本文選題：黃麻 + 漆酶　； 參考：《江南大學》2017年博士論文

【摘要】：近年來,采用自然界豐富的植物纖維(如麻纖維等)替代玻璃纖維和合成纖維作為樹脂基復合材料的增強體日益受到人們的關注。植物纖維增強復合材料具有質量輕、強度高、力學性能好等優(yōu)點,但由于植物纖維具有較強的極性和親水性,使其與非極性樹脂間的界面黏結性差,導致復合材料性能下降。為了得到性能優(yōu)良的植物纖維增強復合材料,需要對植物纖維進行表面改性,降低植物纖維的親水性,提高與疏水性樹脂基體間的相容性。本課題利用黃麻纖維表面富含木質素及漆酶可催化氧化木質素分子結構中的酚羥基產生自由基的特性,引發(fā)具有疏水結構的外源功能單體(沒食子酸月桂酯、十八胺)接枝到黃麻纖維表面的木質素上,實現(xiàn)黃麻纖維的表面疏水化改性,建立一種新型、高效的非均相體系下基于漆酶催化作用的麻纖維生物法接枝功能化改性方法,并將生物法表面疏水改性的黃麻纖維用于增強非極性聚丙烯(PP)樹脂制備復合材料。通過研究麻纖維-酶-功能分子(疏水性單體)三者組成的非均相體系下麻纖維疏水性表面的酶法高效構筑與調控、麻/樹脂復合材料界面結構特征和力學性能及其與纖維表面性能之間的關系,提高麻增強復合材料中麻纖維與樹脂的界面相容性,進而提高界面的黏結強度和復合材料的整體性能。主要研究內容和結論如下:首先,研究了非均相體系下漆酶處理對黃麻纖維中木質素含量、化學結構及黃麻織物性能的影響。黃麻纖維經漆酶處理后,僅少部分木質素(約占總木質素的4%)發(fā)生降解溶于反應液中;大部分木質素仍保留在纖維上,且發(fā)生聚合、分子量增大、分子量分布變寬,同時木質素被漆酶氧化,分子結構中酚羥基及甲氧基含量減少,羰基含量增加,結構單元間連接方式β-O-4和β-β鍵的比例降低,β-5和β-1結構增多;黃麻纖維表面(復合胞間層)的木質素濃度高于纖維主體中,有利于基于木質素的漆酶催化纖維表面改性。漆酶處理黃麻織物表面木質素的酚羥基含量減少,醚鍵基團增多;織物的表面疏水性略有提高,由未處理的靜態(tài)水接觸角98.7°、潤濕時間22.0 s增至漆酶處理的接觸角109.2°、水滴潤濕時間79.4 s;木質素在漆酶催化作用下發(fā)生前期降解-后期聚合的可逆反應,使黃麻纖維表層凸出的木質素在纖維表面移位重組,木質素等較緊密地附著在表面上,黃麻纖維表面變得較為平整、光滑、有序;由于纖維間木質素發(fā)生交聯(lián)聚合,使黃麻織物的拉伸斷裂強力提高,緯向增加4.9%、經向增加2.6%,同時由于纖維表面變得光滑,紗線中纖維間的抱合力降低,織物的斷裂伸長率得到提高,緯向增加173.0%、經向增加151.7%。其次,研究了利用黃麻織物富含木質素及漆酶催化木質素、沒食子酸月桂酯的酚羥基形成自由基引發(fā)交聯(lián)耦合的特性,將分子結構中含長烷基鏈的疏水性外源單體-沒食子酸月桂酯(DG)在非均相體系漆酶催化作用下接枝到黃麻織物表面。首先,通過ATR-IR、XPS、SEM、AFM等測試手段對其進行了定性表征;其次,采用稱重法和皂化返滴定法對黃麻織物的漆酶催化接枝DG反應進行了定量表征,稱重法測得的單體接枝率為4.16%,接枝效率為49%,皂化返滴定法測得的接枝黃麻織物上DG的含量為3.19%;漆酶催化黃麻織物接枝DG的最佳反應條件為緩沖液p H 3、漆酶用量1.0 U/m L、單體用量5 m M、反應溫度50℃、反應時間4 h;黃麻織物經酶促接枝沒食子酸月桂酯后,表面疏水性得到提高,由未處理的靜態(tài)水接觸角29.8°、水滴潤濕時間3.6 s增至接枝改性處理的接觸角111.5°、潤濕時間≥30 min。而后,研究了利用黃麻織物富含木質素及漆酶催化氧化木質素形成自由基引發(fā)伯胺類化合物交聯(lián)耦合的特性,將分子結構中含長烷基鏈的疏水性外源單體-十八胺(OA)在非均相體系漆酶催化作用下接枝到黃麻織物表面的木質素上。首先,通過ATR-IR、XPS、SEM等測試手段對其進行了定性表征;其次,將漆酶催化接枝十八胺后黃麻織物中的木質素提取出來進行MALDI-TOF MS和1H-NMR、13C-NMR、HSQC-NMR等分子結構表征,證明在漆酶催化作用下伯胺類單體以共價鍵接枝到黃麻織物的木質素結構單元上;然后,采用微量凱氏定氮法對黃麻織物的漆酶催化接枝OA反應進行了定量表征,測得的單體接枝率為0.712%,接枝效率為10.571%,由于伯胺類單體本身不能被漆酶催化聚合,只能發(fā)生與木質素自由基的耦合反應接枝到木質素分子上或木質材料表面,剩余單體可回收再用,而酚類單體在漆酶催化作用下不可避免地發(fā)生自聚反應,降低了單體的利用率,故伯胺類單體較酚類單體在實際應用中更具有經濟優(yōu)勢。經酶促接枝十八胺后,黃麻織物的表面疏水性得到提高,由未處理的前進接觸角43.5°、后退接觸角零、水滴潤濕時間4 s增至接枝改性處理的靜態(tài)接觸角112.5°、前進接觸角116.4°、后退接觸角42.7°、潤濕時間1110 s;對漆酶催化接枝反應過程中的單體濃度和反應時間進行工藝優(yōu)化,發(fā)現(xiàn)隨單體濃度增加,OA在黃麻織物上的接枝率逐漸增加,但單體的接枝效率不斷降低。隨反應時間延長,黃麻織物的接枝率與單體的接枝效率均逐漸增加,但超過12 h后增長變得緩慢。黃麻織物的接觸角和潤濕時間表現(xiàn)出不同的增長趨勢,潤濕時間隨單體濃度或反應時間的增加逐漸提高,而接觸角在織物接枝處理后迅速增加,但隨單體濃度或反應時間的增加基本維持不變。最后,將漆酶催化改性后的黃麻織物用于增強PP樹脂制備復合材料。僅經漆酶處理的黃麻織物與PP復合材料的力學性能有所提升,與對照樣相比,拉伸斷裂強力提高4.5%,拉伸模量提高18.2%,剪切斷裂強力提高14.7%,剪切模量提高32.6%,但斷裂伸長率均降低,拉伸斷裂伸長率降低2.9%,剪切斷裂伸長率降低12.8%。動態(tài)熱機械性能中,復合材料的儲能模量增加,基體樹脂熔融溫度略有提高;DG接枝疏水化黃麻織物/PP復合材料的拉伸斷裂強力較未處理樣提高了58.3%,斷裂面較為規(guī)則、整齊,纖維與樹脂同時被拉斷,表現(xiàn)出良好的界面黏結性;OA接枝疏水化黃麻織物/PP復合材料的拉伸斷裂強力和楊氏模量較未處理樣分別提高了82.0%和22.2%,當復合材料拉伸時增強纖維與樹脂基體一起受力斷裂,斷裂面較為平整,同時復合材料的儲能模量與損耗模量提高,表明改性后的黃麻織物與PP樹脂的界面相容性改善,界面黏結牢度增強。
