• Elastomers and Composites
• /
• v.58 no.3
• /
• pp.142-151
• /
• 2023

In this study, we investigate the thermal and mechanical properties of composites comprising ethylene propylene diene monomer (EPDM) and polybutadiene (PB) obtained using carbon black (CB) as a reinforcing and compatibilizing filler. Owing to the significance of elastomeric materials in various industrial applications, blending of EPDM and PB has emerged as a strategic method to optimize the material properties for specific applications. This study offers insights into the blend composition, its microstructure, and the resulting macroscopic behaviors, focusing on the synergetic effects of composite materials. Furthermore, this study delves into curing and rheological behaviors, crosslink densities, and mechanical, thermal, and elastic properties of the elastomeric composites. Through systematic exploration, we believe that this study will be beneficial to material scientists and engineers working on developing advanced elastomeric composites.

• Food Science and Biotechnology
• /
• v.17 no.1
• /
• pp.52-57
• /
• 2008

The effects of transglutaminase (TG) on the pasting and rheological properties of different wheat cultivars ('Sharpshooter', 'Russ', and 'AcAriss') blended with barley (40%) or soy (20%) flour were investigated. In the rapid visco-analyzer (RVA) pasting profile, the addition of barley or soy flour to wheat flour samples induced a decrease in peak, trough, final viscosity, breakdown and setback values. However, TG treatment of these blends significantly increased peak viscosity and breakdown (p<0.05). In particular, TG treatment greatly increased the breakdown of wheat flour blended with soy flour, indicating that the cross-linking of proteins through TG may somehow be related to an increase in starch granule rupturing in pastes. Storage (G') and loss (G") moduli of the sample pastes increased with an increase in frequency ($\omega$), while complex viscosity (${\eta}*$) decreased. In all wheat cultivars, G', G", and $\eta$ were decreased by the addition of barley or soy flour, or TG treatment. Results suggest that protein cross-linking by TG can produce unique and improved properties in wheat flours blended with barley or soy flour.

• Polymer(Korea)
• /
• v.32 no.2
• /
• pp.116-124
• /
• 2008

A commercialized biobased and biodegradable poly(lactic acid)(PLA) containing the functional monomer of glycidyl methacrylate (GMA) was chemically modified using reactive extrusion to enhance its melt strength. Modified PLAs were prepared with various contents of GMA and initiator, and were characterized by observing their gel fraction, thermal properties, melt viscoelasticity and biodegradability. The complex viscosity and storage modulus of chemically modified PLA with the initiator alone was increased by addition of initiator and were more increased in the presence of GMA. There was a optimum content of GMA showing the maximum complex viscosity with the amount of initiator. The biodegradebility of modified PLA was slightly decreased by addition of GMA.

• Polymer(Korea)
• /
• v.39 no.3
• /
• pp.468-474
• /
• 2015

Electrically conductive polymer nanocomposites were prepared by the inclusion of graphene-based nanofillers. Graphene oxide (GO) and reduced graphene oxide wrapped by poly(styrene sulfonate) (PSS-RGO) were used as nanofillers to make good dispersion with the aqueous dispersion of polystyrene (PS) particles. GO sheets were synthesized by the modified Hummers' method from graphite, and PSS-RGO sheets were prepared by the reduction of GO-dispersed PSS solution with hydrazine monohydrate. Morphology and properties of PS/GO and PS/PSS-RGO nanocomposites via latex technology were investigated. Both nanofillers showed well dispersed morphology in PS matrix. Rheological and electrical percolation thresholds were 0.28 and 0.51 wt% for GO, and 0.50 and 1.01 wt% for PSS-RGO respectively. It is speculated that PS/GO nanocomposites showed better conductivity than PS/PSS-RGO counterparts due to the partial recovery of GO by thermal reduction during molding.

• Korean Journal of Agricultural Science
• /
• v.18 no.1
• /
• pp.41-48
• /
• 1991

Rheological properties of gelatinized potato starch were investigated with Brookfield wide-gap viscometer at various conditions. The gelatinized potato starch at 3-7% showed a pseudoplastic behavior with yield stress, and presented thixotropic properties with time-dependent structural decays. The consistency index and yield stress of gelatinized starch were proportional to starch concentration but inversely proportional to measurement temperature, and the flow behavior index did not show constant relationship. The consistency index and yield stress of the gelatinized starch on addition of phosphate decreased as the flow behavior index increased. The values of activation energy at initial and equilibrium were 1.52 kcal/g.mole and 127 kcal/g.mole, respectively.

• Korean journal of food and cookery science
• /
• v.32 no.5
• /
• pp.541-548
• /
• 2016

