Structure and conditioning effect on mechanical behavior of poly(vinyl alcohol)/calcium lactate biocomposites

The structural and mechanical characteristics of polymeric biocomposites based on calcium lactate (CL) and either partially (88 mol%) or fully (98 mol%) hydrolyzed poly(vinyl alcohol) (PVA) were studied using optical microscopy, Fourier transform infrared spectroscopy equipped with attenuated total reflectance accessory, water content determination, and differential scanning calorimetry. In addition, the moisture absorption effect on the mechanical properties of the biocomposites was tested in this work. The results reveal that CL is a suitable modifier for both types of PVA. However, a more efficient enhancement of uniform shape and size distribution of CL particles within the PVA matrix was noticed in fully hydrolyzed matrix at low water contents. It is in agreement with glass transition temperature's observations. The samples conditioned at 50% of relative humidity (RH) showed decrease in E modulus and tensile strength in comparison with the material stored below 20% RH. Nevertheless, the enhancement of tensile properties, because of the modification with CL, was still noticeable especially for the partially hydrolyzed PVA‐based biocomposites. The optimum concentration of the modifier was estimated on the basis of the obtained results. POLYM. COMPOS., 2009.