Preparation And Performance Research Of Wheat Straw Based Compound Packaging Materials

Twin screw extrusion for extracting fiber from wheat straw together with wt4% NaOH pretreatment straw to make a compound material were studied. Waste paper fiber added (at wt3%、wt 5% and wt 7%) to the processed straw for reinforcing purpose, and additives (wood glue powder at wt 10%、wt 15%, industrial alkali lignin were also tried in the study).The strength of the compound material was influenced by adding only water at room temperature and wt4% NaOH as reagents to pretreated wheat straw in addition to extrusion processing. Tests of tensile strength and bending strength of the composite material indicates that pretreatment duration of 72 hours with wt4% NaOH to the straw can improve sample strength significantly, tensile and bending strength raises,48% and 51% respectively.By comparing ways of adding waste paper fiber at the different loading capacity(wt3%、wt 5%、wt 7%、wt12% and wt20%) as the reinforcing material to the pretreated wheat straw fiber, mixing waste paper directly with straw and extruding in the extruder, and re-pulping the waste paper then extruding with pretreated wheat straw fiber showed varied effects to the compounds. The results shown that samples made by re-pulping waste paper at wt7% possess better mechanical properties (the tensile strength is 6.16MPa and the bending strength is 15.76MPa).Wood glue powder was used in the trial with adding contents of wt10%and wt15% to the processed straw; Industrial alkali lignin with varied percentages were added to the processed composite fibers were also studied. It showed that the mechanical strength is significantly improved by adding wt30% industrial alkali lignin.Hot-press process conditions and influences to sample making were analyzed, by varying temperature and holding time while keeping the pressure constantly in the process showed that effects of sample performance impacted by temperature and holding time, the best mechanical strength (the tensile strength is 10.10MPa, and the bending strength is 30.33MPa) will attain when holding 5 minutes under 140℃.