Ethylene-propylene copolymers properties

Although the mbbery properties of ethylene—propylene copolymers are exhibited over a broad range of compositions, weight percentages of commercial products generally range from 50 50 to 75 25 ethylene propylene. 

Two random copolymers of this type are of importance, ethylene-propylene copolymers and ethylene-but-l-ene copolymers. The use and properties of polypropylene containing a small quantity of ethylene in stereoblocks within the molecule has already been discussed. Although referred to commercially as ethylene-propylene copolymers these materials are essentially slightly modified polypropylene. The random ethylene-propylene polymers are rubbery and are discussed further in Section 11.9. 

Properties of Maleated Ethylene-Propylene Copolymer (EPM) Blended with Polyamide-6 (PA-6)... 

Since the excellent work of Moore and Watson (6, who cross-linked natural rubber with t-butylperoxide, most workers have assumed that physical cross-links contribute to the equilibrium elastic properties of cross-linked elastomers. This idea seems to be fully confirmed in work by Graessley and co-workers who used the Langley method on radiation cross-linked polybutadiene (.7) and ethylene-propylene copolymer (8) to study trapped entanglements. Two-network results on 1,2-polybutadiene (9.10) also indicate that the equilibrium elastic contribution from chain entangling at high degrees of cross-linking is quantitatively equal to the pseudoequilibrium rubber plateau modulus (1 1.) of the uncross-linked polymer. 

For example, a PE-fe-poly(ethylene-co-propylene) diblock composed of crystalline PE and amorphous ethylene/propylene copolymer segments was synthesized from ethylene and ethylene/propylene. The addition of MAO and Ti-FI catalyst 40 (Fig. 25) to an ethylene-saturated toluene at 25 °C resulted in the rapid formation of a living PE (Mn 115,000, MJMn 1.10). The addition of ethylene/propylene (1 3 volume ratio) to this living PE formed a PE-/>poly(ethylcnc-co-propylcnc) block copolymer (Mn 211,000, MJMn 1.16, propylene content 6.4 mol%) [30], As expected, the polymer exhibits a high Tm of 123 °C, indicating that this block copolymer shows good elastic properties at much higher temperatures than the conventional random copolymers of similar densities. 

Patri, M., Hande, V. R., Phadnis, S. and Deb, P. C. 2004. Radiation-grafted solid polymer electrolyte membrane thermal and mechanical properties of sulfonated fluormated ethylene propylene copolymer (FEP)-graft-acrylic acid membranes. Polymers for Advanced Technologies 15 622-627. 

Phadnis, S., Patri, M., Chandrasekhar, L. and Deb, P. C. 2005. Proton-exchange membranes via the grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer by a preirradiation technique. III. Thermal and mechanical properties of the membranes and their sulfonated derivatives. Journal of Applied Polymer Science 97 1418-1425. 

Commercial grades of ethylene-propylene copolymers (EPR) contain 60-75 mol% of ethylene to minimize crystallization. The addition of a third monomer, such as 1,4-hexadiene, dicyclopentadiene, or 5-ethylidene-2-norbornene, produces generally amorphous faster-curing elastomers. A large number of such terpolymers, referred to as EPDM, is available commercially. Their properties, performance, and response to radiation vary considerably depending on macrostructure, ethylene/propylene ratio, as well as on the type, amount, and distribution of the third monomer. 

PVC, another widely used polymer for wire and cable insulation, crosslinks under irradiation in an inert atmosphere. When irradiated in air, scission predominates.To make cross-linking dominant, multifunctional monomers, such as trifunctional acrylates and methacrylates, must be added. Fluoropolymers, such as copol5miers of ethylene and tetrafluoroethylene (ETFE), or polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), are widely used in wire and cable insulations. They are relatively easy to process and have excellent chemical and thermal resistance, but tend to creep, crack, and possess low mechanical stress at temperatures near their melting points. Radiation has been found to improve their mechanical properties and crack resistance. Ethylene propylene rubber (EPR) has also been used for wire and cable insulation. When blended with thermoplastic polyefins, such as low density polyethylene (LDPE), its processibility improves significantly. The typical addition of LDPE is 10%. Ethylene propylene copolymers and terpolymers with high PE content can be cross-linked by irradiation. ... 

More recently, modified fluoroplastics such as fluorinated ethylene/propylene copolymer, polychlorotrifluoroethylene, and polyvinylidene fluoride have been offered by DuPont, Allied Chemical, 3M, and Pennwalt respectively, to provide improved processability and mechanical strength at some sacrifice in heat-resistance, electrical properties, and chemical resistance and at prices of 3.70-7.15 these have also been finding appropriate if smaller markets. 

Fig. 11.29 Fiber-length distribution of MOS and feeding protocol for MOS-filled PP containing ethylene-propylene copolymer. [Reprinted by permission from Y. Suetsugu, The Effect of Mixing on Some Properties of Compounds and Composites, in Mixing and Compounding of Polymers, I. Manas-Zloczower and Z. Tadmor, Eds., Hanser, Munich, 1994.]...

Ethylene-propylene copolymers, acrylates and polyisobutylene are the most common competitors to block copolymers in these markets. The narrow molecular weight distributions and star architecture of the SBCs give them a better balance of properties at molecular weights of >100000 than the competing polymers. 

The composition of feed polymers also has an important effect on the properties of products. In the experimental work of Miskolczi et al. commercial waste plastics from the packaging, electronic and automotive industry and the agriculture were used as raw materials. The samples contained high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), ethylene-propylene copolymer (EPC), polystyrene (PS), polyamide 6.6 (PA 6.6) and polyvinyl chloride (PVC). 

Copolymers of ethylene and propylene have come to stay as important materials with diverse practical applications. They span the full range of polymeric properties, from soft elastomers to hard thermoplastics depending on the relative composition of the two monomers and the manner of their enchainment. Ethylene-propylene copolymers are manufactured commercially using Ziegler-Natta catalysts [1]. For the purposes of this discussion, we will treat these copolymers in terms of three distinct classes of materials ... 

Since the discovery of olefin polymerization using the Ziegler-Natta eatalyst, polyolefin has become one of the most important polymers produeed industrially. In particular, polyethylene, polypropylene and ethylene-propylene copolymers have been widely used as commercial products. High resolution solution NMR has become the most powerful analytieal method used to investigate the microstructures of these polymers. It is well known that the tacticity and comonomer sequence distribution are important factors for determining the mechanical properties of these copolymers. Furthermore, information on polymer microstructures from the analysis of solution NMR has added to an understanding of the mechanism of polymerization. 

Bares,J. Properties of ethylene-propylene-vinyl chloride graft copolymers. I. Viscoelasticity of ethylene-propylene copolymers. J. Polymer Sci. A-2, 9, 1271-1285 (1971). 

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