불포화 폴리에스테르 수지의 물성이 폴리머 콘크리트의 강도에 미치는 영향

이필호,박재근,황보 영,이정우 강원대학교 석재복합신소재제품연구센터 1996 석재연 논문집 Vol.1 No.-

본 연구에서는 폴리머 콘크리트의 결합재인 불포화 폴리에스테르 수지(UPR)의 물리적 성질을 조사하였다. 그 결과는 비중 1.1 g/mL, 점도 3.0 poise, styrene의 함량은 40% 내외이고 산값은 약 20이었다. 본 실험에서 제조된 폴리머 콘크리트의 압축강도는 평균 1,056 Kg/cm², 휨강도는 216 Kg/cm², 인장강도는 110 Kg/cm²이었는데, 이는 시멘트 콘크리트에 비해 비교적 좋은 역학적 성질을 나타낸 것이다. 변동계수는 압축강도의 경우 약 3%, 휨강도의 경우 5%, 인장강도의 경우 6% 내외로서 매우 양호하다. 강도비를 산출하여 본 바 압축강도와 휨강도의 비가 4.9, 압축강도와 인장강도의 비가 9.7, 휨강도와 인장강도가 1.97로서 나타났는데 이는 폴리머 콘크리트의 압축강도는 1000 Kg/cm²를 상회함을 감안할 때 휨 및 인장강도가 상대적으로 큼을 보여주는 결과이다. In this study, effect on the strength of polymer concrete of unsaturated polyester Resin's(UPR) property was investigated. The physical property of UPR was as follows; density 1.1 g/mL, viscosity 3.0 poise, the content of styrene 40%, and acid value 20. The mechanical property of Polymer Concrete was relatively good; compressive strength 1,056 Kg/cm², flexural strength 216 Kg/cm², splitting tensile strength 110 Kg/cm², The coefficient of fluctuation was 3% of compressive strength, 5% of flexural strength, and 6% of splitting tensile strength. The ratios of respective strength were 4.9(compressive strength to splitting tensile strength), and 1.97(flexural strength to splitting strength). Therefore, flexural strength and splitting tensile strength of polymer concrete was relatively big under consideration of compressive strength(1,000 Kg/cm²).

전처리한 목섬유로 제조한 섬유판의 물리적 및 기계적 성질

李弼宇,辛榕洙 서울大學校 農業生命科學大學 農業開發硏究所 1996 서울대농학연구지 Vol.21 No.2

This paper reports on dimensional stability of the composites made from acetylated wood-fibers. The fiberboards at this study were made by different face-layer formulation ratios(10, 20, 30, 40 and 50%) of acetylated wood-fibers. In this experiment, acetylation of wood-fiber was reacted with liquid acetic anhydride in stainless steel cylinder. The WPG(weight percent gain) as a result of acetylation was calculated based on the weight of oven-dry untreated wood-fiber, and the 17% WPG could be achieved in reaction time from 2 hours. In physical properties of fiberbodards made from acetylated wood-fiber, thickness swelling and water absorption were more reduced than control fiberboards, but mechanical properties(MOR, MOE and IB) decreased with increasing of face-layer formulation ration of acetylated wood-fibers, which was probably due to poor adhesion and uncontinuous mat forming between acetylated fiberboards and control fiberboards. In the IB test on acetylated fiberboards most failure occurred in the boundary between acetylated face-layer and untreated core-layer. In the acetylated fiberboards, the failure was due to adhesive penetration and compressibility problems associated with acetylated fiber.

