• Polymer(Korea)
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• v.30 no.2
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• pp.118-123
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• 2006

The effect of transesterification on the rheological properties in the melt reactive blending of poly(butylene terephthalate)(PBT) with poly(ethylene terephthalate)(PET) has been studied. The melt viscosity depression in PBT was found in PBT/PET blends due to the intrinsic low melt viscosity of PET compared to PBT. In addition, the thermal degradation in the melt blending and transesterification between two polyesters were considered as other factors fer the lowering of the melt viscosity in the blends. In the PBT/PET blends, calcium stearate was less effective than in PBT as a lubricant, however it accelerated both the thermal degradation and transesterification during melt blending. As a result, further melt viscosity drop was obtained in the reactive melt blending of PBT/PET.

• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.182-190
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• 2009

In this work, effect of antistrip additives to reduce moisture damage of asphalt mixture were studied. Asphalt antistripping agents were prepared by condensation of formaldehyde with tetraethylene pentamine (TEPA), triethylenetetramine (TETA) and bis(hexamethylene)-triamine (BHMT), respectively. And also the metal type antistripping agent was prepatred by neutralization of stearic acid or palmitic acid with metal hydroxide. Mechanical characteristics of the asphalt mixture added antistripping agent were evaluated with Marshall stability, submerging residuals and coating rate. It was found that antistripping agent prepared in this study reduced moisture damages of asphalt mixtures. In particular, asphalt mixtures added BHMT and C/S (Calcium stearate hydroxide) antistripping agent showed highest submerging and coating rate. Because BHMT and C/S type antistripping agent was to improve bonding between asphalt and aggregate owing to increase of amine concentration and role of metal surfactant.

• Polymer(Korea)
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• v.29 no.5
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• pp.475-480
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• 2005

The lowering of melt viscosity has been investigated to achieve the processability enhancement in poly(ethylene naphthalate) (PEN) melt processing by the reactive melt blending with poly(ethylene terephthalate) (PET) and introducing lubricant as well. CaST lubricant resulted in the lowering of PEN melt viscosity but noticeable mechanical property drop was found in PEN with more than $2wt\%$ of lubricant due to the acceleration of thermal degradation by excess lubricant. PEN/PET (90/10) blend has less melt viscosity than PEN and transesterification between two polymers caused the additional viscosity depression. further viscosity lowering was found in PEN/PET blend with CaST since CaST is acting as the catalyst of transesterification as well as a lubricant in PEN/PET blend.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.159-163
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• 1999

Model experiments were conducted to investigate the effect of different fillers on the removal of toner ink. Combinations of different papers (commercial photocopy paper and filler-free paper), fillers (calcium carbonate, kaolin clay, and talc), and chemicals(1-octadecanol, stearic acid, oleic acid, and TOFA) and stearic acid were found to be effective in detachment and agglomeration of toner ink. Furthermore, pH had little effect on toner detachment and agglomeration, indicating both protonated fatty acids and their anions are equally effective. In the presence of either kaolin clay or talc, all these agglomerating agents are equally effective, although a slightly higher dosage(1% for clay and 2% for talc as compared with control) is required, presumably due to the adsorption of chemical by the filler. Calcium carbonate filler, on the other hand, has a significant and adverse effect on the fatty acids used but has little effect on 1-octadecanol with the exception of possible adsorption. While stearic acid is not effective, a much higher level of oleic acid or TOFA is needed when calcium carbonate fillers are present as compared to the filler-free case. Fatty acids react with calcium carbonate to form calcium salts. The availability of fatty acid anion for toner detachment and agglomeration is determined by the solubility of calcium salt of a given fatty acid. Calcium oleate is 10 times more soluble in water than calcium stearate.

