本文選題：廢棄木材人造板 + 脲醛樹脂�。� 參考：《華南農(nóng)業(yè)大學(xué)》2016年碩士論文

【摘要】：廢棄木材中所含的膠粘劑雜質(zhì)一直是廢棄木材回收利用中需解決的重點(diǎn)問題,而脲醛樹脂由于其廉價(jià)、易制備、膠接性能好等特點(diǎn)成為木材中運(yùn)用最廣的膠粘劑。本文選取廢棄木材回收中所含的脲醛樹脂為對(duì)象,通過分析和比較新舊膠粘劑固化體系的界面形態(tài)、化學(xué)結(jié)構(gòu)、熱學(xué)性能的差異,了解舊膠粘劑體系對(duì)于新膠粘劑體系的物理化學(xué)狀態(tài)的影響。通過測(cè)試用含有舊膠粘劑顆粒制備的膠合板的力學(xué)性能,確定舊膠粘劑顆粒大小、含量多少對(duì)于回收制備新人造板的影響,從而為人造板的回收再造提供理論基礎(chǔ)及應(yīng)用指導(dǎo)。在廢棄木材制備纖維素產(chǎn)品的階段,采用了兩種方法分別得到纖維素納米晶與纖維素納米纖絲,通過正交實(shí)驗(yàn)等方法優(yōu)化納米纖維素的制備工藝參數(shù),獲得較為經(jīng)濟(jì)且效率較高的納米纖維素的制備方法。通過對(duì)比較含有脲醛膠對(duì)廢棄纖維板和純凈木粉所制備的各階段產(chǎn)物的產(chǎn)率、成分、熱學(xué)性質(zhì)、微觀形貌及其他物理化學(xué)性質(zhì),從而評(píng)定脲醛膠在廢棄木材制備納米纖維素時(shí)產(chǎn)生的影響。最終利用含有膠粘劑的廢棄人造板制備獲得高附加值的納米纖維素產(chǎn)品,提高廢棄人造板的利用價(jià)值。本文的主要研究結(jié)果可以歸納為:(1)舊的膠粘劑粉末在新的膠粘劑體系中未有融合成較為完整的交聯(lián)體,但是新形成的膠粘劑體系與舊的膠粘劑體系的成分并無變化。通過熱分析表明,在脲醛樹脂固化時(shí)加入粉末雜質(zhì)會(huì)對(duì)其固化反應(yīng)產(chǎn)生多個(gè)吸熱峰,并使固化反應(yīng)產(chǎn)生的總焓量增加。脲醛樹脂中參入雜質(zhì)并壓制膠合板,通過測(cè)定膠合板的膠合強(qiáng)度及浸漬剝離率可知,雜質(zhì)的混比增大會(huì)使得膠合板的膠合強(qiáng)度及浸漬剝離率這些膠合性能顯著下降。通過方差分析亦可知,當(dāng)混比處于較低的2%時(shí)增加雜質(zhì)的粒徑對(duì)于膠合性能造成的下降,不及當(dāng)混比上升到較高的6%時(shí)增加的雜質(zhì)粒徑對(duì)膠合性能造成的下降顯著。(2)在利用廢棄中纖板提取纖維素的階段,各階段產(chǎn)物產(chǎn)率、紅外及熱重結(jié)果表明廢棄木材中存在的脲醛樹脂膠粘劑會(huì)在反應(yīng)中發(fā)生水解,水解主要集中在強(qiáng)堿的處理的階段,脲醛樹脂上的醚鍵及羥甲基等官能團(tuán)上的化學(xué)鍵發(fā)生斷裂,但是水解反應(yīng)并未進(jìn)行完全,仍會(huì)有一些脲醛膠殘留在所制備的纖維素中,并且在中纖板粉末中的脲醛膠雜質(zhì)的殘留要多于直接混入木粉中膠粉的殘留。脲醛膠會(huì)使纖維素的熱解溫度開始溫度提前到250℃左右,而且熱解后的殘留物含量增加到20%以上。(3)在硫酸水解制備納米纖維素階段,設(shè)計(jì)的正交實(shí)驗(yàn)結(jié)果表明,硫酸水解的最佳工藝參數(shù)為:硫酸濃度65%、溫度60°、反應(yīng)時(shí)間為30min。產(chǎn)率和電導(dǎo)率數(shù)據(jù)表明了纖維素中殘存的膠粘劑會(huì)在反應(yīng)時(shí)同時(shí)水解,并可降低所制備的納米纖維素的磺酸化。XRD結(jié)果表明了在脲醛膠的影響下,纖維素和其所制備的納米纖維素的結(jié)晶度都有所降低。(4)在TEMPO氧化階段,不同的NaClO濃度和原料中的膠粘劑對(duì)于氧化階段的產(chǎn)率影響不大,但是從之后的機(jī)械研磨階段的產(chǎn)率可以看出增加NaClO濃度和研磨的時(shí)間會(huì)增大其機(jī)械研磨產(chǎn)率,加入的NaClO為5mmol/g,研磨時(shí)間30min為工藝優(yōu)化和較經(jīng)濟(jì)合理的反應(yīng)條件。而加入膠粘劑雜質(zhì)則會(huì)使其產(chǎn)率降低,增加NaClO濃度會(huì)加大纖維素上的羥基氧化成羧基的程度,而膠粘劑會(huì)使氧化反應(yīng)時(shí)的羧酸化程度降低。不同方法制備的納米纖維的微觀形貌有較大差異,而在沒有膠粘劑雜質(zhì)影響下的CNC沉淀與CNF的纖維寬度會(huì)比雜質(zhì)影響下制備的纖維寬度略小。
[Abstract]:The adhesive impurity contained in abandoned wood has always been the key problem to be solved in the recycling of abandoned wood. Urea formaldehyde resin has become the most widely used adhesive in wood because of its cheap, easy preparation and good adhesive properties. This paper selects urea formaldehyde resin in waste wood recovery and compares new and old adhesives. The influence of the old adhesive system on the physical and chemical state of the new adhesive system. By testing the mechanical properties of the plywood prepared with the old adhesive particles, the size of the old adhesive particles is determined and the content of the new adhesive is made for the preparation of the newlyweds. It provides theoretical basis and application guidance for the recovery and reengineering of wood-based panels. In the phase of cellulose products prepared by waste wood, two methods are used to obtain cellulose nanocrystalline and cellulose nanofibrils respectively. The preparation parameters of nanoscale are optimized by orthogonal experiment, and the results are more economical and more efficient. By comparing the yield, composition, thermal properties, micromorphology and other physical and chemical properties of the products of each phase prepared by the comparison of urea formaldehyde adhesive to the waste fiberboard and pure wood powder, the effects of urea formaldehyde gum on the preparation of nanofiber in waste wood were evaluated. The main results of this paper