[Abstract]:In recent years, more and more attention has been paid to the use of natural rich plant fiber (such as hemp fiber, etc.) instead of glass fiber and synthetic fiber as resin matrix composites. Plant fiber reinforced composites have the advantages of light quality, high strength and good mechanical properties, but the plant fiber has strong polarity and hydrophilic properties. In order to get better performance of the plant fiber reinforced composites, the surface modification of plant fiber, the hydrophilicity of the plant fiber and the compatibility with the hydrophobic resin matrix are needed to obtain the excellent performance of the plant fiber reinforced composites. The quality and laccase can catalyze the properties of free radicals produced by the phenolic hydroxyl groups in the molecular structure of the lignin, and lead to the grafting of the exogenous functional monomers (laurate gallate, eighteen amine) onto the lignin on the surface of jute fiber, and the hydrophobic modification of jute fibers can be realized, and a new and highly efficient heterogeneous system is established. A modified method of functional modification of hemp fiber based on laccase catalysis was used, and the hydrophobically modified jute fiber was used to enhance the preparation of non polar polypropylene (PP) resin. The hydrophobic surface of hemp fibers under the heterogeneous system of three groups of hemp fiber, enzyme functional molecules (hydrophobic monomers) was studied. The relationship between the interfacial structural characteristics and mechanical properties of the hemp / resin composites, the relationship between the interfacial properties and the surface properties of the hemp / resin composites, the interfacial compatibility between the hemp fibers and the resin in the linen reinforced composites, and the bonding strength of the interface and the whole properties of the composites are improved. The main contents and conclusions are as follows: first, The effect of laccase treatment on lignin content, chemical structure and performance of jute fiber in jute fiber was studied under the heterogeneous phase system. After laccase treatment, only a few lignin (about 4% of total lignin) were degraded in the reaction solution, and most lignin was retained on the fiber, and the molecular weight was increased and the molecular weight was increased. The distribution of the seed quantity is broadened, and the lignin is oxidized by laccase, the content of phenol hydroxyl and methoxy in the molecular structure is reduced, the content of carbonyl group is increased, the proportion of beta -O-4 and beta - beta bond between the structural units is reduced, the structure of beta -5 and beta -1 is increased, and the lignin concentration of the jute fiber surface (intercellular layer) is higher than that of the fiber body, which is beneficial to wood based on wood. Laccase laccase catalyzes the surface modification of the fiber. The phenol hydroxyl content of the lignin on the jute fabric is reduced and the ether bond group increases. The surface hydrophobicity of the fabric is increased slightly, the untreated static water contact angle is 98.7 degrees, the wetting time is 22 s to 109.2 degrees of the contact angle of laccase treatment, and the wetting time of water droplets is 79.4 s; the lignin is urging in laccase. The reversible reaction of early degradation and later polymerization under the action of chemical