TMPTA

Majumder and Bhowmick [381] have investigated the influence of the concentration of TMPTA on the surface properties of EPDM mbber, modified in the presence of EB. The surface energy of the TMPTA-modified EPDM mbber has been observed to increase as compared to the unmodified one. Table 31.4 displays the contact angles and the work of adhesion of water, for the control and the modified EPDM surfaces. 

FIGURE 31.4 Absorbance of control and EPDMs modified with different trimethylolpropane triacrylate (TMPTA) levels at an irradiation dose of 100 kGy. (From Sen Majumder, P. and Bhowmick, A.K., J. Adhesion Set Technol., 11, 1321, 1997. With permission.)... 

EPDM backbone, together with the carbonyl and ether groups generated on the rubber itself causes the carbonyl and ether absorptions to increase. The absorption at 1630 cm of the fraw -vinylene bonds of TMPTA is mainly due to the grafting of TMPTA onto EPDM and partly due to the formation of vinylidene bonds at the chain ends on irradiation. The absorptions at 1460 and 1379 cm due to >CH2 scissoring vibration and —CH3 stretching vibration, respectively, result from the rubber and the grafted TMPTA. 

The absorbances at 1730, 1630, 1460, 1379, 1260, 1120, and 1019 cm follow an upward trend with concentration in the case of the bulk-modified samples also (Figure 31.4a through g) in line with the gel content, due to the reasons, pointed out above. Since the surface concentration of TMPTA per unit volume of EPDM is lower in the case of bulk modification as compared to surface modification, the optimum value of the concentration of TMPTA is not observed in these plots. 

Clay hllers were surface modihed with TMPTA or triethoxyvinyl silane (TEVS) followed by EB irradiation by Ray and Bhowmick [394]. Both the untreated and treated fillers were incorporated in an ethylene-octene copolymer. Mechanical, dynamic mechanical, and rheological properties of the EB-cured unfilled and filled composites were studied and a significant improvement in tensile strength, elongation at break, modulus, and tear strength was observed in the case of surface-treated clay-filled vulcanizates. Dynamic mechanical studies conducted on these systems support the above findings. 

The influence of polyfunctional monomers—tripropyleneglycol diacrylate (TPGDA), TMPTA, TMPTMA, TMMT, and TAG on the stmctural changes of fluorocarbon terpolymer poly(vinylide-nefluoride-co-hexafluoropropylene-co-tetrafluoroethylene) has been investigated [425]. The ATR-IR studies show that the absorbance due to the double bond at 1632 cm decreases both in the... 

FIGURE 31.10 (a) Plot showing the variation of ahsorhances at 1740 and 1632 cm of the control and the trimethylolpropane triacrylate (TMPTA) mixed nihher irradiated with 20, 50, 100, 200, and 500 kGy. 

SCHEME 31.6 Grafting of TMPTA on poly (vinylidenefluoride-co-hexafluoropropylene-co-tetrafluoroethy-... 

Thermal degradation studies of EB-cured terpolymeric fluorocarbon rubber [430] by nonisothermal thermogravimetry in the absence and presence of cross-link promoter TMPTA reveal that thermal stability is improved on radiation and more so in the presence of TMPTA. Initial decomposition temperature, maximum decomposition temperature and the decomposition... 

Since the commercially available epoxy acrylate is extremely viscous, it is necessary to thin the formulation with a reactive diluent. A mixture with satisfactory viscosity for brush-on application contains about 45% diluent. Of the diluents tested, TMPTA (trimethylolpropane triacrylate) proved most successful. 

It was found, when an attempt was made to conduct ship trials that the paint applier would be required to wear long sleeves, gloves, safety glasses, and a protective face shield. It is also a requirement that an eyewash fountain be nearby. These requirements were imposed because acrylates are skin, eye and respiratory tract irritants, but the problem lies mostly with the acrylated reactive diluent rather than with the acrylated resin (2,3). To avoid these problems, tests have been performed with use of trimethylolpropane trimethacrylate (TMPTMA) as a replacement for TMPTA. TMPTMA has been shown to be much less of an irritant than TMPTA, and is used in dental restorations. 

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