【作者】 吴楠；

【导师】 任丽丽；

【作者基本信息】 吉林大学 ， 仿生科学与工程， 2024， 硕士

【摘要】 传统的石油基包装材料不可再生、难以降解、价格昂贵,且会造成环境污染。为了实现碳达峰、碳中和的目标,寻找原料可再生、可生物降解的包装材料已经成为了一个亟待解决的问题。可生物降解材料基膜因其原料来源广泛、价格低廉、无污染被广泛地应用在食品包装、土壤监测、废水处理和药物释放等方面。通过添加功能性材料使可生物降解材料基膜具有智能响应性,扩大了可生物降解材料基膜的应用范围。其中,pH响应型可生物降解智能膜具有成本低、无污染,pH响应范围广、响应速度快、持续时间长等特点,被广泛地应用在可视化的食品包装指示和土壤pH值监测等方面。本文首先以玉米淀粉为原料,黑米花青素为pH响应试剂,采用流延法制备了淀粉/黑米花青素复合膜。考察黑米花青素的含量对淀粉/黑米花青素复合膜的表面形貌、物理化学性能和pH响应性的影响和规律。与纯淀粉膜相比较,淀粉/黑米花青素复合膜的最大拉伸强度提高了21.69%;在75%的相对湿度条件下,淀粉/黑米花青素复合膜的水蒸气透过系数(WVP)值减小了31.06%;当环境pH从2逐渐升高到13时,淀粉/黑米花青素复合膜的颜色变化为紫红色到深绿色再到棕黄色。淀粉/黑米花青素复合膜具有显色时间长,反应迅速,不褪色等特点。由于淀粉/黑米花青素复合膜存在力学性能差、水蒸气阻隔性差等缺点,本文进一步以玉米淀粉和酯化淀粉为原料,黑米花青素为pH响应试剂,采用流延法制备了淀粉/酯化淀粉/黑米花青素复合膜,考察了不同花青素含量对淀粉/酯化淀粉/黑米花青素复合膜的表面形貌、物理化学性能和pH敏感性的影响和规律。与淀粉/酯化淀粉膜相比较,含有0.5 wt%黑米花青素的淀粉/酯化淀粉/黑米花青素复合膜的断裂伸长率增加了50.83%,抗拉强度降低了25.86%,WVP值增加了23.38%。在pH改变时,淀粉/酯化淀粉/黑米花青素复合膜的颜色变化为紫红色到棕褐色再到靛蓝色,最后变为棕黄色,并发生了不同程度的卷曲和溶胀。相比较于纯淀粉膜,淀粉/酯化淀粉膜的最大拉伸强度增加了40.12%;相较于淀粉/黑米花青素复合膜,淀粉/酯化淀粉/黑米花青素复合膜的WVP值降低了33.06%,水蒸气阻隔性增强,pH响应性的颜色层次增加。在使用同一种pH响应性试剂的前提下,改变基底的组成可以丰富pH响应型可生物降解智能膜的颜色层次。以聚乙烯醇为基底,木质素磺酸钠为共混材料,黑米花青素为pH响应试剂,采用流延法制备了聚乙烯醇/黑米花青素复合膜,并对其性能进行了表征。0.1 wt%黑米花青素含量下,相较于淀粉/黑米花青素复合膜,聚乙烯醇/黑米花青素复合膜的杨氏模量增加了24.97%,断裂伸长率增加了18.46%。随着pH值从2-13变化,聚乙烯醇/黑米花青素复合膜颜色变化过程为:紫红色-粉红色-粉白色-深绿色-蓝紫色-深紫色。与含有0.1 wt%黑米花青素的淀粉/黑米花青素复合膜相比较,含有0.1 wt%黑米花青素的聚乙烯醇/黑米花青素复合膜的断裂伸长率增加了282.86%。与淀粉/黑米花青素复合膜和淀粉/酯化淀粉/黑米花青素复合膜相比较,聚乙烯醇/黑米花青素复合膜的pH响应性颜色层次增加,在碱性条件下随着时间推移发生颜色转变。为探究不同pH响应试剂对复合膜的影响,以玉米淀粉为基底,羧甲基纤维素为共混材料,硼酸和甲酚红共混粉末为湿度诱导的pH响应试剂,采用流延法制备了复合膜,并对其性能进行了表征。淀粉/甲酚红复合膜的拉伸性能可以通过将淀粉与具有高拉伸强度的膜材料来改善。与淀粉/甲酚红复合膜相比较,羧甲基纤维素/甲酚红复合膜的拉伸强度增加7.21%;淀粉/羧甲基纤维素/甲酚红复合膜的拉伸强度增加了17.38%。复合膜的pH响应速度快、持续时间长。利用水和不同pH条件下所达到的100%相对湿度环境时,材料和复合膜的颜色差异显著。与含有0.3wt%黑米花青素含量的淀粉/黑米花青素复合膜相比较,淀粉/甲酚红复合膜的密度增加了10.71%,最大拉伸强度增加了98.90%,在弱碱性条件下颜色差异性显著,由黄色变为紫色。本文以可生物降解材料为原料制备了pH响应型智能膜,不但可以丰富可生物降解材料基膜的研究内容,而且为pH响应型可生物降解智能膜在食品包装、废水处理和土壤监测中的应用提供了技术支持。更多还原

