• Journal of the East Asian Society of Dietary Life
• /
• v.24 no.3
• /
• pp.400-406
• /
• 2014

Apios (Apios americana Medikus) belongs to Leguminosae and is called 'American groundnut', 'Potato bean', and 'wild bean'. Apios is native to the Northern United States but is not widely distributed in Korea. In this study, cross-linked apios starch was prepared by reaction with epichlorohydrin, followed by characterization. FT-IR spectroscopy confirmed the degree of cross-linking of apios starch. X-ray diffraction patterns of native apios showed typical 'A' type as peaks at 15.1, 17.1, 17.9 and $23.2^{\circ}$, and cross-linking did not affect relative crystallinity and X-ray diffraction patterns of the starch. Scanning electron micrographs showed that apios starch granules were smooth with a globular shape, and there was little damage to starch granules after cross-linking. The lightness value of cross-linked apios starch was lower than that of native apios starch, whereas the redness value was not significantly different between cross-linked apios starch and native apios starch. Blue value showed that cross-linking of starch did not affect the iodine reaction of starch.

• Applied Chemistry for Engineering
• /
• v.1 no.2
• /
• pp.182-189
• /
• 1990

Various crosslinked poly(4-vinylpyridines) having different degrees of crosslinking were prepared by radical copolymerizations of 4-vinylpyridine with N, N'-2, 6-pyridinebisacrylamide as a crosslinker. The abilities of these crosslinked polymers to bind methyl orange and butyl orange were investigated at various temperatures in a buffer solution of pH 7. The first binding constants were evaluated from the equilibrium binding amounts. The first binding constants against the temperatures showed bell-shaped curves. Also, the first binding constants against the degree of crosslinking showed bell-shaped curves. When the temperature and the degree of crosslinking of maximum binding in the curves of these binding systems were compared with those of previous systems containing crosslinked poly(4-vinylpyridines) prepared by using N, N'-methylenebisacrylamide, N, N'-tetramethy-lenebisacryamide and divinylbenzene as crosslinkers, respectively, they were varied with the crosslinked poly(4-vinyl pyridines) containing different crosslinkers. These results were discussed in terms of the properties of the crosslinkers.

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.431-436
• /
• 2002

To develop a method for increasing RS level in maize starch, cross-linked resistant starches treated with annealing were prepared. Maize starch and amylomaize VII were used in the study and annealed at $40{\sim}60^{\circ}C$ before cross-linking modification. To compare effect of annealing below gelatinization temperature, starches were heat treated at 70 and $100^{\circ}C$. RS contents were assayed by pancreatin-gravimetric (P/G) method. When maize starch and amylomaize VII were cross-linked at $45^{\circ}C$ and pH 11.0 by slurrying the starch on a solution of STMP(sodium trimetaphosphate), STPP(sodium tripolyphosphate), and sodium sulfate, RS content was 14.7% and 45.3%, respectively. Annealing below gelatinization temperature before cross-linking increased RS contents of prepared cross-linked starches but did not affect the swelling power. Heat treatment above gelatinization temperature increased the swelling power of cross-linked starch prepared from maize starch. The characteristics by X-ray diffractometry and scanning electron microscopy of cross-linked resistant starch were not changed by annealing.

• Korean Journal of Food Science and Technology
• /
• v.32 no.6
• /
• pp.1298-1305
• /
• 2000

Potato starches were crosslinked with 0.1, 0.5, 1.0, and 2.0% epichlorohydrin. Starch/polyethylene(PE) cast films were prepared to contain 5% of the crosslinked potato starch. Mechanical properties and degradability of these films were measured and compared to those of the films containing native potato starch. Mechanical strength of the films containing crosslinked potato starch was higher than that of the film containing native starch. Thermal degradability measured by a FT-IR and an Instron showed that crosslinked starch/PE films degraded faster than native starch/PE films. Biodegradability of the starch/PE films was accelerated by the addition of crosslinked starch to the PE films.

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.573-579
• /
• 1996

Crosslinked potato starches (XP), from 2,400 to 1,900 anhydroglucose units per crosslinked (AGU/CL), were prepared by reacting with epichlorohydrin. Some of the physicochemical properties of the XPs were then compared with those of native potato and cowpea starches. Crosslinking decreased moisture, protein and ash contents but had no effect on phosphorus content. Water binding capacities of the XPs increased as the degree of crosslinking increased, and that of the XP with 2,100 AGU/CL approached the value of cowpea starch. The absorption maxima of the starch-iodine complex shifted from 594 to 580 nm. Granule size increased slightly and surface appearance of the granule became rough when crosslinked. Both native and crosslinked potato starches showed B type X-ray diffraction pattern, and the relative crystallinity was not affected by crosslinking. Gelatinization temperature and the heat of gelatinization, measured by differential scanning calorimeter (DSC), did not change within the range of crosslinking tested. From X-ray and DSC data, it was concluded that the crosslinking ocurred in the amorphous region of the starch granule.

• The Korean Journal of Rheology
• /
• v.7 no.3
• /
• pp.225-236
• /
• 1995

세가지 가교제 즉 황, tetramethyltyiuram disulfide (TMTD) 및 dicumyl peroxide(DCP)로 각각 가교시킨 카본블랙 충진 고분자 망상 시료들에 대해 일축연신 실험 을 통해 얻은 Mooney plot를 분석, 가교 탄성율 Gc와 엉킴 탄성율 Ge를 각각 구하였다. 각 가교계에 대하여 Gc를 통해서는 가교 사슬간의 평균분자량, 망상사슬과 카본블랙간 결합체 의 밀도 및 평균 면적 등을 Gc를 통해서는 카본블랙 첨가에 따른 관경비를 각각평가하였다. 황 가교제의 경우 Gc가 가장 높았으며 망상 사슬과 카본블랙간의 결합이 가장 잘 이루어졌 다. TMTD와 DCP가교제의 경우는 황의경우보다 카보블랙 입자와의 결합력은 낮았으나 결 합체들의 분포는 더욱 조밀하게 나타났다. 또한 Ge평가로부터는 TMTD 가교계가 카본블랙 충진에 의해 관경이 가장크게 증가함을 알수 있었다.

