環(huán)氧樹脂的改性研究進展外文翻譯

1、<p>　　Modification of epoxy resin are reviewed</p><p>　　Rehana Fowzia and Mahmuda Nasrin </p><p>　　Abstract: the article introduces the characteristics of the epoxy resin and epoxy resin mo

2、dified improve the toughness of epoxy resin, which is the main trend, respectively discusses the rubber toughening epoxy resin, thermoplastic elastomer toughening epoxy resin, thermotropic liquid crystal polymer tougheni

3、ng epoxy resin, flexible chain segment curing agent, toughening epoxy resin, inorganic nanomaterials modified epoxy resin and interpenetrating network (IPN) structure of toughening modificat</p><p>　　Keyword

4、s: epoxy resin; Toughening.;modified</p><p>　　Intorduction</p><p>　　Epoxy resin (EP) is a polymer matrix composites [1-2] the most widely used matrix resin. EP is a kind of thermosetting resin,

5、available since 1930, the United States in 1947 to realize industrialized production, has been more than 50 years history. Because the epoxy resin has excellent bonding properties, abrasion resistance, mechanical propert

6、ies, chemical stability, electrical insulation, and low shrinkage, easy processing and forming, stress transfer and the advantages of low cost, good, ligh</p><p>　　Matrix composite materials and other fields

7、. Crosslinking density is high, but as a result of EP after curing with three dimensional network structure, there exists large internal stress, very brittle and poor fatigue resistance, heat resistance, impact resistanc

8、e, result in the crack of the peel strength, shear strength is poorer, low strain of faults, is difficult to meet the requirements of engineering technology, make its application is limited by certain. Therefore, the mod

9、ification of epox</p><p>　　Many new toughening methods, toughening agent. Research at home and abroad are mainly concentrated in two aspects: on the one hand, with the continuous development of technology, h

10、ow to obtain a higher performance of epoxy resin materials, to meet the requirements of many special occasions, and can make it more widely used; On the other hand, with the continuous development of the market, how to o

11、btain a lower cost of epoxy resin material, so as to adapt to the demand of the market. At present, </p><p>　　1.1 rubber elastomer toughening epoxy resin [8]</p><p>　　Epoxy resin modified with r

12、ubber, can reduce stress, increase the toughness, improve the water resistance, weather resistance and other properties. Rubber its reactive end groups such as carboxyl, hydroxyl, amino and active group of epoxy resin (s

13、uch as epoxy, hydroxy) response form block. In the process of solidification, the precipitation, flexible chain segment from matrix into two phase structure, and the rubber phase of process energy consumption of main fun

14、ction is to induce matrix, and te</p><p>　　1.2 thermoplastics toughening epoxy resin</p><p>　　With thermoplastic resin modified epoxy resin, the study began in the 80 s [9-10]. Use more polyethe

15、r sulfone (PES) and polysulfone (PSF), poly (ether imide) (PEI), poly (ether ketone (PEK), polyphenylene oxide (PPO) and thermoplastic engineering plastic, these thermoplastic resin not only has good toughness, and high

16、modulus and heat resistance, as toughening agent added to the epoxy resin can also be formed in the dispersed phase particles, they join will not affect the modulus and heat resist</p><p>　　To use, so as to

17、prevent crack, increase matrix tenacity. WeiChun etc. [13] to synthesize a kind of end group containing reactive heat</p><p>　　To the liquid crystal polymer (LCPU), with the modified epoxy resin CYD - 128/4,

18、 4 '- diamino diphenyl sulfone (DDS) curing system, the impact on the modified system performance, tensile properties, elastic modulus, elongation at break</p><p>　　Rate, the relationship between glass t

19、ransition temperature Tg and LCPU content are discussed in this paper. Results show that the LCPU join can increase the impact strength of curing system of 2 ~ 3.5 times, the tensile strength increased by 1.6 ~ 1.8 times

20、, elastic modulus increased by 1.1 ~ 1.5 times, 2 ~ 2.6 times higher elongation at break, Tg improve 36 ~ 60 ℃, the morphology of fracture surface modified materials gradually presents ductile fracture characteristics.&l

21、t;/p><p>　　1.4 the flexible chain segment curing agent for toughening epoxy resin</p><p>　　Large molecules containing flexible chain segment curing agent for toughening epoxy resin, the flexible ch