• Computers and Concrete
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• v.23 no.5
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• pp.351-359
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• 2019

In this study, the calcium hydroxide, an inherent product of cement hydration, was treated using biomimetic carbonation method of incorporating stearic acid to generate the hydrophobic calcium carbonate on concrete surface. Carbonation reaction was carried out at various $CO_2$ pressure and temperatures and utilizing the Scanning Electron Microscope (SEM), chloride-ion penetration test apparatus, and compression test machine to investigate the hydrophobicity, durability, and mechanical properties of the synthesized products. Experimental results indicate that the calcium stearate may change the surface property of concrete from hydrophilicity to hydrophobicity. Increasing reaction temperature can change the particles from irregular shapes to needle-rod structures with increased shear stress and thus favorable to hydrophobicity and microhardness. The contact angle against water for the concrete surface was found to increase with increasing $CO_2$ pressure and temperature, and reached to an optimum value at around $90^{\circ}C$. The maximum static water contact angle of 128.7 degree was obtained at the $CO_2$ pressure of 2 atm and temperature of $90^{\circ}C$. It was also found that biomimetic carbonation increased the permeability, acid resistance and chloride-ion permeability of the concrete material. These unique results demonstrate that the needle-rod structures of $CaCO_3$ synthetized on concrete surface could enhance hydrophobicity, durability, and mechanical properties of concrete.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.639-648
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• 1992

For recycling cement hydrate(CH) as waterproofers for mortar and concrete or a filler for rubber & plastics, the cement hydrates were treated with stearic acid(SA). And the bonding characteristics and the water repellency of the CH-SA compounds were investigated by using FT-IR, TGA, SEM, XRD, and contact angle measuring apparatus. Water tightness of the remitars used CH-SA compounds was also tested. The results are summarized as follows : 1) If the cement hydrates are treated with over 2.0% of stearic acid, the CH-SA compounds show very strong water repellency. 2) The stearic acids are solidified on the surfaces of cement hydrate in calcium stearate and aluminium stearate. 3) If CH-SA compounds which is cement hydrate treated with 5~10% of stearic acid are used 3%~6% in remitar, water absorption ratio and water permeatility ratio of remitar are decreased in below 30% of those of the ordinary remitar.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.125-127
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• 1996

This paper deals with the fabrication of 4 poles anisotropic Sr·ferrite plastic magnets. After Polyamide6 and polyamlde12 are kneaded respectively with Sr·ferrite powder, silane coupling and calcium stearate of lwt% are added for coating and pelleting. The pelleted specimen are injection-moulded under the magnetic field using 4 poles mould. For 4 poles anisotropic Sr·ferrite plastic magnets with polyamide6 as a binder, the surface magnetic flux density distribution is +943.8∼-943.87kG and the deviation is 5.2%, where as with polyamide12, the distribution is +1040.9∼-1040.9kG and the deviation is 5.4%. It shows that both of the magnet distributions are stable. As the results of the experiments, we find 4 poles anisotropic Sr·ferrite magnets have good properties as the materials appropriate for manufacturing magnet type synchronous motors.

• Journal of Pharmaceutical Investigation
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• v.10 no.1
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• pp.24-33
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• 1980

Drug product design of phenylbutazone tablets by direct compressing was investigated. Weight variation, hardness, friability, disintegration time, apparent volume and dissolution rate for experimental tablets of nine formulations which were considered to be the effect of the additive concentration were measured. It was found out that direct compressing by the formulation No. 5 was the most suitable condition (phenylbutazone 16.7%, lactose 25%, calcium phosphate dibasic 15%, $Avicel^{\circledR}$ 41.83% and magnesium stearate 1.5%). The coefficient of correlation between disintegration time and dissolution rate, r, was = -0.97 (P<0.01).

• Journal of Pharmaceutical Investigation
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• v.2 no.1
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• pp.31-39
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• 1972

