Prediction of the chemical and thermal shrinkage in a thermoset polymer

• Published in: Composites. Part A, Applied science and manufacturing Vol. 66; pp. 35 - 43
• Main Authors: Kravchenko, Oleksandr G., Li, Chunyu, Strachan, Alejandro, Kravchenko, Sergii G., Pipes, R. Byron
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2014; Elsevier
• Subjects: A. Thermosetting resin; Applied sciences; B. Residual/internal stress; C. Analytical modeling; C. Computational modeling; Cellular; Cures; Deflection; Ethers; Exact sciences and technology; Forms of application and semi-finished materials; Glass transition temperature; Mathematical models; Polymer industry, paints, wood; Shrinkage; Technology of polymers; Thermal expansion; Thermostats; A. Thermosetting resin; C. Analytical modeling; B. Residual/internal stress; C. Computational modeling; Laminate; Fiber reinforced material; Molecular dynamics method; Epoxy resin; Curing (plastics); Mineral fiber; Modeling; Composite material; Optimization; Thermal expansion coefficient; Carbon fiber; Elastic modulus; Mechanical properties; Experimental study; Glass transition temperature; Thermal properties; Diamine; Thermal history; Numerical simulation; Kinetics; Residual stress
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2014.07.002

A multi-scale model for the response of a bi-material “thermostat”, consisting of a single unidirectional lamina of carbon/epoxy and an uncured layer of neat diglycidyl ether of bisphenol F (DGEBF) with curing agent, diethyltoluenediamine (DETDA), is developed in order to measure thermal strains during a prescribed, but arbitrary thermal history. Molecular modeling simulations provided the elastic modulus, coefficient of thermal expansion, glass transition temperature of DGEBF/DETDA as a function of degree of cure. Cure kinetic properties were determined with differential scanning calorimeter measurements. The model allowed separation of strains due to cure shrinkage and thermal expansion. Combining the molecular modeling predictions, cure kinetic measurements and “thermostat” deflection measurements, the complete polymer shrinkage phenomenon is determined over a prescribed thermal cycle. Furthermore, this work can provide a vehicle to develop cure cycles wherein the difference between instantaneous glass transition temperature and specimen temperature is controlled to provide optimum cure cycles for minimum cure shrinkage.