水利工程用环氧树脂改性聚氨酯丙烯酸酯性能研究

水利工程金属结构和水工建筑物常遭受腐蚀、高速含沙水流磨蚀破坏,需对其进行便捷有效的防护。利用环氧树脂对聚氨酯丙烯酸酯(PUA)进行改性提高PUA与基体黏结性能,采用紫外光(UV)固化技术制备PUA涂层。研究了环氧树脂改性PUA的化学结构及环氧树脂用量对PUA的力学性能、热稳定性能、耐溶剂性能和抗冲磨性能的影响。结果表明,环氧树脂改性PUA的拉伸强度随着环氧树脂用量增加,呈下降趋势,当加入5%时,PUA拉伸强度为103.0 MPa,材料呈强而脆的特性。环氧树脂加入提升了PUA的拉伸剪切强度,由0.25 MPa增至1.60 MPa。同时,环氧树脂改性PUA具有良好的耐水性能、耐溶剂性能、抗冲磨性能,5%环氧树脂改性PUA抗冲磨强度为800 h/(kg·m^(2))。

聚醚接枝增韧改性环氧树脂防水密封材料研究

将相对分子质量为650的聚乙二醇单甲醚用于环氧树脂接枝增韧改性,红外光谱及有效接枝率分析表明,柔性聚醚链段有效接枝到环氧树脂基体中,有效接枝率达到70.1%~84.9%,改性环氧树脂冲击强度、断裂伸长率随聚醚接枝量的增加显著提高,拉伸强度及压缩强度在设定理论接枝量不超过10%时均处于较高水平,未出现显著下降,且冲击强度及断裂伸长率均得到了大幅提升,表明柔性聚醚对环氧树脂具有良好的增韧效果,可以提高环氧树脂防水密封材料的综合韧性。

环氧树脂胶粘剂对混凝土裂缝修复性能的影响研究

研究使用环氧树脂胶粘剂修复混凝土裂缝问题,分析环氧树脂胶粘剂对于混凝土结构力学性能的影响,使用丁腈橡胶改性环氧树脂,增加环氧树脂韧性,并与稀释剂、固化剂混合制备修复混凝土的环氧树脂,将该环氧树脂灌注在预制裂缝的混凝土试件中,通过万能试验机等设备测试修复前后试件的抗压、抗折强度变化,并验证丁腈橡胶用量对于修复效果的影响。结果表明,使用改性环氧树脂修复混凝土多种形式的裂缝,能够提升混凝土抗压、抗折强度的恢复率,降低液体向混凝土入渗的速度,提升混凝土的性能,同时在环氧树脂中添加丁腈橡胶8 phr能够提升修复的耐水性。

轮毂用水性烤漆的制备及性能

[目的]为提升车轮毂的耐腐蚀性能,制备出一款水性烤漆。[方法]以水性丙烯酸乳液搭配氨基树脂为成膜物质,探讨了水性丙烯酸乳液与氨基树脂的种类及用量,水性铝银浆的种类及用量,以及烘烤温度对涂层综合性能及外观的影响。[结果]以丙烯酸乳液3711与氨基树脂CYMEL 303按8∶1的质量比交联后得到的涂层性能较好,铅笔硬度3H,附着力0级,耐冲击性(1kg)95cm,耐中性盐雾时间336h。[结论]所制涂料漆膜具有良好的外观及综合性能,在搭配环氧底漆和罩光清漆的情况下可用于车轮毂表面装饰与防护。

低能冲击下复合材料蜂窝夹芯结构表面损伤分析

基于低能量冲击探究复合材料蜂窝夹芯结构表面的损伤模式,分析低能量冲击对结构表面环氧树脂膜的裂纹扩展模式、损伤面积、裂纹长度和数量的影响,通过三点弯曲试验研究了低能冲击后碳纤维增强复合材料层合板的弯曲性能以及损伤极限值。研究结果表明,冲击能量会影响表面环氧树脂膜的损伤扩展模式,裂纹均以冲击落点为中心,向周围不规则地扩展,所形成的损伤面积随冲击能量递增,裂纹扩展长度与冲击能量成正相关,层合板的层间损伤模式以分层和纤维弯曲为主;低能量冲击试验证明了表面环氧树脂膜的裂纹扩展模式、损伤面积等与夹芯结构层合板内部的冲击损伤程度之间具备特定的联系,因此可为设计一种新的无损检测方法用于快速表征结构内部的冲击损伤提供可能性。

