蒸汽爆破膨化改性对玉米秸秆结构及复合板机械性能的影响

Effect of Steam Explosion and Puffing Modification on the Structure of Corn Stalks and the Mechanical Properties of Composite Boards

将玉米秸秆通过单螺杆式蒸汽爆破的方式进行膨化,得到不同类型膨化玉米秸秆,再与聚丙烯树脂(PP)复合制备复合板材。通过扫描电子显微镜(SEM)、反射红外(ATR-FTIR)、热重分析(TGA)、差式扫描量热(DSC)及鲍尔纤维筛分等测试,分析了秸秆膨化前后的纤维变化情况等。分析结果表明:SEM显示通过蒸汽爆破膨化机处理过的玉米秸秆能够有效进行“三素分离”,使得玉米秸秆表面结构由规整变成纤维状和粉末碎片,并且TGA、DSC和ATR-FTIR测试结果显示:在膨化过程中纤维素结构无变化,而半纤维素和木质素发生了部分的热分解。对膨化玉米秸秆与PP复合制备的复合板材的力学性能测试发现:与未膨化玉米秸秆(CS)制备的板材相比,膨化玉米秸秆(SECS)制备的板材的冲击韧性强度和拉伸强度分别增加15.69%和17.24%,而与SECS制备的复合板材的性能相比,分别经苯乙烯-丙烯酸共聚物和乙烯-醋酸乙烯共聚物修饰的膨化玉米秸秆制备的复合板材的冲击韧性强度分别增加了156.74%和100.98%,拉伸强度分别提高了83.42%和12.03%。

The corn stalks were expanded by means of single-screw steam explosion to obtain different types of puffed corn straws,which were compounded with polypropylene resin(PP)to prepare a straw composite board.The changes of fiber before and after the explosion were investigated by scanning electron microscopy(SEM),reflected infrared(ART-FTIR),thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),and Bauer fiber screening tests.The SEM results showed that corn stalks could effectively carry out the"three elements separation"through steam explosion,so that the surface structure of the stalks changed from smooth and regular to fibrous and powdery fragments.Meanwhile,the TGA,DSC and ATR-FTIR results showed that there was no obvious change in the fiber structure during the puffing process,while the hemicellulose and lignin were partially thermally decomposed.The mechanical properties of the straw composite board prepared by expanded corn stalks and PP were tested.Comparing with the board prepared by unexpaned corn stalks as the raw material,the impact resistance and tensile strength of steam expanded corn stalks increased by 15.69%and 17.24%,respectively.Similarly,the impact strength of boards prepared by expanded corn stalks modified by acrylates compolymer and ethylene-vinyl acetate copolymer increased by 156.74%and 100.98%,respectively,and the tensile strength increased by 83.42%and 12.03%,respectively.