Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets

Ji, Huajian; Zhou, Xulin; Chen, Xin; Zhao, Haili; Wang, Yu; Zhu, Huihao; Shan, Xiliang; Sha, Jiahao; Ma, Yulu; Li, Jingchi

doi:10.3390/polym11040618

Cited by 15 publications

(14 citation statements)

References 39 publications

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“…As the stretch ratio of the PP/PA6 blends increased from 1 to 16, the peak (q*) increased from 0.28 to 0.36 nm −1 , and the corresponding long period (L) decreased from 22.12 to 17.46 nm. The reduction of 4.66 nm of L could be a result of the formation of more densely packed PP lamellae in the PP/PA6 MFCs [39]. The secondary peak could be observed in the PP/PA6 blends subjected to stretching, as shown in the SAXS intensity distribution curves of Figure 4c-f, and the corresponding long period was around 10 nm.…”

Section: Samplementioning

confidence: 82%

The Formation of a Highly Oriented Structure and Improvement of Properties in PP/PA6 Polymer Blends during Extrusion-Stretching

et al. 2020

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During the “slit die extrusion-hot stretching” process, highly oriented polyamide 6 (PA6) dispersed phase was produced and retained in the polypropylene (PP) matrix directly. By adjusting the stretching forces, the PA6 spherical phase evolved into the ellipsoid, rod-like microfibril with a decreasing average diameter; then, the PA6 microfibrils broke. Moreover, the effects of the PA6 phases formed in the process of the microfibrillation on PP’s crystallization behaviors were studied systematically. As the stretching forces increased, the crystallization ability and orientation degree of PP crystals improved significantly. Differential scanning calorimetry and polarizing optical microscopy confirmed the formation of PP spherulite, fan-shaped lamellae and a transcrystalline layer under the induction of the PA6 phases with different morphology. In the PP/PA6 microfibrilar composites (MFCs), PP crystals showed smaller average size, more crystals and stronger interface adhesion due to more excellent heterogeneous nucleation ability of the PA6 microfibrils, which made contributions to the improvement of the melt elasticity responses and oxygen barrier properties of the PP/PA6 polymer blends.

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Section: Samplementioning

confidence: 82%

The Formation of a Highly Oriented Structure and Improvement of Properties in PP/PA6 Polymer Blends during Extrusion-Stretching

et al. 2020

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“…However, low temperature brittleness and poor impact resistance restrict its applicability. Among all strategies for PP toughening, the introduction of a β -nucleating agent has been demonstrated to be the most reliable strategy [1,2,3,4,5,6,7,8]. Nowadays, due to the low cost, simple processing, and their non-toxic, macromolecular β -nucleating agents (such as polystyrene (PS), acrylonitrile-butadiene-styrene graft copolymer (ABS), or thermo-plastic phenolic resin) have been reported to have higher β -nucleating efficiency compared with low molecular weight organic β -nucleating agents.…”

Section: Introductionmentioning

confidence: 99%

Influence of Organo-Sepiolite on the Morphological, Mechanical, and Rheological Properties of PP/ABS Blends

Wang

Xie

et al. 2019

Polymers

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To improve the poor impact toughness of polypropylene (PP), organo-sepiolite (O-Sep) filled 80/20 (w/w) polypropylene/poly(acrylonitrile-butadiene-styrene) (PP/ABS) nanocomposites were fabricated. The contents of O-Sep were correlated with the morphological, mechanical, and rheological behavior of PP/ABS/O-Sep blends. Scanning electron microscopy (SEM) was applied to study the morphology and thermogravimetric analysis (TGA) was applied to study the thermal stability. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were applied to study the crystallinity. The obtained results show that O-Sep enhanced the dispersion of ABS in the PP matrix and increased the crystallinity of blends. The rheological results show that O-Sep could increase the viscosity, storage modulus, and loss modulus of blends. Moreover, the mechanical behavior shows that O-Sep (at proper content) simultaneously increased the tensile modulus, flexural modulus, and impact strength of PP/ABS/O-Sep blends.

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“…The melting characteristics of the iPP sheet at different stretching temperatures are shown in Figure 3 . The endothermic peak located at 150 °C was the melting point of the β-modifications (T mβ ), while that located at 165 °C was the melting point of the α-modifications (T mα ) [ 28 ]. In Figure 3 a,b, the melting enthalpy of the α- and β-modifications did not change much after solid-state stretching.…”

Section: Resultsmentioning

confidence: 99%

“…Upon deformation, the isotropic structure of polymer can be transformed into an anisotropic structure [28]. Hence, the transition mechanism and the relationship to the morphology and structure are important for polymer science.…”

Section: Cylindrite Structure Transformation Mechanismmentioning

confidence: 99%

“…The evolution of the microstructure of the iPP sheet at different stretching temperatures was investigated. In our previous work [28], we studied the evolution process of the α-modification lamellae phase transition of pure iPP during solid-state stretching. This work elucidated the temperature-related β-modification lamellae structural transformation and deformation-induced mechanism of β-modification iPP.…”

Section: Introductionmentioning

confidence: 99%

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Deformation-Induced Crystallization Behavior of Isotactic Polypropylene Sheets Containing a β-Nucleating Agent under Solid-State Stretching

Zhou

Chen

et al. 2020

Polymers

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The deformation-induced crystallization of an isotactic polypropylene (iPP) sheet containing a β-nucleating agent was evaluated. The phase transformation of the β-modifications was investigated and the crystal morphology was observed at room temperature after stretching at different temperatures. The results showed that the crystallinity increased after solid-state stretching. When the stretching temperature was below the initial crystallization temperature, stretching deformation promoted the orientation of amorphous molecular chains. When the deformation temperature exceeded the crystallization temperature, part of the β-modifications underwent a phase transformation process and was stretched into a shish-kebab structure. However, once the stretching temperature was close to the melting point, the β-modifications melted and recrystallized, and the shish-kebab structure underwent stress relaxation due to poor thermal stability, transforming into α-modifications. It was revealed that the crystal phase transformation mechanism of the β-modifications was based on the orientation of the molecular chains between the adjacent lamellae. In addition, the shish-kebab cylindrite structure played an important role in modifying the tensile and impact properties of the iPP sheet. The tensile and impact strengths increased by as much as 34% and 126%, respectively.

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Effects of Solid-State Stretching on Microstructure Evolution and Physical Properties of Isotactic Polypropylene Sheets

Cited by 15 publications

References 39 publications

The Formation of a Highly Oriented Structure and Improvement of Properties in PP/PA6 Polymer Blends during Extrusion-Stretching

The Formation of a Highly Oriented Structure and Improvement of Properties in PP/PA6 Polymer Blends during Extrusion-Stretching

Influence of Organo-Sepiolite on the Morphological, Mechanical, and Rheological Properties of PP/ABS Blends

Deformation-Induced Crystallization Behavior of Isotactic Polypropylene Sheets Containing a β-Nucleating Agent under Solid-State Stretching

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