等离子体处理对PLA膜亲水性及与CNF膜粘附性的影响

目的利用低温等离子体处理PLA膜以提高其亲水性及粘附性,为制备PLA/纳米纤维素复合膜提供一种方法。方法利用单因素试验法探究低温等离子体处理时的放电电压(50～175V)和放电时间(10～50s)对PLA膜表面亲水性和粘附性的影响规律。通过测定PLA膜表面接触角及PLA/纳米纤维素复合膜的剥离强度,分析亲水性及粘附性的变化。利用原子力显微镜观察其微观表面形貌、X射线光电子能谱分析PLA膜表面由疏水性向亲水性转变的机理,并对PLA膜的力学性能及阻隔性能进行分析。结果 PLA膜在低温等离子体条件(放电电压为125V、放电时间为40s、电极距离为4.5cm,氧气流速为1 mL/min,真空度为16.0 kPa)下处理后,其亲水性及与纳米纤维素膜的粘附性达到最佳。此时,PLA膜的接触角由90.0°降至42.4°,PLA/纳米纤维素复合膜的剥离强度为39.5 N/m。结论低温等离子体处理使PLA膜表面由疏水性转变为亲水性,且处理后的PLA可较为牢固地与纳米纤维素膜粘附在一起,从而为PLA/纳米纤维素复合膜的制备提供了一种可行方法。同时,低温等离子体处理对PLA膜的力学性能及阻隔性能没有显著影响。

Effects of Plasma Treatment on Hydrophilicity and Adhesion with CNF Film of PLA Film

The work aims to treat PLA films with low temperature plasma to improve their hydrophilicity and adhesion, in order to provide a method for the preparation of PLA/CNF film. Single factor experiment was used to investigate the influence of discharge voltage (50-175 V) and discharge time (10-50 s) on the surface hydrophilicity and adhesion of PLA films during low temperature plasma treatment. The surface contact angle of PLA film and the peel strength of PLA/CNF film were measured to analyze the changes of hydrophilicity and adhesion. The surface morphology was observed by atomic force microscopy; the mechanism of surface property changing from hydrophobicity to hydrophilicity was analyzed according to the X-ray photoelectron spectroscopy results, and the mechanical and barrier properties of PLA film were analyzed. PLA film had the best hydrophilicity and adhesion with CNF film after treated by low temperature plasma (125 V discharge voltage, 40 s discharge time, 4.5 cm electrode distance, 1 mL/min oxygen flow rate and 16.0 kPa vacuum degree). At this time, the contact angle of the PLA film reduced from 90° to 42.4°, and the peel strength of PLA/CNF film was 39.5 N/m. Low temperature plasma treatment changes the hydrophobic surface of PLA film to a hydrophilic one, and the treated PLA can be firmly stuck to the CNF film, thus providing a feasible method for the preparation of PLA/CNF film. Meanwhile, low temperature plasma treatment does not affect significantly the mechanical and barrier properties of PLA film.