Termonomers

The principal monomer of nitrile resins is acrylonitrile (see Polyacrylonitrile ), which constitutes about 70% by weight of the polymer and provides the polymer with good gas barrier and chemical resistance properties. The remainder of the polymer is 20 to 30% methylacrylate (or styrene), with 0 to 10% butadiene to serve as an impact-modifying termonomer. 

Uses. Besides polymerizing TFE to various types of high PTEE homopolymer, TEE is copolymerized with hexafluoropropylene (29), ethylene (30), perfluorinated ether (31), isobutylene (32), propylene (33), and in some cases it is used as a termonomer (34). It is used to prepare low molecular weight polyfluorocarbons (35) and carbonyl fluoride (36), as well as to form PTEE m situ on metal surfaces (37). Hexafluoropropylene [116-15-4] (38,39), perfluorinated ethers, and other oligomers are prepared from TEE. 

Tetrafluoroethylene of purity suitable for granular or dispersion polymerizations is acceptable for copolymerization with ethylene. Polymerization-grade ethylene is suitable for copolymerization with tetrafluoroethylene. Modifying termonomers, eg, perfluorobutylethylene and perfluoropropylene, are incorporated by free-radical polymerization. 

Random insertion of ethylene as comonomer and, in some cases, butene as termonomer, enhances clarity and depresses the polymer melting point and stiffness. Propylene—butene copolymers are also available (47). Consequendy, these polymers are used in apphcations where clarity is essential and as a sealant layer in polypropylene films. The impact resistance of these polymers is sligbdy superior to propylene homopolymers, especially at refrigeration temperatures, but still vastiy inferior to that of heterophasic copolymers. Properties of these polymers are shown in Table 4. 

Miscellaneous Copolymers. VP has been employed as a termonomer with various acryUc monomer—monomer combinations, especially to afford resins usehil as hair fixatives. Because of major differences in reactivity, VP can be copolymerized with alpha-olefins, but the products are actually PVP grafted with olefin or olefin oligomers (151,152). Likewise styrene can be polymerized in the presence of PVP and the resulting dispersion is unusually stable, suggesting that this added resistance to separation is caused by some grafting of styrene onto PVP (153). The Hterature contains innumerable references to other copolymers but at present (ca 1997), those reviewed in this article are the only ones known to have commercial significance. 

AES polymers which use an ethylene-propylene termonomer rubber (see Chapter 11). 

Terpolymers of DMAEMA, the methyl chloride salt of DMAEMA, and a termonomer the sodium salt of 2-acrylamido-2-methylpropane... 

Terpolymers generally have an increased fluorine content of 66-71%. Several different types can be identified, depending on the termonomer used. 

For recently prepared terpolymers of PO/CO2 noticeable improvements in thermal stability were thus achieved. The rate of decomposition decreases with the termonomer content. Part of the effect obviously originates from the lower concentration of propylene carbonate entities and another part from the lower flexibility of the main chain. In addition, another explanation for the increase in thermal stability with termonomers (which is, however, not substantiated) could be found in the solubility of water in the product because every recent study indicates that hydrolysis is a major cause of the initiation of thermal decomposition [23]. Also, additives have been identified as slowing down thermal degradation. 

Miscellaneous Copolymers. VP has been employed as a termonomer with various acrylic monomer—monomer combinations, especially to afford resins useful as hair fixatives. 

Copolymers of ethylene and tetrafluoroethylene (ETFE) essentially comprise alternating ethylene and TFE units. They have an excellent balance of physical, chemical, mechanical, and electrical properties, are easily fabricated by melt-processing techniques, but have found little commercial utility, because they exhibit a poor resistance to cracking at elevated temperatures.59 Incorporation of certain termonomers, so-called modifiers, in amounts 1 to 10 mol% markedly improves the cracking resistance, while maintaining the desirable properties of the copolymer.60 61... 

Termonomer Hydrogen stretch cm-1 Double bond cm1 Hydrogen stretch cm1... 

A specially developed titanium-based catalyst has been used in the suspension process for EPM and EPDM where the termonomer is low-boiling. The advantages claimed, in addition to those characteristic of the suspension process, are better structural control and high catalyst efficiency, resulting in a high-purity product without requiring catalyst removal.51... 

JSR Corp. Ethylene propylene rubber (EPR/EPDM) Ethylene, propylene, termonomer Solution process. Many (jades of EPM/EPDM with excellent characteristics 3 1995... 

Mitsui Chemicals, Inc. Ethylene-propylene rubber Ethylene, propylene, termonomer EPM/EPDM process uses solution polymerization with Ziegler catalyst 1 1994... 

Perfluoroelastomers prepared by Bish [3] and Hung [4] containing roughly 3 wt% of the termonomer perfluoro(8-cyano-5-methyl-3,6-dioxa-l-octene),... 

Thus, ethylene, obtained from petroleum or natural gas hydrocarbons, is also a mon< Qer for the direct formation of a plastic such as polyethylene, or of an elastomer such as Ethylene-Prop ene-Termonomer (EPT) rubber. Acetic add, produced in several stq> from acetylene or ethylene, is also produced directly by the oxidation of a mixture of saturated hydrocarbons (naphtha). 

However, in the case of EPTM synth the formation of gel can be avoided by adopting low terpolymer concentration, low termonomer concentration and very efficient stopping procedures ... 

The structure of the triene used as termonomer plays a crudal role in redudng side reactions and obtaining high utilization of termonomer. The following features are of outstanding importance ... 

The presence of an isolated unsaturation, very reactive toward coordination catalysts (as it is norbornene double bond) allows termonomer utilization higher than 60%. This result was actually obtained with trienes (III), (V), (VII) and (VIII) whereas conjugated trienes such as (I), (VI) and (IX) exhibited utilization near to 35% for termonomer contents lower than 5 wt %. 

Fig. 1. Grafting efficiency vs. termonomer content for some ethylene-propylene based terpolymers. Conditions styrene-acrylonitrile (molar ratio 1.5 1) -2.6 mol/1 terpoiymer 25 -s- 30 g/i BPO = 8.67 mmol/1 solvent = n-hep-tane-benzene (1 I by wt) T =...

As is evident in Fig. 2, the ethylene content and the MW of EPTM do not influence the grafting efficiency, even thou] the impact strength of the resulting material benefits by EPTMs high ethylene content and high MW These experimental observations agree with the assumption that the grafting reaction occurs, essentially, under the conditions adopted, on the termonomer units inserted in EPTM chains. 

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