Ethylene - propylene copolymers

An infrared spectroscopic method for the determination of bound ethylene in ethylene propylene copolymers is described in Method 91. This method utilizes the absorbance of the 732 cm infrared absorption band attributed to (gamma) (CH2)3 groups characteristic of an ethylene unit isolated between two head to tail propylene units  

Various other workers have studied the application of infrared spectroscopy to the determination of propylene groups in ethylene-propylene copolymers. This work is summarized in Table 4.1. 

NMR spectroscopy has also been applied to the determination of the ethylene propylene ratio in diese copolymers.  

Carbon 13 NMR has proved to be an excellent technique for analysis of sequence distributions and comonomer contents in ethylene-prq)ylene copolymer. These analyses are particularly straightforward if one of the monomer units is present at a level of 94% or greater because the other monomer will then occur primarily as an isolated unit. 

Poly(ethylene-co-propylene)s are completely amorphous polymers, and their photo-oxidative degradation has been reviewed in detail [1999]. A number of interesting conclusions have been drawn from the study of photo-oxidative degradation of ethylene-propylene copolymers at 310nm in the presence of air [754, 756-758]  

The Norrish Type II reaction of ketones is the initial chain scission process. 

The photolysis of hydroperoxides does not contribute to main chain scission through -scission of alkoxy radicals. 

As the local concentration of oxidation products (hydroperoxides and ketones) progressively increases, the production of carboxylic acids tends to become the dominant mechanism for chain scission. This proceeds through the photolysis of hydroperoxides hydrogen-bonded to ketones  

The photo-oxidation of ethylene-propylene copolymers is a very short chain reaction since the probabilities for the propagation reaction (3.69), and termination reaction (3.70), are similar  

Tosi and Simonazzi [1] described an IR method for the evaluation of the propylene content of ethylene-rich ethylene-propylene copolymers. This is based on the ratio between the absorbance of the 7.25 pm band and the product of the absorbances by the half width of the 6.85 pm band obtained on diecast polymer film at 160 C (Table 4.1). 

The calibration curve, based on a series of standard copolymers prepared with Relabelled ethylene or propylene, is obtained by plotting the 7.25 absorbance 6.85 absorbance ratio against the C3 weight fraction. The basis for the calibration of many methods for the analysis of ethylene-propylene copolymers is the work published by Natta and co-workers [6], which involves measuring the IR absorption of polymer solntions at 7.25 pm (presumably due to methyl vibrations related to the propylene concentration in the copolymer). In some cases, the dissolution of copolymers with 

Lomonte and Tirpak [12] developed a method for the determination of the percentage of ethylene incorporated in ethylene-propylene block copolymers. Standardisation is done from mixtures of the homopolymers. Standards and samples are scanned at 180 °C in a spring-loaded demountable cell. The standardisation is confirmed by the analysis of copolymers of known ethylene content prepared with C-labelled ethylene. By comparison of the IR results from the analyses at 180 °C and also at room temperature, ethylene homopolymer can be detected. These workers derived an equation for the quantitative estimation of the percentage of ethylene present as copolymer blocks. 

The method distinguishes between true copolymers and physical mixtures of copolymers. The method makes use of a characteristic IR rocking vibration due to 

A series of ethylene-propylene block copolymers prepared with C-labelled ethylene was analysed for percentage of ethylene incorporation by radiochemical methods. These samples when scanned at 180 °C gave IR results that agreed reasonably well with the radiochemical assay. When cooled samples were scanned, the results from the cold calibration were low in comparison with the known ethylene content. These data are shown in Table 4.2. 