PMDI(Polymeric Methylene Diphenyl Diisocyanate)樹脂를 利用한 新聞古紙纖維-木纖維 混合 하드보드의 物理的 및 機械的 性質

李弼宇,李喆周 서울大學校 農業生命科學大學 農業開發硏究所 1996 서울대농학연구지 Vol.21 No.2

Conventional researches have reported that ONP(Old Newspaper) fiber mixed hardboard is inferior to wood fiber hardboard on physical and mechanical properties, specially, internal bond strength and dimensional stability are very poor. It is thought that wetted ONP fiber by using water soluble resin results in poor uniformity of resin distribution. Actually internal bond strength, to a large extent, depends upon the uniformity of resin distribution. The objective of this research was to compare the results from ONP fiber mixed hardboard using water soluble phenol resin with those from ONP fiber mixed hardboard using PMDI(Polymeric Methylene Diphenyl Diisocyanate) which get fiber less wet relatively. Boards were fabricated with ratios of ONP fiber to wood fiber of 0 to 100, 30 to 70, 50 to 50, 70 to 30 and 100 to 0, and tested for static bending strength, internal bond strength, tensile strength, water absorption and thickness swelling. As expected, ONP fiber mixed hardboard using water soluble phenol resin showed that physical and mechanical properties decreased with increasing of ONP fiber mixed level. However, those using PMDI showed opposite results, specially internal bond strength increased, and water absorption and thickness swelling decreased with ONP fiber mixed level ranging from 30% to 70%.

MDI(methylene diphenyl diisocyanate) 樹脂를 利用한 톱밥보드의 物性(Ⅱ) : 열압온도, 열압시간에 관하여 On the press temperature and press time

