本文關(guān)鍵詞： 乙�；男� 纖維素 聚乳酸 復(fù)合材料 超臨界發(fā)泡　出處：《南京理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本文主要研究了三種纖維素(納米纖絲纖維素NFC、納米晶體纖維素NCC、α-纖維素)的乙�；男�,并采用改性后的mNFC、mNCC、mα-纖維素,用溶劑共混法制備了改性纖維素增強(qiáng)的纖維素/聚乳酸復(fù)合材料,嘗試用安全、無(wú)毒無(wú)害無(wú)污染的超臨界二氧化碳工藝制備微孔發(fā)泡材料。乙酰化改性成本較低,且材料表面取代度較高。FTIR、接觸角測(cè)試說(shuō)明了纖維素中的部分羥基被乙�；晒θ〈�,親水性明顯降低,有助于改善纖維素與聚乳酸的界面相容性。其中由~1HNMR可計(jì)算得到三種纖維素乙�；男缘娜〈�(DS):mNCC為1.32,mNFC為1.62,mα-纖維素為1.98。XRD和TEM顯示了改性略微降低了纖維素的結(jié)晶度,但改性后的纖維素仍保留了原本的晶體結(jié)構(gòu),改性多發(fā)生在纖維素的表面。二氯甲烷作為溶劑易揮發(fā),用溶劑共混法分別制備mNFC/PLA、mNCC/PLA、mα-纖維素/PLA復(fù)合材料,操作過(guò)程簡(jiǎn)單,溶劑殘留少。力學(xué)性能測(cè)試顯示了添加mNFC有利于提高聚乳酸的拉伸強(qiáng)度,且隨著含量的增加,拉伸強(qiáng)度逐漸增大,斷裂伸長(zhǎng)率與之相反。TG說(shuō)明了改性后的聚乳酸復(fù)合材料,熱穩(wěn)定性有所下降,而DSC說(shuō)明了 Tg和Tm都有明顯的提高。紫外光譜表征說(shuō)明mNFC含量增加,透光率下降,透明性降低。對(duì)纖維素/聚乳酸復(fù)合材料的超臨界發(fā)泡進(jìn)行了嘗試研究。在泄壓法發(fā)泡工藝中,將發(fā)泡溫度提高到接近復(fù)合材料的熔點(diǎn)附近,延長(zhǎng)保壓時(shí)間(20h左右),可促進(jìn)二氧化碳在聚乳酸中的充分溶解,達(dá)到飽和狀態(tài)。SEM觀察表明在樹(shù)脂基體中可觀察到超臨界二氧化碳形成的泡孔。同時(shí)對(duì)升溫法發(fā)泡工藝進(jìn)行了初步探索,但為獲得泡孔形態(tài)均一、膨脹率較大的發(fā)泡材料,其最佳工藝條件仍需要進(jìn)一步探索。
[Abstract]:In this paper, the acetylation modification of three kinds of cellulose (nano-fiber cellulose NFC, nanocrystalline cellulose NCC-a-cellulose) was studied, and the modified mNFCnCCM 偽 -cellulose was used. Cellulose / polylactic acid composites reinforced by modified cellulose were prepared by solvent blending method. Microcellular foaming materials were prepared by a safe, innocuous and innocuous supercritical carbon dioxide process. The cost of acetylation modification was low. The results of surface substitution. FTIR and contact angle test showed that some hydroxyl groups in cellulose were successfully replaced by acetyl groups, and the hydrophilicity of cellulose decreased obviously. The interfacial compatibility between cellulose and poly (lactic acid) can be improved by 1H NMR. Three kinds of cellulose modified by acetylation can be calculated as DS / MNCC = 1.32mNFC = 1.62mNFC = 1.98.XRD and TEM show that the crystallinity of cellulose is decreased slightly. However, the modified cellulose still retains its original crystal structure, and the modification mostly occurs on the surface of the cellulose. Dichloromethane is volatile as a solvent, and the mNFC / PLAC / MNCC / PLAm 偽 -cellulose / PLA composite is prepared by solvent blending method. The operation process is simple. The mechanical properties test showed that the addition of mNFC was beneficial to increase the tensile strength of polylactic acid, and the tensile strength gradually increased with the increase of content, and the elongation at break was opposite to that of the modified PLA composite. The thermal stability decreased, while DSC showed that TG and TM were improved obviously. UV spectra showed that the content of mNFC increased and the transmittance decreased. The supercritical foaming of cellulose / poly (lactic acid) composites was studied. In the pressure-release foaming process, the foaming temperature was raised to close to the melting point of the composite. Prolonging the pressure holding time of about 20 h can promote the full dissolution of carbon dioxide in polylactic acid. SEM observation showed that the foam formed by supercritical carbon dioxide could be observed in resin matrix. The optimum technological conditions still need to be further explored.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB332

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