Influence of Composition and Processing History on the Cellular Morphology of the Foamed Olefinic Thermoplastic Elastomers

1992 ◽  
Vol 65 (5) ◽  
pp. 932-955 ◽  
Author(s):  
A. Dutta ◽  
M. Cakmak
Keyword(s):  
Fractal Dimension ◽  
Volume Expansion ◽  
Cell Structure ◽  
Extrusion Direction ◽  
Thermoplastic Elastomers ◽  
Maximum Volume ◽  
Rubber Content ◽  
Chemical Blowing Agents ◽  
Ethylene Propylene Diene Terpolymer ◽  
Characteristic Fractal Dimension

Abstract Foam extrusion of a series of dynamically vulcanized polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) blends (commercially available Santoprene) by using chemical blowing agents have been studied. Results suggest that foaming occurs only within the thermoplastic phase and for each composition there exists a limiting density which controls the maximum volume expansion. This limiting density is controlled only by the composition and is independent of the blowing agent concentration, extrusion conditions, and the geometry. For the softest and the hardest blends, maximum volume expansion was found to be about 20 and 100%, respectively. Considerable differences in cell structure were also observed with change in the blend composition. As the rubber content increases, bubbles change their shapes from spherical to highly elongated channels where long axes are primarily along the extrusion direction. When the shapes of the bubbles are viewed by cutting the specimen, the bubbles were found to become highly irregular as the rubber content was increased. The fractal dimension of the perimeter profiles revealed that increases in rubber content give increases in the characteristic fractal dimension. Additionally, wide angle x-ray pole figure analysis, which gives an average orientation behavior of the material, indicates that low levels of preferential crystalline chain orientation develop in the extradates. This preferential orientation was found to vary from skin to core.

Rheology/morphology relationship of plasticized and nonplasticized thermoplastic elastomers based on ethylene-propylene-diene-terpolymer and polypropylene

2011 ◽  
Vol 51 (11) ◽  
pp. 2314-2327 ◽  
Author(s):  
Shant Shahbikian ◽  
Pierre J. Carreau ◽  
Marie-Claude Heuzey ◽  
Maria D. Ellul ◽  
Hari P. Nadella ◽  
...  
Keyword(s):  
Thermoplastic Elastomers ◽  
Ethylene Propylene ◽  
Relationship Of ◽  
Ethylene Propylene Diene Terpolymer

scholarly journals Rotomolding of Thermoplastic Elastomers Based on Low-Density Polyethylene and Recycled Natural Rubber

2019 ◽  
Vol 9 (24) ◽  
pp. 5430 ◽  
Author(s):  
Ramin Shaker ◽  
Denis Rodrigue
Keyword(s):  
Thermoplastic Elastomers ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Melt Blending ◽  
Material Degradation ◽  
Rubber Content ◽  
Ground Tire Rubber ◽  
The Road ◽  
Processing Cost ◽  
Physical Density

In this study, regenerated and nonregenerated off-the-road (OTR) ground tire rubber (GTR) was blended with low-density polyethylene (LDPE) to produce thermoplastic elastomers (TPE) by rotational molding. In particular, blending was performed by two different methods: melt blending (extrusion) and dry blending (high shear mixer). Then, different GTR concentrations (0, 20, 35, and 50 wt %) were used to determine the effect of rubber content on the processability and properties of the rotomolded compounds. From the samples produced, a complete morphological (optical and scanning electron microscopy), physical (density and hardness), and mechanical (tension, flexion, and impact) characterization was performed. The results showed that increasing the rubber content decreased the mechanical rigidity and strength but increased the elasticity and ductility. Finally, although melt blending led to slightly better properties than dry blending, the latter is more interesting to limit possible material degradation (mechanical, thermal, and oxidative), while reducing processing cost and time.

scholarly journals Characterization of Different Chemical Blowing Agents and Their Applicability to Produce Poly(Lactic Acid) Foams by Extrusion

