Plastic deformation mechanism of crystalline polymer materials during the rolling process

Qiu, Jianhui; Murata, Takehide; Wu, Xueli; Kudo, Makoto; Sakai, Eiichi

doi:10.1007/s10853-012-6957-2

Cited by 15 publications

(6 citation statements)

References 50 publications

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“…48 Moreover, tan δ and T g increases as the rolling temperature increases due to the higher degree of orientation, resulting in anisotropy. 49 Figure 8c shows the stress-strain curve parallel to the rolling direction of rolled and unrolled PLA and PLA/3 wt.%CNT nanocomposites. The statistical data is listed in Table 2.…”

Section: Mechanical Behaviormentioning

confidence: 99%

Facile preparation of anisotropic PLA/CNT nanocomposites by hot and cold rolling processes for improving mechanical and conductive properties

Huang

Song

Liu

et al. 2022

J of Applied Polymer Sci

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Poly(lactic acid) (PLA) is one of the most important biodegradable polymers, however, brittleness severely limits its applications. Thus, strengthening and toughening PLA is a cutting‐edge research for both academia and industry. In this study, rolling process was applied to simultaneously improve the toughness and strength of PLA and its nanocomposites by regulating microstructure of PLA molecular chains. Results showed that crystallinity and orientation of rolled PLA and its nanocomposites were significantly improved. When rolling rate was 50% at 75°C, elongation at break increased from unrolled PLA of 5.9% to 190.1%. When the rolling rate was 50% at room temperature, tensile strength and Young's modulus increased from unrolled PLA of 59.4 and 1763.7 MPa to 70.4 and 2557.6 MPa, respectively. In addition, multiwalled carbon nanotubes (MWCNTs) in PLA/3 wt.%CNT nanocomposite rolled at 75°C for 50% were highly oriented, leading to a significant reduction in resistivity along the rolling direction, which endows it many great potential applications, such as sensor, electromagnetic wave absorption, and electronic packaging.

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Section: Mechanical Behaviormentioning

confidence: 99%

Facile preparation of anisotropic PLA/CNT nanocomposites by hot and cold rolling processes for improving mechanical and conductive properties

Huang

Song

Liu

et al. 2022

J of Applied Polymer Sci

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“…Pressurizing the polymer can increase the free volume of the material as the result of plastic defects. The increased free volume from these defects influences the activation of molecular mobility [ 22 , 26 , 27 , 28 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

Nematic-to-Isotropic Phase Transition in Poly(L-Lactide) with Addition of Cyclodextrin during Abiotic Degradation Study

Rydz

Duale

Janeczek

et al. 2022

IJMS

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Poly(L-lactide) is capable of self-assembly into a nematic mesophase under the influence of temperature and mechanical stresses. Therefore, subsequent poly(L-lactide) films were obtained and characterized, showing nematic liquid crystal properties both before and after degradation. Herein, we present that, by introducing β-cyclodextrin into the polymer matrix, it is possible to obtain a chiral nematic mesophase during pressing, regardless of temperature and time. The obtained poly(L-lactide) films exhibiting liquid crystal properties were subjected to degradation tests and the influence of degradation on these properties was determined. Thermotropic phase behavior was investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The degradation process demonstrated an influence on the liquid crystal properties of pressed polymer films. The colored planar texture of the chiral nematic mesophase, which was not observed prior to degradation in films without the addition of β-cyclodextrin, appeared after incubation in water as a result of the entrapment of degradation products in the polymer matrix. These unusual tailor-made properties, obtained in liquid crystals in (bio)degradable polymers using a simple method, demonstrate the potential for advanced photonic applications.

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“…Many solid state forming processes have been recently used to improve structure and properties of monolithic polymers and polymer matrix composite materials. Uniaxial and biaxial deformation, rolling, and extrusion are among the shaping techniques that alter the structural and mechanical properties of polymers and their composites by imposing large plastic deformations. These deformations are usually accompanied by significant reduction in the cross‐sectional area of the initial sample.…”

Section: Introductionmentioning

confidence: 99%

Effect of equal channel angular pressing on thermal and mechanical properties of carbon nanotube/high density polyethylene composite

Shirazi

Zebarjad

Ebrahimi

2017

Polymers for Advanced Techs

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High density polyethylene (HDPE) nanocomposite reinforced with 2 weight percent carbon nanotube (CNT) was fabricated using mechanical milling method. Microscopic evaluations revealed appropriate dispersion of CNTs in the matrix, and tensile tests demonstrated that the tensile strength was increased by 17%. Thermal and mechanical properties of the composite samples were investigated after equal channel angular pressing (ECAP) for up to 3 passes via route A at temperature of 80°C. Density and differential scanning calorimetry (DSC) results represented decrement in crystallinity after ECAP which was led to drop in hardness and tensile yield strength of the deformed samples. Micro Vickers and Shore D hardness results also revealed clear anisotropy in mechanical properties caused by ECAP. Dilatometry results and observation of the impact fractured surfaces of deformed samples demonstrated that oriented structures formed in amorphous and crystalline regions of the composite. This microstructure evolution also caused increase in impact strength of ECAP deformed specimens. Dynamic mechanical behavior of the processed samples was modified following ECAP. The α and γ relaxation temperatures were decreased due to the reduction of thickness of crystalline lamella obtained from DSC results, in 1 pass ECAP deformed sample. Dynamic storage and loss modulus of 3 passes ECAP deformed samples were significantly decreased due to the sharp drop in their crystallinity. KEYWORDS carbon nanotube, equal channel angular pressing, oriented structure, polyethylene 1 | INTRODUCTION Many solid state forming processes have been recently used to improve structure and properties of monolithic polymers and polymer matrix composite materials. Uniaxial 1 and biaxial 2 deformation, rolling, 3 and extrusion 4 are among the shaping techniques that alter the structural and mechanical properties of polymers and their composites by imposing large plastic deformations. These deformations are usually accompanied by significant reduction in the cross-sectional area of the initial sample. However, in severe plastic deformation (SPD) techniques, it is possible to impose large plastic deformation without any change in the initial dimensions of the billet. Among the various SPD techniques, equal channel angular pressing (ECAP) is widely usedto enhance structural and mechanical properties of metals and metal matrix composites. 5 The successful experience of applying ECAP to several metallic systems causes a motivation for some researchers to use this type of SPD technique to improve the properties of polymeric materials. As illustrated in Figure 1, the process consists of pressing a specimen through a die with 2 equal cross-section channels intersecting at an angle. (Here for simplicity, the angle of intersection of 2 channels is taken 90°.) By moving through the intersection of 2 channels, the sample experiences simple shear deformation. Because the cross section of the billet is maintained constant during ECAP, it is possible to press a sample repetitively by...

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Plastic deformation mechanism of crystalline polymer materials during the rolling process

Cited by 15 publications

References 50 publications

Facile preparation of anisotropic PLA/CNT nanocomposites by hot and cold rolling processes for improving mechanical and conductive properties

Facile preparation of anisotropic PLA/CNT nanocomposites by hot and cold rolling processes for improving mechanical and conductive properties

Nematic-to-Isotropic Phase Transition in Poly(L-Lactide) with Addition of Cyclodextrin during Abiotic Degradation Study

Effect of equal channel angular pressing on thermal and mechanical properties of carbon nanotube/high density polyethylene composite

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