Glass transition temperatures functional oils

Fig. 3. Elastomer properties as a function of monomer composition, butyl acrylate (BA), ethyl acrylate (FA), and methoxyethyl acrylate (MEA). (a), (—) glass-transition temperature (------------) swelling in ASTM No. 3 oil (b) (-) residual elongation at break, %, after heat aging.

Table IV summarizes the glass transition temperature of a number of special functional oil-based homopolymers. Many of the polymers shown indeed have T s below the critical value. It is now believed that the synthetically epoxidized oils were fully epoxidized, producing materials with unusually high degrees of crosslinking, which tended to raise their T s beyond the desirable range.

Table IV. Glass Transition Temperatures of Single Networks Made from Special Functional Oils...

In addition, PET can be used to form semi-IPNs with other naturally functionalized triglyceride oils, such as vemonia oU (31). The procedures for PET/vemonia semi-IPNs are essentially the same as those of PET/castor ones, but with important differences. For PET/castor mixtures, the diisocyanate cross-hnker was added at 240°C and the mixture was poured into the molds rapidly before the castor gel point had been reached. In this case, PET/castor polyurethane semi-IPNs were formed, in which crystallization and gelation occurred simultaneously resulting in a single, broad glass transition temperature. For PET/vernonia, the sebacic acid was added at 280°C, which reduced the temperature to about 250°C, where the mixture was held for another 5 min, then poured into a preheated mold and allowed to cool, during which time the PET crystalhzes. In this case, PET/vernonia polyester network was formed, and the PET crystallized prior to network formation because the latter... 

Figure 11.36 shows that the glass transition depression is a linear function of plasticizer concentration. Two ester plasticizers depress the glass transition temperature more extensively than paraffinic oil. Dioctyl sebacate deerease the flexural modulus more rapidly with smaller concentrations of plasticizer (up 10 wt%) then the flexural modulus levels... 

In thermosets, where POSS is reacted into the material, the primary advantage is excellent high temperature modulus retention beyond 300 °C [8]. For example, octa functional POSS epoxies or POSS amines can be added to conventional epoxy or BMI resins to provide very high temperature resins. While traditional resins lose rigidity at and above the glass transition temperature, the POSS modified materials retain modulus even under extreme temperature conditions. Such materials are in demand for oil well applications where the drive to deeper, hotter wells pushes existing... 

The polymerization process yields a random, amorphous terpolymer or a random, amorphous dipolymer (no cure-site monomer). The pol5uner backbone is fully saturated, making it highly resistant to ozone attack even in the absence of antiozonant additives. The fluid resistance and low temperature properties of ethylene-acrylic elastomers are largely a function of the methyl acrylate to ethylene ratio. As the methyl acrylate level increases, the polymer becomes more polar and has better fluid resistance to aliphatic hydrocarbon oils. Also, as the methyl acrylate level increases, the glass-transition temperature (Tg) of the polymer increases slightly. There is a trade-off between oil resistance and low temperature performance. 

Many triglyceride oils such as castor oil, lesquerella oil, and ver-nonia oil have special functionalities on each of their three fatty acid chains in addition to double bonds. For castor and lesquerella, the acid residues have hydroxyl groups, while vernonia oil has oxirane groups. Besides these naturally occurring functionalized oils, linseed, crambe, lunaria, and lesquerella oil have been epoxidized to yield the oxirane functionality wherever a double bond existed. These special functionalities permit the formation of crosslinked polyesters or polyurethanes, which are usually soft elastomers with glass transition temperatures of about -50 C. The castor oil polyester with sebacic acid is especially interesting, since sebacic acid itself is derived commercially from cas-... 

Oil-field elastomers also fail to perform satisfactorily when too near or below their glass transition temperatures. Although the consequences are not as dramatic or well publicized, if blow-out-preventer elastomers are too stiff to function properly, a blow out can occur. O-rings and other seals can fail when they lose resilience causing leaks of contained fluids and gases. 

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