Formation of Rubber Particle Agglomerates During Morphology Development in Dynamically Crosslinked EPDM/PP Thermoplastic Elastomers. Part 1: Effects of Processing and Polymer Structural Parameters

2003 ◽  
Vol 76 (1) ◽  
pp. 239-252 ◽  
Author(s):  
F. Goharpey ◽  
A. A. Katbab ◽  
H. Nazockdast
Keyword(s):  
Interfacial Adhesion ◽  
Structural Parameters ◽  
Rubber Particle ◽  
Thermoplastic Elastomers ◽  
Rubber Content ◽  
Morphology Development ◽  
Dynamic Loss ◽  
Two Phases ◽  
Tan Δ ◽  
Rubber Aggregates

Abstract Formation of agglomerate structure by the rubber particles through flocculation or networking mechanism during dynamic crosslinking of thermoplastic elastomers based on EPDM rubber and polypropylene has been evidenced. Scanning electron microscopy (SEM) examination performed on the crosslinked blend samples which had been etched by hot xylene suggested that agglomeration occurs mainly through a joint shell mechanism. Reduction of the mixing torque after passing the peak maximum at the dynamic crosslinking stage was concluded to be due to the shear induced breaking down of agglomerates leading to a more defined morphology. Samples removed after the maximum mixing torque showed higher dynamic loss tangent (tan δ) above the PP glass transition. This is attributed to the broadening of the retardation time spectra for the PP matrix in the blend system. Higher mixing torque, higher tensile strength, as well as better extensibility were found for the blend samples based on PP with low MFI value as a result of higher density of aggregates and more extent of their interfacial adhesion with the PP matrix. More defined morphology and higher rate of network breakdown was observed at high mixing shear rate. Mixing torque increased significantly with increasing the rubber content of the blend system from 40% to 60% (W : W) as a consequence of higher interaction of rubber aggregates with the PP matrix. Based on the obtained results, the structure of the rubber aggregates and associated networks as well as extent of interaction between the two phases play an important role in controlling the final morphology, processing behavior and therefore mechanical properties of the dynamically cured blend system.

Effect of NR/ABS Ratio on Mechanical, Dynamical and Morphological Properties of Vulcanized NR/ABS Blends

2013 ◽  
Vol 844 ◽  
pp. 61-64 ◽  
Author(s):  
Pinyo Wongthong ◽  
Charoen Nakason ◽  
Qin Min Pan ◽  
Garry L. Rempel ◽  
Suda Kiatkamjornwong
Keyword(s):  
Interfacial Adhesion ◽  
Complex Viscosity ◽  
Morphological Properties ◽  
Elongation At Break ◽  
Vulcanized Rubber ◽  
Thermoplastic Vulcanizates ◽  
Two Phases ◽  
Tan Δ ◽  
Blend Ratios ◽  
Internal Mixer

Dynamically vulcanized NR/ABS blends by phenolic curing were carried out using an internal mixer at 180 °C. The effect of NR/ABS ratio (i.e., 50/50, 60/40, 70/30) on mechanical, dynamical and morphological properties was investigated. It was found that the tensile strength and hardness increased with an increase in ABS loading whilst the elongation at break decreased, indicating that the strength and hardness attributed to thermoplastic component whereas the elasticity of the blends contributed to the vulcanized NR. The results showed that the 60/40 NR/ABS blend provided the well-balanced mechanical properties. The storage modulus of thermoplastic vulcanizates (TPVs) increased with increasing contents of rubber. This is due to that a higher content of vulcanized NR domain was dispersed in the ABS matrix. The results agreed well with the tan δ and complex viscosity of the TPV at various blend ratios. SEM micrographs of 60/40 NR/ABS blend showed that vulcanized rubber domains were dispersed in a continuous ABS phase and it contributed to greater interfacial adhesion between the two phases and thus provided superior properties.

Decoloured Novatein® and PLA Blends Compatibilized with Itaconic Anhydride

2018 ◽  
Vol 884 ◽  
pp. 3-13
Author(s):  
Sandra C.P. Izuchukwu ◽  
Casparus J.R. Verbeek ◽  
James Micheal Bier
Keyword(s):  
Interfacial Adhesion ◽  
Reactive Extrusion ◽  
Side Chain ◽  
Poly Lactic Acid ◽  
Blend Ratio ◽  
Itaconic Anhydride ◽  
Two Phases ◽  
Tan Δ ◽  
Thermoplastic Protein ◽  
Scanning Electron

Poly (lactic acid) (PLA) was modified through free radical grafting of itaconic anhydride to create reactive side-chain groups. Modified PLA was blended with Decoloured Novatein®(DNTP), a thermoplastic protein material using reactive extrusion to produce a degradable material with improved properties compared to neat Decoloured Novatein®. Varying ratios of blends were prepared. Blending DNTP with PLA was found to increase tensile strength between 22% to 538% and modulus between 201 GPa to 3193 GPa, whereas the strain at break decreased between 80% to 94% depending on the blend ratio. The glass transition temperature of the blends which was measured as the tan δ peak, also revealed an increase when compared to neat DNTP. Scanning electron microscope revealed an enhanced interfacial adhesion between the two phases in the blends with PLA-g-IA suggesting a more homogenous microstructure. The results show the possibility and feasibility of blending DNTP with PLA for use in agricultural and packaging applications.

