UNSATURATED POLYESTER UPES

Unsaturated polyesters are used as encapsulants, varnishes, etc. in electrical and electronic applications. PPE-MM s have very high solubility in styrenics monomers. The PPE-MM-D were therefore compared with an isophthalate modified unsaturated polyester (Iso-UPE). Solutions were prepared of 50 wt % in vinyl toluene (VT) monomer. VT was chosen over styrene because of its lower vapor pressure. Properties of cured resins are shown in Table 2. The PPE-MM-DA T resin exhibits a broad range of improved properties. These include lower density. 

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

Variation of Equivalent Weight. In an attempt to produce more flexible coatings, the UPE A formulation was modified to increase the equivalent weight by substituting succinic anhydride for a portion of the maleic anhydride. These unsaturated polyesters were prepared by the same method as above and the compositions and their properties are summarized in Table II. 

The equivalent weight increased from 210 for UPE A to 316 for UPE E with one third of the maleic anhydride was replaced with succinic anhydride and 634 for UPE F with two thirds of the maleic anhydride is replaced with succinic anhydride. This change will effectively decrease the crosslink density of the final cured film. The Brookfield viscosities of the two new polyesters (E and F) are less than those from the first series. Since the molecular weights should be about the same (1760), it is not surprising that the Brookfield viscosities were relatively constant for all three unsaturated polyesters. The slight decreasing trend in viscosity with increasing succinic anhydride in the unsaturated polyester may be due to the increased free volume obtained when succinic anhydride is substituted for maleic anhydride. 

PBDEs are used in different resins, polymers, and substrates at levels ranging from 5 to 30% by weight (EU 2001). Plastic materials that utilize PBDEs as flame retardants include ABS polyacrylonitrile (PAN) polyamide(PA) polybutylene terephthalate (PBT) polyethylene (PE) cross-linked polyethylene (XPE) polyethylene terephthalate (PET) polypropylene (PP) polystyrene (PS) high-impact polystyrene (HIPS) polyvinyl chloride (PVC) polyurethane (PUR) and unsaturated polyester (UPE). These polymers and examples of their final products are summarized inTable 5-2 (Hardy 2002 WHO 1994a). 

Isothermal differential scanning calorimetry (DSC) tests were performed on three unsaturated polyester (UPE) samples at three different temperatures (100°C, 110°C, and 120°C). The output for the three DSC tests are presented in the Fig. 2.70. On the graph, label which curve is associated with which test temperature. From the curves in Fig. 2.70 estimate the total heat of reaction, Qt ... 

Note ABS, acrylonitrile/butadiene/styrene EPS, expandable polystyrene HIPS, high-impact polystyrene PA, polyamide PBT, poly(butylene)terephthalate PC, polycarbonate PE, polyethylene PET, poly(ethylene)terephthalate PP, polypropylene PUR, polyurethane PVC, polyvinylchloride UPE, unsaturated polyester Textile, textile application. 

Polymer concretes show excellent mechanical properties and chemical resistance compared with conventional cement concretes. Polymer concretes can be cured quickly by the use of curing agents. Thus, the applications of polymer concretes are being increased. One of the popular polymers for polymer concretes is unsaturated polyester (UPE) resin. The properties of UPE resin can be modified by changing its molecular features. For the synthesis of the resin, phthalic anhydride or isophthalic acid as well as maleic anhydride can be employed to modify the mechanical properties or hydrothermal resistance. Terephthalic acid which is also used for the synthesis of poly ethylene terephthalate (PET) enhances the thermal resistance of the cured UPE resin. However, the synthesis of unsaturated polyester resin from terephthalic acid is difficult. One method to synthesize unsaturated polyester from terephthalic acid is the use of recycled PET. 

PET is useful polymer used for fiber, film, and plastic containers such as carbonated beverage bottles. Recently, the recycling of polymers such as PET after use is attracting the attention of many researchers aware of environmental problems and wishing to find ways to save earth resources. Previous studies showed that unsaturated polyester resins can be economically prepared from recycled PET and the resins may be useful for resin concretes (1 4). However, there is little information on the molecular features of the UPE resins. Thus, we synthesized various UPE resins from PET. Especially, the PET content, chain flexibility and degree of unsaturation of the resins were systematically varied and the effects of those variables on the mechanical properties of the cured resins and polymer mortars made therefrom were studied. 

Various UPE resins based on recycled poly ethylene terephthalate(PET) were prepared and the properties of the polymer mortar made with the UPE as well as those of the cured resin itself were investigated. It was found that degree of unsaturation of the resins was the most important property affecting thermal and mechanical properties of the cured resin and PM. The cured unsaturated polyester resin or polymer mortar made from resins of higher unsaturation, i.e., less PET content or adipic acid content in the resin, showed higher glass transition temperatures,... 

Two- and three-component interpenetrating polymer network (IPN) elastomers composed of polyurethanes (PU), epoxies (E), and unsaturated polyester (UPE) resins were prepared by the simultaneous technique. Fillers and plasticizers were... 

The IPN elastomers were synthesized by the mixing of two components. In the case of two-component PU/E IPN elastomers, one component contained Nlax 31-28, Isonol-100, T-12 and epoxy catalyst (BFs-etherate, Eastman Chemical). The other component contained epoxy resin (DER-330, Dow Chemical) and Isonate-143L. Whereas In the case of three-component IPN elastomers composed of PU/E/UPE, polyester resin catalyst (TBPB) and unsaturated polyester resin were Incorporated, respectively. In the former and latter components. 

IPNs of PU/E ratios of 40/60 and 50/50 have even larger effects on tan 6 height and breadth. PU/E/UPE IPN elastomers with higher amounts of unsaturated polyester have even higher and broader tan 6 ranges. 

