Study On Surface Polarity Of Modified Straw

Wood-Plastic composite is a kind of new environment-friendly materials,which are formed by wood fiber with thermoplastic in different ways.The limited compatibility between them is due to the fact that the hydrophilic of wood fiber and the hydrophobicity of thermoplastic,therefore,surface modification of wood fibers is an effective method to reduce wood fibers' surface polarity,which can improve the compatibility.We have determined the relative value of surface free energy and its polar part before and after the fibers treated respectively with acetic anhydride,benzyl chloride,sodium hydroxide and silane coupling agent KH-550.The straw were characterized with infrared spectroscopy and thermal gravimetric analyzer.For acetylated straw,benzylated straw and silane straw,the emergence of corresponding characteristic absorption peaks indicated that the modification took place;for alkaline straw,the loss of ligin's and others' characteristic peaks and showed that straw is modified.Thermol gravimetric analysis showed that natural straw,acetylated straw,benzylated straw,alkaline straw and silane straw began to decompose when their temperature respectively reached 181 ??273 ??245 ??258??256 ?;the temperature of their 50%weight loss were 341??361??350??352??353?.The results indicated the thermal stability of straw increased.The results showed that the polarity free energy of straw fibers decreased after being treated.The polarity free energy of untreated straw fiber is 9.15 mN/m,but the polarity free energy of acetylated straw and benzylated straw is 4.02 mN/m and 4.03 mN/m;The best effects of alkali treating time is 72 hours and the most appropriate concentration is 20%,and the polarity free energy is 5.83 mN/m;48 hours is the best treating time of silanization and its polarity free energy is 4.98 mN/m.