• Elastomers and Composites
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• v.45 no.2
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• pp.129-136
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• 2010

In this work, PLLA/EGMA blends were prepared by melt blending of biodegradable Poly-L-lactic acid(PLLA) with Poly(ethylene-co-glycidyl methacrylate)(EGMA) and Engage as impact modifiers by twin screw extruder. Blend compositions of PLLA/Impact modifier blends were 100/0, 75/25, 50/50, 25/75 and 0/100, respectively. Also, Talc was added to 3 PLLA rich phases on PLLA/EGMA blends. The morphology, viscoelastic/mechanical properties were characterized by FESEM, DMA, UTM and Izod impact tester. DMA and Izod impact test data showed that storage modulus at room temperature with increasing EGMA and Engage contents decreased, and impact strength increased. However, storage modulus at room temperature increased by adding talc. From FESEM image, we observed that domain phase was well dispersed into matrix. Although the tensile strength and flexural modulus were decreased with increasing the content of EGMA and Engage in them, they could be supplemented by adding talc.

• Korean Journal of Food Science and Technology
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• v.53 no.1
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• pp.92-98
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• 2021

The effects of heat-moisture treatment (HMT) on rice flour (RF) have been investigated for possibility of texture modifier in protein-based foods matrix, tofu. The optimum condition for preparation of tofu with maximum textural parameters was investigated by using response surface methodology (RSM). Rice flour was subjected to moisture content (10-30%) and heating temperature (100-140℃). Based on the response surface and superimposed plots, the optimized conditions of hydrothermally treated rice flour was as followed: moisture content, 22%; temperature, 130℃, which showed lower swelling power as compared to native RF and became more stable during continuous heating and agitation than native one. Tofu, prepared with HMT-RF, showed a denser network structure than that with RF, thereby inducing an increase in textural parameters. From the above results, the addition of HMT-RF could preserve the quality of tofu and be useful for developing an acceptable protein-based food product.

• KSBB Journal
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• v.16 no.1
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• pp.66-70
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• 2001

Factors affecting the supercritical carbon dioxide extraction of camptothecin(CPT) and 10-hydroxycamptothecin(HCPT) from the dried powder of Cmptotheca acuminata were studied. Only a few amount of CPT and HCPT was extracted with pure supercritical carbon dioxide. Methanol and ethanol were efficient modifiers to extract CPT and HCPT. At $40^{\circ}C$, 250 bar, 1 mL/min flow rate, 41% of CPT and 35% of HCPT were extracted with supercritical carbon dioxide modified with 16% of methanol. The diffusion effect of HCPT on extraction efficiency was studied in this solid-fluid system. Round matrix hot-ball model assumption revealed that the value of D/$r^2$ was 0.0072 $min^{-1}$ which was higher than that of solvent extraction with methanol.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.973-978
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• 1997

The toughness and morphology of epoxy resin based on diglycidyl ether of bisphenol A(DGEBA) cured with of tris (dimethylaminomethy]) phenol(DMP-30) and castor oil (CO) as a toughening modifier have been studied. Mixtures of CO and an epoxy resin showed a higher miscibility than the classical CTBN modified epoxy resin. The glass transition temperature($T_g$) was decreased with the CO content and the cure temperature. It is interpreted that the networks of epoxy matrix obtained at high temperature are apparently looser and more flexible due to the lower crosslinking density. The toughness was slightly increased with the CO content at $40^{\circ}C$ of curing temperature. The toughness increased with increasing the cure temperature and CO content.

• Analytical Science and Technology
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• v.8 no.3
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• pp.273-279
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• 1995

Lyophilized whole blood samples containing various concentrations of Pb and Cd have been prepared as external quality control materials. These materials have been characterized with graphite furnace atomic absorption spectrometry(GFAAS), The optimized conditions for the quantitative determination of Ph and Cd in whole blood using GFAAS were obtained at the ashing temperature of $600{\sim}650^{\circ}C$ with 0.1% ammonium dihydrogen phosphate and 0.1% Triton X-100 as matrix modifier. Homogeniety and stability of the prepared whole blood have been studied at the optimized analytical condition.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.1-13
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• 2006

This paper is one of the studies for developing new methodologies for improving performance of hot-mix recycled asphalt mixtures. The objective of this study is to evaluate rut-resistance characteristics of recycled asphalt mixture which was prepared by newly developed mixing method. The new mixing method provided more sufficient rejuvenation of old binder of reclaimed asphalt pavement (RAP), making homogeneous binder viscosity level in a recycled mixture. Two aggregates (gneiss and granite), two RAP contents (15% and 30%) and two contents (none and 6%) of polymer modifier (LDPE) were used. Recycled mixture was prepared with two methods; method A and method F. To examine difference of binder oxidation level by type of material within a recycled mixture, Gel-permeation chromatography(GPC) analysis was performed on the binders mixed with coarse aggregates and matrix separately. Laboratory tests were performed for evaluation of rut resistance characteristics of each recycled mixture and these includes wheel tracking (WT) test and Kim test. Rut depth and dynamic stability were obtained from WT test and deformation strength $(S_D)$ was obtained from Kim test. The results of regression analysis was shown that correlation $(R^2)$ of F mixing mixtures was higher than one of A mixing mixtures. Therefore, F mixing mixtures showed more consistent rut resistance than h mixing mixtures.

