Thermoplastic elastomeric materials have become important because they have many properties of vulcanized rubbers and can be rapidly fabricated as thermoplastics. in this work, selected grade of polypropylene (PP) was modified with dimethylol-phenolic resin and then it was melt-mixed with acrylonitrile-butadiene rubber (NBR) for several weight ratios. After sufficient mixing time additional phenolic resin was added to mixing chamber and the blends were dynamically vulcanized. In order to study the effects of the compositions and dynamic vulcanization on the physical and mechanical properties, simple blends of unmodified polypropylene and NBR were also prepared. The results show that dynamically vulcanized blends have higher tensile strength, elongation at break, solvent and oil resistance.  

Morphological and thermal properties of PA6/NBR nanocomposites prepared through a direct melt mixing process in an internal mixer were studied. The effects of the NBR content (10, 30, and 50%) and nanoclay loading (3, 5, and 7%) on the microstructure properties of nanocomposites have been reported and compared with PA6/NBR blends as well. The thermoplastic elastomer (TPE) nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), volume swelling in oil, differential scanning calorimeter (DSC) and dynamic mechanical thermal analysis (DMTA). XRD results show that Cloisite 30B is exfoliated into the PA6 and NBR. TEM image of the PA6/NBR/nanoclay composite confirms partial exfoliated structure of silicate layers dispersed into the both NBR and PA6 phases. The SEM photomicrograph of PA6/NBR nanocomposite shows an increasing of the rubber particles size in comparison with unfilled PA6/NBR TPE. By the presence of nanoclay, improved oil resistances of the prepared TPE nanocomposites were achieved. DSC studies show that loading of the nanoclay reduces the degree of crystallinity of the nanocomposite samples. The DMTA test shows that storage modulus of the PA6/NBR nanocomposite increases in comparison with the PA6/NBR blend. It also explains a reduction in damping by loading of the nanoclay.

Thermoplastic elastomers (TPEs) bring a combination of good plasticity of plastics and mechanical properties of elastomers that are important to component designers. These materials are especially used in the automotive industry to make a variety of parts, including strong shields. The injection process is one of the most common methods of making these polymers, which allows mass and industrial production. In this study, the injection process of elastomeric thermoplastic shield made of polypropylene / styrenebutadiene rubber + natural rubber (PP + SBR / NR) was simulated using Autodesk Moldflow software and the appropriate injection port location, optimal process conditions and possible injection defects Were discussed. Injection mold filling time, injection pressure, melt and mold temperature, cooling time, warpage and shrinkage are among the parameters that have been analyzed in this study. Also, possible positions of air trapping and weld lines were identified as the most common possible injection defects.

Stone matrix asphalt is one of the solutions for rutting used worldwide. By providing stone on stone contact, the coarse portion of this type of mixtures bear the loads of axles and transfer them to the lower layer. The mixture of fine aggregate, filler, bitumen and additive including fiber and polymers are to fill the air void of coarse aggregate. Bitumen must hold the coarse aggregates together. As the typical bitumen is not capable of doing so, the use of additive polymers seems essential. Additives consist of fiber and polymers. In order to prevent drain down while fabricating, cellulose fiber is used. The application of elastomer-thermoplastic polymers causes the improvement of rutting resistance in high temperature. Elastomeric properties make the deformations recoverable and thermoplastic properties broaden the performance grade of bitumen. Polyethylene and ethylene-vinyl-acetate copolymers are selected in dosage of 3, 5, 7 and 4, 8, 12 percent, respectively. These polymers could be directly added to the mixture which is a common method to use them in Iran. By applying 50oC as the ambient temperature and 450KPa as the level of the stress for creep tests, while considering high temperature condition, the most severe condition of loading is simulated. Comparing the result of unconfined creep test which is performed on the modified and unmodified specimen, concluded that polyethylene and unmodified specimen has the same creep performance while 8 and 12 percent ethylene-vinyl-acetate has the same creep result as 4 and 6 styrene-butadiene-styrene specimens, respectively.

