The effect of a new liquid crystalline copolymer(LCP-H2) on the crystallization structure of isotactic polypropylene(iPP) was investigated using wide-angle X-ray diffraction.The experimental results show that LCP-H2 o...The effect of a new liquid crystalline copolymer(LCP-H2) on the crystallization structure of isotactic polypropylene(iPP) was investigated using wide-angle X-ray diffraction.The experimental results show that LCP-H2 of low mass fraction can induce β-form in iPP.The nucleating activity of LCP-H2 mainly depended on its content and crystallization temperature.The content of β-form(Kβ) increased with increasing the nucleator content and crystallization temperature,Kβ value reached a maximum value(35%) when the nucleator mass fraction was 0.8% and the crystallization temperature was 125 ℃.展开更多
A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifie...A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.展开更多
In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential ...In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential scanning calorimetry（DSC）, wide-angle X-ray diffraction（WAXD）, dynamic mechanical analysis（DMA） and scanning electron microscopy（SEM）. Interestingly, the impact strength of β-PPR/20 EPDM blend annealed at 120 ℃ is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing.展开更多
The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scan...The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scanning calorimeter （DSC） and polarized light microscope （PLM）. It was found that α-crystallization lagged behind β-crystallization at normal temperatures, but the discrepancy reduced with increasing temperature. TMB-5 could not induce β-iPP when the nucleation agent is wrapped up with α-crystal that crystallized at high temperatures. The polymorphic composition of iPP/TMB-5 was susceptible to the introductory moment of shear. New crystallization process of β-nucleated iPP was proposed to understand the experimental phenomena which could not be explained by those reported in the literature. It was supposed that polymer crystallization initiated from mesophase, and the formations of iPP crystals involved the organization of helical conformation ordering within rnesophase. It was proposed that the iPP melt contained mesophases with stereocomplex-type ordering of right-handed and left-handed helical chains which could be disturbed by shear or TMB-5, leading to different polymorphic structures.展开更多
文摘The effect of a new liquid crystalline copolymer(LCP-H2) on the crystallization structure of isotactic polypropylene(iPP) was investigated using wide-angle X-ray diffraction.The experimental results show that LCP-H2 of low mass fraction can induce β-form in iPP.The nucleating activity of LCP-H2 mainly depended on its content and crystallization temperature.The content of β-form(Kβ) increased with increasing the nucleator content and crystallization temperature,Kβ value reached a maximum value(35%) when the nucleator mass fraction was 0.8% and the crystallization temperature was 125 ℃.
基金Funded by the Natural Science Foundation of Liaoning Province of China(No.20180550432)Natural Science Foundation for Young Doctoral Research(No.2020-BS-158)Basic Scientific Research Project of Colleges and Universities of Liaoning Provincial Department of Education(No.LJKQZ2021060)。
文摘A novel polypropylene random(PPR)composite materials with optimized properties was developed by addingβ-nucleating compound agents(rare earth complex WBG-2 and aryl amide derivative TMB-5)and ternary compound modifier(TPE/WBG-2/CaCO_(3)).The effects of differentβ-nucleating agents and ternary compound modifier on the mechanical properties and crystallization behavior of PPR were analyzed.The results show that,compared with pure PPR materials,both WBG-2 and TMB-5 could significantly improve the impact strength of PPR.The crystallization temperature of PPR increased with the addition ofβ-nucleating agent.The modified PPR prepared with ternary compound modifier showed the most excellent comprehensive properties.
基金financially supported by the Human Resources and Social Security Department of Hebei ProvinceGuangdong Winner Functional Materials Co.Ltd.the oversea training project for outstanding experts of Hebei Province
文摘In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential scanning calorimetry（DSC）, wide-angle X-ray diffraction（WAXD）, dynamic mechanical analysis（DMA） and scanning electron microscopy（SEM）. Interestingly, the impact strength of β-PPR/20 EPDM blend annealed at 120 ℃ is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing.
基金supported by the National Natural Science Foundation of China(Nos.51573131,51173130,21274149 and 21374077)
文摘The crystalline structures and crystallization behaviors of iPP containing β nucleation agent TMB-5 （iPP/TMB-5） were investigated by synchrotron radiation wide angel X-ray diffraction （SR-WAXD）, differential scanning calorimeter （DSC） and polarized light microscope （PLM）. It was found that α-crystallization lagged behind β-crystallization at normal temperatures, but the discrepancy reduced with increasing temperature. TMB-5 could not induce β-iPP when the nucleation agent is wrapped up with α-crystal that crystallized at high temperatures. The polymorphic composition of iPP/TMB-5 was susceptible to the introductory moment of shear. New crystallization process of β-nucleated iPP was proposed to understand the experimental phenomena which could not be explained by those reported in the literature. It was supposed that polymer crystallization initiated from mesophase, and the formations of iPP crystals involved the organization of helical conformation ordering within rnesophase. It was proposed that the iPP melt contained mesophases with stereocomplex-type ordering of right-handed and left-handed helical chains which could be disturbed by shear or TMB-5, leading to different polymorphic structures.
