Effect of the content of β form crystals on biaxially stretched polypropylene microporous membranes and the tuning of pore structures

Wu, Guozhong; Ding, Chao; Chen, Wenbo; Zhang, Ya; Yang, Jie

doi:10.1016/j.polymer.2019.05.003

Cited by 18 publications

(16 citation statements)

References 42 publications

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“…Nevertheless, when stretched along TD (Figure 7C,D), β‐lamellae deforms instantaneously under tensile loading to produce oriented fibril structure in which few cavities are created, resulting in the heterogeneous yielding and transparent region in the tested sample (shown in Figure 5A). 8,12,32,33 …”

Section: Resultsmentioning

confidence: 99%

Preparation of highly oriented β polypropylene and its pore formation mechanism during stretching

Yang

Xiang

et al. 2021

Polymer Crystallization

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In this article, oriented β isotactic polypropylene (β‐iPP) with different aggregation structures were prepared by shearing and adding different β nucleating agents. It is found that the formation mechanism of oriented β‐iPP is nucleating agent induced and their crystalline structures strongly depend on the assembly of β nucleating agents. In the case of adding TMB‐5, the β lamellae orient slightly to form elliptical spherulite based on the spherical growth mechanism and the content of β‐crystal reduces substantially with the increasing shear rate. On the other hand, the “bundle‐like” β‐crystal rotates along the extrusion direction to form highly oriented β‐iPP. Based on the preparation of oriented “bundle‐like” β‐crystal, the morphological evolution of β‐iPP during stretching was systematically investigated by two‐dimensional wide‐angle X‐ray diffraction, two‐dimensional small angle X‐ray scattering and scanning electron microscopy. We found that micropores are directly initiated from the weak interfaces between β‐lamellae instead of β‐α phase transformation. In addition, since the β‐lamellae in oriented β‐iPP have identical deformation mode, the membrane with more uniform pore size distribution could be produced compared with that made by the traditional dry process.

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Section: Resultsmentioning

confidence: 99%

Preparation of highly oriented β polypropylene and its pore formation mechanism during stretching

Yang

Xiang

et al. 2021

Polymer Crystallization

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“…In order to apply the theoretical and computational methods, the creep and recovery responses should be within the linear viscoelastic regime. The linear viscoelastic creep and recovery responses of polypropylene composites have been experimentally studied in the past (Wang et al 2018;Kurt and Kasgoz 2021;Wu et al 2019;Lee et al 2004;Homkhiew et al 2013;Rosa et al 2018). However, the experimental studies vary on the testing methods, the equipment used, and the testing conditions.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…They used the four parameters Burgers model to fit the creep. The effects of adding different crystals and porosities have been studied by Wu et al (2019). Furthermore, several reinforced polypropylene composites have been studied lately using both experimental and complementary theoretical modelling, including materials such Fig.…”

Section: Introductionmentioning

confidence: 99%

Characterising the linear viscoelastic behaviour of an injection moulding grade polypropylene polymer

Gebrehiwot

Espinosa-Leal

2021

Mech Time-Depend Mater

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The linear viscoelastic behaviour of an injection moulding grade polypropylene is studied using theoretical and computational methods. Polypropylene has a variety of engineering applications as a component. However, it commonly exhibits viscoelastic deformations. This paper analyses the creep and recovery responses of the BJ368MO polypropylene copolymer using the Burgers and generalised Maxwell models. Within the linear viscoelastic regime, an experimental creep strain at $20\ \text{MPa}$ 20 MPa is used to determine the rheological constants of the models. These constants (springs and dashpots) are determined using a nonlinear least-squares curve fitting of the experimental creep. Then they are used to predict the creep and recovery responses of the polymer at three different stresses, $10\ \text{MPa}$ 10 MPa , $12.5\ \text{MPa}$ 12.5 MPa and $15\ \text{MPa}$ 15 MPa . The experiments are made using tensile specimens designed according to the ASTM D638-14standard. The theoretical evaluations are made using the creep and recovery equations derived from their constitutive. Whereas COMSOL Multiphysics software is used during the finite element (FE) analyses. The results of the theoretical and FE calculations are verified using creep and recovery experiments. Based on the validation analyses, both viscoelastic models showed lower deviations from the experimental results when a computational approach is used. In addition, the viscoelastic models are compared by evaluating the residuals of the creep and recovery strain predictions. The theoretical analyses showed better predictions at $12.5\ \text{MPa}$ 12.5 MPa and $15\ \text{MPa}$ 15 MPa stresses when the generalised Maxwell model is used. However, the improvements are attributed to the recovery predictions. When FE is used, the Burgers model showed lower mean absolute percentage errors (MAPEs) in all creep and recovery predictions. The model has a minimum of 6.37% error at the $10\ \text{MPa}$ 10 MPa stress and a maximum of 8.23% error at the $15\ \text{MPa}$ 15 MPa . By comparison, the generalised Maxwell model showed a minimum of 9.24% error at $12.5\ \text{MPa}$ 12.5 MPa and a maximum of 12.8% error at $15\ \text{MPa}$ 15 MPa stresses. The novelty of this paper is on predicting the creep and recovery behaviour of the polymer using the FE and theoretical approaches in the linear viscoelastic regime. The findings suggest that the FE analyses using the Burgers viscoelastic material model provide better predictions, with all calculated errors falling below 10%.

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“…However, the (300) diffraction peak of the β-form PP is observed in PP/D-LDH (1h) and barely visible in PP/D-LDH (9h) and (12h). 26 The observation of β-PP illustrates that the incorporation of LDHs affects the crystallized domains of PP but such effect seems to be erratic and not correlated strictly to AMO time. (Fig.…”

Section: -mentioning

confidence: 98%

An aqueous miscible organic (AMO) process for layered double hydroxides (LDHs) for the enhanced properties of polypropylene/LDH composites

et al. 2020

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Effect of the content of β form crystals on biaxially stretched polypropylene microporous membranes and the tuning of pore structures

Cited by 18 publications

References 42 publications

Preparation of highly oriented β polypropylene and its pore formation mechanism during stretching

Preparation of highly oriented β polypropylene and its pore formation mechanism during stretching

Characterising the linear viscoelastic behaviour of an injection moulding grade polypropylene polymer

An aqueous miscible organic (AMO) process for layered double hydroxides (LDHs) for the enhanced properties of polypropylene/LDH composites

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