李弼宇,尹炯雲 서울大學校 農業生命科學大學 農業開發硏究所 1995 서울대농학연구지 Vol.20 No.1

導入羅王材와 國産材를 混用한 合板의 材質改善에 關한 硏究

李弼宇 서울大學校 農科大學 1977 서울대농학연구지 Vol.2 No.1

This study was planned to substitute the impoerted logs by American Sycamore (Platanus occidentalis), Italian poplar (Populus eurmericana), Korean White Oak (Quercus acutissima) and Korean Red Pine (Pinus densiflora) growing as major economical timber species in our country to relieve dem and for domestic plywood industry, which depends upon entirely foreign timber resources at present. Until present, our country has imported and utilized expensive lauan (Shorea, Parashorea and Pentacme of Dipterocarpaceae) logs producted in Indonesia, Malaysia, and Philippines of southern pacific region to supply the demand for domestic plywood industry. However because of the unfavourable conditions of rising cost and buying competition in log producing countries, at a first step of research to exploit the domestic timber products into veneer logs, this study was carried out to develope the plywood manufacturing process composing of imported lauan logs and cheap domestic timber products. Accordingly the study has important meanings for the promotion of plywood manufacture using domestic log products and the decrease of imported log quantities even a little, and also it has advantage for the cost down in plywood manufacture, and saves dollars. At this study the advantageous properties of upgrading plywood qualities were compared and discussed between plywood composed of sole lauan veneers, and plywood constructed by imported lauan and domestic timber species. Important items dealt with in this study were dry and wet shear strength, specific gravities, moisture contents, and bending strength. They were experimented as accordance with A.S.T.M. Standards as general, and analyzed statistically. By the analysis and discussions of the results, this study may be conclyded as follows: 1) In dry shear strength of plywoods composed of two species, most excellent results were shown by Lauan-Oak construction plywoods and strength values were decresed in following orders; Lauan-Sycamore, Lauan-Popar. The worst results were given by Lauan-Pine constructions. In plywoods composed of three species, high strength values were obtained from the plywoods constructed by Lauan, Oak and Sycamore, but comparatively low strength values were obtained from plywoods constructed with pine veneers. 2) In wet shear strength of plywood composed of two species, most excellent results were obtained from Lauan-Sycamore construction plywoods, and Lauan-Poplar constructions next order. Worse strength values were obtained from the plywoods constructed by Lauan-Oak with Lauan-Pine. In plywoods composed of three species, comparatively high strength values were obtained from the plywoods properly constructed by Lauan, Poplar and Sycamore, of Lauan, Oak and Sycamore. The decreasing tendency of wet shear strength as dry shear strength was obtained from plywoods constructed with pine veneers. 3) In dry shear strength of the plywoods constructed by thin 0.7∼0.9mm veneers, the recognizable, more excellent constructions of two species than all lauan veneer construction were Oak-Oak-Lauan(Q-Q-L), Lauan-Sycamore-Lauan (L-S-L), Lauan-Oak-Lauan(L-Q-L), Oak-Lauan-Oak(Q-L-Q), and Sycamore-Sycamore-Lauan(S-S-L) types, and in thick 1.3∼1.5mm veneer construction, they were Oak-Oak-Lauan(Q-Q-L), Lauan-Sycamore-Lauan(L-S-L), Lauan-Oak-Lauan (L-Q-L), Lauan-Poplar-Lauan(L-P-L), Lauan-Sycamore-Sycamore(L-S-S), and Lauan-Lauan-Oak(L-L-Q) types. In plywoods constructed by thin veneers of three species, the recognizable, more excellent con-structions were Oak-Poplar-Lauan(Q-P-L), Oak-Sycamore-Lauan (Q-S-L), Sycamore-Poplar-Lauan(S-P-L), Oak-Pine-Lauan (Q-P-L), and Sycamore-Oak-Lauan (S-Q-L) types, and in thick veneer constructions, they were Oak-Poplar-Lauan (Q-P-L), Oak-Sycamore-Lauan (Q-S-L), Sycamore-poplar-Lauan (S-P-L), Oak-Pine-Lauan(Q-N-L), and Sycamore-Oak-Lauan(S-Q-L) types. 4) In wet sheat strength of the plywoods constructed by thin 0.7∼0.9mm veneers, the recognizedable, more excellent constructions of two species than all lauan veneer construction were Sycamore-Sycamore-Lauan(S-S-L), Lauan-Sycamore-Lauan (L-S-L), Lauan-Poplar-Lauan(L-P-L), and Poplar-Poplar-Lauan(P-P-L), types, and in thick 1.3∼1.5mm veneer constru-ction, they were Sycamore-Sycamore-Lauan(S-S-L), Lauan-Sycamore-Lauan(L-S-L), Sycamore-Lauan-Sycamore(S-L-S), Lauan-Poplar-Lauan(L-P-L), and Lauan-Poplar-Poplar(L-P-P), types. In plywoods constructed by thin veneers of three species, the recognizable, more excellent constructions than all lauan veneer construction were Sycamore-poplar-Lauan (S-P-L), Poplar-Oak-Lauan (P-Q-L), Sycamore-Oak-Lauan(S-Q-L), Oak-Sycamore-Lauan (Q-S-L), and Poplar-Sycamore-Lauan(P-S-L), types. and in thick 1.3∼1.5mm veneer constru-ction, they were Oak-Sycamore-Lauan (Q-S-L), Lauan-Sycamore-Poplar (L-S-P), Sycamore-Oak-Lauan(S-Q-L), Sycamore-poplar-Lauan (S-P-L), Poplar-Oak-Lauan (P-Q-L) types. 5) In shear strength according to the thickness of veneers, the plywoods constructed by thick veneers showed higher values than plywoods constructed by thin veneers. Wet shear strength compared with dry shear strength considerably lowered under the same plywood construction. 6) Wood failures of all plywoods at dry test which composed of different species showed higher values than all lauan veneer plywood. In the wet test, they did not showed a definite tendency, and the avlue considerable lowered in comparison with the results at dry test. 7) In Wood failures according to the thickness of veneers, the plywoods constructed by thin veneers showed higher values than plywoods constructed by thick veneers. 8) In the phenol resined plywoods composed of different species, proper manufacturing condit-joins were considered as 150∼165℃ in plate temperature, 150∼210 1bs/in.²in press pressure, and 180∼240 seconds in pressing time in manufacture of plywood constructed by three sheets veneers of thickness 1.0∼1.2mm, and in the urea resined plywoods considered as 100-120℃ in plate tempertature, 150∼180 1bs/in.²in press pressure, and 90∼120 seconds in pressing time. 9) In the specific gravities of plywoods composed of two species, most excellent high values were obtained from the plywoods constructed by Lauan and Oak, and worst results from Lauan and Poplar construction. Also in the plywood composed of three species, the constructions comp-osed of above these species were remarkably affected by specific gravities of species. Especially all the plywoods composed of Sycamore and Oak showed higher values than all lauan veneer plywoods. 10) In the moisture contents of plywood, wide variation and significant differences were shown among the plywood construction types composed of different species, but its mositure contents differed from those of plywood constructed by single veneer species. 11) In the bending strength of plywood, all the plywoods compsed of different species showed higher values than all lauan veneer plywoods, and the strength decrease was shown prominently according to the increase of lauan veneer sheets which were constructed with veneers from domestic timber species.