Organic peroxides are also used as curing agents for unsaturated polyesters (UPE), as cross-linkers for polyethylene and as rheology modifiers in polypropylene. 

Unsaturated maleic/fumaric acid-containing polyesters (UPEs) dissolved in styrene, (2) acrylate/methacrylate systems, (3) thiol/ene systems, and (4) epoxide- or vinyl ether-containing systems. In the case of systems (l)-(3), free radical polymerizations are operative, while in case (4) cationic species are involved (see Chapter 10). Regarding thiol/ene systems, the mechanism of free radical thiol/aUcene polymerization outlined in Scheme 11.1 is assumed to be operative... 

Unsaturated polyester resins (UPER) are largely used as components in polymer composites 26, 27) Generally, they are obtained by reaction of an unsaturated polyester (UPE) with a vinyl monomer. In our experiments, we have cured the UPE represented in Figure 3 wifti styrene (STY), which is the monomer mostly used for this purpose, or hydroxyethyl acrylate (HEA) and/or a diblocked diisocyanate (i.e., acrylic acid 2-[6-(2-acryloyloxy-ethoxycarbonylamino)-hexylcarbamoyloxy]-ethyl ester, UA). The reaction is highly exothermic, thus allowing for a rapid FP. 

Unsaturated Polyester (UPES) In 1942, unsaturated polyesters were introduced. They result from condensation reactions between diols, (like ethylene glycol HO— CH2— CH2—OH or propylene glycol), and a blend of saturated and unsaturated di-acids, (like phthalic acid or anhydride, maleic and fumaric acids and others). 

When reinforced with mercerized and benzoylated particle fibers. The UPE matrixhas been found to exhibit flexural strength of 55.26, 62.26, 66.29 and 57.26 MPa 61.7, 67.1, 69.52 and 62.32 MPa at 10,20,30 and 40% fiber loading, respectively. The results obtained were found to be consistent with results obtained in the case of AN graft copolymerized Grewia optiva fibers-reinforced unsaturated polyester composites [26]. Rai et al. have also reported similar results during their studies [16]. 

The second synthetic thermoset resin discovered in early 1940 (after phenolic resin) was unsaturated polyester (UPE) resin. UPE consists of an unsaturated polyester, a monomer, and an inhibitor. UPE gained wide industrial applications due to their low viscosity, which offers easy processability, low cost and rapid cure schedules. 

Polyesters are macromolecules made by reacting a diacid or dianhydride with a dihydroxy compound (diols). To make unsaturated polyesters, maleic anhydride or fumeric acid is used in addition to a saturated acid, which provides unsaturation in the structure. The most commonly used anhydrides are maleic anhydride (unsaturated) and phthalic anhydride (saturated). The commonest diols are ethylene glycol or propylene glycol. Use of an unsaturated anhydride is very critical to provide unsaturation in the structure, which is utilised to cure the resin by free-radical polymerisation. The chemical reaction for the synthesis of UPE is shown in Figure 2.13. 

Figure 2.16 Unsaturated polyester molecular weight effects on the experimental T versus composition cloud point curves of a UPE resin. Study on resins of similar chemical structure and fonr molecnlar weights (620,1205,1700 and 2740 g/ mole) indicated that UPE miscibility in styrene changed in the following order 1700>1205>2740>620. Reprodnced with permission from F. Baffa and J. Borrajo, Journal of Applied Polymer Science, 2006,102, 6064 2006,...

As discussed in earlier sections, UPE resins are a mixture of an unsaturated polyester, styrene and an inhibitor. When the resin is mixed with a peroxide initiator and activator (cobalt octoate/napthenate), free radicals are formed. At the initial stage, all or most of the free radicals generated are consumed by the inhibitor. The driving force for the preferable reaction of free radicals with the inhibitor is the higher stability of inhibitor radicals. Once the inhibitor molecules are depleted, free radicals, produced from the initiator, initiate polymerisation of the polyesters. Styrene serves as an agent to link the adjacent polyester molecules. The curing of UPE resin (polyester + styrene) involves different types of reactions ... 

Unsaturated polyester (uPES) resins based on phthalic anhydride were obtained in the 1930s and were known as alkyd or glyptal resins. Crosslinked with polystyrene (PS) they were, and are still used, for fibre impregnation to produce plastic composites. uPES is among the four most important thermosetting resins besides PF, UF and epoxy (EP) resins and nowadays they represent about 20% of the total volume of thermosets [6]. 

A group of synthetic adhesive resins produced from unsaturated acids and glycerol. Unsaturated polyester (uPES) resins based on phthalic anhydride obtained in the early 1930s. They are also called glyptal resins. 

Epoxy resins are widely used as protective coatings and adhesives, for structural applications such as adhesives to bulk out structural components, with extensive use in the aerospace, dental and other medical fields. Moreover, epoxies are widely used as insulating and structural materials in manufacturing microelectronic devices and components such as computer chip packing and circuit boards, due to their excellent combination of chemical and corrosion resistance and good electrical properties. On the other hand, unsaturated polyester (UPE) resin, a resin prepared from a polyester synthesized by esterification of glycol, unsaturated acid and saturated acid dissolved in styrene monomers, is widely used in many applications, such as electronic equipment, containers, automobiles, and cultured marble because of its clarity, and excellent chemical and corrosion resistance. 

To explore the use of different kinds of natural ceUulosic fibers such as Cannabis indica for potential industrial applications, an efficient process for fabrication of C. md/ca/Unsaturated polyester (UPE) composites with properties exceeding the minimum strength and stiffness required by industry standards must be developed. Subsequently these composites can also be used in automotive applications. In this... 

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