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.

Accuracy in locating glass transitions: aging and gamma sterilization of vulcanized thermoplastic elastomers

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Witold Brostow ◽  
Sameer Deshpande ◽  
Dorota Pietkiewicz ◽  
Steven R. Wisner
Keyword(s):  
Loss Modulus ◽  
Accelerated Aging ◽  
Mechanical Analysis ◽  
Thermoplastic Elastomers ◽  
Rapid Decrease ◽  
Practical Reasons ◽  
Glass Transitions ◽  
Γ Irradiation ◽  
Tan Δ

AbstractWe have studied nine thermoplastic vulcanizate elastomers (TPVs) in four series: as made, after accelerated aging, after γ irradiation, after both irradiation and aging. The materials exhibit two glass transitions, one seen in crosslinked regions and the other in un-crosslinked amorphous regions. Three techniques of determination of glass transitions have been used and the results compared, all three based on dynamic mechanical analysis (DMA): as a peak in the loss modulus E’’; as a peak in tan δ; and as the midpoint of the rapid decrease in the storage modulus E’. We recommend the last method for both fundamental and practical reasons.

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.

Double Layer Concrete Paving Blocks Using Waste Tyre Rubber as Aggregate Replacement

2014 ◽  
Vol 554 ◽  
pp. 128-132 ◽  
Author(s):  
Euniza Jusli ◽  
Hasanan Md Nor ◽  
Putra Jaya Ramadhansyah ◽  
Haron Zaiton
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Double Layer ◽  
Rubber Particle ◽  
Test Results ◽  
Rubber Content ◽  
Waste Tyre ◽  
Low Strength ◽  
Strength And Stiffness

This study provided the test results on the mechanical properties of double layer concrete paving blocks (CPBs) obtained by replacing portions of the conventional aggregate with waste tyre rubber. The mechanical properties discussed in this paper were compressive and flexural strength. Results indicated that the density of double layer CPBs containing rubber was lower than that of conventional CPB. The decrease was found to be proportional with the waste tyre rubber content. Due to the low strength and stiffness of waste tyre rubber particle, the compressive and flexural strength of double layer CPBs containing rubber appeared to be lower than that of conventional CPB.

scholarly journals Effects of Crumb Rubber on Compressive Strength of Cement-Treated Soil

2015 ◽  
Vol 61 (4) ◽  
pp. 59-78 ◽  
Author(s):  
F. C. Wang ◽  
W. Song
Keyword(s):  
Compressive Strength ◽  
Cement Content ◽  
Rubber Particle ◽  
Crumb Rubber ◽  
Test Results ◽  
Rubber Content ◽  
Strength Tests ◽  
Strength And Stiffness ◽  
Cement Soil ◽  
Curing Age

A study was undertaken to investigate the effects of crumb rubber on the strength and mechanical behaviour of Rubberized cement soil (RCS). In the present investigation, 26 groups of soil samples were prepared at five different percentages of crumb rubber content, four different percentages of cement content and two different finenesses of crumb rubber particle. Compressive strength tests were carried out at the curing age of 7 days, 14 days, 28 days and 90 days. The test results indicated that the inclusion of crumb rubber within cement soil leads to a decrease in the compressive strength and stiffness and improves the cement soil’s brittle behaviour to a more ductile one. A reduction of up to 31% in the compressive strength happened in the 20% crumb content group. The compressive strength increases with the increase in the cement content. And the enlargement of cement content is more efficient at low cement content.

scholarly journals Durability Properties of Five Years Aged Lightweight Concretes Containing Rubber Aggregates

2017 ◽  
Author(s):  
Malika Medine ◽  
Habib Trouzine ◽  
José Barroso De Aguiar ◽  
Aissa Asroun
Keyword(s):  
Elevated Temperature ◽  
Water Absorption ◽  
Partial Replacement ◽  
Rubber Content ◽  
Experimental Assessment ◽  
Freeze Thaw ◽  
Coarse Aggregates ◽  
Durability Properties ◽  
Mass Losses ◽  
Rubber Aggregates

Scrap tyres are one of the most important wastes. They can be used in different ways because of their availability and their non-degradable nature. This paper aims to demonstrate their reuse through durability properties experimental assessment of lightweight concretes aged five years, incorporating rubber aggregates as partial replacement of 5%, 7.5% and 10% of coarse/fine and coarse aggregates. The effect of the rubber aggregates on the lightweight concretes durability has been analysed. Firstly, the water absorption was evaluated, and then the mass losses were measured through many tests: freeze-thaw, elevated temperature and attack by Na2SO4 and HCl solutions. Wetting-drying cycles were carried out in order to accelerate the aging of the studied lightweight concretes and to reduce the tests duration. It has been observed that the water absorption decreased with small rubber content. The mass losses of the mixes were almost depending on rubber aggregates content and size, and the exposures duration.

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