This article reports on the curing performance of UV-curable acrylic binders prepared with trifunctional monomers and a photoinitiator. The curing reaction was achieved by direct excitation of pressure-sensitive adhesives (PSAs) by irradiation with a 100-W high-pressure mercury lamp with different UV doses. The curing performance of PSAs was studied by photo-differential scanning calorimetry (photo-DSC), gel-fraction determination and Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy. The reaction rate and extent of UV curing were found to be strongly dependent on the curing rates of the trifunctional monomers, trimethylolpropane triacrylate (TMPTA) and trimethylolpropane ethoxylated (6) triacrylate (TMPEOTA), which have different molecular weights. Exothermic areas increased with increasing acrylic acid concentration. Moreover, gel fractions sharply increased after UV irradiation and then remained constant with prolonged UV exposure. TMPTA blends had higher gel fractions than TMPEOTA blends because of TMPTA's fast curing rate. Also, the gel fractions of TMPTA blends showed no variation with acrylic acid concentration. However, the FTIR-ATR absorption peak areas representing the relative concentration of C=C bonds showed more conspicuous trends for the curing reaction. Although the gel fractions of TMPTA blends showed no differences, the relative concentrations of C=C bonds increased with increasing acrylic acid concentration. In addition, TMPTA blends showed higher relative concentrations of C=C bonds because of the faster curing rate of TMPTA.

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The graft polymerization of acrylic acid (AA) onto corn starch well‐swollen in aqueous isopropanol (IPA) was carried out by controlling reaction variables such as the concentrations of AA, initiator (a mixture of ammonium persulfate and sodium metabisulfite) and IPA as well as the temperature and time of reaction for the acquirement of products with good efficiency. Homopoly(acrylic acid) existing in the product mixture was removed by extraction with aqueous ethanol. In the temperature range of 30°C to 60°C the conversion gradually increased with increasing both reaction temperature and reaction time. The graft reaction showed a tendency to give high conversions even at reaction temperatures above 40°C. The reaction in aqueous IPA solution was more homogeneous and efficient than that in water. In addition, even though an equivalent quantity of initiator was used, the reaction conversion increased with increasing the concentration ratio of AA to corn starch. It was also found that the average distance between grafted sites decreased as the quantity of initiator and reaction temperature were increased.

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