22、ain segment can be bonded to the density of the epoxy resin cross-linked networks, and in the curing process of micro phase separation, density, porosity and two phase of the network structure, at the same time improve t

23、he toughness of epoxy resin, and simplifies the molding process. Using double hydroxyl compounds with flexible chain contains epoxy groups of epoxy resin with hydroxyl groups</p><p>　　1.5 inorganic nano-mate

24、rials modified epoxy resin</p><p>　　The present study more epoxy/clay nanocomposites is epoxy resin is inserted into the gap in the clay layer, the preparation of the intercalated, stripping, both two kinds

25、of structure of nanocomposite [15, 16], this materials with good optical transparency, gas barrier property, superior mechanical properties, good solvent resistance. Sol-gel method is a traditional method for preparation

26、 of nanoparticles. The preparation of nanoparticles sol (or through the coupling agent) and epoxy resin compo</p><p>　　1.6 interpenetrating network (IPN) structure of epoxy resin system</p><p>　

27、　IPN is an effective method of preparation of special performance of polymer alloy. IPN composition and configuration is different homopolymer and copolymer through each other, entanglement formed by the physical mixture

28、, is a special system of multiphase. Is characterized by a material without rules through to another material, makes the IPN system produced a synergistic effect between two components, "forced inclusive" effec

29、t, so as to produce more excellent performance than general blend. Yu H</p><p>　　1.7 polyurethane modified epoxy resin</p><p>　　Polyurethane modified epoxy resin research [19] began in the 1960

30、s, the U.S. dow company first developed, the structure of polyurethane modified epoxy resin adhesives products such as polymer matrix composite materials used in the aerospace industry. Since the 80 s, Japan's horizo

31、ntal bin of development of a company's elastic epoxy resin series FEX, broad molecular weight distribution, high resin viscosity, soft and rich flexibility, impact resistance after curing, colorless and transparent,

32、go</p><p>　　1.7.1 the amine liquid rubber toughening epoxy resin system</p><p>　　This method is to use the isocyanate (ITPU) reaction end amino excessive deionized water and polyurethane (ATPU),

33、 use it as a toughening epoxy resin curing agent. Has the following characteristics: (1) the amino polyurethane base with strong polarity, polyether has good flexibility, and can achieve the toughening epoxy resin and it

34、s intensity and basic down is not the purpose. (2) to overcome the ordinary, toxicity is volatile fatty amine curing agent and curing agent ratio of demanding problems</p><p>　　1.7.2 epoxy ring opening</

35、p><p>　　Epoxy with initial agent after open loop end hydroxyl compound formation, the end hydroxyl compounds as a polyol component polyurethane pre polymers, with isocyanate reaction [22].</p><p>　

36、　1.7.3 hydroxyl-terminated polyurethane pre polymers</p><p>　　This kind of material with hydroxyl-terminated polyurethane pre polymers and dicyandiamide, 4, 4 '- methylene amine dimethyl phenyl (MDA) and

37、 4, 4' - 2 amino 3, 3 '- dichloro dimethyl phenyl methane (MOCA), ethylene polyamine together or more</p><p>　　As the curing agent of epoxy resin, solidified material has good flexural performance [2

38、3].</p><p>　　1.7.4 closed isocyanate modified epoxy resin</p><p>　　Foundation isocyanate group (NCO) more lively, and multiple amine fat reaction is difficult to control, also can react with hyd

39、roxyl groups of epoxy resin. If the isocyanate with phenol or organic silicon class roots after a closed, can cooperate with epoxy resin mixed a single component, and can be used ketone and amine as curing agent. This ki

40、nd of material is suitable for humid environment, fast drying, adhesion, good physical and mechanical performance, resistant to moisture, water resistant</p><p>　　1.7.5 high hydroxyl value isocyanate as curi

41、ng agent for epoxy resin curing side roots</p><p>　　Polyurethane pre polymers foundation isocyanate group in polyurethane resin can react with hydroxyl compounds, so that the polyurethane curing. There is a

42、certain amount of hydroxyl in epoxy resin, and therefore there is a chemical reaction between polyurethane and epoxy resin. Polyurethane resin and the commonly used low hydroxyl value, high epoxy value of epoxy resin at

