ABSTRACT
Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were examined for the electrospun samples. The electrospun PVA samples generally had thinner and more uniform fibers than the electrospun PLA samples. For the PVA samples, an increase in total solids content and PVA to gelatin ratio generally resulted in higher average fiber diameter values and wider diameter distributions. Pollock gelatin in both types of electrospun samples remained amorphous. The PVA in electrospun samples had comparable melting temperatures to that of neat PVA, whereas the PLA in electrospun samples had slightly lower melting temperatures than that of neat PLA. Also, the PLA in electrospun samples had crystallization temperatures approximately 30 °C lower than that in neat PLA. This was due to better alignment of PLA chains during electrospinning, which resulted in the chains being more readily crystallized at lower temperatures. In addition, the electrospun PVA samples completely dissolved in water at room temperature after soaking for one day, whereas the electrospun PLA samples remained intact even after soaking for three days.
Subject(s)
Gelatin/chemistry , Lactic Acid/chemistry , Nanofibers/chemistry , Polymers/chemistry , Polyvinyl Alcohol/chemistry , Absorption , Nanofibers/ultrastructure , Polyesters , Spectroscopy, Fourier Transform Infrared , Thermodynamics , WaterABSTRACT
Surface characteristics of untreated and solvent extracted rice straw and intact rice plant stem and sheath tissue have been investigated using reflectance Fourier transform infrared spectroscopy (FTIR-ATR), electrokinetic analysis (EKA), and scanning electron microscopy (SEM). Klason lignin and Kappa numbers were determined according to TAPPI standard methods. Sohxlet extractions were performed with hexanes, ethyl acetate, chloroform, ethanol-toluene and benzene-ethanol azeotropes. The FTIR reflectance spectra showed differences between the untreated sheath and stem tissues. It was found that the functional groups of the stem interior tissues were masked by another substance, which is proposed to be potassium oxalate monohydrate. This mineral salt, readily removed by water-washing, was affected by the solvent extractions with varying results. The extracted amounts ranged from 1 to 7%. While lipid removal was detectable by the FTIR reflectance method, the streaming potential method showed only slight differences between the curves representing the zeta potential (mV) as a function of pH of the untreated versus extracted samples. Reduced values of the iso-electric points were observed for the extracted samples as compared to the untreated rice straw, indicative of more acidic surface characteristics.
