Resins urethane methacrylate

Li J, Isaac DH, Arnold JC (1996) Environmental stress cracking in uniaxial tension of urethane methacrylate based resins. Mater Sci Eng A 214(1—2) 68—77... 

Li J, Arnold JC, Isaac DH (1994) Environmental stress cracking behavior of urethane methacrylate based resins - I. Environmental crazing and cracking under bending conditions. J Mater Sci 29(12) 3095—3101... 

These same rules apply to other resins such as the family of unsaturated polyesters. In these, the reactive diluents dilute the ester groups. A reduction in ester group concentration can be achieved by using more rigid skeletal structures and employing only terminal ester groups (vinyl ester resins) or urethane links (vinyl urethanes, urethane methacrylates). The chemical resistance of these resins is summarized in Table 3.6. 

CAS 868-77-9 EINECS/ELINCS 212-782-2 Uses Crosslinkable paint resin binder for textiles/paper adhesives urethane methacrylates reactive thinners grafting of textile fibers scale inhibitors adhesion promoter for polymers hydrophilic polymers lt.-cuting polymer systems rubber modifiers contact lenses photopolymer plates photoresists... 

Such multifunctional esters are used to promote the formation of a rigid cross-linked structure on polymerization. Quantitation of these esters is normally based on GC analysis using an internal standard. Either narrow or wide bore capillary columns may be used. In the case of ultraviolet cure-initiated formulations, the use of higher-molecular mass urethane-methacrylate resins such as Scheme 7 is involved. 

Figure 4 LC trace of typical UV-curing adhesive. A, adhesion promoter B, photoinitiator C, internal standard D, methacrylate ester (I) E, urethane-methacrylate oligomers F, methacrylate ester (11) G, urethane-methacrylate resin.

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. 

The processability of a resin system determines to what extent it can be used in a variety of processes. Within this field are such factors as viscosity, shelf life, cure regime, etc. The processability and the thermo-mechanical performance of a resin system are the two factors which most effectively characterise resin systems used in composites. The thermoset resins most commonly used in composites are unsaturated polyester, urethane methacrylate, vinyl ester, epoxy and phenolic. The typical range of properties of these resins are given in Table 1.1. More specific information is given in Chapter 3 of the EUROCOMP Design Code. 

These specifications are demanding for polyester or vinylester resin systems. They are more easily achieved with urethane methacrylate which allows a higher level of filler loading. Phenolic resin composites can achieve this performance without fire retardant additives but they are difficult to process. 

Isophthalic polyester is the most commonly used resin but vinylester is important in corrosion resistance applications. Urethane methacrylate has very good fire, smoke and toxicity performance. Epoxy is used in the higher performance applications and almost always with carbon fibre. Phenolic resins are being developed for pultrusion, to take advantage of their excellent fire performance. 

The aliphatic urethane acrylates are more potent sensitizers than the aromatic ones, while the aliphatic urethane methacrylates commonly used in dental resins are weak sensitizers (Nethercott et al. 1982 Bjorkner 1984a). 

J. C. Arnold, Environmental Stress Cracking Behavior of Urethane Methacrylate Based Resins. Part I Environmental Crazing and Cracking under Bending Conditions , J. Mater. Sci. 29, 3095-3101 (1994). 

Figure 9.1 Cure exotherms for urethane methacrylate/methyl methacrylate resins (a), compared with unsaturated polyester/styrene resins (b)...

The practical consequences of an auto-acceleration effect on exotherm and conversion are illustrated by the exotherm curves in Figure 9.1. The urethane methacrylate/methyl methacrylate resin that shows auto-acceleration at all oligomer/monomer ratios is compared with an unsaturated polyester/styrene resin, which only shows an autoacceleration (or gel effect ) at high alkyd/styrene ratios. The urethane methacrylate oligomer copolymerised with styrene shows virtually the same exotherm behaviour as the unsaturated polyester for equivalent styrene/oligomer unsaturation ratios. 

UV-curable liquid crystalline urethane methacrylates Dental resin-based composites Buruiana etal. (2011)... 

The addition—reaction product of bisphenol A [80-05-07] and glycidyl methacrylate [106-91-2] is a compromise between epoxy and methacrylate resins (245). This BSI—GMA resin polymerizes through a free-radical induced covalent bonding of methacrylate rather than the epoxide reaction of epoxy resins (246). Mineral fillers coated with a silane coupling agent, which bond the powdered inorganic fillers chemically to the resin matrix, are incorporated into BSI—GMA monomer diluted with other methacrylate monomers to make it less viscous (245). A second monomer commonly used to make composites is urethane dimethacrylate [69766-88-7]. 

Methacrylates and acrylates are readily synthesized from low-cost commercially available resins and (meth)acrylate intermediates or (meth)acrylic acid [19]. A wide range of structural backbones are available, including epoxies, urethanes. 

NR, styrene-butadiene mbber (SBR), polybutadiene rubber, nitrile mbber, acrylic copolymer, ethylene-vinyl acetate (EVA) copolymer, and A-B-A type block copolymer with conjugated dienes have been used to prepare pressure-sensitive adhesives by EB radiation [116-126]. It is not necessary to heat up the sample to join the elastomeric joints. This has only been possible due to cross-linking procedure by EB irradiation [127]. Polyfunctional acrylates, tackifier resin, and other additives have also been used to improve adhesive properties. Sasaki et al. [128] have studied the EB radiation-curable pressure-sensitive adhesives from dimer acid-based polyester urethane diacrylate with various methacrylate monomers. Acrylamide has been polymerized in the intercalation space of montmorillonite using an EB. The polymerization condition has been studied using a statistical method. The product shows a good water adsorption and retention capacity [129]. 

The majority of resins are composed of two dimethacrylate monomers, 2,2 -bis [4(2-hydroxy-3-methacryloyloxypropyloxy)phenyl] propane (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) [22-28]. Typically, TEGDMA or other methacrylate monomers are added as viscosity modifiers to Bis-GMA to make the solution less viscous and more appropriate for clinical use. These diluents also allow for better distribution of the components during manufacture of these composite systems. Another common monomer used to make dental composites, especially those manufactured in Europe, is urethane dimethacrylate [24,29, 30], Ethoxy bisphenol A dimethacrylate is another modification of the Bis-GMA monomer that can be used to make a more hydrophobic polymer that would better withstand the wet oral environment. Other diluents include low viscosity diacrylates and dimethacrylates. Table 1 lists some of these monomers [31-37]. 

---