Unsaturated polyester oligomer

Synthesis of Unsaturated Polyester A. The unsaturated polyester oligomer A was prepared in a 500 milliliter 4-neck flask fitted with a variable speed stirrer, a heating mantle, a gas inlet tube, a thermometer, a Dean-Starke trap and a condenser. The flask was charged with 147.0 g (1.5 mol) of maleic anhydride (Amoco), 195 g (1.88 mol) of 1,5-pentane diol (BASF), about 35 ml of xylene and 0.3 g of Fascat 4100. Then heated slowly under a nitrogen blanket to 175° C while the water of condensation was removed... 

In recent work [31, 32], attempts were made to produce similar magnesium salts by melt processing mixtures of an unsaturated polyester oligomer (in the absence of a reactive monomer) with various amounts of MgO. As an example. Figure 20.4 shows the effects of increasing MgO concentration on the reaction between UP and MgO in a batch mixer at 220 °C. As the torque data indicate, the reaction rate... 

Figure 20.4 Changes in torque of unsaturated polyester oligomer upon addition of various amounts of MgO in a batch mixer at 220 °C [31, 32].

Vinyl ethers can also be formulated with acryHc and unsaturated polyesters containing maleate or fumarate functionaHty. Because of their abiHty to form alternating copolymers by a free-radical polymeri2ation mechanism, such formulations can be cured using free-radical photoinitiators. With acryHc monomers and oligomers, a hybrid approach has been taken using both simultaneous cationic and free-radical initiation. A summary of these approaches can be found in Table 9. 

The free radicals then initiate curing by attacking residual double bonds in acrylic oligomers and monomers, or in styrene and unsaturated polyester resins. Since most pigments absorb u.v. radiation and can prevent it reaching sufficient photoinitiator molecules, this technique is best suited to transparent coatings or thin pigmented layers (e.g. inks). 

Coating materials may be based on short or medium-oil alkyds (e.g. primers for door and window frames) nitrocellulose or thermoplastic acrylics (e.g. lacquers for paper or furniture finishes) amino resin-alkyd coatings, with or without nitrocellulose inclusions, but with a strong acid catalyst to promote low temperature cure (furniture finishes) two-pack polyurethanes (furniture, flat boards) unsaturated polyester resins in styrene with free-radical cure initiated by peroxides (furniture) or unsaturated acrylic oligomers and monomers cured by u.v. radiation or electron beams (coatings for record sleeves paperback covers, knock-down furniture or flush interior doors). 

Although low-molar-mass aliphatic polyesters and unsaturated polyesters can be synthesized without added catalyst (see Sections 2.4.1.1.1 and 2.4.2.1), the presence of a catalyst is generally required for the preparation of high-molar-mass polyesters. Strong acids are very efficient polyesterification catalysts but also catalyze a number of side reactions at elevated temperature (>160°C), leading to polymers of inferior quality. Acid catalysts are, therefore, not much used. An exception is the bulk synthesis of hyperbranched polyesters reported in Section 2.4.5.1, which is carried out at moderate temperature (140°C) under vacuum in the presence of p-toluene sulfonic acid catalyst. The use of strongly acidic oil-soluble catalysts has also been reported for the low-temperature synthesis of polyester oligomers in water-in-oil emulsions.216... 

Variation of Polyester Molecular Weight. A series of unsaturated polyester (UPE) oligomers were prepared by reacting maleic anhydride with 1,5-pentane diol. (Scheme... 

There are two types of cure reactions of thermosetting resins step (e.g., epoxies, phenolics, urethanes) and chain (e.g., unsaturated polyesters, vinyl esters, acrilates) polymerizations. In the first type, the size of the polymer chain increases because of the linking of the oligomers (e.g., monomers, dimers, etc.) to themselves. Short chains can be linked to long ones in a condensation reaction. In the second case, the size of the polymer chain increases because of... 

