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Study on the Improving Efficiency of Incombustibility of Plywood Treated by Fire Retardants Double Diffusion Method
|關鍵字:||Double diffusion;雙重擴散;Fire retardant plywood;Thermogravimetry analysis;Oxygen index;Surface flaming characteristics;Cone calorimeter;Weight percentage gain;SEM-EDXA;耐燃合板;熱重分析;氧氣指數;表面燃燒性;圓錐量熱儀;重量增加率;掃描式電顯-能量分散式X射線元素分析||出版社:||森林學系||摘要:||
本研究採「雙重擴散」法，磷酸氫二銨為第一液與十三種第二液之無機鹽飽和溶液反應劑處理生材試材，以探討各藥劑處理對試材藥劑重量增加率之影響。並以掃描式電子顯微微鏡─能量分散式χ射線分析儀技術，探討不同藥劑於試材中分布情形。次以熱重分析技術，探討藥劑處理纖維素試材之熱降解特性，並以氧氣指數試驗法，評估各藥劑處理材之抑焰性效應，篩選耐燃效果較佳之藥劑組合，作為製造耐燃合板之藥劑。製得之耐燃合板再以表面燃燒性試驗(CNS 6532)及圓錐量熱儀試驗(ISO 5660)探討各處理合板之耐燃性改善效應。
空氣中：OI (v/v, %) = 1.0408 (CR, %) + 14.5970 (1)R2 = 0.5154*
氮氣中：OI (v/v, %) = 2.0114 (CR, %) + 2.3541 (2)R2 = 0.6388**
耐燃藥劑雙重擴散處理之合板，於高濃度(40 % ~ )處理時，有呈現藥劑沉積於試材表面之虞，此將影響後續加工性質，值得注意。
Despite all the favorable characteristics of wood, such as health
enhancement, minimum environmental impact, comfortable feeling at contact, this eco-material categorized lingocellulosic substance still pertains its unfavorable combustible property. To augment its application, it is of extreme importance to improve its flammability.
Double-diffusion process was introduced to examine the combined effects of various chemicals on the weight percentage gains of the treated specimens. Diammonium phosphate (DAP) was used in the first step for impregnation, followed by thirteen inorganic saturated solutions. SEM-EDXA, andχ-ray diffraction technique were applied to study the distribution of the diffused
chemicals in the specimens. Thermogravimetric analysis was then adopted to explore the pyrolysis characteristics of the said cellulosic materials. Flame inhibition efficiency of the processed specimens was evaluated by the Oxygen Index (OI) method, to screen out the chemical combinations of better fire
retardancy. Fire retardant plywood was produced and examined via surface combustibility test (CNS 6532) and cone calorimeter method (ISO 5660) to study the fire retardant improving efficiency of the processed plywood.
The results showed that the chemical weight percentage gains of the specimens were the functions of impregnation timeof chemicals; DAP's concentration, types of saturated chemicals and species of wood used . Complex salts derived from the reaction of the double diffused reagents were deposited in the wood tissue and observed through SEM-EDXA images. Fire retardant mechanisms such as the reducing of pyrolysis onset temperature and the increasing of char residue were characterized for the treated specimens.
Thermogravimetric analysis was proved suitable for the understanding of processed cellulosic materials' pyrolysis and was thus adopted as a standard for the evaluation of the fire retardant efficiency of chemicals. The double-diffused specimens were proved to possess better flame inhibition through OI method.
Chemicals weight percentage gains. Type of chemicals and wood species were found to be the key factors that affected specimens' flame inhibition.
A linear regression equation could be derived from the Oxygen Index and char residue amount of the double-diffusion specimens with significant to highly significant correlation. Equations (1) and (2) indicated a close relation between chemicals' flame inhibition and char production.
OI air (v/v, %) = 1.0408 (CR, %) + 14.5970 (1) R2 = 0.5154*
OI N2 (v/v, %) = 2.0114 (CR, %) = 2.3541 (2) R2 = 0.6388**
Eight combinations of the diffusing chemicals were screened from the results of thermogravimetric analysis and flame inhibition test. Boric acid, boron oxide, barium chloride, calcium chloride, zinc chloride, zinc sulfate and aluminum sulfate provided better flame inhibition when deposited with the diammonium phosphate solution. These chemicals were recommended to be used for the manufacturing of quality fire retardant plywood.
The incombustibility of most treated plywood met the standard of third grade requirement as specified in CNS 6532 through surface combustion test. Factors affecting the fire retardancy improving for the processed plywood were chemicals weight percentage gains, types of chemicals and resin used.
The average heat or releasing rate, peak of heat releasing rate and total released heat of the processed plywood showed significant improvement via cone calorimeter test. Processed plywood's category could be to 2-3 grade upgraded according to the system combustibility degree by (CAN/ULC S 135-1992).
Processed plywoods were harder and more brittle, comparing to the raw materials, due to the deposition of two inorganic chemicals, which were observable on the surface when the concentration of the chemicals were higher than 40 %. The afterward processing was thus influenced. Processed plywoods that passed 3rd grade fire retardancy standard through surface combustibility test met the 3rd and above grade determined by the cone carolimeter in Canadian materials' standard. Those failed in the 3rd grade fire retardancy of surface combustibility test fulfilled the requirement of the 4th and above grade of the said standard. These comparisons showed that surface combustibility standard is more stringent than the CAN/ULC S 135-1992.
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