Thermosetting resin cross-linking

Determination of Thermoset Resin Cross-link Architecture by Gel Permeation Chromatography... 

AYORINDE ET AE. Thermoset Resin Cross-link Archiieclure... 

Alkyds are formulated from polyester resins, cross-linking monomers, and fillers of mineral or glass. The unsaturated polyester resins used for thermosetting alkyds are the reaction products of polyfunctional organic alcohols (glycols) and dibasic organic acids. 

Poly(methyl methacrylate) and poly(vinyl acetate) precipitate from the resin solution as it cures. This mechanism offsets the contraction in volume as the polyester resin cross-links, resulting in a nonshrinking thermoset. Other polymer additives such as poly(butylene adipate) provide similar shrinkage... 

Higher degrees of cross-linking have a a significant effect for an unsaturated polyester resin with short and stiff cross-links, Tg appeared to be increased by 21 °C when the number of atoms between cross-links amounted to 50, while with 24 atoms between cross-links the increase was 93 °C. So, with thermosets the cross-link density has a large effect on Tg, and, consequently, on the usability at higher temperatures. 

Thermoset polyester Polyester resins cross-linked with amino or phenolic resins May contain lower molecular weight epoxy resin Very good Pack dependent May not be suitable for very acidic and aggressive foods... 

It can be concluded that the beverage can coating is a methyl melhacrylate/eth-ylhexyl acrylate copolymer modified polyester. The polyester is an adipic acid-modified neopentyl glycol iso-/orthophthalic acid type. The electrical appliance coating is a butylated amino resin cross-linked pentaerythritol-orlhophthalic thermosetting alkyd enamel. 

Thermosetting High cross-linking density Phenol-formaldehyde resin... 

One-Stage Resins. The ratio of formaldehyde to phenol is high enough to allow the thermosetting process to take place without the addition of other sources of cross-links. 

Two-Stage Resins. The ratio of formaldehyde to phenol is low enough to prevent the thermosetting reaction from occurring during manufacture of the resin. At this point the resin is termed novolac resin. Subsequently, hexamethylenetetramine is incorporated into the material to act as a source of chemical cross-links during the molding operation (and conversion to the thermoset or cured state). 

The commonly used resins in the manufacture of decorative and industrial laminates ate thermosetting materials. Thermosets ate polymers that form cross-linked networks during processing. These three-dimensional molecules ate of essentially infinite size. Theoretically, the entire cured piece could be one giant molecule. The types of thermosets commonly used in laminates ate phenoHcs, amino resins (melamines), polyesters, and epoxies. 

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