Polyolefin thermoplastic elastomers properties

Rubber matrices have commonly been used as a second phase to improve the toughness of brittle thermoplastic materials, such as polypropylene and polyethylene. These systems, commonly referred to as polyolefin thermoplastic elastomers (TPOs), are a special class of thermoplastic elastomers that combine the processing characteristic of plastics at elevated temperatures with the physical properties of conventional elastomers at service temperature, playing an increasingly important role in the polymer material industry. Polyolefin blends attract additional interest due to the possibility of recycling plastic wastes, avoiding the complex and expensive processes of separation of the different components. 

Polyolefin thermoplastic elastomers are generally blends of polypropylene with up to 65% ethylene-propylene rubber and it is supposed that short propylene blocks in the latter co-crystallize with segments of the polypropylene chains to give microcrystalline regions which act as cross-links. A recent development in this field has been the use of highly cross-linked ethylene-propylene rubbers (and other rubbers) in the blends to give so-called thermoplastic vulcanizates (TPVs). In these blends the rubber is present as finely dispersed particles in a polypropylene matrix. Compared to the simple blends, these materials have generally enhanced properties. 

Polyolefin thermoplastic elastomers are characterized by low cost, good mechanical properties and excellent resistance to oxygen, ozone and polar solvents they are attacked by non-polar and chlorinated solvents, especially... 

Thermoplastic elastomers based on polyolefins (TPO) are blends of PE or PP wifh EPDM elastomers wherein the elastomer is often cross-linked using thermochemical systems. TPOs more suitable for medical producfs with no chemical residuals can be made using EB processing to cross-link the elastomer portion in such an elastomer-plastic blend. The thermoplastic governs the melt transition, and thus the extrusion properties of TPOs. The radiahon response of these materials is also governed by the choice of fhe thermoplastic. An example of an EB cured blend of EPDM and polyefhylene used is for fluid transmission tubing and electrical insulation. ... 

The living character of organolithium polymerizations makes such processes ideally suited for the preparation of pure as well as tapered-block copolymers. Diene-olefin pure-block copolymers have become important commodities because of their unique structure-property relationships. When such copolymers have an ABA or (AB) X [A = polyolefin, e.g., polystyrene or poly(a-methylstyrene) B = polydiene, e.g., polybutadiene or polyisoprene and X = coupling-agent residue] arrangement of the blocks, the copolymers have found use as thermoplastic elastomers (i.e., elastomers that can be processed as thermoplastics). 

Thermoplastic elastomers (TPE s) are characterized by the exceptional property that, without vulcanization, they behave as cross-linked rubbers. They are block-copolymers, in which blocks of the same nature assemble in hard domains, acting as cross-links between the rubbery parts of the chain. These hard domains lose their function when they reach their softening temperature, so that the material can then be processed as a thermoplast. One of the oldest member of the family of TPE s is SBS (styrene-butadiene-styrene block copolymer), but several other TPE s have been developed, i.a. on the basis of polyesters, polyurethanes and polyolefins. In their properties these polymers cover a broad range between conventional rubbers and soft thermoplastics. 

TPOs are basically two-component elastomer systems consisting of an elastomer finely dispersed in a thermoplastic polyolefin (such as polypropylene). The thermoplastic polyolefin is the major component. Thermoplastic elastomers (TPEs) include TPOs, TPVs (thermoplastic vulcanizates), etc. Properties of TPOs depend upon the types and amounts of polymers used, the method by which they are combined, and the use of additives such as oils, fillers, antioxidants, and colors. Blends and reactor-made products compete primarily with other TPEs and metals. There are vulcanizates (TPVs) that have higher elastomeric properties. They compete primarily with TS elastomers. 

The following TPs are the main thermoforming materials processed high-impact and high-heat PS, HDPE, PP, PVC, ABS, CPET, PET, and PMMA. Other plastics of lesser usage are transparent styrene-butadiene block copolymers, acrylics, polycarbonates, cellulosics, thermoplastic elastomers (TPE), and ethylene-propylene thermoplastic vulcanizates. Coextruded structures of up to seven layers include barriers of EVAL, Saran, or nylon, with polyolefins, and/or styreneics for functional properties and decorative aesthetics at reasonable costs.239-241... 

There are two classes of polyolefin blends elastomeric polyolefin blends also called polyolefin elastomers (POE) and nonelastomeric polyolefin blends. Elastomeric polyolefin blends are a subclass of thermoplastic elastomers (TPEs). In general, TPEs are rubbery materials that are processable as thermoplastics but exhibit properties similar to those of vulcanized rubbers at usage temperatures (19). In TPEs, the rubbery components may constitute the major phase. However, TPEs include many other base resins, which are not polyolefins, such as polyurethanes, copolyamides, copolyesters, styrenics, and so on. TPEs are now the third largest synthetic elastomer in total volume produced worldwide after styrene-butadiene rubber (SBR) and butadiene mbber (BR). 