某企业合成树脂产线产污系数研究

结合实例对某企业乙烯基酯树脂生产线有机废气产污情况进行比对,方法包括系数法、实测法和公式法。系数法根据物料或产品产量及其产污系数计算工艺废气的VOCs产生量。实测法通过在正常工况下,对生产线废气排气筒进口进行监测获取污染物排放量数据,未检测特征污染物排放量。公式法参考美国EIIP文件,模拟化学过程,从而计算出不同污染物在投料、搅拌等不同阶段中产生的排放量。比对后,项目最终采用公式法进行产污量计算。

Structural characteristics and properties of polyurethane modified TDE-85/MeTHPA epoxy resin with interpenetrating polymer networks

Diglycidyl-4,5-epoxycyclohexane-1,2-dicarboxylate(TDE-85)/methyl tetrahydrophthalic anhydride (MeTHPA) epoxy resin was modified with polyurethane(PU) and the interpenetrating polymer networks(IPNs) of PU-modified TDE-85/MeTHPA resin were prepared. The structural characteristics and properties of PU-modified TDE-85/MeTHPA resin were investigated by Fourier transform infrared(FTIR) spectrum,emission scanning electron microscopy(SEM) and thermogravimetry(TG). The results indicate that epoxy polymer network (Ⅰ) and polyurethane polymer network (Ⅱ) of the modified resin can be obtained and the networks (Ⅰ) and (Ⅱ) interpenetrate and tangle highly each other at the phase interface. The micro morphology presents heterogeneous structure. The integrative properties of PU-modified TDE-85/MeTHPA epoxy resin are improved obviously. The PU-modified TDE-85/ MeTHPA resin's tensile strength reaches 69.39 MPa,the impact strength reaches 23.56 kJ/m,the temperature for the system to lose 1% mass (t1%) is 300 ℃,and that for the system to lose 50% mass (t50%) is 378 ℃. Compared with those of TDE-85/MeTHPA resin,the tensile strength,impact strength,t1% and t50% of the PU-modified resin increases by 48%,115%,30 ℃,11 ℃,respectively. The PU-modified TDE-85/MeTHPA resin has the structure characteristics and properties of interpenetrating polymer networks.

Isocyanate-terminated Polyethers Toughened Epoxy Resin:Chemical Modification,Thermal Properties,and Mechanical Strength

The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers （ITPE） was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI （tolylene diisocyanate） acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis （DMA） and thermogravimetric analysis （TGA）. It is indicated the glass transition temperature （T） of systems was lower than the T of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m^2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy （SEM） studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.

Fiber Loading of Date Palm and Kenaf Reinforced Epoxy Composites:Tensile,Impact and Morphological Properties

Date palm fiber(DPF)and kenaf fiber were reinforced in epoxy having various fiber loading 40%,50%,and 60%by weight.These hybrid samples were manufactured by hot press technique and then characterized for tensile,impact,and morphological behavior to evaluate the ratio of fibers in the hybrid composites;the addition of kenaf improved the tensile properties,Scanning Electron Microscopy(SEM)revealed the interfacial bonding of fiber/matrix,and dispersion and void content in composites.Impact test studies reflected the effect of natural fiber with epoxy,level of stress transfer from matrix to reinforced material,and reinforced material’s role in absorbing the impacts.It showed that 50%of DPF had the best shock-absorbing capacity.The obtained results indicated that 30%DPF in hybrid composite showed improved tensile properties and homogeneous distribution of fiber without void content;however,50%DPF loading in hybrid composites had the best impact properties.

