Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

Wang, Bin; Chen, Zhengfang; Kang, Jian; Yang, Feng; Chen, Jinyao; Cao, Ya; Xiang, Ming

doi:10.1016/j.tca.2015.01.015

Cited by 19 publications

(14 citation statements)

References 64 publications

(92 reference statements)

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“…The self-nucleation isothermal crystallization kinetics was measured according to the manner proposed by Muller et al [48,49]:The self-nucleating behavior of samples was firstly measured according to Fillon et al [50,51,52], and the temperature region for the self-nucleation domain (Domain Ⅱ) was obtained.The samples were heated from 50 to 200 °C at 10 ℃/min and held for 5 min to destroy any residual nuclei.After that, samples were cooled to 50 °C at 10 °C/min and held for 2 min to create a “standard” thermal history [53], and then they were heated to the self-nucleating temperature (denoted as T SN , the lowest temperature within Domain Ⅱ is preferred) and kept for 5 min.Then, it was rapidly cooled to the predetermined crystallization temperature ( T cSN ) and held for a certain time to allow the completion of crystallization.Finally, the sample was heated to 200 °C at a rate of 10 °C/min.…”

Section: Methodsmentioning

confidence: 99%

Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites

Zhang¹,

Lü

Yang

et al. 2019

Polymers

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In this study, the hyperbranched polyester grafted graphene oxide (GO-H202) was synthesized, and the isotactic polypropylene/graphene oxide (iPP/GO) composites were prepared. Results of X-ray photoelectron spectra (XPS), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) revealed the successful synthesis of GO-H202, while thermogravimetric analysis (TGA) indicated that the weight ratio of grafting was about 35 wt %. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were carried out to investigate the role of GO and GO-H202 on the crystallization kinetics of the composites. Results suggested that the addition of GO enhanced the nucleation rate and crystallizability of the composites, while GO-H202 exhibited a higher crystallization acceleration effect compared to neat GO; results of isothermal crystallization kinetics and self-nucleation isothermal crystallization kinetics showed that both the overall crystallization rate and crystal growth rate increase after the addition of GO and GO-H202, and the crystallization acceleration of GO-H202 became evidently stronger compared to GO. Moreover, the variation trends of Avrami exponent n with the isothermal crystallization temperature TcISO changed significantly after the addition of GO or GO-H202, which might imply that the addition of GO and GO-H202 lead to different crystallization dimensionalities during the isothermal crystallization of the composites. The related mechanism was also discussed.

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Section: Methodsmentioning

confidence: 99%

Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites

Zhang¹,

Lü

Yang

et al. 2019

Polymers

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“…While β ‐phase is a thermodynamically metastable crystalline form whose toughness is higher than α ‐phase , and can only be formed under certain particular ways, such as crystallization in the melt shear field , in a temperature gradient field or in the presence of β ‐nucleating agents ( β ‐NAs) . In these methods, adding β ‐NAs is the most efficient and simplest way to acquire high content of β ‐form . After the addition of small amount of β ‐NA, the impact strength of β ‐iPP is improved evidently compared with α ‐iPP.…”

Section: Introductionmentioning

confidence: 99%

Effects of stereo‐defect distribution on the crystallization and polymorphic behavior of β‐nucleated isotactic polypropylene/graphene oxide composites with different melt structures

Jiang

et al. 2019

Polymer Engineering & Sci

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In this study, we have prepared two β-nucleated isotactic polypropylene/graphene oxide (β-iPP/GO) composites with different stereo-defect distribution (named NPP-B and NPP-A). The role of stereo-defect distribution on the crystallization and polymorphic behaviors of samples with varied melt structures were investigated by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). It was found that NPP-B (who with more uniform stereo-defect distribution) prefers β-crystallization; while NPP-A has a strong α-nucleation tendency and can hardly form β-phase; as fusion temperature decreases from 200 C to 168 C, the relative percentages of β-phase of NPP-B and NPP-A exhibit the same trends, suggesting that the β-nucleation efficiency is enhanced by the ordered structure effect (OSE) and causes β-crystallization even in NPP-A. Moreover, the lower limiting temperatures of Region-II of NPP-B and NPP-A are the same but their upper limiting temperatures are different, indicating the uniformity of stereo-defect distribution also influences temperature window for OSE. Related mechanisms were discussed.

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“…Compared with isotactic polypropylene homopolymer (iPP), the crystallizability of PPR is reduced due to the lower isotacticity with the incorporation of comonomers in the molecular chain; correspondingly its toughness is improved . Similar to iPP, PPR can also crystallize in three crystal forms, namely the monoclinic α‐form, the trigonal β‐form and the orthorhombic γ‐form, depending on the crystallization conditions such as crystallization temperature, shear strength, nucleating agent and cooling rate. α crystal is predominant under conventional processing conditions, and β crystal is thermodynamically metastable and can only be obtained in the presence of β‐nucleating agent (β‐NA).…”

Section: Introductionmentioning

confidence: 99%

“…Compared with iPP, it is more difficult for PPR to form large amounts of β crystal in the presence of β‐NA . Therefore, in our work, Ca‐Pim, a highly efficient β‐NA, was selected as the β‐NA and OSIM was applied to provide strong shear to affect the polymorphic composition and morphology of Ca‐Pim‐nucleated PPR.…”

Section: Introductionmentioning

confidence: 99%

Synergistic enhancement of crystallization and mechanical performance of polypropylene random copolymer by strong shear and β‐nucleating agent

Zhang

Zhao

et al. 2017

Polymer International

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Investigation of microstructure and properties is critical for the development and application of polymer materials. Polypropylene random copolymer (PPR) and -nucleated PPR are widely used in water pipe production. The effect of melt shear flow on the crystalline structure and mechanical properties of PPR containing -nucleating agent needs in-depth understanding. In this paper, we demonstrated the preparation of PPR and PPR containing 0.1 wt% calcium pimelate (Ca-Pim) samples by conventional injection molding (CIM) and oscillation shear injection molding (OSIM). The multilayer structures and morphologies of the samples were characterized by SEM, two-dimensional X-ray scattering and DSC. The mechanical properties and the microstructures of samples prepared by these two injection molding methods were compared. Compared with samples prepared by CIM, the stronger shear provided by OSIM induced the formation of a thicker layer of a shish-kebab structure and a higher content of crystals, and dramatically suppressed the -nucleating effect of Ca-Pim. The OSIM samples have more shish-kebab structures and higher crystallinities than CIM samples and therefore the former exhibit better rigidity than the latter. The crystals in the core layer and the thicker layer of shish-kebab structure endow OSIM-PPR/0.1 wt% Ca-Pim with excellent impact toughness.

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Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

Cited by 19 publications

References 64 publications

Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites

Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites

Effects of stereo‐defect distribution on the crystallization and polymorphic behavior of β‐nucleated isotactic polypropylene/graphene oxide composites with different melt structures

Synergistic enhancement of crystallization and mechanical performance of polypropylene random copolymer by strong shear and β‐nucleating agent

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