PFI磨机械预处理对精制竹纤维性能的影响研究

STUDY ON PROPERTIES OF REFINED BAMBOO FIBER IN BEATING PROCESS BY PFI MILL

采用Cl2/H2O2深度脱木素和机械法预处理(PFI磨打浆),溶解残余木质素,并松动竹纤维细胞壁多层结构,增加纤维素的比表面积暴露更多的游离羟基。采用新型纤维质量分析仪检测预处理过程纤维形态的变化;离心法测定浆料的保水值,评价细胞壁帚化程度;X射线衍射仪(XRD)分析揭示预处理程度与纤维素结晶度变化的关系;最后采用氧化法验证预处理对竹纤维素反应性能的改善程度。结果表明,高转数的PFI机械处理对竹纤维性能影响显著,纤维分丝帚化由0.781%升至1.072%,保水值(WRV)从112.8%升至213.6%。经过PFI的高转速后,纤维素结晶度指数从66.4%降至50.0%。在氧化反应中,纤维素的氧化度从0.85增至1.03 mol/AGU,羟基氧化率增大了约25%,纤维的试剂可达性得到改善,竹纤维的化学反应性能显著提高。

It is proven that more free hydroxyl groups of cellulose molecules can be exposed effectively by fibrillation of fiber walls.A PFI mill beating method is employed to loosen multilayered structure of bamboo fiber cell walls.The changes of fiber morphology are analyzed by a Fiber Quality Analyzer(FQA)and the water-retention values(WRV)are measured to evaluate fibrillation levels.The variation of cellulose crystallinity versus degree of mechanical pretreatment is revealed by the XRD test.Finally,the reaction performances of fibers with different pretreatment degrees are verified by the periodate oxidation titration.Results show that,high intensity of beating process significantly affects the fiber fibrillations,which increases from 0.781% to 1.072%.The WRV raised from 112.8% to 213.6%,indicating a significant fibrillation effect on fiber walls by increment of mechanical pretreatment degree.After high speed revolution of PFI beating,the cellulose crystallinity index is decreased from 66.4% to 50.0%.The oxidation degree of cellulose increases from 0.85 to 1.03 mol/AGU in oxidation reaction,suggesting that the reagent accessibility of fibers is improved and the chemical reaction performance of bamboo fibers is improved significantly.