Effect of Titanium Dioxide Nano Particles Incorporation on Mechanical and Physical Properties on Two Different Types of Acrylic Resin Denture Base

The aim of this study is to clarify the effect of different concentrations of titanium dioxide nanoparticles (Nps) on the properties of two types of heat polymerized acrylic resin. The tested parameters were flexural strength, impact strength, and microhardness. The two types of acrylic resin used in this study were conventional unmodified (Implacryl, Vertex) and high impact heat polymerized acrylic resin (Vertex-Dental, Netherlands). Both types of acrylic resin were modified by using 1% and 5% TiO2 Nps powder. Specimen’s dimensions were prepared according to the American Dental Association Specification No. 12. Three types of specimens were prepared: 1) flexural strength specimens 50 mm × 10 (±0.2) mm × 3 (±0.2) mm, 2) impact strength test specimens 60 mm × 6.0 mm × 4.0 mm, 3) microhardnesss specimens 25 mm × 10 mm × 3 (±0.2) mm. For each test 6 groups were prepared (each group containing 5 samples). Thirty specimens were prepared in each of the three tests, amounting to a total number of 90 specimens. Mechanical properties such as flexural strength (FS), impact strength and microhardness of the above mentioned specimens were determined using universal testing machine, Izod pendulum impact testing machine and Vickers microhardness tester, respectively. ISO Specification No. 1567 was followed in microhardness test. The data was collected and statistically analyzed. Flexural strength considerably decreased by increasing TiO2 concentration in both types of acrylic resin. Impact strength of the conventional acrylic resin modified by 1% of additives significantly increased. The microhardness is significantly increased by addition of 5% of TiO2 Nps. The Incorporation of TiO2 nanoparticles into acrylic resins can adversely affect its flexural strength. Meanwhile, the impact strength can be modified by small percentage of additives (abt. 1%). This effect is directly correlated with the concentration of nanoparticles. On the other hand, concentrations of TiO2 Nps (abt. 5%) positively affect the microhardness of both types of acrylic resin used in the present study.

三种修复方案用于后牙间隙型食物嵌塞的疗效观察

目的:观察瓷贴面、瓷嵌体和大块树脂充填治疗后牙间隙型食物嵌塞的临床疗效。方法:146例间隙型食物嵌塞患者(180颗后牙),随机分为瓷贴面组、瓷嵌体组和树脂充填组,分别给予瓷贴面修复、瓷嵌体修复和大块树脂充填,1年、2年后复查,通过从修复体边缘密合、牙龈健康、邻接关系、过敏症状、继发龋和修复体脱落方面进行比较。结果:第1年在边缘密合、牙龈健康、邻接关系、过敏症状、继发龋和修复体脱落方面,三组无统计学差异(P>0.05)。第2年在边缘密合、过敏症状、继发龋和修复体脱落方面,三组无统计学差异(P>0.05),在牙龈健康、邻接关系方面,三组有统计学差异(P<0.05)。结论:瓷贴面、瓷嵌体是治疗间隙型食物嵌塞较好的方式,在恢复邻面接触、改善食物嵌塞方面均优于大块树脂充填,但瓷贴面更微创,患者更容易接受。

电磁线圈发射器环氧材料高温老化特性研究

因工作在脉冲大电流、高温、大冲击力等极端条件下,电磁线圈发射器容易老化失效,甚至发生结构损坏。为此,对电磁发射器3240玻纤/环氧复合材料在高温下的老化特性进行了研究。将试样放置于110、130、150℃恒温箱中进行热老化处理,并对热老化试样进行了质量损失、抗冲击强度与弹性模量测试。结果表明:老化时间和温度的增加,均会使试样质量损失率增大,抗冲击强度和弹性模量减小。通过扫描电镜以及红外光谱分析可知:在高温环境下,环氧树脂的氧化分解导致其分子链断裂,破坏了其原有的分子空间结构,使其表面出现裂纹等缺陷。上述研究结果可以为电磁发射器温度老化研究提供参考。