43、a certain specific flow mixing, reaction condition is not obvious, longer still not consolidation. Using hydroxyl value is bi</p><p>　　1.7.6 polyurethane epoxy resin graft copolymerization</p><p&g

44、t;　　Polyurethane pre polymers first graft copolymerization with epoxy resin, as a first division points, add curing agent (points for curing. Although this method make the system viscosity, but the success rate is high,

45、but also through the adoption of appropriate thinner, to overcome the low viscosity. Grafting method commonly used in the graft polymerization, namely first the polyol and the isocyanate more aggregated into polyurethane

46、 pre polymers, then the pre polymers with epoxy resin grafted re</p><p>　　2 problems of modified epoxy technology at present</p><p>　　At present, the domestic in EP toughening enhancement resear

47、ch has made great progress, but there are still problems, such as using the reactive liquid polymer and thermoplastic resin toughening EP, can make the impact strength increased exponentially, but modulus, heat resistanc

48、e and tensile properties are decreased; With thermotropic liquid crystal modified EP while at the same time of increasing toughness, keep the other mechanical properties and heat resistance, but its synthesis and raw mat

49、</p><p>　　環(huán)氧樹脂的改性研究進展</p><p>　　摘要:介紹了環(huán)氧樹脂的特性和環(huán)氧樹脂改性的主要趨勢―提高環(huán)氧樹脂的韌性,分別論述了橡膠類彈性體增韌環(huán)氧樹脂、熱塑性塑料增韌環(huán)氧樹脂、熱致液晶聚合物增韌環(huán)氧樹脂、柔性鏈段固化劑增韌環(huán)氧樹脂、無機納米材料改性環(huán)氧樹脂以及互穿網絡(ＩＰＮ)結構的環(huán)氧樹脂體系等環(huán)氧樹脂增韌改性的方法。同時,對聚氨酯的特性、用聚氨酯改性環(huán)氧樹脂的六種

50、方法以及互穿聚合物網絡技術,進行了較為詳細的介紹,并分析了改性環(huán)氧樹脂目前存在的技術問題。</p><p>　　關鍵詞:環(huán)氧樹脂;增韌;改性</p><p><b>　　引　言</b></p><p>　　環(huán)氧樹脂(ＥＰ)是聚合物基復合材料[1-2]應用最廣泛的基體樹脂。ＥＰ是一種熱固性樹脂,自1930年問世,1947年美國實現(xiàn)工業(yè)化生產以來,

51、至今已有50多年歷史。由于環(huán)氧樹脂具有優(yōu)異的粘接性能、耐磨蝕性、力學性能、化學穩(wěn)定性、電器絕緣性,以及收縮率低、易加工成型、較好的應力傳遞和成本低廉等優(yōu)點,廣泛應用于涂料、膠黏劑、輕工、建筑、機械、航天航空、電子電氣絕緣材料、先進</p><p>　　復合材料基體等各個領域。但由于ＥＰ固化后交聯(lián)密度高,呈三維網狀結構,存在內應力大、質脆、耐疲勞性、耐熱性、耐沖擊性差等不足,導致剝離強度、剪切強度較差、開裂應變低等

52、缺點,難以滿足工程技術的要求,使其應用受到一定的限制。因此,對環(huán)氧樹脂的改性工作一直是中外研究的熱門課題,國外研究的多為溶劑型產品[3-5],國內僅少數(shù)單位開發(fā)了無溶劑型產品,大多是共混或半互穿或互穿網絡方式改性物[6],主要是以改善環(huán)氧樹脂的韌性研究為目的。環(huán)氧樹脂的增韌方法[7]很多,雖然研究探討了幾十年,有些增韌方法已經很成熟,但近年來仍有</p><p>　　不少新的增韌方法、增韌劑出現(xiàn)。目前國內外的研究

53、主要集中在兩方面:一方面是隨著技術的不斷發(fā)展,如何獲得具有更高性能的環(huán)氧樹脂材料,以滿足許多特殊場合的要求,并能使其得到更廣泛的應用;另一方面是隨著市場的不斷發(fā)展,如何能夠獲得具有更低成本的環(huán)氧樹脂材料,以適應市場的需求。目前,環(huán)氧樹脂的增韌研究已取得了顯著的成果,其增韌途徑主要有三種:(1)在環(huán)氧基體中加入橡膠彈性體、熱塑性樹脂或液晶聚合物等分散相來增韌;(2)用含"柔性鏈"的固化劑固化環(huán)氧,在交聯(lián)網絡中引入柔性鏈

