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
The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injecti...The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.展开更多
Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the su...Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the surface of the PA6 fiber,which compelled the growth of twisted lamellae perpendicular to the PA6 fiber.As a result,unique interfacial banded transcrystallization was formed,which is rarely found before.Crystallization temperature was dominant in determining the nucleation activity of the PA6 fiber,further affecting the architecture of banded transcrystallization.With the increase of crystallization temperature,the nucleation density decreased to give more growth space for the twisted lamellae around the fiber.The wave-like banded stripes were transformed into fan-like stripes.Accordingly,band spacing and eccentricity respectively showed positive and negative correlation with crystallization temperature.These meaningful results shed light on regulating the architecture of banded crystals in polymer composites.展开更多
Three types of high-density polyethylene （HDPE） with different molecular weights （high, medium and low） were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injec...Three types of high-density polyethylene （HDPE） with different molecular weights （high, medium and low） were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM, 2d-WAXS, DSC, DMA and tensile testing. Various structural factors including orientation, filler dispersion, interfacial interaction between HDPE and mica, etc., which can impact the macroscopic mechanics, were compared in detail among the three HDPE/mica composites. The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence. Obvious transcrystalline structure was found in the composite with low molecular weight HDPE, whereas it was hard to be detected in the composites with increased HDPE molecular weight. The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interfacial adhesion between matrix and mica filler, which arises from the transcrystallization mechanism.展开更多
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。
基金This work was supported by the National Natural Science Foundation of China (Nos. 20404008, 50533050, 50373030 and 20490220). This work is subsidized by the Special Funds for Major State Basic Research Projects of China (No. 2003CB615600) by Ministry of Education of China as a key project (No. 104154).
文摘The hierarchical structure and interfacial morphology of injection-molded bars of polypropylene （PP） based blends and composites have been investigated in detail from the skin to the core. For preparation of injection-molded bars with high-level orientation and good interfacial adhesion, a dynamic packing injection molding technology was applied to exert oscillatory shear on the melts during solidification stage. Depending on incorporated component, interfacial adhesion and processing conditions, various oriented structure and morphology could be obtained. First, we will elucidate the epitaxial behavior between PP and high-density polyethylene occurring in practical molded processing. Then, the shear-induced transcrystalline structure will be the main focus for PP/fiber composites. At last, various oriented clay structures have been ascertained unambiguously in PP/organoclay nanocomposites along the thickness of molded bars.
基金the National Key R&D Program of China(No.2018YFB0704200)the National Natural Science Foundation of China(Nos.52022061,51803192,52033005 and 51803139).
文摘Interfacial crystallization of polyoxymethylene/poly(butylene succinate)blends induced by the polyamide 6(PA6)fiber was investigated.Due to strong heterogeneous nucleating ability,dense nuclei were generated on the surface of the PA6 fiber,which compelled the growth of twisted lamellae perpendicular to the PA6 fiber.As a result,unique interfacial banded transcrystallization was formed,which is rarely found before.Crystallization temperature was dominant in determining the nucleation activity of the PA6 fiber,further affecting the architecture of banded transcrystallization.With the increase of crystallization temperature,the nucleation density decreased to give more growth space for the twisted lamellae around the fiber.The wave-like banded stripes were transformed into fan-like stripes.Accordingly,band spacing and eccentricity respectively showed positive and negative correlation with crystallization temperature.These meaningful results shed light on regulating the architecture of banded crystals in polymer composites.
基金supported by the National Natural Science Foundation of China(Nos.50533050,20874064 and 50873063)
文摘Three types of high-density polyethylene （HDPE） with different molecular weights （high, medium and low） were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM, 2d-WAXS, DSC, DMA and tensile testing. Various structural factors including orientation, filler dispersion, interfacial interaction between HDPE and mica, etc., which can impact the macroscopic mechanics, were compared in detail among the three HDPE/mica composites. The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence. Obvious transcrystalline structure was found in the composite with low molecular weight HDPE, whereas it was hard to be detected in the composites with increased HDPE molecular weight. The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interfacial adhesion between matrix and mica filler, which arises from the transcrystallization mechanism.
