Relationship between dynamic mechanical properties and water absorption of unsaturated polyester and vinyl ester glass fiber composites

The effect of hydrothermal degradation on polyester and vinyl ester mat glass Fiber composites on viscoelastic properties is investigated by dynamic mechanical thermal analysis and flexural modulus. The adhesion between fiber and matrix is studied by short-beam shear test and by SEM microphotographs. Storage modulus in the glass state (T-g - 50 K) and rubber state (T-g + 50 K) is also analyzed for the matrix and composites samples, before and after water immersion. Loss tangent (tan delta) is analyzed taken into account the values obtained for the materials in Moisture sorption experiments.