agent modified nano-cellulose molecular structure in each group have absorption peaks in corresponding position, indicating that the two modified methods all succeed.(2) By studying the film properties which can be influenced by the four parameters——the NCC content, the temperature of mixer, platen time and the modified methods of NCC, the results show that the optimal film prepared process parameters are:the NCC content of5%, mixer temperature of190℃, vulcanizing machine platen time of4minutes, NCC modified by adding the silane coupling agent kh560. Under these conditions, the comprehensive performance of the film is optimal.(3) TGA results showed that the film in alkaline environment degraded fastest and in acidic conditions faster, slower rate of degradation in UV irradiation; and NCC/PLA film rate of degradation is slightly larger than that of PLA film, indicating that NCC enhance the degradation performance of the composite film. XPS results suggest that the PLA films depredated in acidic conditions the—C—O—,—C=O firstly depredated resulting in the O/C decreasing, the—C—C—degradation rate in other conditions is relatively fast, causing the increase of O/C; the NCC/PLA film degraded in the three conditions, the degradation rate of—C—C—is relatively faster causing the increase of O/C.更多还原