reaction makes the convex lignin on the surface of jute fiber displaced and reorganized on the surface of the fiber, and the lignin is attached to the surface more closely. The surface of jute fiber becomes more smooth, smooth and orderly. The tensile fracture strength of the jute fabric is caused by the crosslinking polymerization of the lignin in the fiber. In addition, the latitudes increase by 4.9%, the meridian increase of 2.6%, and the smoothness of the fiber surface, the tensile strength of the fibers in the yarn is reduced, the elongation at break of the fabric is increased, the latitude is increased by 173%, and then 151.7%. is added to the lignin and laccase catalyzed lignin and the phenol hydroxyl group of lauryl gallate. The properties of crosslinking coupling caused by free radicals were formed, and the hydrophobic exogenous monomers of the molecular structure, DG, were grafted onto the surface of jute fabric under the catalysis of inhomogeneous laccase. First, the qualitative characterization was carried out by means of ATR-IR, XPS, SEM, AFM and so on. Secondly, weighing method and saponification were used. The DG reaction of the laccase catalyzed grafting of jute fabric was quantitatively characterized by back titration. The grafting rate of the monomer was 4.16%, the graft efficiency was 49%, the content of DG on the grafted jute fabric obtained by saponification back titration was 3.19%, and the best reaction condition of the laccase catalyzed grafting of jute fabric to DG was the buffer solution P H 3 and the laccase dosage 1 U/m L The monomer dosage is 5 m M, the reaction temperature is 50 C and the reaction time is 4 h, and the surface hydrophobicity of jute fabric is improved by enzymatic grafting of lauryl gallate, the surface hydrophobicity of the jute fabric is improved, the untreated static water contact angle is 29.8 degrees, the wetting time of water droplet is 3.6 s to the grafting modification contact angle 111.5 degrees, and the wetting time is more than 30 min., then the use of jute fabric is studied. The properties of the crosslinking coupling of lignin and laccase catalyzed oxidation of lignin to form free radicals to induce the crosslinking of primary amine compounds, the hydrophobic exogenous monomer - eighteen amine (OA) in the molecular structure was grafted onto the lignin on the surface of jute fabric under the catalysis of inhomogeneous system laccase. First, ATR-IR, XPS, SEM and other testing methods Secondly, the lignin in jute fabric was extracted by grafting laccase catalyzed by laccase to carry out MALDI-TOF MS, 1H-NMR, 13C-NMR, HSQC-NMR and other molecular structures. It was proved that under the catalysis of laccase, the primary amine monomers were grafted onto the lignin structural unit of jute fabric with covalent bonds. The Kjeldahl method was used to quantitatively characterize the OA reaction of the laccase catalyzed grafting of jute fabric. The monomer grafting rate was 0.712% and the graft efficiency was 10.571%. Because the primary amine monomer itself could not be polymerized by laccase, the