Temperature modulated differential scanning calorimeter (DSC) has realized various new techniques of thermal analysis of materials which were not available with the conventional DSC. Usefulness of the temperature modulated DSC has been established through studies by many researchers. However, difficulties in determining the measuring condition and in data processing and explanation are encountered in each study. This paper will introduce the new techniques realized with temperature modulated DSC with explanation why those techniques became possible as well as examples of application.
Degradation occurs at different temperature when the heating rate is changed. This heating rate depend-ence of the degradation temperature (Td) is quite natural from a point of view of physical chemistry. When the Td was plotted again the heating rate in a semi-logarithmic scale, a linear straight line was generally obtained. (1) This straight line shifted toward downward, when oxygen existed in an atmosphere. The ex-tent of the shift was closely related to the type of degradation pattern (random scission, depolymerization) of each polymer. It was in the following order : isotactic PP>PE>PSt>PMMA>P (aM) St. Thus, oxygen showed a degradation promoting effect, the extent of which was larger in the former than in the latter polymer. (2) In the case of elimination type of polymers (PVC, PVA), however, two lines crossed over in this temperature region. (3) In the case of reaction of side groups (PAN), further, the latter line shifted toward upward di-rection. That is, oxygen showed a remarkable retarding effect. We can designate these oxidative degrada-tion pattern : parallel (−), cross-over type, and parallel (+) type-relationship.
Study on effect of the degradation by 3-year outdoor weathering test on the impact strength of polypropylene (PP) materials was carried out with two mechanical tests (high-speed tensile test and SAICAS test) and micrographic observation of exposed surfaces and fractured surfaces. It was found that PP with the stabilizer indicates no decrease in impact strength within 3-year exposure, on the other hand, impact strength of PP without the stabilizer is reduced at early stage of the exposure. Especially, it became clear that SAICAS test detects the degradation by the outdoor weathering test at the earliest stage.
Combustibility and thermal degradation properties were examined for the polyurethane foam and the wood (Japanese cedar) material used as building materials. The flaming combustion time of the wood is extremely long while the polyurethane foam burns rapidly. Moreover, from the results of the measurements of the combustion speed during the combustion tests, it could be inferred that when polyurethane foam and wood of ideally the same mass were burnt, the calorific value of the polyurethane foam was larger. In terms of the thermal degradation properties, in the heat weight measurements the weight decrease curves differed greatly depending on the kinds of isocyanate and polyol, which are the raw materials of polyurethane, Wood showed behavior located in between. Regarding the thermal degradation products, in the case of polyurethane foam the resolution products originating from polyol and polyether, which are the raw materials, were identified, and many products from which the isocyanate ends were substituted for amines were also observed. On the other hand, cellulose, which is the prin-cipal ingredient of wood, and resolution products of lignin origin were observed in the wood, and acetaldehyde hydroxy was generated in great amounts in particular.
The transparent ink absorbing layers containing poly (N-vinylpyrrolidone) have been prepared on polyester films. The resulting films showed less than 0.01 absorbance at 350-800nm. Soaking the recording material in water during 14 days caused almost no large change in color patterns printed on it, and the flaking-off and whitening of the recording layers were not observed. The retention rates of black, cyan, and yellow colors, except for magenta one, were more than 50% under an accelerated weathering test during 144 hours. The high weather resistances suggest the formation of a semi-interpenetrating polymer network (SIPN) by a self-condensation reaction of melamine-formaldehyde resin, and the polymer complex formation through hydrogen bonding interactions by a template polymerization of monomers containing carboxyl groups.
The industrial beverage equipments are producing and dispensing various kinds of beverages such as alcohol containing beverages, coffee, fruit juice beverages, and soft drinks. These equipments are composed of many functional components that are directly contacted with the beverages as well as various kinds of resins that are used according to their uses. Since many of these parts are often used as pressure vessels, various complaints for the crack, discoloration, swelling, and etc. due to deterioration of resins may occur in these parts under various environments. In the present study, as the first step, the influence of the beverage syrups on the polycarbonate, which has been conventionally used in the beverage equipments, was examined in the physicochemical properties and the coloring degree. As the second step, the influence of the syrups on the hydrophobic nylon materials, which are being used as an alterative material to polycarbonate, were examined. Moreover, the swelling and the changes on the physicochemical properties in various kinds of resins by alcohol containing beverages such as shochu and vodka were also examined since alcohol containing beverages have been recently dealt with the industrial beverage equipments.