Kevlar fiber （KF） is a synthesized product with strong mechanical properties. We used KF as a reinforcement to improve the mechanical properties of wood-flour/polypropylene （WF/PP） composites. KF was pretreated w...Kevlar fiber （KF） is a synthesized product with strong mechanical properties. We used KF as a reinforcement to improve the mechanical properties of wood-flour/polypropylene （WF/PP） composites. KF was pretreated with NaOH to improve its compatibility with the thermoplastic matrix. Maleated polypropylene （MAPP） was used as a coupling agent to improve the interfacial adhesion between KF, WF, and PP. Incorporation of KF improved the mechanical properties of WF/PP composites. Treatment of KF with NaOH resulted in further improvement in mechanical strength. Addition of 3% MAPP and 2% hydrolyzed KF （HKF） led to an increment of 93.8% in unnotched impact strength, 17.7% in notched impact strength, 86.8% in flexure strength, 50.8% in flexure modulus, and 94.1% in tensile strength compared to traditional WF/PP composites. Scanning electron microscopy of the cryo-fractured section of WF/PP showed that the HKF surface was rougher than the virgin KF, and the KF was randomly distributed in the composites, which might cause a mechanical interlocking between KF and polypropylene molecules in the composites.展开更多
Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting ...Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.展开更多
采用阴离子接枝法对K ev lar纤维(KF)进行改性。利用偏光显微镜研究了未改性K ev lar纤维(KF 0)和改性K ev lar纤维(KF 1)增强尼龙6复合材料的结晶情况,界面横晶的形成机理及影响因素。结果表明,在尼龙6/KF复合体系中,KF 0和KF 1的加入...采用阴离子接枝法对K ev lar纤维(KF)进行改性。利用偏光显微镜研究了未改性K ev lar纤维(KF 0)和改性K ev lar纤维(KF 1)增强尼龙6复合材料的结晶情况,界面横晶的形成机理及影响因素。结果表明,在尼龙6/KF复合体系中,KF 0和KF 1的加入都能诱发其表面的基体PA 6形成横晶,在低温下纤维的诱发横晶能力小,形成的横晶不致密、不完整;在高结晶温度Tc下形成的横晶完整而致密,纤维的诱发横晶能力大;KF 1与基体有较强的结合力,故其诱发横晶能力较KF 0强。展开更多
基金supported by the National Natural Science Foundation of China (Project Nos. 31010103905 and31070507)Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-11-0608)the Fundamental Research Funds for the Central Universities (DL12DB02)
文摘Kevlar fiber （KF） is a synthesized product with strong mechanical properties. We used KF as a reinforcement to improve the mechanical properties of wood-flour/polypropylene （WF/PP） composites. KF was pretreated with NaOH to improve its compatibility with the thermoplastic matrix. Maleated polypropylene （MAPP） was used as a coupling agent to improve the interfacial adhesion between KF, WF, and PP. Incorporation of KF improved the mechanical properties of WF/PP composites. Treatment of KF with NaOH resulted in further improvement in mechanical strength. Addition of 3% MAPP and 2% hydrolyzed KF （HKF） led to an increment of 93.8% in unnotched impact strength, 17.7% in notched impact strength, 86.8% in flexure strength, 50.8% in flexure modulus, and 94.1% in tensile strength compared to traditional WF/PP composites. Scanning electron microscopy of the cryo-fractured section of WF/PP showed that the HKF surface was rougher than the virgin KF, and the KF was randomly distributed in the composites, which might cause a mechanical interlocking between KF and polypropylene molecules in the composites.
基金partly supported by the Shaanxi Education Research Foundation(02JK064)Natural Science Foundation of Shaanxi Province(Grant No.2003B013).
文摘Horseradish peroxidase catalyzed grafting of acrylamide (AM) onto Kevlar fibers has been studied. The modified fiber has been characterized with scanning electron microscopy (SEM), elemental analysis and the grafting yield. From the SEM micrographs, the surface of the grafted Kevlar fiber is rougher than that of the untreated fiber, and the elemental analysis indicated that the nitrogen content of the treated fibers is higher than that of the untreated fiber. All the results suggested that AM must have been grafted onto the Kevlar surface through HRP-mediated radical initiated grafting reaction. The probably mechanism of HRP catalyzed grafting of AM onto Kevlar surface is proposed.
文摘采用阴离子接枝法对K ev lar纤维(KF)进行改性。利用偏光显微镜研究了未改性K ev lar纤维(KF 0)和改性K ev lar纤维(KF 1)增强尼龙6复合材料的结晶情况,界面横晶的形成机理及影响因素。结果表明,在尼龙6/KF复合体系中,KF 0和KF 1的加入都能诱发其表面的基体PA 6形成横晶,在低温下纤维的诱发横晶能力小,形成的横晶不致密、不完整;在高结晶温度Tc下形成的横晶完整而致密,纤维的诱发横晶能力大;KF 1与基体有较强的结合力,故其诱发横晶能力较KF 0强。
