Morphological evolution and orientation development of stretched iPP films: Influence of draw ratio

Zhou, Ying‐Guo; Turng, Lih‐Sheng; Shen, Changyu

doi:10.1002/polb.22013

Cited by 30 publications

(43 citation statements)

References 36 publications

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“…23,24 Chatterjee et al reported excellent barrier and optical properties for blown high-density polyethylene (HDPE) lms with optimized draw ratios to achieve special lamellar organization as well as orientation of the amorphous phase. Melt stretching is an effective way to induce chain extension and enhance molecular orientation, thus improving the mechanical properties of polyolens.…”

Section: Introductionmentioning

confidence: 99%

The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtainedviamelt stretching

et al. 2015

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In this study, the orientation, structure and mechanical performance of a series of uniaxially oriented films based on olefin block copolymers (OBC) have been investigated in terms of the differences in hard block content and draw ratio (DR). Three OBCs with different hard block contents of 35 wt%, 25 wt% and 12 wt% were used. For un-stretched films, a change from close-packed spherulites into tiny crystallites is observed with decreasing hard block content, accompanied by an almost linear decrease in crystallinity.However, the change in mechanical properties does not follow the same path, with obviously higher tensile strength and modulus for OBC-35, but a lower and almost the same tensile strength and modulus for OBC-25 and OBC-12, in spite of the big difference in hard block content and crystallinity between them. For melt-stretched films, the degree of orientation of the amorphous phase is almost the same and slightly increases with the increase in the draw ratio for the three OBCs, disregarding their hard block contents. Crystalline orientation and shish content are much higher for OBC-35, and an obvious increase is seen as the draw ratio increases from 4.95 to 8, corresponding to the sharp increase in Young's modulus and stress. For OBC-25 and OBC-12, similar crystalline orientation and shish content are seen, which increase linearly with draw ratio and are consistent with the linear increase in modulus and stress as the draw ratio increases. Our study demonstrates the importance of the hard block content of OBC to determine the mechanical properties and the response to external stretching. A critical hard block content exists (in this case 35 wt%), above which a strong network is constructed by the hard block crystalline phase, resulting in a higher tensile strength and modulus. This strong network is destroyed as the draw ratio reaches a certain value (herein, 4.95 to 8), leading to an obvious increase in crystalline orientation, as well as a sharp increase in tensile strength and modulus. When the hard block is below the critical content (herein, 25 wt% and 12 wt%), the network constructed by the hard block is weak and less dependent on its content.

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Section: Introductionmentioning

confidence: 99%

The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtainedviamelt stretching

et al. 2015

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“…[16][17][18][19] The higher intensity of elongation ow eld results in the higher degree of orientation of lamellar crystalline along the draw direction. [16][17][18][19] The higher intensity of elongation ow eld results in the higher degree of orientation of lamellar crystalline along the draw direction.…”

Section: Resultsmentioning

confidence: 99%

“…The elastic polymer usually has been suggested to obtain the large elastic region for the conductive composite capable of substantial stretching and bending. 18,19 The morphology evolution of matrix have a profoundly inuence on the composite mechanical property, which correlates with the piezoresistive of composites. 15 By playing with lamellar crystalline structure through special processing method, the polyolen may be promising candidate for use in the highly stretchable electronic devices.…”

Section: Introductionmentioning

confidence: 99%

A highly-deformable piezoresistive film composed of a network of carbon blacks and highly oriented lamellae of high-density polyethylene

et al. 2015

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The electrical resistance change of highly extensible films consisting of a network of carbon blacks in highdensity polyethylene, with different regularity of stacked lamellae, is investigated. The film was fabricated by melt mixing of high-density polyethylene (HDPE) and carbon black (CB) via cast film extrusion. The morphology of particle network and regularity of stacked lamellae were affected by draw ratio during the cast film extrusion process. Testing has shown that the regularly stacked lamellar structure furnishes the film with hard elastic behavior and is conducive to the enhancement of the reversible level for the conductive film, which correlates with the piezoresistance response during the stretching and strain recovery. A rebound peak of R/R 0 is observed at the beginning of each loading cycle within the relatively low deformation level and a marked growth of the amplitude of R/R 0 , as the number of cycle increases, is observed within the high deformation level for the film with highly regular stacked lamellae. It indicates that the regularity of stacked lamellar structure of matrix has a significant influence on the piezoresistivity of the film. The results could be utilized for the development of smart sensing and structural health monitoring of CB composite materials.

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“…The obtained XRD images were further analyzed using a Bruker AXS general area detector diffraction system (GADDS). Following the same method in Zhou et al's paper, 28 the orientation of iPP crystals was quantified using the Hermans orientation function,…”

Section: Experimental Designmentioning

confidence: 99%

Investigation of crystallization behavior of solid and microcellular injection molded polypropylene/nano-calcium carbonate composites using carbon dioxide as a blowing agent

Chen

Sun

Turng

et al. 2013

Journal of Cellular Plastics

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This work is aimed at investigating the crystallization behavior of solid and microcellular injection molded polypropylene/nano-calcium carbonate composites. The effects of processing conditions, such as injection speed, mold temperature, and carbon dioxide concentration (used in microcellular injection molding), as well as the filler concentration on the crystal form, crystal orientation, and crystallinity were studied using 2D-wide-angle X-ray diffraction and differential scanning calorimetry. β-form crystals found in the surface layer of injection molded samples under high injection and mold temperature due to stronger shear effect. The orientation degree calculated from the X-ray diffraction images by the Hermans function was high in the surface layer and decreased as the distance from the mold surface increased. The addition of the nano-calcium carbonate filler promoted the formation of β-form crystals but reduced the orientation degree and crystallinity as the nanoparticles disturbed the orientation of the molecular chains. On the other hand, when using the foaming process, the formation of β-form crystals was inhibited and the orientation degree was reduced, but the crystallinity of the samples increased, likely due to enhanced molecular chain mobility from the supercritical carbon dioxide which acted as a plasticizer. The crystallinity of the samples was greater in the surface layer but showed no dependence on the injection speed or mold temperature.

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Morphological evolution and orientation development of stretched iPP films: Influence of draw ratio

Cited by 30 publications

References 36 publications

The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtainedviamelt stretching

The effect of hard block content on the orientation and mechanical properties of olefin block copolymer films as obtainedviamelt stretching

A highly-deformable piezoresistive film composed of a network of carbon blacks and highly oriented lamellae of high-density polyethylene

Investigation of crystallization behavior of solid and microcellular injection molded polypropylene/nano-calcium carbonate composites using carbon dioxide as a blowing agent

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