低温等离子体处理zein膜及接枝PLA性质研究

发布时间：2018-08-31 18:40

【摘要】：玉米醇溶蛋白(zein)是通过湿法生产的副产物玉米蛋白粉中提取的醇溶蛋白,具有良好的成膜性,主要应用在食品包装,生物医药活性包装,药物缓释材料等方面。聚乳酸(PLA)其分子式为[CH(CH3)CO]n-,是一种可降解类的高分子材料,具有生物降解性,生物相容性,生物再生性等优点。低温等离子体(DBD)是通过激烈的撞击使得气体分子发生电离,这时物质就变成激发态的自由电子或带电离子组成的混合物,低温等离子体技术常用于材料表面改性。本课题主要是通过将玉米醇溶蛋白溶于80%的乙醇水溶液,浇铸成膜后,通过低温等离子体对玉米醇溶蛋白膜进行改性,经不同处理功率(30W、50W、70W)低温等离子体处理后,测定薄膜表观形貌、热学性质、机械性质及薄膜应用性质包括水蒸气透过率、亲水性。然后根据低温等离子体改性技术对玉米醇溶蛋白膜改性后,薄膜的疏水性降低,接下来的实验通过运用低温等离子体的接枝改性作用,对玉米醇溶蛋白膜接枝聚乳酸提高薄膜疏水性,并研究接枝改性后薄膜的性质变化。结果表明玉米醇溶蛋白膜表面粗糙,整体完整;处理后薄膜表面亲水性明显提高,接触角大小随处理功率的增加由65.37°下降到45.71° ;断裂时的拉伸强度和断裂伸长率没有显著变化;水蒸气透过率由4.57×10-8g·m/m2·h·Pa降低到3.55×10-8 g·m/m2·h·Pa;变性焓变化不明显;原子力显微镜观测显示等离子体处理增加,表面粗糙程度增加,均方根粗糙度由3.45 nm增加到75 nm;红外光谱和X射线衍射谱图分析表明等离子体处理使蛋白质的有序程度降低。通过单因素正交试验,确定了玉米醇溶蛋白膜接枝聚乳酸的工艺条件,接枝前处理功率50W、接枝聚乳酸浓度0.6g/L、接枝时间30min时薄膜的疏水性较好,通过正交试验发现,接枝时间对改性后薄膜的疏水性具有明显的提高。在外界湿度条件变化大的情况下,改性薄膜性质稳定。通过其机械性研究分析显示,改性后薄膜的抗拉强度没有明显变化,但薄膜的可塑性提高。通过DSC、TGA,热特性结果分析显示,改性后薄膜的热降解稳定提高。通过扫描电镜(SEM)断面观察显示出二者在低温等离子体的作用下,接枝聚乳酸时间在30min以上时接合紧密,断面呈均一一致状态。傅里叶红外光谱(FT-IR)及X射线衍射光谱(XRD)结果从微观角度证明了二者在结构上发生反应,显示玉米醇溶蛋白膜及聚乳酸在低温等离子体的作用下具有很好的接合。通过调节等离子体处理功率可以明显改善玉米醇溶蛋白膜的表面亲水性及粗糙程度,为进一步研究玉米醇溶蛋白膜应用性质提供基础。
[Abstract]:Zein (zein), a by-product extracted from corn protein powder produced by wet process, has good film-forming properties. It is mainly used in food packaging, biomedical active packaging, drug delivery materials and so on. Polylactic acid (PLA), whose molecular formula is [CH (CH3) CO] n-, is a biodegradable polymer material with the advantages of biodegradability, biocompatibility and bioregeneration. Low temperature plasma (DBD) is a mixture of free electrons or charged ions in the excited state, which is ionization of gas molecules by intense impact. Low temperature plasma technology is often used to modify the surface of materials. In this paper, Zein was dissolved in 80% ethanol solution, then cast into film, then modified by low temperature plasma, and treated by low temperature plasma with different treatment power (30W, 50W, 70W). The surface morphology, thermal properties, mechanical properties and application properties of the films include water vapor transmittance and hydrophilicity. Then the hydrophobicity of corn gliadin film was reduced after modified by low temperature plasma, and then the graft modification of low temperature plasma was used to modify the film. The hydrophobicity of polylactic acid grafted with Zein film was improved and the properties of the modified film were studied. The results showed that the surface of Zein film was rough and intact, the hydrophilicity of the film was obviously increased after treatment, the contact angle decreased from 65.37 掳to 45.71 掳with the increase of treatment power, and the tensile strength and elongation at break did not change significantly. The water vapor transmittance decreased from 4.57 脳 10 ~ (-8) g m/m2 h Pa to 3.55 脳 10 ~ (-8) g m/m2 h Pa; 's denaturation enthalpy, and atomic force microscopy (AFM) showed that the surface roughness increased with the increase of plasma treatment. The RMS roughness increased from 3.45 nm to 75 nm; IR spectra and X-ray diffraction spectra. The results showed that plasma treatment reduced the order of protein. Through single factor orthogonal experiment, the technological conditions of grafting polylactic acid with Zein film were determined. The pretreatment power was 50 W, the concentration of graft polylactic acid was 0.6 g / L, and the grafting time was 30min. The hydrophobicity of the film was found by orthogonal test. The grafting time improved the hydrophobicity of the modified films. The properties of the modified film are stable under the condition of large change of external humidity. The mechanical analysis shows that the tensile strength of the modified film does not change obviously, but the plasticity of the film is improved. The results of DSC,TGA, thermal analysis showed that the thermal degradation of the modified films was improved steadily. Scanning electron microscope (SEM) (SEM) cross-section observation showed that when the time of grafting polylactic acid was higher than 30min, the grafting time was close and the cross section was homogeneous and consistent under the action of low temperature plasma. The results of Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) spectra show that the structure of Zein film and polylactic acid are well bonded under the action of low temperature plasma. The surface hydrophilicity and roughness of Zein film can be improved obviously by adjusting plasma treatment power, which provides a basis for further study on the application properties of Zein film.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2

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