coupling reaction with lignin free radicals could only be grafted onto the lignin molecule or the wood material surface. The body can be reclaimed and reused, and the self polymerization of the phenolic monomers will inevitably occur under the catalysis of laccase, which reduces the utilization of the monomer. Therefore, the primary amine monomers have more economic advantages than the phenolic monomers in the practical application. After the grafting of eighteen amine, the surface water thinability of jute fabric is improved and the untreated advance contact angle is 43.5. The wetting time of water droplet was 4 s to 112.5 degree of static contact angle of graft modification, 116.4 degree of advance contact angle, 42.7 degree back contact angle and 1110 s wetting time, and the grafting of monomer and reaction time during the reaction process of laccase were optimized, and the grafting of OA on jute fabric with the increase of monomer concentration was found. The grafting efficiency of the monomer gradually decreased, but the grafting efficiency of jute fabric and the grafting efficiency of the monomer increased gradually with the reaction time. The contact angle and wetting time of jute fabric showed a different growth trend, and the wetting time increased with the increase of monomer concentration or reaction time with the increase of the reaction time. Gradually, the contact angle increased rapidly after the grafting of the fabric, but with the increase of the monomer concentration or the reaction time. Finally, the jute jute fabric modified by laccase was used to enhance the PP resin composite. The mechanical properties of the jute and PP composites treated only by laccase were improved and compared with the control samples. Tensile fracture strength increased by 4.5%, tensile modulus increased by 18.2%, shear fracture strength increased by 14.7%, shear modulus increased by 32.6%, but elongation at break decreased by 2.9%, elongation at shear elongation decreased in 12.8%. dynamic thermal mechanical properties, the storage modulus of composite material increased and the melting temperature of matrix resin increased slightly. The tensile strength of DG grafted hydrophobically hydrophobic jute fabric /PP composite is 58.3% higher than that of untreated sample, and the fracture surface is more regular and regular. The fiber and resin are broken at the same time, showing good interfacial adhesion; the tensile strength and Young's modulus of the OA graft hydrophobic jute fabric /PP composite are higher than those of the untreated samples. 82% and 22.2%, when the composite is stretched, the strength of the reinforced fiber and the resin matrix is broken, the fracture surface is more flat, and the energy storage modulus and loss modulus of the composites are improved, indicating that the interfacial compatibility of the modified jute fabric and the PP resin is improved, and the adhesion strength of the interface is enhanced.

【學位授予單位】：江南大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TS102.223;TS195.6

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