Thermoplastic elastomeric materials have many important applications including cable and wire especially in mineral, electronic equipment, and automobile industries. The most commonly used method of obtaining thermoplastic elastomer in materials is to toughen plastics by blending rubbers and plastics. Among the most versatile polymer matrices, polyolefins such as PP are the most widely used thermoplastics because of their well-balanced physical and mechanical properties and their easy processability at a relatively low cost, which makes them a versatile material. PP has the disadvantage of... 

A variety of specialty polyolefins and polyolefin alloys can now be made directly in the reactor taking advantage f the new technology. Examples are the catalloy materials from Himont, which are polyolefin alloys made by synthesis and not by the conventional route of compounding. Hivalloy is a polypropylene/polystyrene alloy made by synthesis and combines the properties of both crystalline and amorphous engineering polymers. Such materials could challenge the established positions of several thermoplastic elastomers. 

Uses Metal deactivator in stabilization of polyolefins shelf life extender for PP, PE, and poly-(ethylene-propylene) and certain thermoplastic elastomers used as primary insulators in contact with copper for elec, parts, plugs, wire insulation and jacketing, polymer powd. and other coatings on metal, hot melt and sol n. adhesives, deactivation of catalyst residue, oils and lubricants in contact with metals and contaminants at high temps. Regulatory DOT nonregulated Properties Wh. powd. m.w. 204 m.p. 302 C... 

Uses Lt. stabilizer for PP, ABS, PS, nylon, LDPE, LLDPE, HOPE, acrylics, PC, thermoplastic polyester, SAN, thermoplastic elastomers, surf, coatings, suitable for thin films, fibers, or molded parts Features Esp. effective in polyolefins for outstanding heat and processing stability use with UV-Chek AM-340 Properties Lt. amber micro-pastille very sol. in aromatic hydrocarbons, ketones, esters, some alcohols very low sol. in aliphatic hydrocarbons and water misc. with methylene, methylene chloride m.w. > 2400 sp.gr. 1.03 bulk dens. 5.8 Ib/gal soften, pt. 100 C min. 

Chem. Descrip. Zinc borate CAS 1332-07-6 EINECS/ELINCS 215-566-6 Uses Flame retardant, smoke suppressant for plastisols, coatings for cellulosics, textiles, and adhesives synergist in PVC and halogenated polyester formulations, and in elastomers, thermoplastic elastomers, polyamides, and polyolefins strong char promoter Properties Wh. free-flowing powd., nonhygroscopic 6 p avg. particle size 99.9% < 30 p sol. 0.5 g/100 ml water sp.gr. 2.50 bulk dens. 18.1 Ib/ff oil absorp. 39 ref. index 1.48 Zb -237 [Great Lakes]... 

Thermoplastic elastomer (TPE) blends have been broadly studied as a new class of materials. TPEs offer various advantages and require no state-of-the-art processing machinery, while scrap and rejects are recyclable. Blends can be homogeneous, phase separated or both. TPEs are multi-phase polymer systems consisting of hard and soft domains that can be copolymers or mechanical blends. This phase separation leads to materials having unique and viable commercial physical properties. TPEs exhibit the thermoplastic characteristics of the hard thermoplastic phase, and resilience as a result of the rubbery domains. TPEs based on natural rubber (NR) and thermoplastic blends are known as thermoplastic natural rubber (TPNR) blends. There are two types of TPNR, namely thermoplastic polyolefin (TPO) and thermoplastic vulcanizate (TPV).3... 

As much as 30% of all polyolefin products involve blends (Robeson 2007). It has been found, for example, that blending metallocene-catalyzed linear low-density polyethylenes (mLDPEs) with HDPE improves the Izod impact strength and some tensile properties of HDPE. Adding mLLDPE to LDPE increases the ductility of LDPE (Cran and Bigger 2009). In general, PE blends can be divided into three categories (1) PE lots blended to meet standard specifications for density and melt flow, (2) PE modified with <15 wt% of other polymer(s), and (3) PE bends with other thermoplastics or thermoplastic elastomers. 

Only two classes of polypropylene (PP) blends have achieved commercial success blends wiA polyolefins and with polyamides (PA). With PP/polyolefin blends, the goal is either to improve the impact resistance of the base resin (impact-modified PPs) or to produce thermoplastic elastomers (d)mamically vulcanized blends). PA/PP blends aim at bridging the property gap between the two pol5oners. Therefore, sigitificant information on processing is available only for these two families of blends. 

Hemmati M, Narimani A, Shariatpanahi H (2011) Study on morphology, rheology and mechanical properties of thermoplastic elastomer polyolefin (TPO)/carbon nanotube nanocomposites with reference to the effect of polypropylene-grafted-maleic anhydride (PP-g-MA) as a compatibilizer. Int J Polym Mater 60 384—397... 

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