High Performance Kenaf Fiber Reinforced Plastics by Surface Modification and Recycling Method

从红麻、木槿中提取红麻纤维，利用其作为增强纤维。研究了红麻玻璃钢的力学性能及回收方法。用5wt%氢氧化钠溶液在80℃下对红麻茎的韧皮进行处理。红麻纤维经中和、洗涤、干燥得到。制备了两种红麻纤维；5mm长度的短纤维用于随机方向FRP，连续纤维用于单向FRP。在长纤维的情况下，预制体是由长纤维束在一个方向上排列并压制而成。用不饱和聚酯树脂浸渍预制体，然后固化。对红麻玻璃钢进行三点弯曲试验，评价其抗弯强度和模量。随机取向FRP纤维含量限制为30wt%。在纤维含量较低的区域，FRP的强度和模量下降，填充纤维越多，强度和模量恢复。对于单向长纤维FRP，纤维含量可达50wt%。单向FRP的抗弯强度是纯树脂的3倍。弯曲模量为5倍。采用硅烷处理过的红麻，以改善界面结合。在低含量区域，处理有效。另一方面，在高含量区域，处理后的红麻玻璃钢的性能没有明显改善。采用碱性溶液对红麻玻璃钢进行化学分解，以达到回收利用的目的。它很难充分分解到低分子量。然后，将红麻玻璃钢的破碎颗粒作为红麻玻璃钢的填料进行材料回收。通过优化复合材料的结构，可使再生红麻玻璃钢的力学性能总体良好。

Kenaf fiber was collected from the kenaf, Hibiscus cannabinus L. in order to use the reinforcing fiber of FRP. Mechanical properties of kenaf FRP and recycling methods were investigated.The bast (skin) of kenaf stem was treated in 5wt% sodium hydroxide solution at 80℃. Kenaf fiber was obtained after neutralization, washing, and drying. Two types of kenaf fiber were prepared ; 5 mm length short fiber for random orientation FRP and continuous fiber for unidirectional FRP. In the case of long fiber, preforms were fabricated by arranging bundles of long fiber in one direction and pressing. The preforms were impregnated by unsaturated polyester resin and then cured. Three point bending tests of kenaf FRP were carried out to evaluate flexural strength and modulus.The fiber content limit was 30wt% for random orientation FRP. The strength and modulus of FRP decreased in the low fiber content region and they recovered by filling more fibers. In the case of unidirectional long fiber FRP, the fiber content could be 50wt%. The flexural strength of unidirectional FRP was 3 times as large as that of neat resin. The flexural modulus was 5 times.The silane treated kenaf was used in order to improve the interfacial bonding. In the low content region, the treatment was effective. On the other hand, the properties of treated kenaf FRP were not improved remarkably in the high content region.Chemical decomposition of kenaf FRP was tried by using alkaline solution for the purpose of recycling. It was difficult to decompose sufficiently to low molecular weight. Then, crushed particles of kenaf FRP was used as filler of kenaf FRP as material recycling. The mechanical properties of recycled kenaf FRP could be stated good in general by optimizing the constitution of laminates.