POLYURETHANE DIACRYLATE

Materials. The radical-type photopolymerizable formulation consisted of a mixture of hexanediol diacrylate (HDDA from UCB) and a polyurethane-diacrylate (Actilane 20 from Arkros). A bis-acylphosphine oxide (BAPO from Ciba) was used as photoinitiator at a typical concentration of 1 wt %. The cationic type photopolymerizable resin consisted of a mixture of the divinylether of triethyleneglycol (RapiCure DVE-3 from ISP) and a divinylether derivative of bis-phenol A (DVE-BPA). The cationic photoinitiator (Cyracure UVI-6990 from Union Carbide) had a composition of 50 wt % of mixed triarylsulfonium hexafluorophosphate salts and 50 wt % of propylene carbonate. The BAPO initiator... 

The efficiency of various substituted benzophenones for initiating the photopolymerization of multifunctional monomers in condensed phase was evaluated by IR spectroscopy from conversion versus exposure time kinetic curves. The best results were obtained with diphenoxy- benzophenone (DPB) associated to an hydrogen donor, like methyl- diethanolamine, for a one to one mixture of hexanetfrol-diacrylate (HDDA) and of a polyurethane-diacrylate (Actilane 20 fix)m SNPE). Figure 1 shows some typical polymraization profiles obtained for a 30 im thick film exposed, in the presence of air, to the UV radiation of a medium pressure mercury lamp at a light intensity of 1.5 X lO einsteins l cm-2. 

Similar results were obtained with a resin formulation containing these new monomers as diluent and a polyurethane-diacrylate or an epoxy-diaciylate oligomer (Figure 4). The rates of polymerization were significantly increased compared to formulations based on neat mono- or diacrylate monomers and the photosensitivity (S), i.e., the energy required to reach 50 % conversion, dropped as low as 0.4 mJ cm (Table I). 

Figure 15 Temperature profiles recorded by RTIR spectroscopy upon UV-curing of a polyurethane-diacrylate at two light intensities...

In a pioneer study from Christian Decker the photopolymerization of polyurethane-diacrylates was investigated by using the RT-FTIR technique [Decker Moussa, 1988]. The RT-FTIR conversion curves as a function of irradiation time were examined for different systems (Fig. 6). 

V. F. Rosovizky, M. Ilavsky, J. Hrouz, K. Dusek, and Yu. S. Lipatov, Viscoelastic Behavior of Interpenetrating Networks of Polyurethane and Polyurethane Acrylate, /. AppL Polym. ScL 24, 1007 (1979). SINs of polyurethane diacrylate and polyurethane. Swelling, mechanical, and optical properties. Interfacial layer interpretation. 

The hydroxyl groups can be esterified normally the interesting diacrylate monomer (80) and the biologicaky active haloacetates (81) have been prepared in this manner. Reactions with dibasic acids have given polymers capable of being cross-linked (82) or suitable for use as soft segments in polyurethanes (83). Polycarbamic esters are obtained by treatment with a diisocyanate (84) or via the bischloroformate (85). 

The reactive oligomer can be any low-molar-mass polymer containing at least a couple of double bonds. It can be based on a polyester, polyether, or polyurethane backbone. One mole of a, oo-OH-terminated polyester or polyether is prereacted with two moles of acrylic acid to obtain an a, oo-diacrylate oligomer. For polyurethanes, 1 mole of a, m-diisocyanate oligomer is prereacted with 2 moles of hydroxyethylacrylate (Sec. 2.2.3c). 

Reaction-induced phase separation is certainly also the reason for which an inhomogeneous structure is observed for photocured polyurethane acrylate networks based on polypropylene oxide (Barbeau et al., 1999). TEM analysis demonstrates the presence of inhomogeneities on the length scale of 10-200 nm, mostly constituted by clusters of small hard units (the diacrylated diisocyanate) connected by polyacrylate chains. In addition, a suborganization of the reacted diisocyanate hard segments inside the polyurethane acrylate matrix is revealed by SAXS measurements. Post-reaction increases the crosslink density inside the hard domains. The bimodal shape of the dynamic mechanical relaxation spectra corroborates the presence of a two-phase structure. 

