• Journal of the Korean Wood Science and Technology
• /
• 제25권4호
• /
• pp.68-74
• /
• 1997

This research was studied dissolving pulp for rayon production, which is not KP, SP methods but steam explosion and oxygen alkali treatment. The variation of characterization in wood cellulose after steam explosion and oxygen alkali treatment this follows. In the oxygen alkali treatment of exploded pine wood, yield of dissolving pulp was lower than steam-exploded oak wood, and we have obtained dissolving pulp that high purity cellulose, but degree of polymerization was inclined to decrease less than 200. In the case of steam-exploded oak wood, degree of polymerization was higher than steam-exploded pine wood but purity of cellulose was lower than its.

• 접착 및 계면
• /
• 제6권4호
• /
• pp.7-11
• /
• 2005

Multi-walled carbon nanotubes (CNTs), which were purified by etching in 25% $H_2SO_4/HNO_3$ solution at $60^{\circ}C$ for 2 h, were modified via plasma polymerization coating of acrylic acid, allylamine or acetylene, and then utilized to prepare PEI/CNT composites. First, plasma polymerization conditions were optimized by measuring the solvent resistance of coatings in THF, chloroform and NMP, and the tensile strength of PEI/CNT (0.5%) composites as a function of plasma power (20~50 W) and monomer pressure (20~50 mTorr). The tensile strength of PEI/CNT composites was further evaluated as a function of CNT loading (0.2, 0.5 and 1%). Finally, FT-IR was utilized to provide a better understanding of the improved tensile properties of PEI/CNT composites via plasma polymerization coating of CNTs. Plasma polymerization of acrylic acid greatly enhanced the tensile strength of PEI/CNT composites, as did allylamine but to a lesser degree, while acetylene plasma polymerization coating decreased tensile strength.

• 방사선산업학회지
• /
• 제6권3호
• /
• pp.251-255
• /
• 2012

Pulp is typically used for paper industry to manufacturing various types of papers. However simply chemical modification makes enable the pulp to a wide range of application in various industrial fields. To bring the polymerization the gamma ray irradiated on the mixture of kenaf and PEGMA in various dose ranges from 20 to 60 kGy. As a results, the graft degree of 20.0% was obtained from 475 g of gamma ray irradiated pulp and PEGMA. After the polymerization, the chemical structure and morphology of the surfaces were examined by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscope. Chemical structure of grafted pulp has significantly growth in carbonyl content with increasing the radiation dose. Also surface morphology was distinctly changed with decreased the degree of roughness and increasing the diameter. These results were explained gamma ray irradiation improve performance of graft polymerization efficiency.

• KSBB Journal
• /
• 제13권4호
• /
• pp.378-382
• /
• 1998

Agar hydorlysates or agarooligosaccharides from agar prepared by Cytophaga agarase showed eight spots on TLC plate and the degree of polymerization of the spots were in the reange of 2.5 - 6.5. Each component of the hydrolysate as tested the several functionalities such as antimicrobial activity, anticavity activity, and anticoagulant activity. The anticativity activity and anticoagulant acitvity were found in all fractions of hydrolysates and several spot on TLC, whereas the anticoagulant activity was very low.

• 대한치과보철학회지
• /
• 제52권3호
• /
• pp.195-201
• /
• 2014

목적: 본 연구에서는 세 가지 중합 방법에 따른 이원 중합 레진 시멘트의 중합 수축률을 비교하고 광조사가 중합 정도에 미치는 영향에 관하여 알아보고자 하였다. 재료 및 방법: 네 가지 종류의 이원 중합형 레진 시멘트(Smartcem 2, Panavia F 2.0, Clearfil SA Luting, Zirconite)가 사용되었다. 각 재료 당 세가지 서로 다른 중합 방법(자가 중합, 즉시 광중합, 5분 지연 광중합)으로 중합하였으며, 각 방법 당 5개의 시편을 사용하였다. Bonded disk method를 사용하여 $37^{\circ}C$에서 30분간, 시간에 따른 중합 수축률을 측정하였다. 측정값은 일원분산분석과 다중 분석을 위한 Scheff$\acute{e}$ test를 사용하였고, 유의수준은 0.05으로 하였다. 결과: Panavia F 2.0를 제외한 나머지 세 종류의 이원 중합 레진 시멘트들은 지연 광중합 반응에서 가장 높은 중합 수축률을 보였다. Panavia F 2.0의 중합 수축률은 중합 방법간에 통계학적 유의성이 없었다. 중합이 개시된 초기 10분 내에 즉시 혹은 지연 광중합에서 모든 시멘트는 90% 이상의 중합수축을 보였다. 결론: 이원 중합 레진 시멘트의 지연 광중합이 중합 효율을 높인다.

