Blend morphology development during melt flow: Correlation of a model concept based on dynamic phase volume with practical observations

Namhata, S.; Guest, M; Aerts, L.

doi:10.1002/(sici)1097-4628(19990110)71:2<311::aid-app15>3.3.co;2-v

Cited by 3 publications

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“…A co-continuous structure with good regularity developed and grew in an injection-molded blend of PP/HDPE (60/40 by weight) observed by Sano et al [26], which could be not obtained by a simple melt mixing of immiscible polymer pairs only by the spinodal decomposition (under zero shear rate in mold) from a single-phase mixture attained (by upper critical solution temperature (UCST) depression or LCST elevation) in high shear fields in an injection machine. In the injection-molded part of the blend of polycarbonate/acrylonitrile-butadiene-styrene copolymer (PC/ABS) (70/30 by volume) studied by Namhata et al [38], there existed a co-continuous structure in the skin region and a dispersed phase structure in the core region, which was in line with the anticipation of the model based on dynamic phase volume. It was suggested that the change in dynamic volume fraction, determined by the actual phase volume fraction and the viscosity ratio between phases, resulted in the variations of phase morphology.…”

Section: Hierarchy Structure Of the Co-continuous Phase Morphologymentioning

confidence: 60%

Injection molding-induced morphology of thermoplastic polymer blends

Zhong

2005

Polym. Eng. Sci.

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Various morphologies induced by injection molding are reviewed here. The structural hierarchy in the direction perpendicular to flow direction always appears in the injection-molded blends. The hierarchy involves three aspects: phase behavior hierarchy for the dispersed phase, crystalline or orientated structural hierarchy for the matrix, as well as hierarchy structure of co-continuous phase morphology. There are usually three layers in the injection-molded bars, i.e., the skin layer and the core region as well as the shear zone between them. The morphology of the dispersed phase is usually different between the skin zone (usually including shear zone) and the core region: deformed particles may exist in the skin layer, whereas spherical droplets in the core region. Moreover, the size of crystals usually increases with the increase of the distance to the surface due to the increase of crystallization time, and the orientation is often severe near the surface due to the high shear stress. Defects of the injection-molded parts, such as weldline and flow marks, are also reviewed. The dispersed phase morphology in the weldline region is significantly different from the region out of the weldline and the morphology of the flow marks is also different from the out-offlow marks. POLYM. ENG. SCI., 45:1655-1665, 2005.

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Section: Hierarchy Structure Of the Co-continuous Phase Morphologymentioning

confidence: 60%

Injection molding-induced morphology of thermoplastic polymer blends

Zhong

2005

Polym. Eng. Sci.

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“…a twin-screw extruder). In particular, there have been several reports of experimental studies on co-continuous morphology and/or a dispersed morphology, depending upon melt blending conditions and blend compositions [37][38][39][40]. The basic concept is the use of immiscible polymers to obtain heterogeneous systems with a multiphase morphology [37].…”

Section: Fully Interconnected Porous Scaffolds By Melt Co-continuous Polymer Blending (Mcpb)mentioning

confidence: 99%

“…During this process, potentially important factors influencing the morphology of forming dispersed phases may be the phase relative volume fraction, chemical and physical properties of constituent polymers (e.g., interface tension, viscosity, elastic moduli), as well as the processing conditions expressed by working temperature and shear rate [38]. By modulating all these parameters, the phase inversion point can be reached with full interconnectivity of phases, to form a continuous pathway [38,40]. Starting from this basic observation from polymer blending, biocompatible and bioresorbable porous scaffolds may be efficiently obtained by the selective extraction of one polymer phase from co-continuous blends.…”

Section: Fully Interconnected Porous Scaffolds By Melt Co-continuous Polymer Blending (Mcpb)mentioning

confidence: 99%

“…This technique was the gold standard in scaffold preparation for a long time. However, scaffolds made by particle leaching methods tend to have a porous structure with intact pore walls and limited interconnection points due to the contact between adjacent crystals in the polymer network [40]. Such a pore structure, i.e.…”

Section: Multiscale Porous Scaffolds By Adapting Temperature-driven Processes To Salt Leaching Techniquesmentioning

confidence: 99%

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Temperature-driven processing techniques for manufacturing fully interconnected porous scaffolds in bone tissue engineering

Guarino

Ambrosio

2010

Proc Inst Mech Eng H

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The development of structures with a predefined multiscale pore network is a major challenge in designing tissue engineering (TE) scaffolds. To address this, several strategies have been investigated to provide biocompatible, biodegradable porous materials that would be suitable for use as scaffolds, and able to guide and facilitate the cell activity involved in the generation of new tissue regeneration. This study seeks to provide an overview of different temperature-driven process technologies for developing scaffolds with tailored porosity, in which pore size distribution is strictly defined and pores are fully interconnected. Here, three-dimensional (3D) porous composite scaffolds based on poly(epsilon-caprolactone) (PCL) were fabricated by thermally induced phase separation (TIPS) and by melt co-continuous polymer blending (MCPB). The combination of these processes with a salt leaching technique enables the establishment of bimodal porosity within the polymer network. This feature may be exploited in the development of substrates with fully interconnected pores, which can be used effectively for tissue regeneration. Various combinations of the proposed techniques provide a range of procedures for the preparation of porous scaffolds with an appropriate combination of morphological and mechanical properties to reproduce the requisite features of the extracellular matrix (ECM) of hard tissues such as bone.

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“…Subscripts represent phases 1 and 2. Namhata et al [22] also showed a condition for co-continuity for PC/ABS using a parameter called the dynamic volume fraction, F, by:…”

Section: Development Of a High-flow Pc/abs Resinmentioning

confidence: 99%

Rheology Enhancement in PC/ABS Blends

2000

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Polycarbonate is a very broadly used material across various industries; however, in order to improve its processability, it is generally blended with acrylonitrile–butadiene–styrene copolymer (ABS). As presented here, the proportion of ABS used is a highly important parameter, since it can affect the useful properties of polycarbonate such as heat resistance and toughness (the Figure shows the variation of toughness (Izod impact) with amount ABS used).

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Blend morphology development during melt flow: Correlation of a model concept based on dynamic phase volume with practical observations

Cited by 3 publications

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Injection molding-induced morphology of thermoplastic polymer blends

Injection molding-induced morphology of thermoplastic polymer blends

Temperature-driven processing techniques for manufacturing fully interconnected porous scaffolds in bone tissue engineering

Rheology Enhancement in PC/ABS Blends

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