리기다소나무 (Pinus rigida Miller) 판재의 압축이상재 (壓縮異常材) , 대응재 (對應材) 및 측면재 특성에 관한 주사전자현미경적인 연구

이필우,엄영근 한국목재공학회 1985 목재공학 Vol.13 No.1

In Korea, a study on the anatomical features of pitch pine(pinus rigida Miller) branch wood through photo-microscopical method was reported in 1972 by Lee. Therefore, as a further study of Lee's on the anatomical features in branch wood of pinus rigida miller that grows in Korea, compression wood, opposite wood, and side wood were selected and treated for the purpose of comparing their structures revealed on cross and radial surface through scanning electron microscope in this study. The obtained results in this study were summarized as follows: 1. The trachied transition from earlywood to latewoad is very gradual and the tracheids are nearly regular in both arrangement and size in compression wood but this transition in opposite wood and side wood is abrupt and the tracheids in opposite wood and side wood are less regular than those in compression wood. Also, the annual ring width of opposite wood is narrower than that of compression wood or side wood and the rays revealed on cross surface of side wood are more distinct than compression wood and apposite wood rays. 2. The tracheids of compression wood show roundish trends especially in earlywood but those of apposite wood and side wood show same angular trends. And intercellular space, helical cavity, and spiral chock are present in both earlywood and latewood of compression wood but not present in opposite wood and side wood irrespective of earlywood and latewood. 3. The wall thickness of latewood tracheid is similar to that of earlywood tracheid in compression wood whereas the wall thickness of latewood tracheid is by far thicker than that of earlywood tracheid in opposite wood and side wood and the S₃ layer of secondary wall is lack in comgression wood tracheid unlike opposite wood and side wood traeheid. 4. The tracheids in compression wood are often distorted at their tips unlike those in opposite wood and side wood and the bordered pit in compression wood tracheid is located at the bottom of helical groove unlike that in opposite wood and side wood tracheid. 5. The bordered pits in radial wall of apposite wood and side wood tracheids are oval in shape but those of compression wood tracheids show some modified oval shape. 6. in earlywood of side wood, the small apertures of cross-field pits are roundish triangle to rectangle and the large one are fenestriform through the caalition of two small ones. However, the small apertures of cross-field pits are upright oval and the large ones are procumbent oval shape in earlywood of opposite wood and the apertures of cross-field pits in compression wood are tilted bifacial convex lens shape in earlywood and slit in latewood because of the border on tracheid side.

