Study On The Preparation Of Functional Water-retaining Mulch Film Based On Corn Stalk-based Paper Composite Cellulose Crystal Gel

The mulching technology is an important means in modern agricultural cultivation,since it has the functions of heat preservation and moisturizing,promoting growth and increasing yield.Plastic is a widely-used mulch material.However,they have such disadvantages as non-degradable property,and the serious environmental and soil pollution after long-term use.Development and usage of degradable film have become a new research direction for solving the problem from plastic-mulch application.Corn is widely planted in China,and there are a large amount of corn stalks that are wasted every year.Corn stalk pith are primarily composed of parenchyma cells and short fibers.Poorly physical strength makes parenchyma cells unsuitable for fiber-manufacturing indust ry such as pulping and paper-making,so parenchyma cells were usually treated as a waste.In this study,soda-additive?AQ or Na₂S?pulp from corn stralk bark was used to make paper mulch;Subsequently,cellulose from corn stalk pith was dissolved in DMAc/Li Cl solvent system and regenerated to form cryogels.Paper and cryogels were composited so as to prepare an environmentally-friendly paper mulch with water retention function.These provides a new way for the high value utilization of agricultural wastes.The study results were shown as follows:?1?The corn-stalk-bark pulp,which was used for the paper-mulch preparation,was obtained under the conditions of 20%NaOH,0.05%AQ,the maximum temperature 150?,the time for the maximum temperature 90 min,and the time at the maximum temperature 150 min.And its properties were optimum?effective alkali6.35 g/L,p H 12.76,Kappa index 7.64,and screened yield 4 3.5%?.The paper mulch was processed by pulp-beating,paper-making and double-coating on the one side of paper surface.The experimental results found that with the increase of cati onic starch and PVA dosages as well as beating degree,the physical propert ies such as folding endurance,bursting index,tensile strength and tearing resistance of paper mulch enhanced firstly and then reduced.The optimal conditions were attained through single-factor and response-surface experiments that the usages of PAE as a wet strength agent,cationic starch and PVA were 20 mg/g,10.5 g/m2,and 9.0 g/m2,respectively,and the beating degree was 39.2°SR.?2?The corn stalk pith was milled,delignifie d by acidified sodium chlorite and extracted by alkali solution in order to obtain its cellulose.Cellulose was dissolved in DMAc/Li Cl,and then fully derivatized by organic acids as an esterfied agent.Finally,cryogels with the water absorption property were prepared by regeneration of dissolved cellulose in water.The research was found that the addition of tartaric acid had a positive effect on the water absorption of cryogels.With the increase of organic-acid dosage,reaction temperature and time,the water absorption of the cryogels increased firstly and then decreased.The optimal conditions from single-factor experiments and response surface optimization were:24.3%TA,105?and 60 min.?3?The paper mulch was composited with cryogels by partially dissolving/regeneration of cellulose with Zn Cl ₂:The comparative study found that the water retention capacity and tensile strength of the composited paper mulch increased,while the water vapor,oxygen permeability and ductility gradually decreased with an enhancement of the the cryogel thickness.The reason was speculated that the greater the thickness of the cryogels,the higher the amount of modified regenerated cellulose polymers with hydrophilic functional groups;During the adhesion process,a dense a dhesive layer will be formed and the pore of the cryogels surface will be d estroyed.In order to exert the good water retention performance of the composite material,the appropriate cryogels thickness was needed.