54、段,提高網鏈分子的柔順性,達到增韌的目的;(3)用熱固性樹脂連續(xù)貫穿于環(huán)氧樹脂網絡中形成互穿、半互穿網絡結構來增韌從而使環(huán)氧樹脂韌性得到改善。環(huán)氧樹脂增韌改性的方法[4-25]</p><p>　　1.1　橡膠類彈性體增韌環(huán)氧樹脂[8]</p><p>　　用橡膠對環(huán)氧樹脂改性,可以降低內應力,增加韌性,提高耐水、耐候等性能。橡膠其活性端基(如羧基、羥基、氨基)與環(huán)氧樹脂中的活性基團(如環(huán)

55、氧基、羥基等)反應形成嵌段。在固化過程中,這些彈性鏈段從基體析出,形成兩相結構,橡膠相的主要作用在于誘發(fā)基體的耗能過程,終止、分枝裂紋,誘導剪切變形來提高環(huán)氧樹脂的斷裂韌性,而其本身在斷裂過程中的耗能占次要地位。目前用于環(huán)氧樹脂增韌的反應性橡膠及彈性體品種主要有:端羧基丁腈橡膠(ＣＴＢＮ)、端羥基丁腈橡膠(ＨＴＢＮ)、聚硫橡膠、液體無規(guī)羧基丁腈橡膠、丁腈-異氰酸酯預聚體、端羥基聚丁二烯(ＨＴ-ＰＢ)、聚醚彈性體、聚氨酯彈性體等。其中ＣＴ

56、ＢＮ是研究得最早和最多的增韌劑,在理論和實際應用上都是最成熟的。彈性體增韌的環(huán)氧樹脂,在膠黏劑中的應用,已經取得很大成功。但還存在下述一些問題:(1)改性基體的韌性會轉移到它的纖維復合材料中去;(2)由于低剪切模量的橡膠粒子的加入,復合材料層與層之間的剪切強度降低;(3)橡膠組分的加入,會降低體系的玻璃化溫度,這不符合復合材料日趨升高的耐熱性要求。這種方法,不適合于用作高性能復合材料的基體樹脂的改性。因此,人們研究出了新的</p&

57、gt;<p>　　1.2熱塑性塑料增韌環(huán)氧樹脂</p><p>　　采用熱塑性樹脂改性環(huán)氧樹脂,研究始于80年代[9-10]。使用較多的有聚醚砜(ＰＥＳ)、聚砜(ＰＳＦ)、聚醚酰亞胺(ＰＥＩ)、聚醚酮(ＰＥＫ)、聚苯醚(ＰＰＯ)等熱塑性工程塑料,這些熱塑性樹脂不僅具有較好的韌性,而且模量和耐熱性較高,作為增韌劑加入到環(huán)氧樹脂中同樣能形成顆粒分散相,它們的加入不會影響環(huán)氧固化物的模量和耐熱性,但對環(huán)氧

58、樹脂的增韌改性效果顯著。聚醚砜(ＰＥＳ)由于和環(huán)氧樹脂有很好的相容性,是最早被研究用于環(huán)氧樹脂增韌改性的熱塑性樹脂。王惠民等[11]用聚醚砜(ＰＥＳ)改性Ｅ-51,不僅可較大幅度地提高ＥＰ的韌性,而且不降低ＥＰ的模量和耐熱性。在100份ＥＰ中加入12.5份ＰＥＳ時,沖擊強度分別提高了3.34倍,拉伸強度分別提高1.20倍和1.27倍,玻璃化轉變溫度升高了7.6℃和7.8℃。徐修成等[12]研究了聚醚砜(ＰＥＳ)改性Ｅ-51/ＤＤＳ和Ｅ&