• 폴리머
• /
• 제24권5호
• /
• pp.610-620
• /
• 2000

아세트산비닐(VAc)을 아조비스디메틸발레로니트릴(ADMVN) 및 삼차부틸알코올 (TBA)을 각각 개시제 및 용매로 하여 30, 40 및 5$0^{\circ}C$에서 용액중합하였다. 합성된 폴리아세트산비닐 (PVAc)을 비누화함으로써 고분자량 혼성배열 폴리비닐알코올(PVA)을 제조하였다. 중합조건들이 전환률, 가지화도 및 PVAc와 PVA의 분자량에 미치는 영향을 고찰하였다. TBA에서의 VAc의 중합 속도는 ADMVN 농도의 0.49승에 비례하였고, 이는 이론치 0.5와 잘 일치하였다. 저온에서 개시가 가능한 ADMVN 및 낮은 사슬이동상수를 갖는 TBA를 사용함으로써 고분자량 및 고수율의 PVA가 얻어졌다. PVAc의 평균 중합도는 전환률 약 35%부터 70%의 범위에서 10000~13000이었고, 이를 비누화하여 얻은 PVA의 평균 중합도는 2400~6100이었다. 교대배열 다이애드기 함량은 중합온도를 낮춤에 따라 조금씩 증가하였고, 중합시 TBA의 입체장애 효과 때문에 TBA의 양을 증가시킴에 따라서도 증가하였다.

• Macromolecular Research
• /
• 제11권6호
• /
• pp.495-500
• /
• 2003

UV-induced graft polymerization of glycidyl methacrylate (GMA) to a polypropylene (PP) membrane was carried out in the vapor phase with benzophenone (BP) as a photoinitiator. Attenuated total reflection Fourier transform infrared spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were utilized to characterize the copolymer. The degree of grafting increased with increasing reaction time, increased UV irradiation source intensity, and increased immersion concentration of the BP solution. The optimum synthetic condition for the PP-g-GMA membrane was obtained with a reaction time of 2 hrs, a UV irradiation source intensity of 450 W, and an immersion concentration of the BP solution of 0.5 mol/L. The pure water flux decreased upon increasing the degree of grafting and increasing the amount of diethylamino functional group introduced. The analysis of AFM and SEM images shows that the graft chains and diethylamino groups of PP-g-GMA grew on the PP membrane surface, resulting in a change in surface morphology.

• 한국인쇄학회지
• /
• 제30권3호
• /
• pp.13-21
• /
• 2012

This study was carried out to evaluate the stability of archival documents produced using papers. The properties of archival documents depend on the type of fillers of papers that are used such as fiber, non cellulose fiber, and mineral. The physio-chemical characteristics of archival documents were analyzed by employing acid hydrolysis against cellulose fiber substances. Fibers of Korean hand-made (Hanji), flex, and cotten papers showed higher pH and the degree of polymerization (DP) than wood fiber and mechanical fiber. Mechanical pulp containing 12.8% of lignin showed the greatest decrease of DP due to acid hydrolysis, and this resulted in increase of degree of aging. The filler found to clay and talc did not contain metal such as $Fe^{+2}$, $Fe^{+3}$, and $Cu^{+2}$. The alkaline metals such as Mg, Ca, and Ti showed greater resistance to acid hydrolysis.

• Fibers and Polymers
• /
• 제5권1호
• /
• pp.75-81
• /
• 2004

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25℃ by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P/sub n/): 30,900-36,100) and of high yield (ultimate conversion of MMA into PMMA: 83-93 %) with diminishing heat generated during polymerization. The P/sub n/ and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.

• 동력기계공학회지
• /
• 제19권5호
• /
• pp.86-92
• /
• 2015

p-DCPD were prepared by in-suit ROMP polymerization using $MoCl_5$ and $Et_2AlCl$. The results showed that $MoCl_5:Et_2AlCl:DCPD$ mole ratio of 1:2.0:350 had the curing-time of 60sec and crosslinking degree of 90.44%. The curing time of DCPD polymerization by $MoCl_5/Et_2AlCl$ was shortened, and monomer conversion and crosslinking degree were decreased with temperature and the number of moles of $MoCl_5$ and $Et_2AlCl$. $MoCl_5$ and $Et_2AlCl$ is damaged its function by the reaction with the air in the atmosphere and did't proceed the polymerization properly.