玉米苞叶可降解育果袋材料制备及其性能分析

Preparation of a degradable fruit bagging material from corn bracts and its relative performance

为了提高废弃玉米苞叶的再利用率,降低育果袋的生产成本,该研究采用碱煮法将玉米苞叶脱胶后提取玉米苞叶纤维,运用湿法成网技术将(5±0.5)mm的玉米苞叶纤维与废旧书本纸屑按1.5:1的配比快速成型制备了育果袋材料样品,并对其和市场具有代表性的5种育果袋的透气、保温、遮光性能以及水份管理能力等相关性能进行测试分析。结果表明:与市场参比样品相比,所制备的材料具有优良的套袋相关性能,其透气率和透气量分别达到了73.5mm/s和173.7 L/m^(2)·s;热量损失仅为265k J/h;可见光和紫外光范围内透过率分别为0.4%和0.09%;不仅如此,所制备的材料在30 min内芯吸高度达到了31 mm,平均湿蒸发速率为0.1165 g/h,保水性能明显优于市场葡萄专用育果袋样品。

This study aims to improve the utilization rate of abandoned corn bracts,while decreasing the production cost of the bag of fruit cultivating in sustainable agriculture.Five representative bags of fruit cultivating were collected in the market as the controlled samples,including the plastic film bag A,special bag B for grape,one-,two-and three-layered bag C,D,and E.The basic structural characteristics of controlled samples were firstly analyzed.Then,alkali cooking was used to degum the corn bracts for the extraction of fibers.Subsequently,the corn bract fibers were cut into 5±0.5 mm long,thereby mixing evenly with the waste paper scraps in a ratio of 1.5:1.The wet mesh forming was adopted to prepare the fruit-cultivating bag material F.The mechanical properties of material F were tested after fabrication.The experimental results showed that the prepared material F behaved a strong tensile resistance,where the tensile loads for the dry and wet material F were up to 20.02 and 13.79 N,respectively.Furthermore,an excellent extension performance was achieved for the high requirements of mechanical properties in the fruit bagging.A scanning electronic microscopy(SEM)was adopted to observe the microstructure of the prepared materials F and the controlled samples in the market,further to analyze the distribution of holes in the matrix.The bagging properties were also measured,including air permeability,heat-insulating property,shading property,and water management ability.The experimental data demonstrated that the fruit-cultivating bag material F presented an excellent air permeability.Specifically,the air-flow rate and permeability of material were 73.5 mm/s and 173.7 L/m^(2)·s,respectively.In contrast to the controlled samples,the maximum air-flow rate and permeability were only 2.5 mm/s and 0.3 L/m^(2)·s,respectively.In addition,the heat loss of boiling water was about 265 kJ,when the prepared material was used to keep the boiling water for 60 min.The transmittance of the material F was about 0.4%in the visible light range,and 0.09%in the ultraviolet light range.The shielding properties showed that the prepared material ensured the photosynthesis of fruits during the growth process.Meanwhile,material F was expected to protect the fruit from ultraviolet light burning.Excellent ability of water conductivity was also achieved,where the core suction height reached 31 mm within 30 min.As such,the water in the fruit-cultivating bag during rainy days discharged quickly to enhance the quality of fruit products.Low wet evaporation indicated that the water retention performance was obviously better than that of the special bag B for the grape in the market.Most significantly,the thermal insulation performance of the new fabricated material was better than that of the controlled samples in the market.