Preparation of thermoplastic elastomers based on silicone rubber and polyethylene by thermomechanical reactive blending: Effects of polyethylene structural parameters

2003 ◽  
Vol 90 (12) ◽  
pp. 3402-3408 ◽  
Author(s):  
A. Jalali-Arani ◽  
A. A. Katbab ◽  
H. Nazockdast
Keyword(s):  
Silicone Rubber ◽  
Structural Parameters ◽  
Thermoplastic Elastomers ◽  
Reactive Blending

Thermoplastic Elastomers and Rubber-Toughened Plastics from Recycled Rubber and Plastics

2002 ◽  
Vol 75 (1) ◽  
pp. 49-63 ◽  
Author(s):  
H. Liu ◽  
J. L. Mead ◽  
R. G. Stacer
Keyword(s):  
Rubber Particle ◽  
Thermoplastic Elastomers ◽  
Degree Of Crystallinity ◽  
Reactive Blending ◽  
Molecular Weights ◽  
Rubber Toughened ◽  
Plastic Phase ◽  
Commercial Sources ◽  
Batch Mixer

Abstract An experimental investigation has been conducted to evaluate the use of recycled rubbers in blends for the development of new thermoplastic elastomers (TPE) and rubber-toughened plastics. The recycled rubbers were obtained from various commercial sources and included representatives from the EPDM, SBR, and NR/SBR blend families, as well as a range of particle sizes. A series of five different virgin polypropylenes (PP) were used as the plastic phase, representing a range of molecular weights and suppliers. Blends were prepared in a Haake Buechler batch mixer over a broad range of constituent fractions. Compatibilization and reactive blending techniques were used to improve the quality of the scrap rubber/plastic blends with respect to both mechanical and rheological properties. Results indicate that these blending techniques are required to obtain acceptable mechanical strength in the resultant materials. Additional parameters that significantly enhanced properties included elevating the blending temperature, reducing rubber particle size, and increasing PP molecular weight. This later conclusion was attributed to a lower degree of crystallinity in the PP phase that contributes to better blending between the phases.

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.

Novel poly(vinyl chloride) based thermoplastic elastomers incorporating vinyl-functionalized silicone rubber

2018 ◽  
Vol 55 (7) ◽  
pp. 507-512 ◽  
Author(s):  
Hisham A. Essawy ◽  
Salwa H. El-Sabbagh ◽  
Ahmed I. Hussein ◽  
Magda E. Tawfik
Keyword(s):  
Vinyl Chloride ◽  
Silicone Rubber ◽  
Thermoplastic Elastomers ◽  
Poly Vinyl Chloride

Computing cell tractions from particle displacements on silicone rubber substrata

1994 ◽  
Vol 52 ◽  
pp. 162-163
Author(s):  
Tim Oliver ◽  
Akira Ishihara ◽  
Ken Jacobsen ◽  
Micah Dembo
Keyword(s):  
Plane Stress ◽  
Linear Elasticity ◽  
Silicone Rubber ◽  
Mathematical Analysis ◽  
Elastic Recovery ◽  
Video Images ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Better Than

In order to better understand the distribution of cell traction forces generated by rapidly locomoting cells, we have applied a mathematical analysis to our modified silicone rubber traction assay, based on the plane stress Green’s function of linear elasticity. To achieve this, we made crosslinked silicone rubber films into which we incorporated many more latex beads than previously possible (Figs. 1 and 6), using a modified airbrush. These films could be deformed by fish keratocytes, were virtually drift-free, and showed better than a 90% elastic recovery to micromanipulation (data not shown). Video images of cells locomoting on these films were recorded. From a pair of images representing the undisturbed and stressed states of the film, we recorded the cell’s outline and the associated displacements of bead centroids using Image-1 (Fig. 1). Next, using our own software, a mesh of quadrilaterals was plotted (Fig. 2) to represent the cell outline and to superimpose on the outline a traction density distribution. The net displacement of each bead in the film was calculated from centroid data and displayed with the mesh outline (Fig. 3).

Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

1993 ◽  
Vol 51 ◽  
pp. 188-189
Author(s):  
Tim Oliver ◽  
Michelle Leonard ◽  
Juliet Lee ◽  
Akira Ishihara ◽  
Ken Jacobson
Keyword(s):  
Silicone Rubber ◽  
Molecular Motors ◽  
Video Frame ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Local Cell ◽  
Microscopic Measurement ◽  
Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

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