The glass transition temperatures, Tg, and thermal effects of polymerization, Att, have been determined for five epoxy adhesives of unknown composition. From the trends AHvs./tcure it has been possible to attain a phenomenologieal kinetic order of the polymerization rate at 100 ~ through an iterative calculation procedure. For most of the investigated adhesives there are reasons (double peak of polymerization and double Tg signal) to assume that they are graft copolymers.Studies on epoxy materials, prepregs and adhesives have been greatly developed in view of their important technical applications: specially devised investigations have been reported on their elastic properties, thermal expansion, strains associated with the polymerization process, etc. [1,2].Qualitative and quantitative chemical analysis is in any case essential in the research into such materials: as a rule it requires an extremely refined instrumentation, allowing the separation and recognition of the individual components within a number of compounds accompanying the main epoxy bulk [3,4].As typical investigations, differential thermal analysis (DTA) and/or differential scanning calorimetry (DSC) have been employed either to evaluate the thermal effect accompanying the polymerization or to check the glass transition temperature, Tg [5][6][7][8][9][10].In the present work quantitative DTA determinations were carried out for different adhesives behaving as thermosets, in order to establish: i) the thermal effect accompanying the polymerization, ii) the phenomenologieal kinetics of the cure process, iii) the correlation curve between the degree of polimerization, ~, and Tg. The compositions of these materials are only partially known, but their main ingredients are bisphenol, epichlorhydrine, Novolac, tetraglycidylmethylene dianiline, nitrilerubber, etc., depending on the particular resin. ExperimentalThe storage temperature of the prepolymer tapes was about -18 ~ From tight rolls of such tapes small soft cylinders of prepolymer (dia. ,,~ 3 mm, length ,-~ 3 mm) were rapidly cut, weighed (the usual weight was about 50 mg), sealed in silver DTA pans at room temperature and again cooled down to -18 ~

The tip of a rod is heated with a torch and brought into contact with the center of a metal sheet. A thermal camera is then used to image the temperature profile of the surface as a function of time. The infrared camera is capable of recording radiometric data with 1 mK resolution in nearly 105 pixels, so thermal diffusion can be monitored with unprecedented precision. With a frame rate of approximately 10 Hz, the pace of the data acquisition minimizes the loss of accuracy due to inevitable cooling mechanisms. We report diffusivity constants equal to 1.23 ± 0.06 cm2/s in copper and 0.70 ± 0.05 cm2/s in aluminum. The behavior is modeled with a straightforward but oddly under-utilized one-dimensional finite difference method.

Plastic packaging forms a significant portion of household waste, and PET soft drink bottles represent a major percentage of the waste. Consequently, PET bottle grade material makes up a significant portion of the feedstock in the recycling plant at Visy plastics. The end uses are theoretically many, however, there are few applications for less purified grades of recycled PET. This paper presents the preliminary results of an industry based collaborative research project which aims to investigate the breaking down of recycled PET into its chemical building blocks using glycolysis. The main objective is to produce a polyester polyol for the polyurethane industry from recycled PET and to compare the properties with that of a virgin resin.

Abstract

Viscoplastic fluids are the class of fluids with a yield stress that governs their ability to flow. This research deals with the effect of temperature difference applied across a viscoplastic fluid (carbopol gel) and studies the various flow regimes depending on the onset of the flow. Reasonable efforts have been made to estimate the experimental flow onset times and investigate the onset of the flow at different yield stress values. The idea behind the proposed research is to characterize the natural convection of yield stress fluids. The flow field characterization is carried out using a PIV system. The post processing is done using PIVlab, a useful add-on for MATLAB. In this paper, ∆T refers to the temperature difference across the cavity. We investigated that noflow ∆T is increased as yield stress increases. We also found that flow development is delayed with an increase in yield stress and decreases with increasing ∆T for all carbopol concentrations.