59、lt;/p><p>　　-51/ＤＩＣＹ體系,發(fā)現(xiàn)ＰＥＳ大分子長鏈中貫穿著環(huán)氧微區(qū)結構,兩者形成半互穿網絡,大大增加了環(huán)氧樹脂的韌性。1.3熱致液晶聚合物(ＴＬＣＰ)增韌環(huán)氧樹脂ＴＬＣＰ增韌環(huán)氧樹脂是通過原位復合的方法來實施的,與其它添加型增韌劑相比較,具有更高的物理力學性能和耐熱性。它在加工過程中受到剪切作用,形成纖維結構,具有高度自增強作用。ＴＬ-ＣＰ改性環(huán)氧樹脂,只需少量就可使增韌樹脂的韌性得到改善,同時還能提

60、高環(huán)氧樹脂的彈性模量和耐熱性。ＴＬＣＰ的增韌機理主要是裂紋釘錨作用機制。固化后體系為兩相結構,ＴＬＣＰ作為第二相以原纖的形式存在于體系中(剛性與基體接近),本身就具有一定的韌性和較高的斷裂伸長率,只要第二相的體積分數(shù)適當,就可以發(fā)生裂紋的釘錨增韌作</p><p>　　用,從而阻止裂縫、提高基體韌性。韋春等[13]合成了一種端基含有活性基團的熱</p><p>　　致性液晶聚合物(ＬＣＰＵ

61、),用其改性環(huán)氧樹脂ＣＹＤ-128/4,4′-二氨基二苯砜(ＤＤＳ)固化體系,對改性體系的沖擊性能、拉伸性能、彈性模量、斷裂伸長</p><p>　　率、玻璃化轉變溫度Ｔｇ與ＬＣＰＵ含量的關系進行了探討。結果表明,ＬＣＰＵ的加入可以使固化體系的沖擊強度提高2～3.5倍,拉伸強度提高1.6～1.8倍,彈性模量提高1.1～1.5倍,斷裂伸長率提高2～2.6倍,Ｔｇ提高36～60℃ ,改性后材料斷裂面的形態(tài)逐漸呈現(xiàn)韌性

62、斷裂特征。</p><p>　　1.4柔性鏈段固化劑增韌環(huán)氧樹脂</p><p>　　含有柔性鏈段的大分子固化劑增韌環(huán)氧樹脂,其柔性鏈段能鍵合到致密的環(huán)氧樹脂交聯(lián)網絡中,并在固化過程中產生微觀相分離,形成致密、疏松相間的兩相網絡結構,在提高環(huán)氧樹脂韌性的同時,又簡化了成型工藝。利用具有柔性鏈的雙羥基化合物中所含的羥基與環(huán)氧樹脂中的環(huán)氧基進行反應,將柔性鏈段引入到環(huán)氧主鏈中,制得低黏度的環(huán)氧

63、樹脂,再用丙烯酸酯化,得到紫外光固化的低黏度環(huán)氧丙烯酸酯涂料[14]。</p><p>　　1.5無機納米材料改性環(huán)氧樹脂</p><p>　　目前研究較多的環(huán)氧樹脂/黏土納米復合材料是將環(huán)氧樹脂插入到黏土層間隙中,制備出插層型、剝離型以及兼具兩種結構的納米復合材料[15-16],該類材料具有良好的光學透明性、氣體阻隔性、優(yōu)越的力學性能、良好的耐溶劑性。溶膠凝膠法是制備納米粒子的一種傳統(tǒng)方

64、法。將制備的納米粒子溶膠(或通過偶聯(lián)劑)與環(huán)氧樹脂進行復合制備環(huán)氧樹脂/納米復合材料。ＵｓｕｋｉＡ等[17]進行了飛機用鋁基底材環(huán)氧樹脂雜化涂層的研究,在空氣中鋁表面有一層金屬氧化物,用磷酸陽極氧化處理鋁表面可產生厚度約50ｎｍ的硬質多孔氧化鋁層,此層在潮濕環(huán)境下產生大量羥基,這些表面羥基可參與溶膠凝膠固化反應,形成ＭＯＡＬ化學鍵,這些化學鍵在鋁基底材和環(huán)氧樹脂膜之間形成強的化學作用。研究結果表明,雜化涂層具有較好的機械強度,如硬度和抗

65、刮性,提高固化溫度,可改善環(huán)氧樹脂雜化涂層的耐潮濕性。</p><p>　　1.6互穿網絡(ＩＰＮ)結構的環(huán)氧樹脂體系</p><p>　?。桑校问侵苽涮厥庑阅艿母叻肿雍辖鸬挠行Х椒ā＃桑校问墙M成和構型不同的均聚物或共聚物相互貫穿、纏結而形成的物理混合物,是特殊的多相體系。其特點是一種材料無規(guī)則地貫穿到另一種材料中,使得ＩＰＮ體系中兩組分之間產生了協(xié)同效應,起著"強迫包容&quo

