Preparation And Properties Of CMC/Jute Mulch Films

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.