High molecular weight esters

Studies on the use of high molecular weight esters in nitrile mbber have led to further studies to compare DINP with DBP. These showed that at the 10 phr level the nitrile mbber was effectively plasticized with DINP (35). 

Uretha.nes. Urethane elastomers are prepared by the reaction of an isocyanate molecule with a high molecular weight ester or ether molecule. The result is either an elastomeric mbber form or a Hquid prepolymer that can be vulcanised with an amine or a hydroxyl molecule (see Urethane POLYAffiRS). 

Kishore, K H. K. Shobha, and G. J. Mattamal, Structural Effects on the Vaporization of High Molecular Weight Esters. J. Phys. Chem., 1990 94, 1642-1648. 

Perry, E.S., Weber, W.H. (1949) Vapor pressures of phlegmatic liquids. 11. High molecular weight esters and silicone oils. J. Am. Chem. Soc. 71, 3726-3730. 

It combines a complex polymer system with a high molecular weight ester to form a synergistic union that is unsurpassed in reducing or eliminating cracks and abrasion problems in processing filament yarns. 

The over-all yield from ester and acid chloride is 38-58%. (2) Selfcondensation of high-molecular-weight esters and hydrolysis of the resulting /3-keto esters gives symmetrical ketones of the type RCH,COCH,R. 

The hydrolysis of esters is accomplished by refluxing with aqueous or alcoholic alkali hydroxides. Acid-catalyzed hydrolysis is an equilibrium reaction usually favoring ester formation. High-molecular-weight esters with branching in either acid or alcohol portions are sometimes hydrolyzed with difficulty. 

As work on lipid chemistry has developed, a tremendous number of HMWHCs of one t5fpe or another have been found in high abundance in the lipids of various plants, animals, microorganisms and insect waxes (Nelson Blomquist 1995). High molecular weight esters are components of cuticular waxes of higher plants (C36-C52 Cranwell Volkman 1981). Lipids and insoluble fractions from several freshwater... 

Long-Chained Aliphatic Hydrocarbons, Phytosterols, Solanesol, High Molecular Weight Esters, etc.)... 

Two macroemulsion.s. one 0/W and another W/O. were tested, together with other classical fomiulaiions, as vehicles for 4-bipheny[acetic acid, a nonsteroidal anti inflammatory agent (13). According to the authors, the 0/W emulsion, prepared with Polawax, was better tolerated than the W/O emulsion (containing Dehymuls E. a mixture of high molecular weight esters) and displayed slgniticani antiinflammatory activity in a rabbit model of ocular inflammation. 

From the above, it may readily be seen that AB type coalescing solvents give the best performance in use. These are the high molecular weight esters and ester alcohols. Other species have some of the benefits of these materials but have side effects, which render them less suitable. Minimization of the quantity used tends to be a key financial issue, as well as offering the best environmental option. In virtually all cases, the efficiency of the AB group in application is so marked, that they have become the industry standards. Several other properties, perhaps less important, than efficiency must then be considered when selecting between these. 

High-molecular-weight esters, such as wax esters, steryl esters, triterpenoid esters and triacylglycerols, are often hydrolysed, after which the liberated moieties are GC analysed however, this procedure provides only limited compositional information. The very convenient one-pot small-scale hydrolysis-silylation procedure, applicable to ester-emulsifiers, oils, fats, wax esters and other hydrolysable lipids, has been proposed by the lUPAC (Briischweiler and Hautfeune, 1990). The procedure involves the saponification of esters (ca. 10 mg) in 0.5 N ethanolic KOH solution (0.25 mL) at 80 °C for 3 h, evaporation to dryness in a stream of nitrogen and then silylation of the hydrolysis products. This enables the components of very small samples to be determined (< 0.1 mg). This procedure was used for the hydrolysis of wax esters and triterpenoid esters in potato and eggplant cuticular waxes (Szafranek Synak, 2006 Halinski et al., 2009). A solution of 1-2% (v/v) concentrated sulphuric acid in methanol can be easily used for the transesterification of acyl lipids and the esterification of free fatty acids (Christie, 1994). More procedures for ester hydrolysis and transesterification and for fatty acid esterification are described in detail by Christie (1994). 

Santos, S. Schreiber, L. Graga, J. (2007). Cuticular waxes from Ivy leaves (Hedera helix L.) analysis of high-molecular-weight esters, Phytochemical Analysis, Vol.18, No.l, (January 2007), pp. 60-69, ISSN 1099-1565... 

A general class of lubricants is alkyl acids and their derivatives (esters, amides, alcohols, and metallic salts). Esters, including fatty esters, polyol esters, and wax esters, are reasonably compatible with PVC. They are also used in polystyrene and acrylic polymers. High-molecular-weight esters are used as external lubricants, and low-molecular-weight esters are used as internal lubricants. Simple primary fatty amides possess unique mold-release properties and are used as slip and mold-release agents for polyolefins and other polymers. The more complex bisamides, such as ethylene bis-stearamide, offer mold release as well as internal and external lubricity in materials such as PVC and ABS. Fatty alcohols are used primarily in rigid PVC. They are used as both internal and external lubricants, and they are useful when clarity is important. 

Urethanes. Urethane elastomers are prepared by the reaction of an isocyanate molecule with a high molecular weight ester or ether molecule. The result... 

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