• Korean Journal of Food Science and Technology
• /
• v.27 no.6
• /
• pp.1028-1034
• /
• 1995

Acid-modified and cross-linked chestnut starch properties and their gel properties were examined. Hardness and cohesiveness of acid-modified starch gels were all reduced as acid treatment time was increased. And hardness of crossed-linked starch gels were increased but cohesiveness were not significantly different. Reduction rate of transmittance in acid-modified starch suspensions were higher than that of unmodified starch suspension. Hardness changes of cross-linked starch gels during 4 days of storage were little, especially in the gels made at $75^{\circ}C\;and\;85^{\circ}C$ of heating temperatures.

• Journal of the Korean Chemical Society
• /
• v.37 no.9
• /
• pp.787-792
• /
• 1993

Semiempirical MNDO calculations are employed to study relation properties on bridging OH group with Al-O(P-O) bond length and Al-O-P bond angle of structural characteristics using birdging $(OH)_3AlOP(OH)_3$ and $(OH)_3AlOHP(OH)_3^+$ model culster. We know that the O-H bond dissociation energy of bridging OH group is increased with increasing Al-O(P-O) bond length and decreasing Al-O-P bond angle. The bridging OH group is formed into enlarged Al-O(P-O) bond length and shortened Al-O-P bond angle in bridging oxygen atom by a hydrogen migration. The negative net charge of bridging oxygen atom is increased with longer Al-O-P bond angle, while the positive net charge is decreased with longer Al-O-P bond angle.

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.580-586
• /
• 1996

Gelatinization behavior and morphology of epichlorohydrin-crosslinked potato starches (XPs) were investigated. Native potato starch showed a very steep single stage swlling pattern, but crosslinked starches showed various patterns with the degree of crosslinking. Swelling power, solubility and light transmittance were reduced drastically as the degree of crosslinking increased. Brabender initial pasting temperature and peak temperature of crosslinked starches increased because the crosslinking reinforces the intermolecular net work of the starches. Although the swelling of the potato starch granule was inhibited by crosslinking as compared to that of the native one, Brabender peak viscosities (6.5% w/v, db) were on the order of 2,500 units for the native potato starch, 3,700 for the XP with 2.300 anhydroglucose units per crosslinking (AGU/CL) and 3,400 for the XP with 2,100 AGU/CL, due to the decreased breakdown of the swollen granule resulting from the resistance to heat and shear. The XP with 1,900 AGU/CL, however, did not show the peak viscosity and the viscosity was on the order of 500 units because of the excessive unhibition of the swelling. Unlike the native potato starch, 6.5%(m/v, db) pastes of the crosslinked potato starches could form gels, which could be predicted from the Brabender setback and consistency index. When the degree of crosslinking is low, random contraction and radial swelling of the granule was possible. As the degree of crosslinking increased, morphological change became similar to the single dimensional tangential swelling observed from the lenticular wheat starch. These morphological change during heating in excess water explained the gelatinization behaviors of crosslinked starches tested.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.240-240
• /
• 2003

SiC 섬유의 고온강도를 향상시키기 위한 소결조제로 boron, aluminum 등을 사용할 수 있다. 본 연구에서는 폴리카보실란에 aluminum precursor를 첨가한 후 중합반응을 거쳐 Al-contained polycarbosilane을 합성하였다. 합성된 Al-contained polycarbosilane을 용융방사하여 섬유화 하고 열분해 공정을 통해 Si-Al-C-O 나노복합 섬유를 제조하였다. 먼저 aluminum butoxide와 polycarbosilane(commercial)을 200m1 xylene에 용해시켜 14$0^{\circ}C$에서 1시간 동안 reflux하였다. evaporator를 이용하여 xylene를 제거한 후 autoclave에서 25$0^{\circ}C$/30$0^{\circ}C$ 중합과정을 통해 가교결합 시켰다 이와 같이 합성된 시료는 ICP분석을 통해 aluminum 함량을 확인하였고 FT-IR(Fig.1) 및 GPC분석(Fig.2)으로부터 화학구조 및 분자량변화를 확인하였다. aluminum 첨가량이 증가함에 따라 Si-H/Si-$CH_3$의 결합크기의 비가 감소하였으며 이로부터 aluminum butoxide와 polycarbosilane의 가교결합이 이루어진 것으로 보이며 중합 후 분자량의 증가 또한 가교결합에 의한 결과로 사료된다 열무게감량(TGA) 측정 결과는 40$0^{\circ}C$부터 유기리간드의 분해가 일어나며 80$0^{\circ}C$이상에서 세라믹화 과정이 완료되었음을 알 수 있었다 또한 aluminum 첨가량이 증가함에 따라 세라믹 수율도 증가하였음을 확인하였다. 합성된 aluminum-contained polycarbosilane은 20$0^{\circ}C$에서 1시간 동안 불융화과정을 거쳐 환원 및 진공 분위기에서 고온 열처리하였으며 이로부터 얻어진 시료에 대해 XRD분석을 수행하였다. SEM과 TEM을 이용하여 미세구조를 관찰하였다.