Polymer impregnation of macro-defect-free cements

Impregnation of MDF cements based on Secar-71 with high-strength heat-resistant polymers, like the novolac epoxies, produces composites with vastly improved properties. Some typical properties are: (1) at 1 MHz and 0% relative humidity, dielectric constant of 8 to 9, dissipation factor of 0.005 to 0.008, and d.c. resistivity of about 1013 Ω cm; (2) less than 5% increase in dielectric constant after exposure to 90% humidity for extended periods of time; (3) flexural strengths of 150 to 200 M Pa; and (4) thermal stability up to 350° C. © 1989 Chapman and Hall Ltd.