PP/EPDM

Interfacial adhesion and, thereby, compatibility can be enhanced by the selective crosslinking reaction in polymer blends. Inoue and Suzuki [26] reported the properties of blends dynamically crosslinked PP-EPDM blends. The crosslinking agent was yV,N -/w-phenylene-bismaleimide - poly(2,2,4 - trimethyl - 1,2-dihydroquino -line) system. Increase in interfacial adhesion leads to... 

It was found that a high-impact strength is obtained in PP-EPDM blends by slow curing with sulfur. Thiuram disulfide N-(cyclohexylthio)phthalimide was used as an inhibitor of curing, and its effect on the impact strength of dynamically cured PP-EPDM blends was studied (Table 6). It was also found that the one-step method of blend preparation also has a favorable effect on the impact strength of the resultant blend system. 

It was found that PP-EPDM blends [30] with a slow curing EPDM have a high-impact strength. Effect of tet-ramethyl thiuram disfulfide (TMTD) concentration on the Charpy notched impact strength of PP-EPDM blend is given in Table 8. 

The effect of ionomer concentration on the mechanical properties of PP-EPDM blends is given Table 9. It is seen that the tensile strength and modulus show a maximum at 5 wt% of both ionomer A and B, thereafter, it decreases at higher ionomer loading. The properties are higher for ternary blends containing ionomer B than these containing ionomer A. On the other hand, addition... 

Table 8 Effect of Composition of TMTD Curing System on the Charpy Notched Impact Strength (ai<) for 85/15 and 80/20 PP/EPDM Blends...

Table 9 Effect of Ionomer Concentration on the Tensile Properties of Blends of PP-EPDM...

Polymeric blends are popularly known to show desired properties based on the components. But their nanocomposites have been prepared to further modify the properties. Various blends like NR-ENR and PP-EPDM [188,189] with nanofillers have also been smdied. 

Cakmak M. and Wang M.D., Structure development in the tubular blown film of PP/EPDM thermoplastic elastomer, Antec 89, 47th Annual Tech. Conference of SPE, New York, May 1, 1989, 1756. Hashimoto T., Todo A., Itoi H., and Kawai H. Domain boundary structure of styrene-isoprene block copolymer films cast from solution. 2. Quantitative estimation of the interfacial thickness of lamellar microphase systems. Macromolecules, 10, 377, 1977. 

Use of 29Si NMR can generally be avoided in favour of 1II NMR. For example, Narayan et al. [253] have used proton NMR for the detection of a HALS stabiliser based on silicon technology, after extraction from a PP matrix. 170 1-NMR and s-NMR have been used for the study of PP, EPDM, PIP and NR oxidatively degraded with enriched 02 [204,254]. 

Usually polymeric substances of appropriate chemical structure and morphology which promote the miscibility of incompatible materials. Block copolymers are especially useful surfactants at the polymer/polymer interface because the two blocks can be made up from molecules of the individual polymers to be mixed. Typical compatibilisers in polymer blends are LDPE-g-PS in PE/PS CPE in PE/PVC acrylic- -PE, -PP, -EPDM in polyolefin/PA and maleic-g-PE, -PP, -EPDM, -SEBS in polyolefin/polyesters. 

PP/EPDM-V better elasticity and good thermal resistance PP/NBR-V same elasticity plus oil resistance PP/IIR-V same elasticity plus gas impermeability TPU high mechanical properties... 

Airtight boxes with integrated TPV seal (bi-injection moulding of PP and PP/ EPDM-V)... 

PP/EPDM-V Vulcanized EPDM dispersed in polypropylene PP/NBR-V Vulcanized nitrile rubber dispersed in polypropylene PP/IIR-V Vulcanized butyl rubber dispersed in polypropylene... 

PP/EPDM Unvulcanized EPDM blended with polypropylene or block copoly-... 

TPOs, mainly PP/EPDM produced by blending of a polypropylene matrix and a dispersed unvulcanized EPDM or by copolymerization of polypropylene and sequences of EPDM TPVs... 

PP/EPDM-Vs are marketed in two series, one for technical applications and the other for general-purpose and economical applications. Differences concern technical performances and cost. 

PP/EPDM-Vs are handicapped by a lower elasticity than conventional rubbers, the more so as the hardness increases certain risks of creep, relaxation and permanent set, the more so the higher the temperature some swelling in mineral oils and oily products inherent flammability, but FR grades are marketed limited thermal behaviour higher cost than TPOs. 

As for all plastics, the costs fluctuate greatly with the crude oil price. PP/EPDM-Vs are more expensive than TPOs and SBS. 

PP/EPDM-V targets specific applications and has lower consumption than TPOs. PP/EPDM-Vs are used in the appliance, automotive, construction, consumer goods, packaging, electrical electronics (E E), industrial, food and medical sectors for various moulded and extruded technical goods, soft-touch overmoulding, grips. .. 

Figure 4.137 displays examples of compression sets after 22 h at 70°C, which is not a severe condition, for PP/EPDM-V grades with hardnesses in the Shore A and D scales. Note ... 

Figure 4.137. PP/EPDM-V compression set (%) after 22 h at 70°C versus Shore A hardness 678...

PP/EPDM-V resists hydrolysis well but is naturally sensitive to light and UV. It must be protected by addition of anti-UV and other protective agents and possibly by a few percent of an appropriate carbon black. 

PP/EPDM-V absorbs little water and is not very sensitive to it. Moreover, hydrolysis-resistant grades are marketed and used, for example, in washing machines. 

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