Hypothesis: Thermoplastic polyurethane elastomers are generally synthesized by one of the methods of one-shot, pre-polymer and semi pre-polymer. In the preparation of polyurethanes by these methods the viscosity is increased as the reaction progresses, while the reaction is difficult to control. Therefore, the reaction extrusion method has received much attention in recent years due to high temperature reaction, better mixing of components and more convenient reaction control as well as increased reaction rate due to the elimination of post curing time. The purpose of this study was to study the process parameters of polyurethane elastomer synthesis using reactive extrusion. Methods: Here a prepolymer was synthesized with a polyester polyol (based on adipic acid) and diphenyl methane diisocyanate in a glass reactor. Then butanediol chain extender was added to the prepared prepolymer in a micro extruder at three different temperatures and residence times to obtain the final polymer. FTIR and intrinsic viscosity tests were then taken from 9 prepared samples to determine the optimum temperature and residence time. Finding: The results showed that the temperature of 165° C and the residence time of 10 min were the optimum conditions for the elastomer synthesis through reactive extrusion. Then, by designing three formulations, three thermoplastic elastomer specimens were prepared by adding butanediol chain extender to the prepolymers, in a micro-extruder, and their physical mechanical properties were studied. The results showed that using this method and the obtained process conditions, it is possible to provide polyurethane thermoplastic elastomers with desirable properties in shorter time.

Poly (vinyl chloride) (PVC)/thermoplastic polyester elastomer (Hytrel) blend system prepared in 50/50 composition was found to have the highest possible percentage elongation-at-break. This is due to better molecular compatibility between the two; however, they had lower strength and modulus values. In order to improve the strength and modulus property, alumina nano-particles were added as a reinforcing agent in concentrations as 1, 3, 5, and 7 phr in the blend system. The prepared nanocomposites were characterized for mechanical, thermal, rheological, morphological, and electrical properties. The 5-phr nano-alumina loaded PVC/Hytrel blend had optimal improvement in its strength values, but above that concentration nano-alumina started forming aggregates as was apparent from scanning electron microscopy (SEM) analysis. SEM images showed uniform distribution of nano-alumina in both PVC and Hytrel phases of the blend. Tensile strength and modulus were found to have increased by about 20 and 97%, respectively, whereas elongation at maximum load decreased by 50%, indicating the effect of nano-alumina as a reinforcing agent in the PVC/Hytrel system. The glass transition temperature, onset degradation temperature, viscosity, surface resistivity and volume resistivity increased, whereas degradation weight loss (%) decreased with increase in nano-alumina concentration in PVC/Hytrel blend system. No chemical interaction happened between PVC, Hytrel or alumina nano-particles, as proved by FTIR analysis.

In this study, in order to increase the impact strength of polyacetal, the polymer was alloyed with thermoplastic elastomer polyurethane (TPU). In this regard, alloys of polyacetal consisted of 5-50% of thermoplastic elastomer polyurethane were prepared and the physical-mechanical, thermal, rheological and morphological properties were investigated. This study indicates that between these prepared alloys, the impact strength and elongation-at-break reach to a maximum level with 15% and 30% of TPU, respectively. Meanwhile, the impact strength, elastic modulus and crystallinity decrease with increasing the amount of TPU. Studying the dynamic-mechanical properties implies that the damping peak would be higher with increasing the amount of TPU. Morphological investigations indicate that the size of particles of TPU dispersed phase will change in the range of 1-10 mm with increasing the amount of TPU.

Thermoplastic polyurethane (TPU) elastomers are widely used in industries such as automotive and medical due to their unique mechanical properties. However, their complex deformation behavior, resulting from the interaction between soft amorphous and hard crystalline phases, necessitates accurate numerical modeling for reliable prediction under various loading conditions. This study aims to characterize the deformation behavior of TPU through experimental testing and the implementation of a suitable constitutive model. A phenomenological material framework was developed and implemented in the ABAQUS/Explicit finite element software via a user-defined VUMAT subroutine. The model consists of an equilibrium hyperelastic component representing the soft phase, based on the Arruda-Boyce eight-chain model, and a elastic-viscoplastic- component for the hard phase. The latter is formulated using a linear elastic spring, a nonlinear viscous damper based on a modified Ree-Eyring model, and a frictional element. The model parameters were calibrated using a series of uniaxial compression tests under monotonic and cyclic loading at various strain rates at room temperature. The results showed that, as the fraction of the hard component increased, TPU exhibits stronger plastic behavior, with more energy dissipation and less shape recovery. Moreover, when subjected to a strain of -1.0 after each loading-unloading cycle, it exhibits a residual strain that is not fully recovered even several weeks after the end of the test. Furthermore, the model demonstrates the capability to simulate TPU response under other loading scenarios such as tension and stress relaxation. This work offers physical insight into the deformation mechanisms of TPU and provides a practical modeling tool for its complex elastomeric-plastic behavior.