국산산성백토(國産酸性白土)를 정제(錠劑)의 붕노제(崩努劑)로 개발(開發)하고자 종내(從來) 붕해제(崩解劑)로 사용(使用)해 오든 corn starch, calcium methylcellulose, kaolin, calcium silicate 및 Pectin과 국산산성백토(國産酸性白土)를 붕해제(崩解劑)로하고 정제(錠劑)의 주약성분(主藥成分)으로서는 불용성(不溶性)인 Ca-PAS KP II 를 택(澤)하였다. 이상(以上)의 각(各) 붕해제(崩解劑)의 一錠當(일정당) 함양(含量)을 0%에서 25%까지 7종(種)으로 달리하고 이것을 각각(各各) 사용(使用)하여 만든 과립(顆粒)의 입자도(粒子度)도 각각(各各) 4종류(四種類)로 분류(分類)하였다. 여기에 활택제(滑澤劑) 로서 0.5% mg-stearate를 공통(共通)으로 첨가(添加)하였다. 이상(以上)을 각각(各各) 동일(同一)한 조건하(條件下)에서 타정(打錠)하여 수종(數種)의 정제(錠劑)를 만들었다. 이들 정제(錠劑)에 대(對)하여 경도(硬度)및 붕해도시험(崩解度試驗)을 하여 비교검토(比較檢討)한 결과(結果) 다음과 같은 결론(結論)을 얻었다. 1. Corn starch는 우수(優秀)한 붕해제(崩解劑)이나 그첨가량(添加量)이 8%이상(以上)이 될 때 는 타정시(打錠時) 압력(壓力)을 받지 않어 정제(錠劑) 붕해제(崩解劑)로서 사용(使用)할 수 없었다. 2. Ca-Mc는 붕해제(崩解劑)로서 첨가량(添加量)이 8%이상(以上) 일때에도 사용가능(使用可能) 하였으나 15%이상(以上) 일때는 타정시(打錠時) 압력(壓力)이 약(弱)해졌다. 3. Kaolin 붕해제(崩解劑)로서 부적당(不適當) 하다고 사려(思慮)되였다. 4. Ca-silicate도 붕해제(崩解劑)로서 적당(適當)하였으나 Pectin은 가장 부적당(不適當)하였다. 5. 산성백토(酸性白土)는 정제붕해제(錠劑崩解劑)로서 타정시(打錠時) 25% 첨가시(添加時)에도 압력(壓力)을 잘 받어 정제(錠劑)의 경도(硬度)를 유지(維持)할수 있었을 뿐만 아니라 붕해도(崩解度)도 양호(良好)한 성적(成績)을 나타내여 가장 우수(優秀)한 붕해제(崩解劑)임을 확인(確認)하였다. 6. 일반적(一般的)으로 타정(打錠)에 사용(使用)되는 과립(顆粒)의 size가 적을수륵 붕해시간(崩解時間)은 짧았으며 정제(錠劑)의 경도(硬度)가 높을수록 붕해시간(崩解時間)은 길었다. 그러나 정확(正確)한 비예성(比例性)은 찾기힘들었다.

• Journal of Veterinary Clinics
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• v.13 no.2
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• pp.184-194
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• 1996

A comparative study of three absorbable suture materials of chromic catgut, Dexon II (a polyglycolic acid suture with a polycaprolate coating system) and Coated Vicryl (a polyglactin 910 suture with a glycolide-lactide-calcium stearate coating system) was undertaken in terms of tensile strength, breaking elongation, appearances of the suture materials in the subcutaneous layer of rats and of tissue reaction in the intramuscular layer of rats. The initial tensile strength of chromic catgut and the tensile strength after 21 days were about 1.55 kg and 0.19 kg, respectively. Those of Dexon II were about 2.01 kg and 0. 20 kg, respectively. Those of Coated Vicryl were about 2.39 kg and 0.48 kg, respectively. Coated Vicryl showed the highest tensile strength among the three materials during the whole period. On the other hand, Dexon II showed the highest breaking elongation among the three materials during the first week. But the breaking elongation of Dexon II rapidly continuously decreased during the whole period. The appearances of the suture materials in the subcutaneous layer of rats showed that chromic catgut was the fastest among the three materials, whereas it formed comparatively much connective tissue. The intramuscular absorption rate and tissue reaction of Dexon II were similar to those of Coated Vicryl. The intramuscular absorption rate of these was fairly late when compared with chromic catgut. And the tissue reaction appearance of these showed the formation of a granuloma with foreign body giant cells, macrothages and epitheloid cells by the 28th day in the experimental period.