UBC Theses and Dissertations
Alpha-T-T and T-T-alpha-T diagrams in intelligent processing of thermosetting composites Osinski, Barbara
The majority of existing models for processing in thermoset matrix composites concentrate nearly exclusively on heat and mass transfer problems and account for material-related aspects in a very simplified manner The objective of this work is to provide that missing element by proposing a clearly defined system which yields all the information of Gillham' s T-T-T diagram but can beused for non-isothermal curing cycles. To build the system, three elements are needed: the gelation and vitrification curves, expressed as functions of degree of conversion; the kinetic model of conversion; and a diagram combining all complex information provided by the system. The proposed system for the Narmco 5208 resin incorporates a recently developed mechanistic model for the kinetics of conversion. The algorithm calculates and graphically presents the progress of thermoset processing using the developed diagrams which re-introduce time as an independent variable. Themost important part of the system is its graphical output: a-T-T diagrams, originally developed in this work. Their role is to enhance the understanding of the process by providing the rheological information. Practical applications of the system, with an increasing degree of its sophistication, are presented using four examples. The first case demonstrates the basic value offered by the diagrams - prediction of the moment of gelation and vitrification in advance; the second application shows the advantage of the system in thick composite processing; the third is the generation of the T-T-T diagram for the Narmco resin based on the kinetic model of conversion; the fourth application, where the systemis used in the reverse mode, in a new capability - the search for an optimum curing cycle in the RTP method. In experimental part of the work, the kinetic model of conversion incorporated into the system was verified using the Differential Scanning Calorimetry (DSC) technique, and the rheology of the resin was investigated using the Rheometric Dynamic Analyser (RDA) and DSC apparatus.
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