环氧树脂复合材料疲劳损伤微观分析

为探究环氧树脂复合材料在受到冲击时的疲劳损伤微观情况,选择以两种类型环氧树脂复合材料作为原材料,制备规格为100 mm×100 mm,厚度为2 mm的试验试件。合理选择试验所需材料和机械设备,对试件开展了冲击试验。结果表明,在550 MPa的应力强度下,试件出现了断裂,且断裂面有纤维断裂、界面脱黏和层间剥离现象。进一步通过超声微观探伤表明,在冲击能量不断增加的条件下,环氧树脂复合材料试件的孔隙、分层等缺陷问题都会增加,并且试件自身剩余强度会随着冲击能量的增加而逐渐减小,二者之间存在非线性的负向相关关系。通过试验得到的结果为环氧树脂复合材料的制备和合理运用提供可靠依据。

环氧乙烯基酯树脂/玻璃鳞片复合材料冲击韧性的影响因素

研究了树脂性能及含量、玻璃鳞片形状、球形填料以及表面活性剂等因素对树脂基玻璃鳞片复合材料的冲击韧性影响。发现树脂增韧以及含量增加可显著提升复合材料的冲击韧性;减小玻璃鳞片片径虽可有效提升材料冲击韧性,但会导致材料水蒸气渗透量增加,因此鳞片片径不宜小于0.4 mm;白炭黑含量在1.5 wt%时冲击韧性达到峰值;偶联剂含量不高于1 wt%时,冲击韧性随偶联剂含量提高而增长。

Impact of SF_(6) Decomposition Products on Epoxy Resin Chemical Stability and Doping-nano-Al_(2)O_(3)-based Enhancement Using the ReaxFF-MD Method

Chemically active by-products formed by corona discharge in SF_(6) gas are prone to damaging the exposed epoxy resin,or even leading to an entire insulation failure of the operational GIS/GIL power equipment.In this proposed research,reactive force field molecular dynamic simulation methodology is applied to investigate the chemical reaction kinetics of epoxy polymer under the impact of highly energetic particles(F,S,SOF,SF,OH and O)so as to explain the degradation mechanism.Among all cases,SF particle-impacted epoxy resin suffers the most serious surface erosion with the lowest remnant mass of 9%and deepest damage penetration of 32.6Å,to which the S particle-caused damage showed similar results.Due to high reactivity of the S atom,it can merge into the epoxy molecules to promote long chain breaking,causing a six-membered ring opening and further dissociation of short carbon chains,which makes the epoxy resin molecules undergo faster spontaneous dissociation with increased temperatures.The changes of small molecular gas products,such as CO_(2),H_(2)O and CH_(2)O,as well as that of the characteristic products,such as HF,CS_(2),SO and H_(2)S,are also evaluated under the impact of different particles.The presented research indicates that enhancing the resistance strength of epoxy polymer against S and SF particles'corrosion is the key approach to improving chemical stability in the SF_(6) environment.Further studies were implemented to optimize the concentration and diameter of nano-Al_(2)O_(3) doped in the composites.According to this paper,aluminum nanoparticle with a diameter of 1nm could significantly reduce the erosion caused by SF and S particles.The micro-scale mechanism lies primarily within two aspects:the nanoparticles improve the surface heat transfer efficiency as to reduce temperature rise,and also provide an effective protection area by balancing distribution and self-exposing,which finally slows down the pyrolysis process of epoxy resin,as well as the reaction intensity with the incident particles.

复合绝缘子伞裙护套材料耐冲击力学特性研究

鸟啄复合绝缘子为输电线路的安全运行带来了严重的隐患。为进一步理解材料特性与鸟啄损伤程度之间的关系,文中基于冲击动力学理论,对复合绝缘子的伞裙护套材料的耐冲击力学特性进行了研究。建立了包含材料弹性模量、密度、泊松比、鸟嘴形状系数等相关参数的复合绝缘子鸟啄冲击模型。模型根据鸟啄速度分为弹性变形、塑性变形与流体变形3个阶段,描述了复合绝缘子伞套材料的鸟啄深度与鸟啄速度之间的关系。设计了模拟鸟啄的人工冲击试验,以硅橡胶与脂环族环氧树脂两种伞套材料为例,对比了两种材料的耐冲击特性。结果发现,硅橡胶伞套材料随冲击高度的增加,经历了弹性变形至塑性变形阶段。鸟啄冲击模型可以很好的描述硅橡胶材料所受冲击速度与冲击深度之间的关系。脂环族环氧树脂材料的冲击过程同样存在弹性、塑性变形阶段,但最终以裂纹扩展断裂形式开裂,与鸟啄冲击模型中侵入深度逐渐增加最终贯穿的过程不符,因此不适合该模型。相较于硅橡胶材料,脂环族环氧树脂伞套材料具有更好的耐冲击力学特性,更能抵御鸟啄侵害。

