The curing reactions of epoxy resin with aliphatic diamines and the reaction of phenyl glycidyl ether with butylamine as a model for the curing reactions were investigated with a differential scanning calorimeter (DSC) operated isothermally. The heat of reaction of phenyl glycidyl ether with butylamine is equal to 24.5 ± 0.6 kcal/mole. The rate of reaction was followed over the whole range of conversion for both model and curing reactions. The reactions are accelerated by the hydrogen‐bond donor produced in the system. The rate constants based on the third‐order kinetics were determined and discussed for the model reaction and for the chemically controlled region of curing reactions. The activation energies for these rate constants are 13‐14 kcal/mole. At a later stage of conversion, the curing reactions become controlled by diffusion of functional groups. The final extent of conversion is short of completion for most isothermally cured and even for postcured samples because of crosslinking. It was quantitatively indicated that the final conversion of isothermal cure corresponds to the transition of the system from a viscous liquid to a glass on the basis of the theory of glass transition temperature of crosslinked polymer systems.

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These results suggest that blackcurrant anthocyanins act as phytoestrogens in vitro and in vivo.

synopsisThe mechanisms of hydrolysis and condensation of a silane coupling agent, y-methacryloxypropyltrimetoxysilane (y-MpTs) were investigated by the me of both 13C and ?3i nuclear magnetic resonance ( N m ) spectroscopies. The NMR peaks of the hydrolyzed monomer and condensed polymer were asaigned readily. The rate of hydrolysis and condensation of y-MPTS was dependent on water content. On the basis of the time-dependent behavior of these peaks, the mechamam . of hydrolysis and condensation were clear.

Blackcurrants (Ribes nigrum L.) contain high levels of anthocyanin polyphenols, which have beneficial effects on health, owing to their antioxidant and anticarcinogenic properties. Phytoestrogens are plant-derived substances with estrogenic activity, which could have beneficial effects on the skin. Estradiol secretion decreases during menopause, reducing extracellular matrix (ECM) component production by skin fibroblasts. Using a normal human female skin fibroblast cell line (TIG113) and ovariectomized rats, the present study investigated whether an anthocyanin-rich blackcurrant extract (BCE) and four blackcurrant anthocyanins have novel phytoestrogenic activities that could benefit the skin in menopausal women. In TIG113 cells, a microarray and the Ingenuity® Pathway Analysis showed that 1.0 μg/mL of BCE upregulated the expression of many estrogen signaling-related genes. A quantitative RT-PCR analysis confirmed that BCE (1.0 or 10.0 μg/mL) and four types of anthocyanins (10 μM) altered the mRNA expression of ECM proteins and enzymes involved in ECM turnover. Immunofluorescence staining indicated that the anthocyanins stimulated the expression of ECM proteins, such as collagen (types I and III) and elastin. Dietary administration of 3% BCE to ovariectomized rats for 3 months increased skin levels of collagen, elastin, and hyaluronic acid. This is the first study to show that blackcurrant phytoestrogens have beneficial effects on skin experimental models.