Interferometric Methods Applied to Polymeric Analysis

GUSTAVO ARENAS; NELIDA ARACELI RUSSO; RICARDO DUCHOWICZ

Interferometry Principles and Applications

Nova Publishers

Lugar: New York; Año: 2010;

Several epoxies and photo- or thermal- cured polymers found their way in almost every field of structures manufacturing. These materials can compete with metallic ones and even substitute them in several applications. However, it is well known that their mechanical properties are highly dependent upon the curing process of the matrix. Curing evolution is connected directly to the contraction process occurring in the material. Relevant information include the evolution and final conversion (degree of cure) related to the amount of the chemical cross-linking occurring during cure, the gel point where a phase change from liquid-like to solid-like occurs, the glass transition temperature and the induced residual strain produced during the curing process causing structure distortion and intrinsic strain accumulation. Several cure monitoring techniques have been proposed and applied in the past. Among these techniques, optical approaches seem to be the best candidate in polymer based materials manufacturing monitoring. On this way, different methods based on interferometric techniques by using fiber optics technologies have been developed. In this work, we discuss the feasibility of different approaches. First, we analyze optical sensors based on a Fizeau fiber optic interferometer to measure polymer contraction that occurs during cure with a measure resolution better than 100 nm; second, we discuss the simultaneous application of a cantilever and the Fizeau interferometer, and, finally, the use of a pair of fiber Bragg grating based sensors to uncouple strain and temperature (assuming a thermal related cure process). Properties and relevant information extracted from of the different techniques are discussed.