Thermoplastic polyester elastomers Tripropylene glycol diacrylate Triphenyl phosphate Thermoplastic polyurethane Trimethylolpropanetrimethacrylate Thermal volatilisation analysis Transmitter signal... 

A large number of compositions containing poly(vinyl alkyl ethers), multifunctional acrylates and benzophenone were irradiated and examined for their pressure-sensitive adhesive properties. Among the components which were found to confer useful properties on the films were the methyl, ethyl, and isobutyl poly(vinyl alkyl ethers) and the multifunctional acrylate derivatives of neopentyl glycol, pentaerythritol, certain epoxidized oils and an aliphatic polyurethane (9). For our present discussion, however, we will focus on the behavior of the poly(vinyl ethyl ether) (PVEE/neopentyl glycol diacrylate (NPGDA) system. 

Figure 1 Polymerisation profiles recorded by RTIR spectroscopy upon UV-exposure of an aliphatic polyurethane-acrylate (PUA) or an aromatic polyether-acrylate (PEA) in the presence of a monoacrylate or a diacrylate reactive dilnent (25 wt%), respectively. Light intensity 40 mW cm. Laminated film.

Figure 2 Inhibitory effect of oxygai tm the jiiotqxilymaisalion of a polyurethane-aaylate + diacrylate resin exposed to UV-radiation (/= 20 mW cm ). Film thickness 10 pm.

DSC has been applied to the determination of Tg in a variety of other polymers including polyimines [1], polyurethanes (PU) [2], Novolac resins [3], polyisoprene, polybutadiene, polychloroprene, nitrile rubber, ethylene-propylene-diene terpolymer, and butyl rubber [4], and bisphenol-A epoxy diacrylate-trimethylolpropane triacrylate [1516]. 

The electron beam crosslinking of PVC/ENR blends by electron beam irradiation has been extensively reported by Ratnam and coworkers. The influence of MFAs such as trimethylolpropane trimethacrylate (TMPTA), 1,6-hexaediol diacrylate (HDDA) and 2-ethylhexyl acrylate (EHA), as well as acrylated polyurethane oligomer on the 70/30 PVC/ENR blend, was investigated. TMPTA was found to give the blend the best mechanical properties. Studies were also done on the effect of irradiation on various formulations of PVC/ENR blends with doses ranging from 50 to 200 kGy these studies included the influence of various additives on the efficiency of the radiation crosslinking of the blends. 

Tg measurements have been performed on many other polymers and copolymers including phenol bark resins [71], PS [72-74], p-nitrobenzene substituted polymethacrylates [75], PC [76], polyimines [77], polyurethanes (PU) [78], Novolac resins [71], polyisoprene, polybutadiene, polychloroprene, nitrile rubber, ethylene-propylene-diene terpolymer and butyl rubber [79], bisphenol-A epoxy diacrylate-trimethylolpropane triacrylate [80], mono and dipolyphosphazenes [81], polyethylene glycol-polylactic acid entrapment polymers [82], polyether nitrile copolymers [83], polyacrylate-polyoxyethylene grafts [84], Novolak type thermosets [71], polyester carbonates [85], polyethylene naphthalene, 2,6, dicarboxylate [86], PET-polyethylene 2,6-naphthalone carboxylate blends [87], a-phenyl substituted aromatic-aliphatic polyamides [88], sodium acrylate-methyl methacrylate multiblock copolymers [89], telechelic sulfonate polyester ionomers [90], aromatic polyamides [91], polyimides [91], 4,4"-bis(4-oxyphenoxy)benzophenone diglycidyl ether - 3,4 epoxycyclohexyl methyl 3,4 epoxy cyclohexane carboxylate blends [92], PET [93], polyhydroxybutyrate [94], polyetherimides [95], macrocyclic aromatic disulfide oligomers [96], acrylics [97], PU urea elastomers [97], glass reinforced epoxy resin composites [98], PVOH [99], polymethyl methacrylate-N-phenyl maleimide, styrene copolymers [100], chiral... 

Cross- linked Epoxies Diacrylics Polyimide Polyurethane P/F R/F M/F Toughened acrylics Polyvinyl formal-P/F Nitrile phenolic ... 

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