【Abstract】 Traditional petroleum-based packaging materials are non-renewable,difficult to degrade,expensive and cause environmental pollution.In order to achieve the goal of peak carbon dioxide emissions and carbon neutrality,the search for packaging materials with renewable and biodegradable raw materials has become an urgent problem.Biodegradable material-based films are widely used in food packaging,soil monitoring,wastewater treatment and drug release due to their wide source of raw materials,low price and non-pollution.By adding functional materials to make biodegradable base film with intelligent responsiveness,the application scope of biodegradable base film is expanded.Among them,pH-responsive biodegradable intelligent films with low cost,no pollution,wide pH response range,fast response and long duration are widely used in visual food packaging indication and soil pH monitoring.In this thesis,starch/black rice anthocyanin composite films were firstly prepared by casting method using corn starch as raw material,and black rice anthocyanin as pHresponsive reagent.The effects and patterns of black rice anthocyanin content on the surface morphology,physicochemical properties and pH responsiveness of starch/black rice anthocyanin composite films were investigated.The maximum tensile strength of the starch/black rice anthocyanin composite film was increased by 21.69% compared with that of the pure starch film;the WVP(water vapor permeability)value of the starch/black rice anthocyanin composite film was reduced by 31.06% at 75% relative humidity;When the environmental pH gradually increased from 2 to 13,the color of the starch/black rice anthocyanin composite film changed from purplish red to dark green to brownish yellow.The starch/black rice anthocyanin composite film has the characteristics of long color development time,rapid reaction and no fading.As starch/black rice anthocyanin composite films have the disadvantages of poor mechanical properties and poor water vapor barrier,in this thesis,starch/esterified starch/black rice anthocyanin composite films were further prepared by casting method using maize starch and esterified starch as the raw materials,and black rice anthocyanin as the pH-responsive reagent,and the effects and laws of different anthocyanin contents on the surface topography,physicochemical properties,and pH-responsiveness of starch/esterified starch/black rice anthocyanin composite films were investigated.The elongation at break of the starch/esterified starch/black rice anthocyanin composite film containing 0.5 wt% black rice anthocyanin increased by 50.83%,the tensile strength decreased by 25.86%,the WVP value increased by 23.38%,as compared to the starch/esterified starch film.The color of the starch/esterified starch/black rice anthocyanin composite film changed from purplish red to brownish brown to indigo blue and finally to brownish yellow with varying degrees of curling and swelling when the pH was changed.The maximum tensile strength of starch/esterified starch film was increased by 40.12% compared to that of the pure starch film,and the starch/esterified starch/black rice anthocyanin composite film showed a 33.06% decrease in WVP value,an increase in water vapor barrier,and an increase in pH-responsive color levels compared to that of the starch/black rice anthocyanin composite film.Changing the composition of the substrate can enrich the color hierarchy of pHresponsive biodegradable intelligent film,provided that the same pH-responsive reagent is used.Poly(vinyl alcohol)/black rice anthocyanin composite films were prepared by a casting method using poly(vinyl alcohol)/black rice anthocyanin as the substrate,sodium lignosulfonate as the blending material,and black rice anthocyanin as the pH-responsive reagent,and their properties were characterized.At 0.1 wt% black rice anthocyanin content,the Young’s modulus of poly(vinyl alcohol)/black rice anthocyanin composite film increased by 24.97% and elongation at break increased by18.46% compared to starch/black rice anthocyanin composite film.The color of polyvinyl alcohol/black rice anthocyanin composite film changed with the change of pH from 2-13 as follows: purple,pink,pink white,dark green,blue violet,and deep purple.The polyvinyl alcohol/black rice anthocyanin composite film containing 0.1 wt%black rice anthocyanin showed an increase in elongation at break of 282.86% compared to the starch/black rice anthocyanin composite film containing 0.1 wt% black rice anthocyanin.The polyvinyl alcohol/black rice anthocyanin composite film showed an increased pH-responsive color hierarchy,with a color shift over time under alkaline conditions,when compared to the starch/black rice anthocyanin composite film and the starch/esterified starch/black rice anthocyanin composite film.In order to investigate the effect of different pH-responsive reagents on the composite film,the composite films were prepared using corn starch as a substrate,carboxymethylcellulose as a blending material,and boric acid and cresol red blended powder as a humidity-induced pH-responsive reagent,and the properties of the composite films were characterized using a flow-casting method.The tensile properties of starch/cresol red composite films can be improved by combining starch with film materials having high tensile strength.The tensile strength of carboxymethylcellulose/cresol red composite film increased by 7.21% compared to starch/cresol red composite film;starch/carboxymethylcellulose/cresol red composite film showed an increase in tensile strength of 17.38%.The pH response of the composite films was fast and long lasting.Significant differences in the color of the materials and composite films were observed when using water and the 100% relative humidity environment achieved at different pH conditions.Compared with the starch/black rice anthocyanin composite film containing 0.3 wt% black rice anthocyanin content,the starch/cresol red composite film showed an increase in density of 10.71%,an increase in maximum tensile strength of 98.90%,and a significant color differentiation from yellow to purple under weak alkaline conditions.In this thesis,pH-responsive intelligent films were prepared from biodegradable materials,which can not only enrich the research on biodegradable material-based films,but also provide technical support for the application of pH-responsive biodegradable intelligent films in food packaging,wastewater treatment and soil monitoring.更多还原