No abstract

No abstract

Ultrasonic spectroscopy provided a powerful, efficient, and reliable tool for a number of investigations, including those of polymer solution dynamics, molecular interaction, and the miscibility and compatibility of biopolymers in aqueous solutions. Ultrasonic velocity and related acoustic parameters were measured as a function of the concentration of poly(vinyl alcohol) (PVA), dextran, and a PVA-dextran mixture in water with the resonance method at a frequency of 3 MHz over a temperature range of 20 -50°C. From the comparative results of sound velocity, density, adiabatic compressibility, acoustic impedance, and viscosity relaxation time as a function of temperature and concentration, the mode of interaction and the compatibility and miscibility between the two biologically active macromolecules were probed and were considerable at all concentrations and temperatures because of crosslinking via hydrogen bonding involving the hydroxyl groups of both of the biomacromolecules. The interpretations of the acoustic results were confirmed by the intrinsic viscosities of the ternary systems. The significant interaction and compatibility of these biopolymers should lead to the development of pharmaceutically active molecules.

Hydrogels of macroporous copolymer, 2-hydroxyl ethyl methacrylate with acrylic acid, were prepared in the presence of N,N'-methylene-bis-acrylamide as crosslinker and benzoyl peroxide as initiator. The structure of the copolymer was characterized by FT-IR, H1-NMR and scanning electron microscopy and the thermal stability by thermogravimetric analysis. Its hydrogel character was observed by studying the swelling of the copolymers simply by measuring weight gain and weight loss. The swelling was determined in distilled water, saline solution and buffers of pH, 4 and 9.2, was found to increase with increasing pH, attaining a maximum at pH 9.2. The biodegradability of the copolymers was studied by introducing microbes to the culture media along with the prepared sample and it was verified by examining the surface morphology by SEM. The rate of biodegradation was monitored by the CO2 release method.

Natural fiber copolymers were prepared by grafting hydrophobic monomer, methyl methacrylate (MMA), onto chemically modified pineapple leaf fiber (PALF) using a complex initiating system: Cu (II) SO4 / histidine / ammonium persulfate (APS) in an aqueous medium. The overall activation energy (Ea) of grafting was computed to be 21.8 kJ mol−1. The PALF–g–PMMA copolymers so obtained were characterized by FT-IR, their thermal behaviour by TGA and their morphology by scanning electron microscopy (SEM). Their tensile strength, elongation and tenacity were measured. The extent of water absorption by the grafted PALF showed that grafting of MMA imparts hydrophobicity onto PALFs. The biodegradation of the copolymers was evaluated in sludge water and soil and by using cultured microorganisms.