Star-like lignin-poly(propylene oxide) copolymers were prepared by chain-extending steam exploded lignins (tulipifera liriodendron) with propylene oxide and by subsequent endcapping with ethylene oxide. Epoxidation of these copolymers was carried out with epichlorohydrin at room temperature, using KOH as oxyanion forming reagent. The epoxidized compounds were fractionated by solvent precipitation to remove poly(alkylene oxide) homopolymers and to prepare fractions of narrow molecular weight distributions. The epoxides were cross-linked with meta phenylene diamine yielding thermosets which were, depending on lignin content, either low modulus elastomers, or high modulus materials with considerable ductility. The modulus of elasticity was a strong and linear function of lignin content, whereby the highest value was 1100MPa (57% lignin). The curing reaction was of nth-order type, whereby the reaction order changed from close to one at the beginning of the curing reaction to 2, once the reaction becomes diffusion controlled. Curing induced partial demixing of the lignin and poly(propylene oxide) phases which yielded a secondary structure where lignin rich domains in the order of 10 nm were interspersed in a matrix of lignin poor material. However, from TEM and ¹³C solid state cross-polarized NMR analyses it was evident that the domain structure was not that of a classical micro-phase separated copolymer with well defined phase boundaries, but rather had broad interphases. Additionally, the results of multifrequency dynamic mechanical thermal analysis showed that the lignin containing thermosets have very broad glass transition ranges which most likely were due to transitional phase inhomogeneities and provided these materials with good vibrational damping ability. / Ph. D.

The intent of this research was to enhance our knowledge of aqueous phenolformaldehyde resin cure as it is affected by the elevated water vapor pressures that occur during hot-pressing of a wood-based composite. Microdielectric spectroscopy (DEA) was used to monitor the cure reaction, and thermomechanical analysis (TMA), swelling tests and scanning electron microscopy (SEM) techniques were used to characterize the final resin-network. Microdielectric results showed that as the water vapor pressure of the sy stem increases the time to gelation increases. It was also found that the injection of saturated water vapor sharply decreased the gelation time when compared to the other water vapor environmental conditions. In addition, it was found that the higher the water vapor pressure the lower the residual ion viscosity. Thermomechanical analysis and swelling test experiments showed that as the water vapor pressure increases the glass transition temperature and the cross-link density of the cured resin-network decreases. Considerable differences in the morphology of the network were found using SEM. Thus, it can be established that during the curing process under elevated water vapor pressures of a liquid phenol-formaldehyde adhesive some water is trapped into the resin network and it is acting as a plasticizer. A theoretical approach to model the cure kinetics of phenol-formaldehyde has been developed. The model is based on the occurrence of two simultaneous processes (condensation polymerization and evaporation of water) and on the concentration dependency of the activation energy of polymerization. / Ph. D.

The purpose of this study was to determine the effect of exposure conditions, resin composition, and resin treatment on film formation on metal surfaces exposed to epoxy resin. Epoxy rods were prepared from novolac hardened by 4-4' methylenedianiline (MDA). The curing and post curing temperatures were 60, 125 °C and 125, 160 °C. The composition of the epoxies used were 27.0 and 31. 5 parts (MDA) per 100 parts epoxy. The metals investigated were pure gold, silver, and copper; gold-copper alloys; gold-silver alloys; and electroformed gold-copper alloys. The alloys ranged in composition from 75 to 92 per cent gold. These samples were cleaned, weighed, placed in individual, covered, glass containers with the epoxy rods, and then were exposed at 30, 60, and 90 °C. The change in weight of the metal samples was determined at intervals of about. 30 days for five months. Weight increases of 0.1 to 0.4 milligram were observed for the samples exposed to the epoxy rods, and were negligible for samples stored without epoxy rods. The contaminating materials, apparently, are organic compounds consisting of unreacted monomer and degradation products. The film forms from a heavy, stagnant, low-lying, vapor-phase from the epoxy, with the vapors adsorbed or reacted on the surface of the metal samples. Film formation is not affected to any appreciable extent by the combined effect of increased curing temperatures and increased hardener content. The effect of increasing the temperature from 30 °C to 60 or 90 °C, on the rate of film formation was inconclusive. Epoxy film formation was observed on all metal samples tested, pure gold, copper, and silver; gold-copper and gold-silver alloys. The metal composition affects the rate of film formation with the rate increasing with decreased golJ composition for both copper and silver alloys. / Master of Science

Thesis (Elec.E)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references. / by Huan Lim Lee. / Elec.E

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains viii, 107 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 66-71).

M. Tech. Polymer Technoliogy. / Studies the basic curing, rheological and thermomechanical behaviours of hybrids composed of a VE resin and acrylated epoxidised soyabean oil (AESO). The hybrid systems were cured by free radical initiated radical copolymerisation with styrene. The prospective outcomes were: To find suitable initiators/accelerators for the VE/AESO hybrids which work within the entire composition range? To contribute to the selection of VE resins for AESO modification To establish the optimal quantity of AESO required obtaining the best cure characteristics, the most acceptable reduction in Tg, and stiffness as compared with the parent VE resin.

Thesis (M.S.)--University of Michigan, 1988.

Thesis (M.S.)--University of Michigan, 1975.

Thesis (M.S.)--University of Michigan, 1971.

Thesis (M.S.)--University of Michigan, 1978.