RP116 - In-Situ Cure Monitoring of Isocyanate Adhesives Using Microdielectric Analysis, Michael P. Wolcott and Timothy G. Rials
ABSTRACT
Recent advances in microelectronics have produced small electrodes that can be used for remote dielectric measurements. These miniature sensors are small enough to be embedded in a composite panel during manufacture with little disturbance to the manufacturing process. Small particleboard panels (5 by 4.5 by 0.25 in.) were manufactured with 6 percent polymeric diphenylmethane diisocyanate resin in a laboratory hot-press. A dielectric sensor was embedded in the core of each panel to measure both temperature and dielectric responses. The curing behavior of the particleboard furnish was also examined using dielectric analysis in a controlled oven and differential scanning calorimetry. Close agreement was found between the curing response detected by both these techniques. In addition, the curing response of particleboard furnish in a controlled oven was remarkably similar to that seen in situ during particleboard manufacture using four different platen temperatures. The contribution of moisture changes during pressing to the dielectric signal was evaluated. Finally, two different sensor designs were evaluated on a limited basis.
RP119 - The Viscosity and Ion Conductivity of Polydimethylsiloxane Systems: 1-Chain length and Ion Size Effects; 2-Ion Concentration Effects , School of Chemical Engineering, Georgia Institute of Technology, J.E.Companik and S.A.Bidstrup
ABSTRACT
The zero-shear-rate viscosity and ion conductivity of a homologous series of polydimethylsiloxane (PDMS) oils and six homologous series of PDMS salts of various univalent cations (sodium, potassium, tetramethylammonium, tetraethylammonium, tetrapropylammonium and tetrabutylammonium) were measured over the temperature range -45C to 80C. Free volume and Arrhenuis type viscosity and ion conductivity models were successfully applied to these data. The effects of polymer chain length and ion size on the values of the best-fit model parameters were explored.
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RP093 - Curing Characteristics of a Zinc-Catalyzed Cynate Ester Resin System, Syracuse University, Yong Deng and George Martin
ABSTRACT
Cyanate-based resins have been the focus of a number of recent publications. Their attractive features include excellent adhesion characteristics, good mechanical properties, low dielectric constants and glass transition temperatures in the range of 260C. Thus, the resins are considered especially suitable for composite and electronic applications.
The major reaction pathway for the cyanate resins is the cyclotrimerization of cyanate groups to form triazines. Unlike many epoxy resins, such as epoxy-amines, the curing of cyanate resins has been found to become diffusion-controlled even in the pre-gel stage. As the diffusion control may also affect the structural properties, understanding the diffusion-related curing characterisitcs is important for elucidating the structure-property relationship of the cyanate resins.
The objective of the present work was to examine the dielectric behavior and molecular size distribution of a zinc-catalyzed cyanate ester resin in order to estimate the average diffusivity in the cure system, and to develop a quantitative model to predict the diffusion-controlled cure kinetics of cyanate resins.
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RP057 - Cure Studies of Interpenetrating Networks by Microdielectrometry; Naval Research Laboratory, B.S.Holmes and C.A.Trask
ABSTRACT
Microdielectrometry has been use to follow the cure kinetics of interpenetrating polymer networks (IPNs). The rate of formation of a polyurethane-poly(n-butyl acrylate) IPN has been characterized at three temperatures. The dielectric data indicate that the relative homonetwork formation rates dominate the resultant material properties.
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RP048 - Filled Acrylic Systems: Cure Monitoring using Microdielectrometry, Ceramics Process Systems Corporation,, K.Venkataswamy and R.Waack
ABSTRACT
Microdielectrometry was employed to monitor cure of a polymer binder precursor based on acrylic monomer systems. Polymeric binders, in general, are crucial in forming applications of ceramics such as tape casting to manufacture ceramic substrates or packages. In this process technology, the principles of reinforcing polymer systems with powders are applied in processing the fillers themselves. A very novel method is investigated; high solids loading of ceramic powders was dispersed in acrylic monomer systems, which can be cured by free radical mechanism. The effects of solids loading, initiator level, and cure temperature on the cure rate are examined by Microdielectrometry in such highly filled systems.
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RP096 - A Microdielectric Analysis of Moisture Diffusion in Thin Epoxy/Amine films of Varying Cure State and Mix Ratio, Micromet Instruments, Inc. David Day, David Shepard, and Kelly Craven
ABSTRACT
This work shows that dielectric sensors can be used to monitor moisture diffusion in polymer materials ranging from composites to thin films. When the technique is used with thin films, diffusion coefficients and degree of moisture uptake can be determined very quickly. This paper describes preliminary moisture diffusion analysis carried out in thin epoxy films as a function of ultimate cure state and mix ratio of epoxide to amine components.
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