For catalyst comparison, the same monomer was polymerized with [Mo] and [Ru], affording polymers of equal branch content and M values of 72.0 and 

4 kg mol respectively. Upon thermal analysis of these two polymers, both produced sharp melt transitions at 57 °C, indicating no difference in polymer morphology across this range of molecular weights. In-depth discussions on structural and thermal characterization are included in this report [71]. These synthetic studies proved that ADMET step-growth chemistry was a viable 

Major polymer applications automotive radiator hose, garden hose, wire and cable, tires, roofing, gaskets, conveyor belts 

Important processing methods extrusion, molding, calendering, coating 

Typical fillers calcium carbonate, calcinated clay, aluminum hydroxide, magnesium carbonate, magnesium hydroxide, antimony trioxide, calcium borate, huntite, hydromagnesite, zinc oxide, talc, silica 

Typical concentration range carbon black 20-40 wt%, most others 30-65 wt% 

Anxiliary agents organic silane, aliphatic alcohols  

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The weight percent propylene in ethylene-propylene copolymers for different Ziegler-Natta catalysts was measuredt for the initial polymer produced from identical feedstocks. The following results were obtained ... 

FEP film pLUORINE COMPOUNDS, ORGANIC - PERFLUORINATED ETHYLENE-PROPYLENE COPOLYMERS] (Vol 11) -P7E film for pLUORINE COMPOUNDS, ORGANIC - POLY(7UNYL FLUORIDE)] (7E111)... 

Perfluorinated ethylene—propylene copolymers, Tetrafluoroethylene—ethylene copolymers, Tetrafluoroethylene—perfluorovinyl ether copolymers, Poly(vinyl fluoride),... 

Many cellular plastics that have not reached significant commercial use have been introduced or their manufacture described in Hterature. Examples of such polymers are chlorinated or chlorosulfonated polyethylene, a copolymer of vinyUdene fluoride and hexafluoropropylene, polyamides (4), polytetrafluoroethylene (5), styrene—acrylonitrile copolymers (6,7), polyimides (8), and ethylene—propylene copolymers (9). 

Organic peroxides are used in the polymer industry as thermal sources of free radicals. They are used primarily to initiate the polymerisation and copolymerisation of vinyl and diene monomers, eg, ethylene, vinyl chloride, styrene, acryUc acid and esters, methacrylic acid and esters, vinyl acetate, acrylonitrile, and butadiene (see Initiators). They ate also used to cute or cross-link resins, eg, unsaturated polyester—styrene blends, thermoplastics such as polyethylene, elastomers such as ethylene—propylene copolymers and terpolymers and ethylene—vinyl acetate copolymer, and mbbets such as siUcone mbbet and styrene-butadiene mbbet. 

Combination techniques such as microscopy—ftir and pyrolysis—ir have helped solve some particularly difficult separations and complex identifications. Microscopy—ftir has been used to determine the composition of copolymer fibers (22) polyacrylonitrile, methyl acrylate, and a dye-receptive organic sulfonate trimer have been identified in acryHc fiber. Both normal and grazing angle modes can be used to identify components (23). Pyrolysis—ir has been used to study polymer decomposition (24) and to determine the degree of cross-linking of sulfonated divinylbenzene—styrene copolymer (25) and ethylene or propylene levels and ratios in ethylene—propylene copolymers (26). 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

Steel [52013-36-2] suture is made from 316-L stainless steel wire. The suture may be monofilament, known as fixation wire, or multifilament twisted wires. The steel is heat-treated to improve ductility. The multifilament strands are either uncoated, or coated with Tefion (polytetrafiuoroethylene) or Tefion-fiuorinated ethylene—propylene copolymer. 

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. 

By block copolymerisation so that one component of the block copolymer has a Tg well below the expected service temperature range (e.g polypropylene with small blocks of polyethylene or preferably polypropylene with small amorphous blocks of ethylene-propylene copolymer). 

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. 

A hexagonal phase is found at room temperature and atmospheric pressure in some ethylene-propylene copolymers containing a small amount of diene component [86,93]. 

Sivaram, S. and Singh, R. P. Degradation and Stabilization of Ethylene-Propylene Copolymers and Their Blends A Critical Review. Vol. 101, pp. 169-216. 

Plastics are susceptible to brittle crack-growth fractures as a result of cyclic stresses in much the same way as metals. In addition, because of their high damping and low thermal conductivity, plastics are prone to thermal softening if the cyclic stress or cyclic rate is high. Examples of the TPs with the best fatigue resistance include PP and ethylene-propylene copolymers. 

Tosi, C. and Ciampelli, F. Applications of Infrared Spectroscopy to Ethylene-Propylene Copolymers. Vol. 12, pp. 87-130. 

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