數種의 增量劑 粒度와 增量比率에 따른 尿素樹脂合板의 接着 特性

楊翰承,尹炯雲,李弼宇 서울대학교 농과대학 농업개발연구소 1993 서울대농학연구지 Vol.18 No.2

The purpose of this research was to evaluate and to examine the substitutional feasibility of paper sludge extender instead of wheat flour. As the extending materials, taro flour, paper sludge, wood flour and wheat were selected and dried at 103±2℃ during 24 hours in the drying oven and pulverized into three levels(-50∼+100, -100∼+200, -200∼mesh). The extenders were mixed with urea formaldehyde resin in the ratio of 10, 20 and 30%. After plywoods were manufactured by the above extended ratios, dry and wet shear strength were examined. The results obtained at this research were summarized as follows : 1) In 10% extionsion on -50∼+100 mesh particle size, paper sludge showed the highest dry and wet shear strength among the extenders. 2) As 20% extension, wheat showed the highest value. 3) the shear strength was affected by the particle size and extending ratios, and the shear strength extended by paper sludge powder was sensitively varied with particle sizes and extending ratios. 4) The shear strength extended by taro and wheat flour were less affected by the particle size of extender. Therefore, the particle size of extender would be considered along the extention ratios and extender types.

경사판 시험에 의한 내화도료 처리가 목질판상재료의 내화성능 및 열저항변화에 미치는 영향

金顯中,尹榮基,李弼宇 서울대학교 농과대학 농업개발연구소 1991 서울대농학연구지 Vol.16 No.2

In this study the inclined panel test was used to compare the relative effectiveness in fire resistance among plywood. particleboard and medium density fiberboard which was treated with fire-retardant of chlorinated resin and non-coated ones. The results obtained were summarized as follows: 1. The medium density fiberboard ranked first in flammablility followed in turn by particleboard and plywood in non-coated treatments. 2. The rate of weight loss decreased with increasing level of coating quantity. 3. The highest fire-retardant effectiveness was found in plywood with C treated level. This effectiveness was mostly found in particleboard with C treated level. 4. The temperature of back in non-treated and treated board decreased with increasing level of coating quantity. 5. The weight loss of the tested samples which had high value of temperature decreasing showed low values. 6. The time that reached 99℃ on the back of plywood, PB and MDF in nontreated-board was 300sec, 180sec and 150sec, respectively but time that reached 99℃ on the back of PB, MDF in treated-board was 210sec, l50sec, and plywood did not reach 99℃.

A Study on the Physical Properties of wood Chip-Bark Mixed Particleboard

Lee, Phil Woo,Park, Heon 서울大學校 農科大學 1982 서울대농학연구지 Vol.7 No.1

本 硏究에서는 더글러스-훠 樹皮와 메탄티칩을 보드의 構成 原料로 하여 樹皮混入 파티클 보드를 製造하였다. 보드 전체 重量에 대하여 10, 20, 30, 80%로 수피 혼입량을 점차 增加시켰으며, 보드에 混入할 樹皮는 코아(中層)에 混合하여 그 構成方法을 세가지로 區分하였다. 즉, 樹皮를 코아 內層에 配置하고 木林칩을 코아 外層에 나누어 配置하는 方法, 木林칩을 코아內層에 配置하고 樹皮를 코아 外層에 나누어 配置하는 方法, 木林칩과 樹皮를 섞는方法 等으로 區分하여 다음과 같은 세가지 事項을 調査하였다. 첫째, 보드內의 樹皮混入量을 增加시킴에 따라 强度가 어떻게 감소하는가. 둘째, 樹皮 混入 파티클보드의 中層의 構成方法을 變化시킴에 따라서 强度가 어떻게 變化하는가 세째, 파티클보드의 强度를 維持하고 製造原價를 낮출 수 있는 適切한 樹皮混入水準을 알고자 하는 것이다. 實驗結果를 要約하면 다음과 같다. 1) 30% 樹皮 混入 파티클 보드중에서 中層 構成方法이 木林칩과 樹皮를 混合하는 方法인 경우와 80% 樹皮混入 파티클 보드를 除外하고 모든 보드의 휨强度가 KS F 3104에 規定되어 있는 100type 規格을 만족시킨다. 2) 剝離抵抗强度는 80% 樹皮混入 파티클보드를 除外하고는 모든 보드가 KS F 3104의 規格을 만족시킨다. 3) 樹皮混入率이 增加함에 따라 보드의 휨强度, 剝離抵抗, 두께 수膨脹率等이 減少한다. 4) 含水率은 樹皮混入率이 增加함에 따라서 점차 增加한다. 5) 휨 强度에 있어서 코아의 構成方法에 따른 有意差는 없었지만, 목재칩을 코아 外層에 나누어 配置하고 樹皮를 코아 內層에 配置한 方法의 平均 휨强度가 세가지 構成方法 중에서 가장 높았다. 6) 木林칩을 코아 內層에 配置하고 樹皮를 코아 外層에 나누어 配置하는 方法의 剝離抵抗이 다른 方法보다 높았으며, 특히 木林칩과 樹皮를 섞는 方法의 경우와는 有意差를 나타냈다. 7) 木林칩을 코아 內層에 配置하고 樹皮를 코아 外層에 나누어 配置한 方法의 두께 膨脹率이 다른 두가지 方法보다 훨씬 낮아서 有意差를 나타냈다. 8) 두께 膨脹率의 경우와 같이 木林칩을 코아內層에 配置하고 樹皮를 코아外層에 配置한 보드의 含水率이 다른 두가지 方法보다 훨씬 낮아서 有意差를 나타냈다. 9) 樹皮混入 파티클보드의 경우, 熱壓時一般製造 方法보다 壓力을 높게하였을 때 휨강도와 박리저항 강도가 더욱 向上된다.

