Polyurethane (PU) elastomers from castor oil based polyol, polyethylene glycol (PEG) of various molecular weight (200, 400, and 600) and toluene diisocyanate were prepared in the form of transparent sheets. The sorption, mechanical and thermal properties have been studied. The solubility parameter, molecular weight between two crosslinks and degree of crosslinking of PU samples were calculated from equilibrium swelling experiments. The kinetic study of swelling revealed that sorption is anomalous in nature in all the samples. Diffusion coefficient (D) and sorption coefficient (S) were found to decrease with an increase in chain length of PEG. The stress-strain data showed that the elastomers obtained using PEG-200 gave the best mechanical properties. The thermal degradation of all elastomers starts at $ 250 C, regardless of the PEG chain length. The values of activation energy of degradation were in the range of 60À72 kJ=mole.
The present work adds to the continuing efforts of designing a natural bone like structure. In these studies the hydroxyapatite (HA) impregnated polymeric composites of polyacrylamide (PAm) and poly (vinyl alcohol) (PVA) have been synthesized by free radical polymerization for the purpose of studying their blood compatibility, water sorption behavior mechanical properties, and porosity. The prepared PAm PVA HA composites were characterized using techniques like fourier transform spectroscopy, X ray diffraction stud ies, thermogravimetric analysis and scanning electron microscopy. The composites were also evaluated for mechanical properties like compressive strength and modulus.
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