66、t;作用,從而產生出比一般共混物更加優(yōu)異的性能。于浩[18]等考察了不同聚合物配比、不同聚合物組成對ＩＰＮ性能的影響。得出結論:在所選用的不同種類環(huán)氧樹脂中,以雙酚Ａ型環(huán)氧樹脂(ＥＰ)形成的ＥＰ/ＰＵＩＰＮ性能最佳,ＥＰ/ＰＵ質量比為90/10時,網絡互穿程度高,兩相界面不明顯。催化劑的作用尤為重要,其用量的確定應保證ＥＰ與ＰＵ兩個網絡同步形成。通過調節(jié)交聯(lián)劑ＴＭＰ與擴鏈劑的比例,可達到ＥＰ/ＰＵＩＰＮ最佳相容性。</p>

67、<p>　　1.7聚氨酯改性環(huán)氧樹脂</p><p>　　聚氨酯改性環(huán)氧樹脂的研究[19]開始于20世紀60年代,美國陶氏公司首先研制成功聚氨酯改性環(huán)氧樹脂結構膠黏劑,復合材料基體樹脂等產品用于航空航天工業(yè)。80年代以來,日本橫賓一家公司開發(fā)的彈性環(huán)氧樹脂系列ＦＥＸ,分子量分布寬,樹脂黏度高,固化后柔軟富彈性、耐沖擊性,且無色透明,與普通環(huán)氧樹脂相溶性好。國內研制單位亦不少,如上海市合成樹脂研究所在Ｄ

68、Ｗ-4耐超低溫膠中,應用了環(huán)氧改性聚氨酯樹脂;天津市合成材料研究所的ＨＹ-912超低溫膠,使用了聚氨酯改性環(huán)氧樹脂;黑龍江省石油化學研究所研制出聚氨酯改性環(huán)氧樹脂膠黏劑,提高了它的剪切強度和剝離強度,用于轎車車門折邊的膠接;機械工業(yè)部上海材料研究所研制成功的ＳＫ3系列聚氨酯- -環(huán)氧樹脂,黏度適中、適于操作、貯存穩(wěn)定,固化后具有極佳的柔韌性和彈性[20]。聚氨酯增韌環(huán)氧樹脂的方式很多,以下做一簡單介紹:</p><p

69、>　　1.7.1端胺基液體橡膠增韌環(huán)氧樹脂體系</p><p>　　該方法是用端異氰酸酯(ＩＴＰＵ)與過量的去離子水反應制成端胺基聚氨酯(ＡＴＰＵ),利用其作為環(huán)氧樹脂增韌固化劑。具有以下特點:(1)端胺基聚氨酯基具有較強的極性,聚醚有較好的柔性,因而可達到環(huán)氧樹脂增韌而其強度又基本不下降的目的。(2)克服了普通脂肪胺固化劑易揮發(fā)、毒性大和固化劑配比要求嚴格的問題。(3)可室溫反應,固結體具有良好的耐化學腐

70、蝕性[21]。</p><p><b>　　1.7.2環(huán)氧開環(huán)</b></p><p>　　環(huán)氧用起始劑開環(huán)后形成端羥基化合物,該端羥基化合物作為聚氨酯預聚體的一種多元醇組分,與多異氰酸酯反應[22]。</p><p>　　1.7.3端羥基聚氨酯預聚體</p><p>　　這類材料以端羥基聚氨酯預聚體與雙氰胺、4,4′-

71、二胺二甲苯基甲烷(ＭＤＡ)、4,4′-二胺基3,3′-二氯二甲苯基甲烷(ＭＯＣＡ),或多乙烯多胺一起</p><p>　　作環(huán)氧樹脂的固化劑,固結物具有很好的撓曲性能[23]。</p><p>　　1.7.4封閉異氰酸酯改性環(huán)氧樹脂</p><p>　　異氰酸根基團(-ＮＣＯ)比較活潑,與脂肪多元胺反應難以控制,也能與環(huán)氧樹脂中的羥基反應。如果用酚類或有機硅類將異氰

