聚乳酸/乙酰化纳米纤维素复合薄膜
的制备及性能研究
摘要
为了改善聚乳酸（PLA）的性能，采用纳米纤维素进行改性。本文首先将纤维素原材料通过化学预处理和一步研磨法处理，制备得到了纤维素纳米纤维（CNFs）。取适量的纳米纤维素在真空冷冻干燥机中干燥，加入醋酸配置成纳米纤维素溶液，再进行超声使CNFs活化并分散均匀。将上述溶液等分为三份，每份加入不同比例的乙酸酐和不同比例的硫酸并加热搅拌，之后离心即获得乙酰化纳米纤维素。以N,N-二甲基甲酰胺为溶剂溶解经过预热的聚乳酸。然后，将乙酰化纳米纤维素加入聚乳酸溶液制备成复合溶液，把复合溶液倒入培养皿并置于烘箱中烘干制得复合薄膜。实验还采用红外光谱仪、全自动单一纤维接触角测量仪和紫外光度计对薄膜进行表征。通过傅立叶红外光谱研究表明，纳米纤维素在1625.36cm－1处存在羟基并发生断裂，并在1713.12cm－1处有羰基峰出现，羰基峰的出现说明对纳米纤维素的乙酰化改性实验成功。通过接触角实验表明，聚乳酸薄膜的接触角theta;=25.5°小于聚乳酸/乙酰化纳米纤维素复合薄膜的接触角theta;=66.6°，由于薄膜的疏水性与接触角大小成正比关系。可知，以聚乳酸为基材、乙酰化纳米纤维素为填充材料的薄膜的疏水性能得以提高。而添加乙酰化纳米纤维素对复合材料的透光性能没有明显影响，复合薄膜依然保持着高透光性。
关键词：聚乳酸，乙酰化，纳米纤维素，薄膜
Preparation and characterization of
PLA/acetylated nanocellulose films
ABSTRACT
In order to improve the properties of poly (lactic acid) (PLA),nano cellulose was used to modify the properties.At first,cellulose nanofibers (CNFs) were prepared by chemical pretreatment and one-step grinding.Drying appropriate amount of nano cellulose in vacuum freeze dryer, then adding some acetic acid into nano cellulose solution, the ultrasound is carried out to disperse the solution evenly at last. Dividing the above solution into three parts, heating and stiring each portion which added with acetic anhydride of different proportions and different proportions of sulfuric acid, achieving Acetylated nano cellulose by centrifugation, using N, N- two methyl formamide solvent to dissolve the preheated polylactic acid.Preparing composite solution by adding acetylated cellulose into polylactic acid solution.finally, the composite solution is poured into a culture dish and dried in an oven to prepare a composite film. Infrared spectrometer, automatic single fiber contact angle measuring instrument and optical testing machine were adopted in the experiment to investigate the film.Studies by Fu Liye infrared spectroscopy show that ,hydroxyl in nano cellulose breaks at 1625.36cm－1,And there is a carbonyl peak at 1713.12cm - 1. The occurrence of carbonyl peaks showed that the acetylation modification of nano cellulose was successful .The contact angle experiment shows that,the contact angle of poly (lactic acid) film is 25.5 °， smaller than the contact angle of polylactic acid / acetylated nanocomposite cellulose film which is 66.6 °. Because the hydrophobicity of the film is directly proportional to the contact angle, so the Hydrophobicity of film which using Polylactic acid as substrate、Acetylated nano cellulose was used as filling material, got improved. The addition of acetylated nano cellulose has no obvious influence on the transmittance of the composite,The composite film still has high transmittance.
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