Urethanes acrylate terminated

There are two approaches to forming urethane-acrylic hybrids. First, an acrylate terminated urethane oligomer can be used [147]. Alternatively, polyisocyanate and benzoyl peroxide can be combined in one side of the adhesive, and methacrylate monomers and urethane curatives (especially polyols) in the other [148]. 

Reactive oligomers such as epoxy resins, isocyanate-terminated compounds, and urethane-acrylates are extremely useful in the adhesive, coating, reaction injection molding (RIM), sealant and... 

In an earlier investigation by Yang [1] triblock urethane acrylate oligomers terminated with acrylic acid were prepared and used in curable pressure sensitive adhesive compositions. 

Spontak, RJ, Robergem, RL, Vratsanos, MS, Starner, WE. 2000. Model acrylate-terminated urethane blends in toughened epoxies A morphology and stress relaxation study. Polymer Al 6341-6349. Spotheim-Maurizot, M, Mostafavi, M, Douki, T, Belloni, J. 2008. Radiation Chemistry From Basics to Applications in Material and Life Sciences. Ulis, France EDP Sciences. 

The essential ingredients of a free-radical adhesive formulation are an acrylate-terminated prepolymer and a photoinitiator. A wide range of prepolymers can be acrylated, including epoxies, urethanes, polyesters, polyethers, and rubbers. Those most commonly used in adhesive formulations are epoxy and urethane acrylates. Epoxy acrylates have properties similar to those of the parent epoxy resin, with excellent adhesion, chemical resistance, and toughness. Urethane acrylates, on the other hand, are noted for their high reactivity, good adhesion, flexibility, and tear resistance. 

Urethanes have also been used to toughen vinyl-terminated acrylic adhesives for improved impact resistance. Thus rubber-toughened urethane acrylates [79,80], water-dispersible urethane acrylates [81], and high-temperature-performance urethane-acrylate structural adhesives have been reported [82]. Polyurethanes terminated with acrylic functionality are also used for anaerobic or radiation-cured adhesives with improved toughness [83]. 

Urethane-acrylate. See Urethane-acrylate resin Urethane-acrylate resin Synonyms Polyurethane-acrylic Urethane-acrylate Urethane-acrylic Definition Acrylate-terminated PU prepolymers, producing inks and coatings characterized by toughness and good chem. resist. 

Dymax Light Weld 931/ urethane acrylate 0.5 2,053/N/A UV light 5 sec Coil termination and wire tacking... 

Baccei (21) discloses polymerizable adhesive and sealant compositions having as an important ingredient urethane-acrylate-capped oligomers based on liquid hydroxyl-terminated polybutadiene or polybutadiene/ acrylonitrile copolymers. Properties associated with impact and thermal improvements are noted as well as the ability to cure adequately through the bondline gap. Model systems are largely triethylene glycol dimethacrylate based. Impressive adhesive performance properties are recorded. (Cf. Paper by Malofsky and Baccei in this... 

PU-based acrylate-terminated polymers have also been introduced for use in UV-cured or electron beam (EB)-cured elastomer coatings. They are usually used in conjunction with di- or trifunctional acrylate resins such as 1,6-hexane diol diacrylate (HDDA) (Fig. 12.8) whose function is to control hardness and flexibility in the final elastomeric lacquer. A series of these special monomers and urethane oligomers is marketed under the trade name Photomer (Harcross Chemicals). 

Acrylate-terminated urethane resins have been formulated with peroxides and have been cited as being useful as molding and adhesive compositions. " These systems are said to be insensitive to moisture. Curing is brought about by heating to 140°C. 

This technique has found the following applications in addition to those discussed in Sections 10.1 (resin cure studies on phenol urethane compositions) [65], 12.2 (photopolymer studies [66-68]), and 13.3 (phase transitions in PE) [66], Chapter 15 (viscoelastic and rheological properties), and Section 16.4 (heat deflection temperatures) epoxy resin-amine system [67], cured acrylate-terminated unsaturated copolymers [68], PE and PP foam [69], ethylene-propylene-diene terpolymers [70], natural rubbers [71, 72], polyester-based clear coat resins [73], polyvinyl esters and unsaturated polyester resins [74], polyimide-clay nanocomposites [75], polyether sulfone-styrene-acrylonitrile, PS-polymethyl methacrylate (PMMA) blends and PS-polytetrafluoroethylene PMMA copolymers [76], cyanate ester resin-carbon fibre composites [77], polycyanate epoxy resins [78], and styrenic copolymers [79]. 