Addition poly(imide) oligomers are used as matrix resins for high performance composites based on glass-, carbon- and aramide fibers. The world wide market for advanced composites and adhesives was about 70 million in 1990. This amounted to approximately 30-40 million in resin sales. Currently, epoxy resins constitute over 90% of the matrix resin materials in advanced composites. The remaining 10% are unsaturated polyester and vinylester for the low temperature applications and cyanate esters and addition poly(imides) for high temperatures. More recently thermoplastics have become important and materials such as polyimides and poly(arylene ether) are becoming more competitive with addition polyimides. 

The best materials are produced by curing unsaturated polyester during copolymerization with different types of unsaturated monomers and oligomers, such as styrene and its derivatives, methyl methacrylate, vinylacetate, sulfone-type compounds, allyl esters, and oligo(ester acrylates).5... 

Although the polymerization of e-caprolactam was described above, there is no difference in principle from the process flow sheets for centrifugal molding of items from other polymers and oligomers. Nevertheless, in most cases, the high temperatures used in lactam polymerization are not required, and the flow sheet as a whole is simplified. In industrial practice, poly(methyl methacrylate) pipes,172 and sheets of polyurethanes and unsaturated polyesters are obtained by centrifugal casting. 

The solution of the precursors of the thermosetting polymer (mixture of monomers or oligomers with or without initiators, catalysts and different additives) is usually a liquid at room temperature e.g., unsaturated polyester styrene, some epoxy anhydride and epoxy amine formulations, cya-nate esters, one-stage phenolics, etc. Cooling any of these solutions below room temperature leads to a glass. The temperature at which the glass-liquid transition of the initial formulation takes place is denoted as Tg0. Some other particular formulations, such as two-stage phenolics (novo-lac-hexa mixtures), some epoxy-amine systems, etc., exhibit a Tg0 above room temperature. 

The majority of the monomers and oligomers used in UV curable inkjet ink formulations are acrylates of varying functionalities, although occasionally materials such as unsaturated polyester resins are used as well. Figure 2 shows examples of the acrylate moiety. Acrylates are skin sensitizers and should be handled with caution. 

An almost complete agreement between experimental and calculated (Eq. (16)) dependences of conversion on time, /S(t), is obtained for curing of epoxy [63, 114], epoxy silicone [19], silicone oligomers [20, 109], low-molecular-weight silicone rubbers [46, 105], unsaturated polyester [97, 121], melamine-formaldehyde [122], methylolpolyamide [123] and carbamide resins [122]. 

All-trans unsaturated ester oligomers have been synthesized by lipase-catalyzed polymerization of diesters of fumaric acid and 1,4-butanediol.217 No isomerization of the double bond was observed, as opposed to the extensive isomerization found during chemical polycondensations. Crystallinity was found in the enzymatically formed unsaturated oligoesters prepared in acetonitrile, whereas industrial unsaturated polyesters are amorphous. 

The Effect of Amine Structure In order to evaluate the effects of eunine functionality and substitution on the crosslinking reaction/ several amine terminated urethane oligomers were synthesized by the same procedure as used in the synthesis of the LPUR. The oligomers were prepared in Urethane Grade MEX. These amines were evaluated with the allyl terminated unsaturated polyester as the unsaturation source. The composition and the properties of the oligomers are shown in Table IV. 

Del De La Caba, K., Guerrero, P., Gavalda, J., Mondragon, I. Fracture behavior-morphology relationships in an unsaturated polyester resin modified with a liquid oligomer. J. Polym. Sci. B Polym. Phys. 37 (1999) 1677-1685. 

Let us consider the properties of an adhesive based on the following mixture of oligomers an unsaturated polyester resin and a prepolymer with end isocyanate groups (or macrodiisocyanate) based on polydiethylene glycol adipate of molecular weight 800 and on TDI (a mixture of the 2,4- and 2,6-isomers in ratio of 65 35), with the... 

Photopolymerizable monomers and oligomers can be classified under four main groups including radical monomers and oligomers, unsaturated polyester resins, thiol-ene systems, and cationic monomers. In addition to these systems, particular photopolymerizable systems are also available such as expanding monomers, liquid crystalline monomers, and some other miscellaneous monomers. 

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