Because polymers are viscoelastic and, hence, their elastic propeties are time dependent, these properties are usually not reported.
But, as an approximation for Poisson's Ratio, try something around 0.33 for the neat resins, but between 0.19 and 0.34 for fiber reinforced composites.
The shear modulus, Poisson's ratio, and Young's Modulus should be related by the standard equation; but remember the Modulus of elasticity of a polymer is time dependent (and most reported measurements are based on the smount of deformation that occurs at a given stress over 10 seconds.)