2018 ◽  
Vol 8 (10) ◽  
pp. 1960 ◽  
Author(s):  
Ákos Kmetty ◽  
Katalin Litauszki ◽  
Dániel Réti
Keyword(s):  
Lactic Acid ◽  
Cell Structure ◽  
Mechanical Tests ◽  
Poly Lactic Acid ◽  
Foaming Agent ◽  
Blowing Agents ◽  
Twin Screw ◽  
The Individual ◽  
Chemical Blowing Agents

This study presents the applicability of different types (exothermic and endothermic) of chemical blowing agents (CBAs) in the case of poly(lactic acid) (PLA). The amount of foaming agent is a fixed 2 wt%. We used a twin-screw extruder and added the individual components in the form of dry mixture through the hopper of the extruder. We characterized the PLA matrix and the chemical blowing agents with different testing methods. In case of the produced foams we carried out morphological and mechanical tests and used scanning electron microscopy to examine cell structure. We showed that PLA can be successfully foamed with the use of chemical blowing agents. The best results were achieved with an exothermic CBA and with PLA type 8052D. The cell population density of PLA foams produced this way was 4.82 × 105 cells/cm3, their expansion was 2.36, their density 0.53 g/cm3 and their void fraction was 57.61%.

Thermoplastic elastomers based on high-density polyethylene, ethylene-propylene-diene terpolymer, and ground tire rubber dynamically vulcanized with dicumyl peroxide

2013 ◽  
Vol 131 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Rosa Idalia Narro Céspedes ◽  
José Francisco Hernández Gámez ◽  
María Guadalupe Neira Velázquez ◽  
Felipe Ávalos Belmontes ◽  
Ramón Enrique Díaz de León ◽  
...  
Keyword(s):  
High Density Polyethylene ◽  
Thermoplastic Elastomers ◽  
High Density ◽  
Dicumyl Peroxide ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Ethylene Propylene ◽  
Ethylene Propylene Diene Terpolymer

A Suitability Evaluation Method Based on Fractal Dimension in Geomagnetism Matching Navigation

2012 ◽  
Vol 588-589 ◽  
pp. 994-997
Author(s):  
Ying Liang ◽  
Qing Yang Xu
Keyword(s):  
Fractal Dimension ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Suitability Evaluation ◽  
Fractal Characteristic ◽  
Region Selection ◽  
Fractal Characteristics ◽  
Characteristic Fractal Dimension ◽  
Geomagnetic Anomalies ◽  
Selection Of

The suitability evaluation has an important influence on suitable-matching region selection of geomagnetism matching navigation. Geomagnetic anomalies have a fractal characteristic. Fractal dimension can describe the self-similar characteristics and subtle changes of irregular, broken, uneven and infinite detail form of geomagnetic anomalies. A comprehensive evaluation function based on fractal characteristics was established, and the ranks of region suitability were gotten finally.

scholarly journals Correlating the Cellular Network, in Foamed Concrete containing Ash, with their Physical Properties

2020 ◽  
Author(s):  
Jonathan Stolz ◽  
Yaman Boluk ◽  
Vivek S Bindiganavile
Keyword(s):  
Fractal Dimension ◽  
Portland Cement ◽  
Physical Properties ◽  
Cellular Network ◽  
Sound Absorption ◽  
Cell Structure ◽  
Thermal Constants ◽  
Foamed Concrete ◽  
Alkali Activated ◽  
Cellular Concrete

Cellular concrete is a lightweight solid cementitious foam that is used mainly for thermal insulation and sound absorption. Either partially or wholly, when the Portland cement in the binder is replaced with ash, the environmental impact of the material is reduced. However, the resulting changes in the cell structure and their subsequent impact upon the physical properties of the material have not been well examined. In this study, cellular concrete was prepared from alkali activated fly ash binders and separately, from Portland cement binders blended with wood ash. The cell structure was photographed using laser confocal microscopy and the images were analyzed to quantify the cellular network in terms of the porosity and the fractal dimension of the porous phase. Alongside, the cellular concrete specimens were tested for their thermal constants and sound absorption. The results show that there was an increase in the fractal dimension and an associated drop in thermal conductivity for an increase in the porosity.

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