發(fā)布時(shí)間：2018-12-30 21:16

【摘要】：納米纖維素以其獨(dú)特的性能成為一種優(yōu)良的聚合物增強(qiáng)材料,采用納米纖維素復(fù)合水性涂料,有望改善水性涂料的漆膜性能,擴(kuò)展納米纖維素在水性涂料領(lǐng)域的應(yīng)用。以往的研究中,纖維素納米晶(CNC)已被較多地應(yīng)用于增強(qiáng)水性涂料,但纖維素納米纖絲(CNF)的應(yīng)用還不多,主要原因是其在水相中的分散穩(wěn)定性和與有機(jī)聚合物基質(zhì)的相容性還沒完全解決。鑒于此問題,本研究提出采用雙親性化學(xué)偶聯(lián)劑來改性纖維素納米纖絲并使其與水性涂料基體形成化學(xué)交聯(lián),從而實(shí)現(xiàn)纖維素納米纖絲在水性涂料中的均勻分散、長(zhǎng)期穩(wěn)定和良好的界面親和性,進(jìn)而綜合提高涂料的成膜性能。論文首先通過化學(xué)預(yù)處理結(jié)合高強(qiáng)度超聲波的方法制備了纖維素納米纖絲,考察了添加不同比例的硅烷偶聯(lián)劑(KH550)對(duì)其表面接枝改性和分散穩(wěn)定性的影響效果,并將改性后的纖維素納米纖絲水懸浮液添加到水性丙烯酸涂料中,制備得到納米纖維素復(fù)合涂料并通過澆鑄法和刷涂法得到相應(yīng)的復(fù)合涂膜。通過透射電子顯微鏡、傅里葉紅外變換光譜、X射線光電子能譜、旋轉(zhuǎn)流變儀、差式掃面量熱儀和萬能力學(xué)實(shí)驗(yàn)機(jī)等手段對(duì)改性纖維素納米纖絲的分散狀態(tài)、表面化學(xué)結(jié)構(gòu)、流變和相轉(zhuǎn)變特性,對(duì)復(fù)合涂料及其所制成復(fù)合涂膜的成膜特性、透明性、光澤度、微觀形貌、斷裂形式、熱機(jī)械性能、硬度和耐磨性等進(jìn)行了綜合考察。主要結(jié)果如下：(1)纖維素納米纖絲水懸浮液的濃度對(duì)其分散穩(wěn)定性有很大影響,濃度過低在制備完成后很快就會(huì)出現(xiàn)沉降分層現(xiàn)象,濃度過高會(huì)出現(xiàn)凝膠現(xiàn)象。采用KH550可以提高纖維素納米纖絲在水中的分散穩(wěn)定性,但是添加量過少或過多都不能達(dá)到最好的效果。實(shí)驗(yàn)表明添加量為0.16%時(shí),水懸浮液可保持長(zhǎng)期穩(wěn)定狀態(tài)。(2)經(jīng)過KH550改性后的纖維素納米纖絲在涂料中能夠分散均勻,且與涂料有良好的界面相容性。改性纖維素納米纖絲水懸浮液的添加量會(huì)對(duì)復(fù)合涂料的整體產(chǎn)生影響,隨著纖維素納米纖絲添加量的增加,復(fù)合涂料的粘度、彈性模量、玻璃態(tài)轉(zhuǎn)變溫度、硬度和耐磨性等均明顯提高,其中彈性模量最高可提高5倍,硬度提高2級(jí),磨損量降低35%。(3)復(fù)合涂料成膜后具有良好的光透明性,纖維素納米纖絲在漆膜中均勻分散,不會(huì)形成團(tuán)聚而影響可見光的透過率,其可見光透光率可保持在80%-90%,光澤度幾乎沒有變化。綜上表明,采用適量的KH550改性后的纖維素納米纖絲來增強(qiáng)水性丙烯酸涂料,不會(huì)明顯影響其透光性和光澤度,但可顯著提高涂料的綜合性能。
[Abstract]:Nanocellulose has become an excellent polymer reinforced material with its unique properties. The application of nano-cellulose composite water-based coatings can improve the film properties of water-based coatings and expand the application of nano-cellulose in water-based coatings. In previous studies, cellulose nanocrystalline (CNC) has been widely used in water-based coatings, but cellulose nano-fiber (CNF) has not been widely used. The main reason is that the dispersion stability and compatibility with organic polymer matrix in aqueous phase have not been completely solved. In view of this problem, an amphiphilic chemical coupling agent was proposed to modify cellulose nanofilaments and form chemical crosslinking with waterborne coatings matrix, so as to achieve uniform dispersion of cellulose nanofilament in waterborne coatings. Long-term stability and good interface affinity, and then improve the film-forming properties of the coating. Cellulose nanofilaments were prepared by chemical pretreatment and high intensity ultrasound. The effects of silane coupling agent (KH550) on the surface grafting modification and dispersion stability were investigated. The modified nano-fiber water suspension was added to the waterborne acrylic coatings to prepare the nano-cellulose composite coatings and the corresponding composite coatings were obtained by casting and brushing methods. By means of transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, rotary rheometer, differential scanning calorimeter and universal mechanical tester, the dispersion state and surface chemical structure of modified cellulose nanofilament were studied. The properties of film formation, transparency, gloss, micromorphology, fracture, thermo-mechanical properties, hardness and wear resistance of composite coatings and their films were investigated. The main results are as follows: (1) the concentration of cellulose nanofilament aqueous suspension has a great influence on its dispersion stability. When the concentration is too low, the phenomenon of sedimentation and delamination will occur soon after the preparation, and the phenomenon of gel will occur when the concentration is too high. KH550 can improve the dispersion stability of cellulose nanofilament in water, but too little or too much addition can not achieve the best effect. The experimental results show that the water suspension can maintain a stable state for a long time when the addition amount is 0.16. (2) the cellulose nanofilament modified by KH550 can be dispersed uniformly in the coating and has good interface compatibility with the coating. The content of water suspension of modified cellulose nanofilament will have an effect on the whole composite coating. With the increase of the amount of cellulose nanofilament, the viscosity, elastic modulus and glass transition temperature of the composite coating are increased. The hardness and wear resistance of the composite coatings were obviously improved. The elastic modulus was increased by 5 times, the hardness was increased by 2 grades, and the wear amount was reduced by 35. (3) the composite coatings had good transparency after forming film. Cellulose nanofilament was uniformly dispersed in the paint film and could not form agglomeration which affected the transmittance of visible light. The visible light transmittance of cellulose nanofilament could be kept in the range of 80-90 with almost no change in glossiness. The results show that proper amount of cellulose nanofilament modified by KH550 to strengthen waterborne acrylic coatings will not obviously affect its transmittance and gloss, but can significantly improve the comprehensive properties of the coatings.
【學(xué)位授予單位】：東北林業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O636.11;TQ637

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本文編號(hào)：2396158