Nonisothermal crystallization and multiple melting behaviors of β‐nucleated impact‐resistant polypropylene copolymer

Li, Xiaoxi; Wu, Haiyan; Chen, Jingwei; Yang, Jing‐hui; Huang, Ting; Zhang, Nan; Wang, Yong

doi:10.1002/app.36633

Cited by 14 publications

(9 citation statements)

References 50 publications

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“…It is observed that the relative fraction of β‐crystal indeed decreases with increasing in cooling rate. This result is different from that reported by Wang and coworkers . They observed that the relative fraction of β‐crystal slightly increases with the cooling rate when the cooling rate is smaller than 20°C/min.…”

Section: Resultscontrasting

confidence: 99%

A highly efficient β‐nucleating agent for impact‐resistant polypropylene copolymer

Liu

Tong

et al. 2014

J of Applied Polymer Sci

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In this work, we reported calcium tetrahydrophthalate as a high efficient b-nucleating agent (b-NA) for impact-resistant polypropylene copolymer (IPC). The relative fraction of the b-crystal can reach as high as 93.5% when only 0.03% b-NA is added. The non-isothermal and isothermal crystallization behaviors, morphology, lamellar structure and mechanical properties of IPCs with various b-NA contents were studied. During non-isothermal crystallization, the cooling rate has an important influence on the relative fraction of the b-crystal, which decreases remarkably as the cooling rate increases. The b-NA also greatly accelerates crystallization rate of IPC, resulting from both more crystal nuclei and larger Avrami exponent. The small angle X-ray scattering characterization shows that more amorphous components are included into the inter-lamellae after addition of b-NA. Dynamical mechanical analysis (DMA) reveals that the storage modulus at low temperature and the loss factor above 0 C from the PP component can be enhanced upon addition of b-NA and reach a maximum at the b-NA content of 0.05 wt %. Impact test shows that the impact strength of the IPC at 0 C can be improved as much as 40% when the content of calcium tetrahydrophthalate is 0.10 wt %. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40753.

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Section: Resultscontrasting

confidence: 99%

A highly efficient β‐nucleating agent for impact‐resistant polypropylene copolymer

Liu

Tong

et al. 2014

J of Applied Polymer Sci

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“…However, due to the thermodynamic instability of the β‐modification, it can be rarely obtained in a significant amount in commercial iPP products, unless the crystallization conditions are favorable for the β‐modification growth. There are some approaches to obtain high proportion of β‐modification, for example, crystallization under a high degree of supercooling, quenching the melt to a certain temperature gradient, shearing or elongation of the melt during the crystallization or adding the β‐nucleating agent (β‐NA) . Among these, the addition of β‐NA is a reliable, simple operating, high repeatability and currently the only one industrialized way to obtain high content of β‐modification …”

Section: Introductionmentioning

confidence: 99%

Crystallization behavior and morphology of β‐nucleated isotactic polypropylene with different stereo‐defect distribution

Chen

Wang

Kang

et al. 2014

Polymers for Advanced Techs

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Aiming at further investigating the combination effect of concentration of β-nucleating agent (β-NA) and stereo-defect distribution on the crystallization behavior of β-nucleated isotactic polypropylene (β-iPP), in this study, the crystallization behavior and polymorphic morphology of twoβ-iPP resins with nearly same average isotacticity (PP-A and PP-B) but different uniformities of stereo-defect distribution were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). The results of DSC and WAXD showed that the addition of TMB-5 increases the crystallization temperature and decreases the spherulite sizes of both PP-A and PP-B, and reduces their crystallization energy barriers as well; however, the polymorphic behaviors of PP-A and PP-B exhibit different dependence on the TMB-5 concentration. For PP-A with less uniform distribution of stereo-defects, β-phase can be observed only when the TMB-5 concentration is no less than 0.1 wt.%, while for PP-B with more uniform stereo-defect distribution, addition of 0.01 wt.% TMB-5 can induce the formation of β-phase. Moreover, the analysis of POM indicated that the crystalline morphologies of both PP-A and PP-B change greatly with the TMB-5 concentration, and the variation features of PP-A and PP-B are quite different from each other. PP-B with more uniform stereo-defect distribution was more favorable for the formation of large amount of β-phase in the presence of wide concentration range of TMB-5. The different polymorphic behaviors and their different dependences on the β-NA concentration were related to the different uniformities of stereo-defect distribution of the samples, since the distribution of stereo-defects could restrain the regular insertion of molecular chains during crystallization and thus determine the tendency the α-phase crystallization of the sample.

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“…Some important factors are normally considered to influence the property of IPC, like the inherent structures (molecular weight, molecular weight distribution, compatibility between rubbery EPR phase and hPP matrix, and the morphology of dispersed phase) − and the external parameters (temperature , and fillers , ). To further expand the application of IPC, a large amount of research have been conducted to improve its toughness, mainly by means of optimizing crystalline polymorphism by adding a β-nucleating agent. − Luo et al investigated the effect of phase morphology on the toughening behavior of IPC with a β-nucleating agent. The β-nucleated IPC showed a highly improved toughness under 0 °C as the content of the β-nucleating agent increased.…”

Section: Introductionmentioning

confidence: 99%

Toughness Reinforcement in Carbon Nanotube-Filled High Impact Polypropylene Copolymer with β-Nucleating Agent

Chen¹,

Song²,

Yang³

et al. 2016

Ind. Eng. Chem. Res.

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In this work, carbon nanotubes (CNTs) were introduced into an impact polypropylene copolymer (IPC) with β-nucleating agent to prepare IPC composites just by means of a simple mechanical blending method without any special treatment of the CNTs. The resultant IPC composites demonstrated an impressively improved impact property (97.78% increment of toughness compared to pure IPC). It was found that CNT aggregates were dispersed in the polypropylene homopolymer (hPP) matrix rather than the interface between the dispersed phase and hPP host. At the presence of CNTs, the size of the ethylene–propylene random copolymer elastomer particles in the IPC nanocomposites was decreased as evidenced by scanning electronic microscopy, and moreover, the mobility of molecular chains in the amorphous phase of the hPP matrix and crystalline lamellae was enhanced as confirmed by dynamic mechanical analysis and small-angle X-ray scattering measurement. The selective distribution of CNTs, the decreased size of elastomer particles, and the enhanced mobility of molecular chains of PP amorphous phase were proven to be responsible for the significantly reinforced toughness of the CNT-filled IPC with β-nucleating agent. Our work demonstrated that CNT aggregates were able to impart a remarkable toughness reinforcement to polymers, without the need for nanodispersion of the CNTs.

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Nonisothermal crystallization and multiple melting behaviors of β‐nucleated impact‐resistant polypropylene copolymer

Cited by 14 publications

References 50 publications

A highly efficient β‐nucleating agent for impact‐resistant polypropylene copolymer

A highly efficient β‐nucleating agent for impact‐resistant polypropylene copolymer

Crystallization behavior and morphology of β‐nucleated isotactic polypropylene with different stereo‐defect distribution

Toughness Reinforcement in Carbon Nanotube-Filled High Impact Polypropylene Copolymer with β-Nucleating Agent

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