Purpose: For dissecting the possible benefits and usages of Cheonggukjang, five different beans, soybean, black soybean, red bean, chickpea, and lentil bean, underwent the fermentation process along with Bacillus subtilis. Methods: Resultant Cheonggukjang physicochemical and sensory properties such as pH, amino type nitrogen, slime contents, rheological properties, and sensory strength and consumer acceptance were analyzed. Results: Values of pH were found to be highest in Cheonggukjang made with soybean (SC), followed by Cheonggukjang made with black bean (BSC) and Cheonggukjang made with red bean and soybean mixture (RBSC), and lastly Cheonggukjang made with chickpea (CBC) and lentil bean (LBC). Amino type nitrogen values were shown to be highest in SC with a value of $394.74{\pm}28.80mg%$, subsequently were values taken from RBSC, followed by BSC, CBC, and lastly LBC. Slime contents were the highest in SC with a value of $3.44{\pm}0.36%$, with RBSC, BSC, CBC, and LBC without statistical difference. Total colony count was found to show higher value in BSC, SC, and RBSC, in contrast to the lower values found in CBC and LBC. Color was shown to be lightest in CBC and with darker shades shown that of SC, LBC, RBSC, and BSC in descending order. In rheological properties, hardness, adhesiveness, and viscosity were found to be highest in SC. Sensory strength analysis and sticky appearance were highest in SC, with fermented odor being lowest in CBC and BSC. The strength of sweetness, sourness, and umami taste did not show statistical difference, however, bitterness was shown to be highest in LBC and lowest in CBC, SC, and BSC. In the consumer acceptance test, overall acceptance was highest in SC and CBC. Conclusion: In conclusion, SC was found to be the best bean variety for making Cheonggukjang fermented with Bacillus subtilis, however, CBC may act as an alternative for manufacture of Cheonggukjang resulting in sound consumer acceptance.

• Journal of Biosystems Engineering
• /
• v.15 no.3
• /
• pp.207-218
• /
• 1990

Grains display characteristics of both elastic bodies and viscous fluids when they are subjected to mechanical treatments in harvesting, handling, and processing. This viscoelastic behavior of grains when mechanically stressed must be fully understood to establish maximum machine efficiency and have a minimum degree of grain damage and the highest quality of the final product. The studies were conducted to examine the effect of the moisture content, the loading rate and the initial deformation on the stress relaxation behavior of whole kernel of rough rice, and develop the rheological model to represent its stress relaxation behavior. The following results were obtained from the study. 1. Moisture content had the greatest influence on the initial portion of the relaxation curve. With elapsing time the lower moisture content resulted in the lower residual stress for the Japonica-type rough rice and vice versa for the Indica-type rough rice. But within the ranges of moisture content tested, the degree of stress relaxation per unit strain on the Indica-type rough rice was a little higher than those on the Japonica-type rough rice. 2. The slower loading rate resulted in less initial stress. The decreasing trend of residual stress for all the samples tested with increasing loading rate was shown. 3. The higher initial deformation for all the samples resulted in less initial stress. The increasing of amount of stress relaxation per unit strain with increase of initial stress indicated that viscoelastic properties of rough rice depended not only upon duration of load applied but also initial stress applied. This means that rough rice is nonlinear viscoelastic material. 4. The compression stress relaxation properties of rough rice kernel can be described by a generalized Maxwell model representing by the Maxwell elements.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.1
• /
• pp.1-7
• /
• 2007

The chemical and rheological properties of deproteinated porphyrans from laver Porphyra yezoensis were investigated to obtain basic data for the production of food materials with biological functionality. Deproteinated porphyran was prepared by acid extraction (pH 4.0, $80^{\circ}C$, 4 hr) and successive hydrolysis with 0.5% Alcalase and 0.5% Flavourzyme. The porphyran constituted 10.7% of the dry laver and consisted of 0.6% protein, 14.8% ester sulfate, 3.2% 6-O-methyl galactose, 16.0% 3,6-anhydro-L-galactose, and 67.3% galactose. The effects of concentration and temperature on the apparent viscosity were examined by applying the power law and Arrhenius equations. The porphyran solution showed the typical behavior of a pseudoplastic liquid and the flow behavior index decreased with increasing concentration. The activation energy of the deproteinated porphyran solution at a 1,000 L/s shear rate also increased from $1.4954{\times}10^{4}\;to\;1.9544{\times}10^{4}\;J/kg$ mol with the concentration.

• Polymer(Korea)
• /
• v.36 no.3
• /
• pp.364-371
• /
• 2012

Polystyrene/single-walled carbon nanotube (PS/SWCNT) nanocomposites were prepared by latex technology and the effect of surfactant (SDS) on nanotube dispersion, rheological and electrical properties was investigated. The nanocomposites were prepared through freeze-drying after mixing PS particles and aqueous SWCNT/SDS suspension. As the SDS content increased, the storage modulus and complex viscosity of the nanocomposites were increased due to enhanced dispersion of nanotubes, but if the content excessively increased, the modulus and viscosity began to decrease due to low molecular weight of SDS. The electrical conductivity sharply increased with the addition of SDS, and then did not show significant changes. This result is speculated to be the competition between the increased dispersion of nanotubes and the deterioration of electrical conductivity by SDS adsorption. An optimal ratio of SDS to SWCNT for improving electrical conductivity and end-use properties was 2. With this ratio, the electrical percolation threshold of SWCNT was less than 1 wt%.

• Culinary science and hospitality research
• /
• v.7 no.3
• /
• pp.179-191
• /
• 2001

The effects of whole wheat flour on the Rheological Properties of dough gassing power of yeast S.cerevisiae and breadmaking properties were studied. The blending ratios of whole wheat flour to bread making flour were 0, 25, 50, 75 and water absorption in the farinography increasedlinerly from 62.5%in 100% bread making flour and 77.5% in 100% whole wheat flour. The hardness and cohesiveness of dough prepared with optimum moisture content was constant regardless of the blending ratio of whole wheat flour. whole wheat flour had no effect on the total gas production or the internal gas content in the dough at a constant moisture level but had detrimental effect on the loaf volume. In a dough at the optimum moisture level, whole wheat flour increased the two former parameters sensory evaluation indicated that the replacement in the range of 25 to 50% with whole wheat flour at the optimum moisture level was acceptable