【作者】 徐洁；

【导师】 杨建平；

【作者基本信息】 东华大学 ， 纺织工程， 2020， 硕士

【摘要】 本课题主要研究了CMC/黄麻地膜的制备工艺、性能和工艺优化。选用黄麻纤维和羧甲基纤维素(CMC)为原料,采用流延成膜方法,经过乙醇-盐酸溶液酸化处理和热烘焙处理,制备具有较好耐水性和湿强的CMC/黄麻地膜,并研究了不同制备工艺参数对麻地膜性能的影响以及麻地膜制备工艺的优化。首先,通过单因素分析方法研究了原料质量比、纤维长度、乙醇浓度(v/v)、烘焙温度和烘焙时间这5个工艺参数对CMC/黄麻地膜的抗张性能(抗张指数和断裂伸长率)的影响,优选出抗张性能较好的制备工艺参数。结果表明,CMC是优良的成膜剂,成膜后其表面致密性良好,但纯CMC膜的耐水性极差,由于湿强太小而无法测试,因此添加黄麻纤维并通过酸化和热烘焙处理来提高混合膜的湿强。CMC/黄麻地膜的抗张指数随着原料中黄麻纤维含量、纤维长度、乙醇浓度的增加而呈现先增后减的趋势。当烘焙温度和烘焙时间增加时,干抗张指数总体上呈下降趋势,但湿抗张指数能达到一个峰值。结合成本考虑,当原料质量比为CMC/黄麻45/55,纤维长度为5.68mm(粉碎时间为30s),乙醇浓度为50%,烘焙温度为140℃,烘焙时间为30min时,麻地膜的抗张性能较佳。此工艺条件下,麻地膜的干、湿抗张指数分别为10.031(N·m)/g、4.831(N·m)/g,干、湿断裂伸长率分别为1.45%、2.00%,透气量为7.07mm/s,透湿率为69.258g/(m~2·h),且保水性良好,与其他麻地膜相比各性能均较好,弯曲刚度为10.049mN·cm。根据单因子分析结果,选取原料质量比、烘焙温度和烘焙时间作为麻地膜制备工艺的主要研究参数,以抗张指数和断裂伸长率为主要指标,采用二次通用旋转设计方法,通过目标函数法对麻地膜制备工艺进行最优化设计。根据最优化计算结果,并考虑成本等因素,得出麻地膜最优制备工艺为CMC/黄麻42/58,烘焙温度为136℃,烘焙时间为49min。此时麻地膜的干、湿抗张指数分别为15.130(N·m)/g、5.000(N·m)/g,干、湿断裂伸长率分别为1.75%、2.35%,透气量为8.53mm/s,透湿率为72.202g/(m~2·h)。由于制备的麻地膜柔软性能较差,为提高麻地膜的使用性,本课题采用甘油对地膜进行软化处理,提高柔软性,通过测试几种地膜的弯曲刚度,研究麻地膜软化处理方法的可行性和软化效果。结果表明,甘油软化处理后的麻地膜柔软性明显改善,弯曲刚度从10.049mN·cm减小到2.556mN·cm,抗张性能、透湿性在软化前后变化不显著,但透气量增大。同时,麻地膜的表面疏水性差,本课题采用环保型碳氢化合物无氟防水剂对地膜进行防水处理,增强防水效果,提高耐水能力,通过测试麻地膜的接触角和评价麻地膜的沾水度,研究防水剂的可行性和防水效果。结果表明,防水处理后麻地膜防水效果较好,接触角均大于90°,沾水度等级均在4-5级,且麻地膜湿强损失较小,兼备优良的透湿透气性能。此外,本课题还测试比较了塑料地膜、苎麻/棉地膜、黄麻/棉地膜、黄麻地膜和CMC/黄麻地膜这5种地膜的降解性、保温性和保水性,结果表明,塑料地膜的保温性最佳,但在土壤中不易降解。本课题研制的CMC/黄麻地膜的保温性优于其他麻地膜,且表面不会像塑料地膜一样出现结露现象。几种麻地膜在一段时间后均会在土壤中完全降解,而防水处理后的CMC/黄麻地膜的降解速度变慢,延长使用寿命,更适应作物生长需求。更多还原