72、酸根基團封閉后,就能與環(huán)氧樹脂混合作單獨一個組分,并可用酮亞胺作固化劑。這類材料適用于潮濕環(huán)境,干燥迅速,附著力強,物理機械性能好,耐潮、耐水、耐熱,且配制方便,價格低廉,施工簡便,儲存期長,可滿足許多土木工程的需要[24]。</p><p>　　1.7.5高羥值環(huán)氧樹脂作固化劑固化端異氰酸根基</p><p>　　聚氨酯預聚體聚氨酯樹脂中的異氰酸根基團能與含羥基化合物發(fā)生化學反應,從而使

73、聚氨酯固化。環(huán)氧樹脂中有一定量的羥基,因而聚氨酯與環(huán)氧樹脂之間存在著化學反應。聚氨酯樹脂與常用低羥值、高環(huán)氧值的環(huán)氧樹脂以一定的配比量混合,反應情況不明顯,較長時間仍不固結。使用羥值比較大、環(huán)氧值比較小而且分子量大呈固態(tài)的環(huán)氧樹脂,再加入稀釋劑、催化劑、選擇最佳比,即能反應,結果產生復雜的交聯(lián)網狀結構產物[25-26]。</p><p>　　1.7.6聚氨酯環(huán)氧樹脂接枝共聚</p><p>

74、;　　先將聚氨酯預聚體與環(huán)氧樹脂進行接枝共聚,作為甲組分,再加入固化劑乙組分進行固化。這種方法雖然使體系的黏度增大,但成功率高,而且可以通過采用適當?shù)牡宛ざ鹊南♂寗┘右钥朔?。接枝方法中一般采用接枝聚?即先將多羥基化合物與多異氰酸酯聚合成聚氨酯預聚體,然后把預聚體與環(huán)氧樹脂接枝反應直至-ＮＣＯ為定值,最后加入交聯(lián)劑。目前研究最多的聚氨酯增韌環(huán)氧樹脂體系是以聚氨酯與環(huán)氧樹脂形成ＳＰＩＮ(半互穿網絡)和ＩＰＮ(互穿網絡)結構,這兩種結構可起

75、"強迫互容"和"協(xié)同效應"作用,使聚氨酯的高彈性與環(huán)氧樹脂良好的耐熱性、粘接性有機的結合在一起,取得滿意的增韌效果[23-26]。互穿聚合物網絡(ｉｎｔｅｒｐｅｎｅｔｒａｔｉｎｇｐｏｌｙｍｅｒｎｅｔ-ｗｏｒｋ,ＩＰＮ)是指聚合物中存在兩種或兩種以上的網絡相互貫穿在一起,互穿網絡聚合物可以看作是一種特殊的聚合物的共混物。以聚氨酯作為一種組分的ＩＰＮ是極有發(fā)展前途的一類材料,因為聚氨酯的預聚物易與其他

76、單體或預聚體混合,進行互不干擾的平行反應,得到性能優(yōu)異的ＩＰＮ材料。環(huán)氧樹脂中具有可與異氰酸酯基反應的羥基,使聚氨酯與環(huán)氧樹脂的網絡間產生一定的化學連接,使得這一ＩＰ</p><p>　　2目前改性環(huán)氧技術存在的問題</p><p>　　目前,國內在ＥＰ增韌增強研究方面取得了很大進展,但仍存在問題,如用反應性液態(tài)聚合物和熱塑性樹脂增韌ＥＰ,可使沖擊強度成倍地提高,但模量、耐熱性能、拉伸性能

77、均有所下降;用熱致液晶改性ＥＰ雖然在增加韌性的同時,保持了其它力學性能和耐熱性,但其合成和原料來源困難,造價昂貴,且熱致性液晶的熱變形溫度很高,難與通用型基體聚合物匹配,造成加工成型困難。因此,今后ＥＰ增韌增強的研究應從以下三個方面著手[23]:(1)合成和尋找新的具有優(yōu)異力學性能,能與ＥＰ很好相容且能在ＥＰ中分散良好的增韌增強材料。(2)尋找新的制備方法,使改性劑和ＥＰ成型或加工方便,使改性易于進行。(3)拓寬ＥＰ研究和應用領域,使改