Liquid organic rubbers with reactive functionality can be prepared by several methods. End-functional oligomers are preferred. Chains attached to the network at only one end do not contribute as much strength to the network as those attached at both ends [34], Urethane chemistry is a handy route to such molecules. A hydroxy-terminated oligomer (commonly a polyester or a polyether) can be reacted with excess diisocyanate, and then with a hydroxy methacrylate to form a reactive toughener [35]. The methacrylate ends undergo copolymerization with the rest of the acrylic monomers. The resulting adhesive is especially effective on poIy(vinyl chloride) shown in Scheme 2. 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

Further expts were conducted on candidate proplnts for space environments. Horton (Ref 112) subjected a urethane-based propint, a polybutadiene-acrylic acid-acrylonitrile based propint, and a carboxyl-terminated polybutadiene based proplnt to 1.5 x 107 R, as well as to high and low temp and pressure. The data indicated that the urethane proplnt withstood the tests best. Scott et al (Ref 126) conducted tests on two polycarbutene solid proplnts which were irradiated to 107 R and subjected to high vacuum exposure as a function of temp without much change... 

The functionalization of SAMs via ruthenium-catalyzed cross metathesis of vinyl-terminated SAMs has been reported by Lee et al.76 to install a variety of acrylic derivatives on SAMs bearing vinyl groups on their outer surface. The major drawback of this approach is the intra-SAM metathesis which causes the formation of a mixture of surface-bound products, limiting the reproducibility of the method. The formation of urethanes by the reaction of diisocyanates77 or isothiocyanates78 with hydroxyl- and amino-terminated SAMs has been reported as well. The reaction of hydroxyl-terminated SAMs with diisocyanates, allowed the preparation of isocyanate SAMs that proved to be reactive towards amines, alcohols, and water, displaying the standard chemistry of the isocyanate groups.77... 

The prepolymers can be different types of materials. They must, however, contain residual unsaturation in order to react and crosslink with the monomers. Examples of such materials may be polyurethane acrylates that are prepared from urethane prepolymers. The excess isocyanate groups are treated with hydroxyethyl or hydroxypropyl acrylates. Other prepolymers with terminal and/or pendant hydroxy groups are also often esterified with acrylic acid. The oligomers might also be bisphenol A diglycidyl ethers prereacted with acrylic acid to form terminal acrylate groups. An example of these would be ... 

Vinyl ester resins are thermosetting resins that consist of a polymer backbone with acrylate or methacrylate termination. The backbone component of vinyl ester resins can derived from an epoxide resins, polyester resins, urethane resin, and so on, but those base epoxide resins are of particular commercial significance. 

Vinyl esters are thermosetting resins that consist of a polymer backbone with an acrylate or methacrylate termination. The backbone component of vinyl ester resins can be derived from epoxide, polyester or urethane but those based on epoxide resins have most commercial significance. Bisphenol A epoxy formed vinyl esters were designed for chemical resistance and commonly formulated for viscosity for use in filament winding of chemical containers. Typically styrene is used as a reactive dilutent to modify viscosity. Phenolic novolac epoxies are used to produce vinyl esters with higher temperature capability and good solvent resistance, particularly in corrosive environments, and their FRP composites have demonstrated initial economy and better life cycle costs compared with metals. 

Elastomer-modified epoxy resins are used in composites and structural adhesives, coatings, and electronic applications. Similar approach to toughen epoxy vinyl esters using other elastomeric materials has been reported (204). Other elastomer-modified epoxies include epoxy-terminated urethane prepolymers, epoxy-terminated polysulfide, epoxy-acrylated urethane, and epoxidized polybutadiene. Preformed dispersions of epoxy-insoluble elastomers have been developed and reported to achieve toughening without Tg reduction (205,206). 

Some hydroxyl-terminated thiopolyesters (123) were used for preparing thiopoly(ester-urethane)s (293,295,296) (see next section). The novel thiopolyesters (123e) (M of 2000-2600), because of their structures incorporating benzophenone imits, may also be considered as new diol components of uv-autopolymerizable polyurethane-(meth)acrylate oligomers. 

One can also make combined acrylic/urethane (hybrid) aqueous dispersions (33). Acrylic monomers are emulsion polymerized in the presence of an aqueous dispersion of a hydroxy-terminated polyurethane. The polyurethane stabilizes the aqueous dispersion, minimizing need for surfactant. Coalescence requires balance of the Tg of both the urethane and acrylic parts of the system. Compositions based on an IPDl/polypropylene glycol/DMPA urethane with styrene/methyl methacry-late/butyl acrylate are reported to form films at low temperatures. 

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