Crosslinkable polyesters

IPNs are found in many applications though this is not always recognised. For example conventional crosslinked polyester resins, where the polyester is unsaturated and crosslinks are formed by copolymerisation with styrene, is a material which falls within the definition of an interpenetrating polymer network. Experimental polymers for use as surface coatings have also been prepared from IPNs, such as epoxy-urethane-acrylic networks, and have been found to have promising properties. 

Today, glycerol has over 2000 different applications, in cosmetics, pharmaceutics, foods and drinks, tobacco, paper, inks and printing colors, the production of phthalic and maleic alkyd resins and crosslinked polyesters, and as a hydraulic agent. Polyglycerols have a wide range of applications as emulsifiers, and technical esters of glycerol with fatty acids are used as synthetic lubricants [4]. 

Fig. 16. Molar mass dependencies of the intrinsic viscosity [rf] for the same samples as shown in Fig. 15 (end-linked PS-stars [94] and randomly crosslinked polyesters [92,93,95]...

Simple polyesters of the type described by Eq. 2-170 are too limited to be of commercial interest. Almost all crosslinked polyesters are either unsaturated polyesters or alkyd polyesters. These offer a greater ability to vary the final product properties to suit a targeted market. Also, they offer greater process control since different chemical reactions are involved in the polymerization and crosslinking reactions. A typical unsaturated polyester... 

PVC, polyamides, unsaturated crosslinked polyesters, ABS, and wood . Di- and tri-benzotriazole photostabilizers, such as (874) and (875) are synthesized from 2-nitro-benzenediazonium salts and an excess of 1,3-dihydroxybenzene or 1,3,5-trihydroxybenzene <85Mi 40i-0l>. The dibenzotriazole derivatives (874b and 875b) can be used as polymerizable acrylic UV absorbers <84PB237>. A few or/Ao-urethane and -trimethylsilane substituted 2-phenylbenzotriazoles (876 and 877) show similar photostabilization activity . Weather resistance of low-density polyethylene is improved by the addition of a benzotriazole-type photostabilizer <90M140i-04>. 

Fig. 32. Methodology for synthesis and processing of crosslinked polyesters as adhesives...

Then, the knowledge of K and v allows us to calculate all the other elastic constants. Typically, the Poisson s ratio of glassy thermosets at temperatures close to 20°C ranges between 0.37 (styrene-crosslinked polyesters) and 0.42 (certain amine-crosslinked epoxies), which corresponds to tan Ap values ranging between about 0.01 and 0.1. 

R.K. Bharadwaj, A.R. Mehrabi, C. Hamilton, C. Trujillo, M. Murgs, R. Fan, A. Chavira, and A.K. Thomson, Structure-properties relationships in crosslinked polyester-clay nanocomposites, Polymer, 2002, 43 3699-3705. 

Diacylperoxide is used mainly as an initiator for radical polymerizations as well as for hardening and crosslinking polyester resins as a result of its ability to easily thermally decompose. 

In this experiment, both linear and crosslinked polyesters are synthesized by step-growth polymerization The reactions are carried out in the melt (or neat), meaning that no solvents are used in the preparation and the final product does not have to be purified. Preparations such as these are sometimes called green reactions. 

Composite—A material that contains two or more structurally different components with properties different from that of any individual component. Examples include crosslinked polyester resin reinforced with glass fiber and rubber filled with carbon black. 

Swelling data for macronet crosslinked polyesters were reported by Takahashi [144], His polymers were prepared by causing a mixture of propylene glycol and an equivalent amount of diacid (maleic anhydride plus succinic acid) to undergo... 

Another way of producing highly crosslinked polyesters (see Exercise 64) is to use glycerol. Alkyd resins are a polymer of this type. The polymer forms very tough coatings when baked onto a surface and is used in paints for automobiles and large appliances. Draw the structure of the polymer formed from the condensation of... 

Polyesters - Aliphatic crosslinked polyesters undergo chain scission and crosslink breakage during photooxidation while using ESCA phenolic hydroxyl groups have been identified in photooxidised poly(ethylene terephtha-late). ° The presence of an optical brightener has been found to enhance the surface stability of poly(ethylene terephthalate). ... 

In general crosslinked polyesters have better light and weathering resistance than uncured polyester resins. Apparently the concentration of unsaturated double bonds is a determining factor. In our previous studies (14) we have shown that under UV irradiation of unsaturated polyesters the primary photoreactions involve excitation of conjugated structures carbonyl groups ( in ester... 

The kinetics of photo-oxidation of a crosslinked polyester were studied by ATR (Fig.l) and the ESCA (Figs 2-4) measurements. 

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