The purpose of this research was to improve the mechanical properties of gypsum board by introducing modi-fied and unmodified wood fibers. The influence of fiber size (0.38-1.70 mm, 212-380 μm, 160-212 μm and not sieved), wood fiber proportion (1%, 3%, 6% and 10%), and treatment of silane coupling agent on the properties of gypsum board was studied. The bending strength, elastic modulus, internal bonding strength, density, and dimensional stability due to water absorption of were examined. The reasons of the improved performance were ana-lyzed with the Fourier Transform Infrared Spectrometer (FT-IR), scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results showed that the gypsum boards with 0.38-1.70 mm fibers and 3% fiber content showed the best reinforcement in all tested groups. Compared to the pure gypsum board, the elastic modulus, bending strength and internal bond strength of the wood fiber reinforced gypsum boards increased by 14.24%, 35.73% and 57.41%, respectively. The sieved fibers of 0.38-1.70 mm were long and thin, however, 160-212 μm and un-sieved groups contained more dust. When wood fiber was treated with silane coupling agent, the elastic modulus, bending strength and internal bond strength of the gypsum boards reinforced with the same fiber amount increased by 25.75%, 92.22% and 100.67%, respectively, compared to the pure gypsum board. It was found that, during the SEM observa-tion, modified wood fibers showed more breakages and left less hole in the fracture surface of the gypsum board com-pared to unmodified fibers, and there were more gypsum crystals ticked to the wood fiber surface and no obvious gap between the modified wood fibers and the gypsum. It indicated that the adhesion between gypsum and wood fibers was improved. The results of the FT-IR showed that—OH of the coupling agent treated fiber was weakened and—NH and—CH2 were presented, indicating that the polarity of wood fiber was weakened and the compatibility between fiber and gypsum could be potentially improved. The results of the XRD showed that the crystallinity of gypsum increased. This might be one of the reasons for the improvement in mechanical property of gypsum boards. In addition, in the addition of a reasonable content of wood fiber could reduce the brittleness without affecting the dimensional stability of gypsum boards.%利用木纤维及其表面改性手段提高石膏板的强度,并探讨纤维形态和尺寸对石膏板性能的影响.在木纤维不同粒径(0.38～1.70 mm、212～380 μm、160～212 μm和未筛分)、不同使用比例(1%,3%,6%和10%),以及添加硅烷偶联剂表面处理因素条件下制备木纤维增强石膏板,研究上述因素水平对石膏板力学性能、密度及吸水厚度膨胀率的影响,并利用红外光谱、扫描电子显微镜和X射线衍射仪对性能改进的原因进行了分析.试验结果表明,粒径为0.38～1.70 mm的木纤维增强效果最好,当添加量为3%时,板材的弹性模量、静曲强度和内结合强度最高,与纯石膏板相比分别提高了14.24%,35.73%和57.41%.经硅烷偶联剂处理改性后,木纤维表面极性减弱,与石膏界面的结合得到改善,并提高了石膏结晶度.添加量为3%改性木纤维增强石膏板的弹性模量、静曲强度和内结合强度分别达到7501.43,6.67和1.08 MPa,与纯石膏板相比,分别提高了25.75%,92.22%和100.67%.此外,适当添加木纤维还能减小石膏板的脆性.研究证明,对木纤维进行筛分有利于提高石膏板的增强效果,硅烷偶联剂KH550的加入可改善木纤维和石膏间的结合,提高石膏板的力学性能.
展开▼