• Elastomers and Composites
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• v.45 no.2
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• pp.112-121
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• 2010

In this study, styrene butadiene rubber(SBR)/organoclay nanocomposites were manufactured using the latex method with 3-aminopropyltriethoxysilane(APTES) as a modifier. The X-ray diffraction(XRD), transmission electron microscopy(TEM) images, Fourier transform infrared(FTIR) spectroscopy, swelling ratio and mechanical properties were measured in order to study the interaction between filler and rubber according to the mixing temperature in the internal mixer. In the case of SBR/APTES-MMT compounds, the dispersion of the silicates within the rubber matrix was enhanced, and thereby, the mechanical properties were improved. The characteristic bands of Si-O-C in APTES disappeared after hydrolysis reaction in the MMT-suspension solution and the peak of hydroxyl group was increased. Therefore the formation of chemical bonds between the hydroxyl group generated from APTES on the silicate surface and the ethoxy group of bis(triethoxysilylpropyl) tetrasulfide(TESPT) was possible. Consequently, the 300% modulus of SBR/APTES-MMT compounds was further improved in the case of using TESPT as a coupling agent. However, the silanization reaction between APTES and TESPT was not affected significantly according to the increase of mixing temperature in the internal mixer.

• Analytical Science and Technology
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• v.12 no.5
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• pp.355-359
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• 1999

Trace cadmium was determined in urine by flame and nameless AAS. Inflame method, cadmium was extracted into MIBK from Cd-DDTC complex. In flameless method, samples were pretreated with 1%, Triton X-100. 1% $HNO_3$ and matrix modifier $Pd(NO_3)_2$. Analysis of cadmium was, performed at $450-750^{\circ}C$ ashing temperature by use of pyrocoated tubes. Results of analysis, flameless method superior in sample treatment and reproducibility to flame method and highest absorbance was obtained at $550^{\circ}C$ ashing temperature. 100 mg/L $Pd(NO_3)_2$ concentration. Proposed method were applied to the determination of cadmium in standard urine Lononorm-Metalle 3.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.21-24
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• 2003

In general, to enhance physical properties of PET-layered silicate nanocomposites $(P_{et}LSNs)$, it has been well known that the organic modifiers should introduce into gallery regions. However, the organic modifiers in$(P_{et}LSNs)$ may result in thermal decomposition by melt processing at high temperature, and it necessarily lead to deteriorate various physical properties of final products. Therefore, in this study, $(P_{et}LSNs)$ excluding and including organic modifiers were prepared by solution method $(S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom})$ and we (focused on the effects of the organic modifiers in $P_{et}$ LSNs with exfoliation structure on the crystallization behaviors, the optical transparency, the thermal stability and the mechanical property. The absence and existence of organic modifiers in $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were investigated by EA and TGA, and nano-structure of silicate layers in $S-P_{et}LSNs$ was evaluated by using WXRD, SAXS and TEM. $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were mixed with neat PET as masterbatches by melt method $(M-P_{et}LSNs_{eom} and M-P_{et}LSNs_{iom})$, and also neat PET was mixed with organically modified layered silicates (OLS) by conventional direct melt method $(D-P_{et}LSNs) at 270^{\circ}C$. As results, it was found that $M-P_{et}LSNs_{eom}, M-P_{et}LSNs_{iom}, and D-P_{et}LSN$ showed a exfoliated structure and exhibited faster crystallization rate, better thermal stability and mechanical property than those of neat PET due to the dispersed and detaminated silicate layers in PET matrix. Whereas, considering organic modifiers effect, $M-P_{et}LSNs_{eom} and D-P_{et}LSN$ exhibited slower crystallization rate, poorer optical, thermal and mechanical properties, in comparison to $M-P_{et}LSNs_{eom}> due to the thermal decomposition of organic modifier in $D-P_{et}LSNs$ during melt method.

• Polymer(Korea)
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• v.25 no.1
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• pp.71-77
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• 2001

Unsaturated polyester(UP) resin is one of the major thermosetting resins. It is very useful as the matrix resin of the composite material because of its low viscosity. The polymer resin, however, has several drawbacks; The volume shrinkage occurs during the crosslinking reaction of the UP resin with styrene monomer and the resulting polymer is weak to the alkali and also brittle. The mechanical properties of UP resin can be improved by blending various materials. In this study, polyurethane(PU) was used as a modifier in order to enhance the toughness of the UP resin. The goal of the research is to study the effect of the polyol molecular weight as a PU soft segment and the PU contents on the toughness of PU-modified UP resins. UP/PU polymer network may occur through the reaction between isocyanate group in the methyldiisocyanate(MDI) and hydroxyl group in the UP molecules. The maximum toughness value was shown at 2 wt% of the PU content. This effect results from the incorporation of the PU segment into the UP resin.