can be summarized as follows: (1) the old adhesive powder has not fused into a more complete cross body in the new adhesive system, but the newly formed adhesive system and the old adhesive system There is no change in composition. It is shown by thermal analysis that the addition of powder impurities in urea formaldehyde resin will produce a number of endothermic peaks and increase the total enthalpy of the curing reaction. The urea formaldehyde resin enters into the plywood with impurities and presses the plywood. It is known that the mixture ratio of the plywood is increased by measuring the adhesive strength of the plywood and the exfoliation rate of impregnation. The adhesive strength of plywood and the exfoliation rate of the plywood decreased significantly. By the analysis of variance, it can be found that when the mixing ratio is at a lower 2%, the particle size of the impurity is reduced to the gluing performance, and it is not as significant as the increase of the particle size to the gluing performance when the mixed ratio rises to a higher 6%. (2) The yield of the products in various stages, infrared and thermogravimetric results show that the urea formaldehyde resin adhesive in the abandoned wood will hydrolyze in the reaction. The hydrolysis is mainly concentrated in the stage of the treatment of strong alkali. The ether bonds on the urea formaldehyde resin and the chemical bonds on the Qiang Jiaji and other functional groups break, but the hydrolysis is hydrolyzed. The reaction is not complete, and some of the urea formaldehyde glue remains in the prepared cellulose, and the residue of urea formaldehyde in the MDF powder is more than that in the direct mixed wood powder. The urea formaldehyde glue will make the temperature of the cellulose pyrolysis temperature start to about 250 C, and the residue content after the pyrolysis is increased to 2. More than 0%. (3) the preparation of nanofibers in the hydrolysis of sulfuric acid. The orthogonal experimental results show that the optimum process parameters for the hydrolysis of sulfuric acid are as follows: the concentration of sulfuric acid 65%, the temperature 60 degree, the reaction time of 30min. yield and electrical conductivity data show that the residual adhesives in the cellulose can hydrolyze at the same time in the reaction and reduce the prepared nanofibers. The results of the sulfonated.XRD showed that the crystallinity of the cellulose and the nanoscale prepared by the UF was reduced. (4) in the TEMPO oxidation stage, the different NaClO concentration and the adhesive in the raw material had little effect on the yield of the oxidation stage, but the yield of the mechanical lapping phase after that was seen. The increase of NaClO concentration and grinding time will increase the mechanical grinding yield, the added NaClO is 5mmol/g, the grinding time 30min is the process optimization and the more economical and reasonable reaction conditions. The addition of the adhesive impurities will reduce the yield, the increase of NaClO concentration will increase the oxidation of the hydroxyl group on the cellulose to the carboxyl group, and the adhesive will make oxygen. The micromorphology of the nanofibers prepared by different methods is greatly different, but the width of CNC precipitation and the fiber width of CNF will be slightly smaller than that of the fibers under the influence of impurities.

【學(xué)位授予單位】：華南農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：X705;TQ352

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