聚合物改性钢纤维再生混凝土抗冲击性能研究

目的研究水性环氧树脂质量分数、再生粗骨料取代率和超短微丝钢纤维体积分数对RAC抗冲击性能的影响,以促进其工程应用。方法对RAC进行抗压和落锤冲击试验,通过极差分析法研究各因素对RAC抗冲击性能的影响,并分析水性环氧树脂的改性机理;同时基于Weibull分布理论对冲击试验结果进行拟合检验和冲击寿命预测分析。结果钢纤维体积分数对RAC抗冲击性能的影响最大,纤维体积分数由0增至1.0%时,RAC初裂冲击耗能和破坏冲击耗能的增幅分别接近150%和900%;再生粗骨料取代率对水性环氧树脂的改性效果影响较大;双参数Weibull分布能较好地描述RAC抗冲击次数的分布特征。结论水性环氧树脂掺入后可改善界面过渡区的密实性;钢纤维掺入后能显著提升RAC基体的冲击韧性和延性。

铁路货车用高弹性防腐涂料的研制

以聚氯乙烯(PVC)糊树脂和醋酸乙烯酯改性的聚氯乙烯糊树脂(氯醋共聚糊树脂)为主体树脂,制备了一种适用于铁路货车恶劣装卸工况的高弹性防腐涂料。通过研究3种聚合工艺生产的PVC糊树脂对防腐涂料黏度、拉伸性能、耐冲击性和杯突实验结果的影响,选择了种子乳液聚合工艺生产的PVC糊树脂作为主体树脂。通过向涂料体系中加入适量的氯醋共聚糊树脂,可以在不降低涂料拉伸强度的条件下,提高涂料耐冲击性。此外,通过加入一定量特殊的聚酰胺类PVC专用附着力促进剂,提高了涂料对铁路货车车体的附着力。

两次冲击距离对CFRP层合板冲击损伤和剩余压缩强度的影响

为了研究预损伤冲击对复合材料二次冲击及冲击后压缩行为的影响,对复合材料层合板进行预损伤冲击试验、二次冲击试验及冲击后压缩试验,探究预损伤冲击和二次冲击之间的距离与冲击损伤和剩余压缩强度之间的关系。基于三维Hashin准则和渐进损伤刚度退化方案,在ABAQUS/Explicit中建立预损伤冲击-二次冲击-压缩仿真模型,采用预制分层损伤的方法,将第一次冲击损伤预制进第二次冲击模型中。研究表明:所建立模型的仿真结果与试验结果吻合良好。当两次冲击距离小于两次冲击损伤面积纵向半径和的125%时,二次冲击损伤沿纤维方向向预损伤冲击位置延伸。当第二次冲击与预损伤冲击的距离为两次冲击损伤面积纵向半径和的150%时,剩余压缩强度最小,对层合板造成破坏最大。

n-CeO_(2)与CTBN/EP共混增韧改性及其机理研究

采用物理共混的方法制备以端羧基丁腈橡胶(CTBN)和纳米二氧化铈(n-CeO_(2))为增韧剂对环氧树脂(EP)进行增韧的复合材料,利用XRD、FTIR、SEM及万能拉伸试验仪,研究了在15 phrCTBN下不同n-CeO_(2)含量对复合材料力学性能的影响。结果表明,当n-CeO_(2)含量为5 phr时增韧效果最好,n-CeO_(2)-CTBN/EP的拉伸强度达73.2 MPa,弯曲强度达191.4 MPa,冲击强度达31.1 KJ/m^(2),较未添加n-CeO_(2)的CTBN/EP分别提高了16.1%、112%、42.2%。