We can evaluate the optimum time-temperature cycles for the cross-linking of polymers in the manufacturing of fiber-reinforced composites!
Reaction kinetics could be mathematically described. The speed for any chemical reaction is based on some physical laws. As the polymer formulations for composites structures do not change within a process the reaction rate is manly determined by the time-temperature cycle.
DSC (Differential Scanning Calorimetry) is a well-known thermo analytical technique, commonly used to perform kinetic studies of materials in the thermal analysis (TA). DSC-machines can measure heat flow into or out of a sample as it is exposed to a controlled time-temperature-profile. DSC-measurements provide information about material transitions (e.g., glass transition, crystallization, curing, melting, and decomposition). DSC-studies can analyze the temperature at which the transition (reaction) occurs, and how much total heat is generated. Furthermore, DSC-scans provide information about the rate (kinetics) of reactions. For example, heat-flow-curves and their corresponding integrals as exothermic or endothermic energy balance can be coupled with the reaction rate. The Knowledge of the influence of temperature on the reaction rate of different resin allows the polymerization rate to be predicted.
Overview evaluation methods
The Automation Steeg und Hoffmeyer GmbH uses a software application based on the method developed by Borchard and Daniels. This allows the evaluation and the description of the curing behavior of cross-linking polymers with just a set of three DSC measurements. As a result, the customer’s needs for an optimized temperature-time cycle can be calculated.
In addition, a sensitivity analysis allows the identification of possible impacts of variations in the processing parameters (e.g., ΔT in the manufacturing process) and thus capture the robustness of the process. The software application is also suitable as a tool for quality assurance.
As an additional feature it is possible to monitor the “thermoplastic”-polymerization of Cyclic Butylene Terephthalate.
- TA-Instruments: A REVIEW OF DSC KINETICS METHODS,
(7 June 2011)
- Kamal, M. R.: Thermoset Characterization for Moldability Analysis. Polymer Engineering and Science, 14, 3 (1974), pp. 231-239
- Steeg, M.; Mitschang, P.; Chakraborty, P.; Hartmann, T.: MODELING THE VISCOSITY AND CONVERSION OF IN-SITU POLYMERIZING PBT USING EMPIRICAL DATA. In: ICCM-17 17th International Conference on Composite Materials, Edinburgh, July 27-31, 2009
- Steeg, M.: Prozesstechnologie für Cyclic Butylene Terephthalate im Faser-Kunststoff-Verbund. In: Prof. Dr.-Ing. Peter Mitschang (Hrsg.): IVW Schriftenreihe Band 90. Kaiserslautern: Institut für Verbundwerkstoffe GmbH, 2010