【Abstract】 Preparation and properties of jute mulch films was researched.Jute mulch films are made of jute noil fibers and carboxy methyl cellulose(CMC)as raw material by the casting film method.After acid soaking in ethanol-hydrochloric solution and baking,CMC/jute mulch film with better properties of water resistance and wet strength had been prepared.And its performances were tested and the process was optimized.Firstly,the single factor analysis method was used to research the influence of five technological parameters including mass ratio of raw material,length of jute fibers,ethanol concentration(v/v),baking temperature and baking time on the mechanical properties(tensile index and breaking elongation)of CMC/jute mulch films.The results showed that the CMC is an excellent film-forming agent,the surface of CMC film would have a good densification.However,water resistance of CMC film was extremely poor,and the wet strength was too low to be tested.Therefore,jute fibers were added into mixed film and then treated with acidification and baking to improve the wet strength.With the increasing of the content of jute fiber,the length of fibers and ethanol concentration,the tensile strength of CMC/jute mulch film increased first and then decreased.When the baking temperature and baking time increased,the dry tensile strength generally decreased,while the wet tensile strength would reach a highest value.Considering the cost,when mass ratio of the raw material is CMC/jute 45/55,the length of fiber is 5.68mm(the crushing time is 30s),the ethanol concentration is 50%,the baking temperature is 140℃ and the baking time is 30 min,the tension performance of the CMC/jute mulch film is better.Under these conditions of process,the dry and wet tensile strength of the film are 10.031(N·m)/g and 4.831(N · m)/g,the dry and wet breaking elongation are 1.45% and 2.00%,respectively;the air permeability is 7.07 mm/s,the moisture permeability is 69.258 g/(m2 · h),bending rigidity is10.049 m N·cm;the water retention was good.Thus,compared with other films,all the properties of CMC/jute mulch film are better.Secondly,according to the results of the single factor analysis,the mass ratio of raw materials,baking temperature and baking time were selected as the main parameters of the preparation process of CMC/jute mulch film,and the tensile strength and elongation were taken as the mainindexes.The secondary universal rotation design method was adopted to optimize the preparation process of CMC/jute mulch film by objective function method.As the calculating results and taking the cost and other factors into account,it is concluded that the optimal process for mulch film is CMC/jute 42/58,the baking temperature is 136℃ and the baking time is 49 min.At this time,the dry and wet tensile strength of the film are 15.130(N · m)/g and 5.000(N · m)/g,respectively;the dry and wet elongation are 1.75% and 2.35%,respectively;the air permeability is8.53 mm/s,and the moisture permeability is 72.202 g/(m2·h).Due to the poor softening property of prepared CMC/jute mulch film,glycerin had been used to soften the film.The feasibility and softening effect of softening treatment method for CMC/jute mulch film was evaluated through testing the bending rigidity of several kinds of mulch film.The results showed that the softening treated with glycerin significantly improved the softness of the CMC/jute mulch film,and the bending stiffness decreased from 10.049 m N·cm to 2.556 m N·cm.The tensile properties and moisture permeability did not change significantly before and after softening,but the air permeability increased.Meanwhile,because of poor surface hydrophobicity of films,the waterproofing treatment is conducted by environmentally hydrocarbon fluorine-free water-repellent agent in order to improve the water-repellent effect and water-resistance of the mulch film.The feasibility and waterproofing effect of the water-repellent agent were studied by testing the contact angle and evaluating the degree of water penetration of the mulch film.The results showed that the waterproofing effect of the mulch film is good,the contact angle is greater than 90°,the degree of water penetration was at grade 4-5,the loss of wet strength of mulch film was less,and the mulch film had excellent moisture permeability and permeability.In addition,the warm performance,water retention and bio-degradation of five different types mulch film included plastic film,ramie/cotton mulch film,jute/cotton mulch film,jute mulch film and CMC/jute mulch film were tested and compared.The results showed that the warm performance of plastic film is the best,but it is difficult to be degraded in natural conditions.The warm performance of CMC/jute mulch film is better than other mulch films tested in this study,and its surface does not appear condensation phenomenon like plastic film.All of mulch film could be completely degraded in the soil after a period of time,while the degradation rate of CMC/jute mulch after waterproof treatment is slower,which extends the service life and is more suitable for the growth of crops.更多还原