Effectiveness factors were predicted from measurements of basic parameters made on single oligosaccharides, and the prediction
was compared to experimental effec tiveness factors for the reaction of each oligosaccharide in the immobilized enzyme catalyst.
Kinetic parameters were obtained for the hydrolysis of each oligosaccharide catalyzed by soluble glucoamylase, and were fit
with a subsite model equation capable of generalization to all sizes of oligosaccharide. Diffusion coefficients in free solution
were determined from movement out of a capillary tube. Spatial characteristics of the immobilized enzyme bed were obtained
from pulse response experiments, allowing the calculation of effective diffusivities. Experimental effectiveness factors plotted
against modulus were in reasonable agreement with the predictions. 相似文献
Study on degradation behaviors of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) blended with different compositions of thermoplastic starch (TPS) under soil burial and natural weathering environments is vital in order to predict the product service-life and planning for in situ biodegradation after product disposal. In this article, different compositions of TPS (0%, 20%, 40%, 50%, and 60%) were compounded with PBAT using single screw extruder. The samples were characterized for their tensile properties, fractured surface morphology, water barrier and surface hydrophorbicity properties in order to investigate the effect of starch fractions in PBAT blends. The degradation behavior under natural weathering and soil burial conditions was also determined during the 9 months duration by observing the change of physical appearance, weight loss, surface morphology, chemical structural, and tensile properties. The findings showed that the addition of TPS (20%, 40%, 50%, and 60%) had led to a reduction in tensile strength (41.47%, 60.53%, 63.43%, and 68.53%), and reduction in elongation at break (42.92%, 92.1%, 92.23%, and 93.22%, respectively) and water barrier properties. The findings also showed that there were distinct degradation behavior under both conditions. Upon exposure to natural weathering, photodegradation and Norrish type I & II occurred whereas under the soil burial condition, hydrolytic, and enzymatic degradation take places. Sample with the highest starch contents underwent the highest weight loss and reduction in tensile properties under both environments. The findings in this study are useful in order to investigate the feasibility of PBAT/Tapioca starch blends for biodegradable plastic film for various industrial applications especially in packaging and agricultural mulch. 相似文献
Starch grafted acrylic acid-acrylamide hydrogel was synthesized using an aqueous solution polymerization method. The microstructures of the vacuum-dried hydrogel (VDH) and vacuum-freeze-dried hydrogel (VFDH) were studied by means of scanning electron microscopy and biomicroscopy. The water-absorption rate of the hydrogel was tested. The results showed that the microstructure of the two kinds of dried hydrogels exhibited significant differences. Before absorbing water, VDH had a relatively dense surface whereas the surface of VFDH had a clear macroporous structure. After absorbing water, a three-dimensional network structure was clearly visible in VDH. Many interlaced and free filaments occupied the space between the main skeleton and channels. The holes formed by vacuum-freeze-drying had the effect of squeezing the surrounding network structure, which had an impact on the water-absorption rate and water absorbency of the hydrogel. 相似文献
Banana fiber (BF)-reinforced low-density polyethylene (LDPE) unidirectional composites were fabricated by the compression molding process with 40 wt% fiber loading. The fibers were modified with methylacrylate (MA) mixed with methanol (MeOH) along with 2% benzyl peroxide under thermal curing method at different temperatures (50–90 °C) for different curing times (10–50 min) in order to have better compatibility with the matrix. The effect of fiber surface modification on the mechanical properties (tensile and impact properties) of the composites were evaluated. Monomer concentration, curing temperature, and curing time were optimized in terms of polymer loading and mechanical properties. The mechanical properties were found to be improved based on the improved interaction between the reinforcement and the matrix. Optimized BFs were again treated with 2–5 wt% starch solutions and composites made of 4% starch treated BF showed the highest mechanical properties than that of MA treated composites. Scanning electron microscopy (SEM) was performed to get an insight into the morphology of the composites. Water uptake and soil degradation test of the composites were also investigated. 相似文献
An attempt to quantitative evaluation of the functionality of food grade chemically modified starches in the emulsion systems by estimation of their surface activity as well as the capability of thickening food products was the main purpose of this present work. It was stated that chemically modified starches reveal higher surface activity at air/water and toluene/water interfaces in comparison to the native starch. The increase of the degree of substitution of polar carboxyl groups as well as rather non-polar acetyl ones results in an enhance of surface activity. Starch sodium octenylsuccinate stands out from other investigated starches, in its excellent capability of lowering surface and interfacial tension. Cross-linked starches reveal excellent stabilisation activity at a pH range of 5.5–7.0 but their surface activity is lower than those of other modified starches. Acetylated starch as well as starch sodium octenylsuccinate reveal satisfactory thickening capability up to pH 4.5 and moreover their surface activity (especially of E 1450) allows us to recommend them as functional constituents of food emulsions. Low thickening capability of oxidised starches rather excluded these derivatives from the group of potential functional additives for food emulsions. 相似文献
This review article deals with the technically important carboxymethyl ethers of cellulose and starch. Recent developments of synthesis, characterization, and application are presented considering adequately own research work in this field. In particular, the structure characterization by means of chromatographic (HPLC) and NMR-spectroscopic techniques as well as commercially important synthesis paths and alternative methods are described. 相似文献
Summary: Several rubber/starch composites in which the starch particles are in an amorphous state and are smaller than 1 μm, prepared by directly mixing and co-coagulating rubber latex and starch paste, exhibit higher hardness, stress at 100%, tensile strength, and tear strength relative to the corresponding rubber/starch composites prepared by direct blending.