Biaxial stress of precursor polymers using holographic interferometry

Holographic interferometry is applied to precursor films to determine their biaxial stresses. The theory of membrane deformation and vibrations is bri efly reviewed to establish the relationship between stress and measured fre quencies. Membranes for vibrational analysis are prepared using a circular precursor polymer. The biaxial stresses of the PHA, PAA, and 50/50 PHA/PAA are fairly constant with increasing frequencies: 6.85-7.61 MPa, 27.01-27.70 MPa, and 11.13-12.08 MPa, respectively. Regardless of the vibration modes, the biaxial stresses remain constant. (C) 1999 Elsevier Science Ltd. All r ights reserved.