Some implications of the gel point concept to the chemistry of alkyd resins

Abstract

SynopsisThis study explored the effects of chemical composition, extent of polyesterification and possible side-reactions upon the rheological behavior of a variety of oil-modified, glyceryl phthalate alkyds in both melt and in dilute solutions with several solvents. Correlative data were obtained on molecular weight and on other aspects of solubility and drying properties important to paint technology. Viscometric data proved very useful in relating variances of reaction degree with usage properties of these polymeric materirtls. Those data suggest a viewpoint of the gel point, mechanism which enhances practical utility of polyesterification theory. This hypothesis proposes that alkyd synthe& is not a homogeneous reaction throughout, and that phase separation creates a colloidal dispersion in the reacting mass long before gelatification occurs. Classical polyeaterification theory can predict the event of initial phase separation; other process variables affect the relative stability of the transition colloid which ultimately coalesces into the final gel structure. Practical properties of alkyds in paint vehicles can be adjusted to satisfy varying requirements by arresting the reaction at different levels before or in the transition region. Measurements of melt viscosity and intrinsic viscosity are especially sensitive and convenient probes for control of process and product in terms of this concept.

ESR spectroscopic evaluation of void parts in microheterogeneously crosslinked monomethacrylate/dimethacrylate resins by using copper(II) tetraphenylporphyrin spin probe

“…In general, thermosetting resins are conceived consisting of colloidal particles or microgels 1,2) , leading to the lowering of physical properties as compared with the calculated ones by assuming a homogeneous network 3) . In this connection, the great discrepancy of the actual gel point from the theoretical one calculated according to Flory-Stockmayer gelation theory 4,5) in the free-radical crosslinking polymerizations of multivinyl monomers and their copolymerizations with monovinyl monomers have been discussed in terms of cyclization, reduced reactivity of pendant vinyl groups of prepolymer compared with monomer, intramolecular crosslinking leading to the formation of multiple crosslinkage, microgel formation and excluded volume effect 6) .…”

Small-angle neutron scattering from polystyrene—DVB networks containing a delta fraction of deuterated polystyrene: Evidence for aggregation during polymerization

“…These results are strongly suggestive of aggregation. The aggregation of chains formed during a given interval of conversion has long been suspected (15)(16)(17)(18), and some data, particularly electron microscopy and mechanical studies, have supported this hypothesis (17,18). However, quantitative verification has never been maud.…”

Comparative Studies of Oil-Modified Alkyd Resins Synthesized from Epoxidized and Crude Neem Oil

“…The reaction was quenched when the acid value dropped to 13.01mgKOH/g and 16.09mgKOH/g respectively for epoxidized and crude neem oil modified alkyd resins. The acid value of aliquots samples taken were determined by titrating with a 0.1M KOH solution to the phenolphthalein end point after dissolution in a mixture of toluene and ethanol (1:1) [3]. Table 6.…”