碳酸钙原位改性植物纤维及其复合材料性能表征

为研究原位沉积对竹、杉木、黄麻3种植物纤维的表面改性效果,采用平压工艺制备了植物纤维增强聚丙烯复合材料,并通过SEM、原子力学显微镜、光学纤维接触角测量仪等方法分别表征了植物纤维的表面形貌、表面粗糙度、静态接触角、拉伸性能以及复合材料的断口形貌和力学性能。结果表明:CaCO3原位沉积改性对单根植物纤维的表面性能有显著影响,不仅提高了单根植物纤维的拉伸性能,还改善了植物纤维增强热塑性聚合物的界面性能,增强了复合材料的界面强度。原位沉积改性后,3种植物纤维表面均有CaCO3附着,杉木纤维的CaCO3上载量最高,达16.08%;竹纤维最低,为6.96%。改性竹纤维的表面粗糙度Rq值降低了32.95%,静态接触角增加了1.85%;改性杉木纤维的Rq值和静态接触角分别增加了42.51%、3.12%;改性黄麻纤维的Rq值增加了62.77%,静态接触角降低了0.4%。单根改性植物纤维的拉伸性能均有所提高,相同CaCO3原位沉积改性条件下,改性竹纤维的拉伸强度和弹性模量最大,分别为1 134.83 MPa、37.25 GPa。断口形貌SEM图中,改性植物纤维与聚丙烯结合紧密,复合材料的断裂主要以改性植物纤维的断裂为主,表明复合材料的界面性质得到改善。改性植物纤维增强聚丙烯复合材料的拉伸性能得到提高,而且其弹性模量的变化趋势与改性植物纤维CaCO3附着量的变化趋势一致。改性杉木纤维增强聚丙烯复合材料弹性模量最大,为2.28 GPa;改性竹纤维增强聚丙烯复合材料拉伸强度最大,为54.04 MPa。 

Properties of plant fibers and their composites modified in situ with calcium carbonate

To study the effect of surface modification,we modified three kinds of plant fibers ( bamboo fiber, fir fiber, jute fiber) in situ with calcium carbonate. The pressing technology was used to prepare plant fibers reinforced polypropylene composites. The surface morphology, surface roughness, statics contact angle ( SCA) and tensile property of plant fibers and their composites were examined by scanning electron microscopy (SEM), atomic force microscope and optical contact angle measuring device. The results indicated that CaCO3 in situ modification had a marked effect on the surface properties of single plant fibers, which not only improved the tensile properties of single plant fibers, but also developed the interface properties of plant fiber-reinforced thermoplastic polymer and enhanced the interface strength of the composite. After the treatment of in situ deposition, CaCO3 particles were successfully deposited to all three kinds of plant fibers, and the CaCO3 loading of fir fiber was the highest, reaching 16. 08%, and that of bamboo fiber was the lowest, 6. 96%. The Rq value of bamboo fibers was reduced by 32. 95%, SCA was increased by 1. 85%, and Rq value and SCA of fir fibers were increased by 42. 51% and 3. 12%, respectively, while the Rq value of jute fibers was increased by 62. 77% and SCA was reduced by 0. 4%. The tensile properties of all three kinds of single modified plant fiber were improved, and that of the single modified bamboo fibers were the best, reaching 1 134. 83 MPa and 37. 25 GPa, respectively. SEM images of fracture morphology showed that the interfacial adhesion between modified plant fiber and PP was stronger, forming a dense interfacial bonding layer. Fiber pullout decreased at the junction of composites, and the damage was mostly in form of fiber breakage. CaCO3 in situ modification developed the interface properties and thus improved the tensile properties of modified plant fiber-reinforced PP composites. In addition, the trend of change of MOE was consistent with that of loading of CaCO3 , and the MOE of modified fir fiber-PP composites was maximum, reaching 2. 28 GPa, while the tensile strength of modified bamboo fiber-PP composites was the highest, achieving 54. 04 MPa.