将热塑性酚醛树脂熔融纺丝, 再在盐酸和甲醛的混合液中进行固化交联反应制备出酚醛纤维, 研究纤维的物理和化学变化. 结果表明, 采用高浓度甲醛能提高交联基团供应体的浓度, 也提高了对初生纤维的溶胀作用; 盐酸不仅是交联反应的催化剂, 也能使酚羟基之间、 酚羟基与亚甲基之间发生热缩聚反应. 对固化反应过程参数的研究表明, 在甲醛浓度18.5\%, 酸浓度12\%和升温速率15.4℃/h时, 在固化反应过程中纤维内部、 外层的交联反应速度与总的交联反应时间达到最佳匹配, 可制备出拉伸强度为260 MPa高度均匀交联的酚醛纤维, 在800℃炭化收率达到63\%.
Phenolic fibers were prepared by the cross--linking of heat-meltable spun filaments derived from the melt--spinning of a novolak resin in a combined solution of formaldehyde and hydrochloric acid. The physical and chemical changes of the fibers during curing reaction were investigated. The results show that formaldehyde with high concentration can increase both the content of the crosslinking agent and the swellability with the resin. Hydrochloric acid not only promotes the formation of $^{+}$CH$_{2}$OH as a catalyst, but also leads the polymer branching occurring. It is found that under the conditions of formaldehyde concentration of 18.5\%, hydrochloric acid concentration of 12\%, and the heating rate of 15.4℃/h, the highly homogeneous crosslinking fibers with the maximum tensile strength of the 260 MPa can be obtained, suggesting that the crosslinking rate in both the skin and the inner of the fibers and the curing time are well--matched in these conditions, and the carbon yield of the fibers at 800℃ was 63\%.
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