Blends elastomer/thermoplast

Thermoplastic polyolefin elastomer/ polyolefin blend elastomer Thermoplastic vulcanizate elastomer TPV TPR, Santo-prene, Geolast, Vyram, Nex-prene, Alcryn... 

Considerable amounts of EPM and EPDM are also used in blends with thermoplastics, eg, as impact modifier in quantities up to ca 25% wt/wt for polyamides, polystyrenes, and particularly polypropylene. The latter products are used in many exterior automotive appHcations such as bumpers and body panels. In blends with polypropylene, wherein the EPDM component may be increased to become the larger portion, a thermoplastic elastomer is obtained, provided the EPDM phase is vulcanked during the mixing with polypropylene (dynamic vulcani2ation) to suppress the flow of the EPDM phase and give the end product sufficient set. 

For the compatible elastomer-thermoplastic blends, melting of the two polymers is the first step followed by subsequent vulcanization of the elastomeric phase. A typical mixing cycle for dynamically vulcanized NR-PE blend (DVNR) in a Brabender mixer is as follows [58] ... 

A route to compatibility involving ionomers has been described recently by Eisenberg and coworkers [250-252]. The use of ionic interactions between different polymer chains to produce new materials has gained tremendous importance. Choudhury et al. [60] reported compatibilization of NR-polyolefin blends with the use of ionomers (S-EPDM). Blending with thermoplastics and elastomers could enhance the properties of MPR. The compatibility of copolyester TPE, TPU, flexible PVC, with MPR in aU proportions, enables one to blend any combination of these plastics with MPR to cost performance balance. Myrick has reported on the effect of blending MPR with various combinations and proportions of these plastics and provided a general guideline for property enhancement [253]. 

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. ... 

Keywords Dynamic vulcanization Polymer blends and alloys Reactive processing Thermoplastic elastomers Thermoplastic vulcanizates... 

Just as in the manufacture of sheet natural rubber and the asphaltic sheet linings, the basic material as the sheet lining manufacturer receives it from the plantation (rubber) or from the refiner or importer (asphalt), the manufacturer of the synthetic lining materials will receive his synthetic elastomer, thermoplastic or other basic resin from the company that produces it-and will have to blend it with fillers, stabilizers, plasticizers, and other materials to make a suitable compound which will-as a lining—perform its function satisfactorily under the anticipated conditions, and for an economical length of time. The actual amount of the basic resinous material in the compound may be as low as 70% of the total weight. 

Nitropore . [Uniroyal] 4,4 -Oxybis (bCTzenesulfcmhydrazide) nioogen-re-leasing blowing agent for elastomers, thermoplastics, rubbernresin blends. 

Elastomers are often blended with thermoplastics in order to combine in the final product the thermoplastic resin processability and elastomeric behavior in the solid state. 

Costs can be reduced by blending engineering thermoplastics (ETPs) with less expensive commodity resins. Also, the distinction between plastics and elastomers can be breached by PAB s and is in fact narrowing. 

Blends of butadiene-acrylonitrile copolymer rubber (nitrile rubber or NBR) and PVC are among the oldest known examples of commercial elastomer/ thermoplastic blends. The shortage of natural rubber during World War II stimulated research in the USA on the compounding and modification of synthetic polymers to produce rubber-like materials. An outcome of this research was the commercial introduction of NBR/PVC blends by B.F. Goodrich in 1947 under the trade name of Geon Polyblends [Pittenger and Cohan, 1947]. The blend showed improved ozone resistance and melt processability compared to the nitrile rubber (Table 15.12). 

COPO blend with thermoplastic elastomers (e.g. polyurethanes)... 

A. Y. Coran, Thermoplastic elastomers based on elastomer-thermoplastic blends dynamically vulcanized, in Thermoplastic Elastomers—A Comprehensive Review, N. R. Legge, G. Holden, and H. E. Schroeder (eds.), Hanser Publishers, Munich, 1987. 

Miscible blends of elastomers differ from corresponding blends of thermoplastics in two important areas. First, the need for elastic properties requires elastomers to be high molecular weight. This reduces both the kinetic rate and the thermodynamic driving force for the interdiffusion and thus formation of a miscible single phase of dissimilar elastomers. Second, elastomers are plasticized in conventional compounding with process oils. The presence of plasticizers leads to both a higher free volume for the blend components and a decrease of the endothermal interactions. 

In the same manner as blends of thermoplastics or thermoplastic/ elastomer, irradiated blends of elastomers can undergo chain scission due to degradation or cross-linking, depending especially on the dose range. For example, Zurina et al. i measured tanS versus temperature for 50/50 epoxidized natural rubber (ENR-50)-EVA blends by DMA. At 60 kGy the irradiation-induced cross-link enhanced the Tg of the blend, whereas at higher dose (100 kGy), the Tg decreased due to the occurrence of oxidative degradation that broke the cross-link structure. 

Steller, R., Zuchowska, D., Meissner, W., Paukszta, D., Garbarczyk, J., Crystalline structure of polypropylene in blends with thermoplastic elastomers after electron beam irradiation. Radiation Physics and Chemistry 2006, 75, 259-267. 

Foams are blends of thermoplasts, thermosets, or elastomers with gases. They are classified according to their hardness, their cellular structure, or the plastic on which they are based. 

Commercial ABS/TPU blends contain thermoplastic polyurethane elastomer (TPU) as the main blend component. The blends were first introduced in 1990 by Dow Chemical Co., under the trade name Prevail . These blends characteristically exhibited low modulus (340-1,000 MPa) and high impact strength at low temperatures, e.g., notched Izod values of 370-1,500 J/m at —29 °C. The TPU component of the blend imparts high toughness and also allows paintability without a primer. ABS component imparts heat resistance (for paint ovens) and good tensile strength in the blend. The blend was projected to be useful for automotive soft bumper fascias, but faced stiff competition from TPOs. Typical properties of ABS/TPU blends are shown in Table 19.9. 

Figure 3.6 Batch mixer process flow diagram for production of elastomer-thermoplastic blends.

Keywords blends, processing, elastomer modification, d)mamic vulcanization, morphology, injection molding, extrusion molding, thermoplastic elastomer, thermoplastic dynamic vulcanizates (TDV), application. 

Development of TPEs with various types of elastomers and polyolefins has been extensively reported by many researchers. Ethylene-propylene-diene monomer (EPDM) or its modified form is used as the elastomer in most polyolefin TPEs. Natural rubber (NR) and thermoplastic blends have become an area of interest only recently. These materials are known as thermoplastic natural rubber (TPNR). The development of TPNR was principally based on the criteria set by EPDM blends with thermoplastics. Two types are known, one belonging to the TPO class and the other belonging to the TPV class. 

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