Degradation and Structural Changes of Wheat Straw Pulp Cellulose In Lactic Acid Medium

[Objective] The study was to provide the basis for preparation of thermoplastic polymer material with cellulose.[Method] The pretreated raw materials(dry wheat straw pulp)were immersed into a certain amount of lactic acid at certain temperature.After stirred for some time,they were dried to constant weight.The effects of temperature,time on polymerization degree and iodine adsorption value of cellulose were studied,and the change of chemical structure of wheat straw cellulose in acid medium was analyzed.[Results] When temperature was higher than 30 ℃,the cellulose began to degrade,and the higher the temperature was,the more the cellulose degradation.The effects of temperature and stirring time on polymerization degree and iodine adsorption value of cellulose were bigger,while the effect of lactic acid dosage on them was small.The analysis of infrared spectrum and X-ray diffraction pattern showed that,when temperature was lower than 60 ℃,the physical swelling of wheat straw pulp was the main action in lactic acid medium,and a small amount of wheat straw pulp was degraded.When the temperature was above 70 ℃,the degradation and chemical reaction of wheat straw pulp were all occurred,but the cellulose crystalline of cellulose had no change.[Conclusion] The study provided the information for cellulose modification in acid medium.