Wood Anatomical Characteristics of Korean Coniferous and Broad-leaved Trees

Lee, Phil Woo 서울大學校 農業生命科學大學 附屬樹木園 1998 서울大學校 樹木園 硏究報告 Vol.- No.18

本 연구는 韓國産 針葉樹와 闊葉樹의 本材解剖學的 特性을 考察하기 爲하여 착수하였다. 木材試片, 解籬纖維 및 永久스라이드는 서울大學校 수원캠퍼스의 農業生命科學大學, 林産工學科, 木材解剖實驗室에 所藏되어 있는 材料를 利用하였다. 실험재료는 針葉樹 16屬, 31種, 61個體이였으며 闊葉樹 153屬, 286種, 514個體로 全國에서 採取한 材料이다. 肉眼的 特徵의 調査項目으로는 年輪, 心材와 邊材, 放射線, 材色, 香氣와 味등을 調査하였다. 그리고 顯微鏡的 特徵은 導管, 假導管, 本纖維, 垂直柔細胞와 放射柔細胞, 放射組織의 構造와 細胞間構 等의 특징을 光學顯微鏡으로 觀祭하고 調査하였다. 관찰된 肉眼的·顯微鏡的 特性을 樹種別로 종합하였다. 이 結果에 의하여 韓國産 針葉樹材와 闊葉樹材의 出現特徵率이 계산되었으며 針葉樹材와 闊葉樹材 사이에 나타나는 特徵率을 比較 考察하였다. This study was carried out to investigate the wood anatomical characteristics of coniferous and broad-leaved trees growing in Korea. The wood specimens, macerated wood fibers, and permanent slides were utilized for the experimental materials stored in Wood Anatomy Laboratory, Department of Forest Products, College of Agriculture and Life Sciences, Seoul National University. Examined materials were 61 individuals, 31 species and 16 genera in coniferous and were 514 individuals, 286 species and 153 genera of hardwood trees. The macroscopical items of the features such as annual rings, sap and heartwoods, wood rays, wood colors, odors and tastes were observed. The macroscopical items of the features such as vessels, tracheids, wood fibers, longitudinal and ray parenchymas, ray constructions, and intercellular canals were examined by light microscope. From the results of the macro- and microscopic features of the species, the anatomical characteristics by the species were synthesized. The appearing feature percentages of Korean softwoods and hardwoods were calculated and investigated.