空心玻璃微珠/环氧树脂复合材料制备及其性能研究

研究了空心玻璃微珠/环氧树脂复合材料制备工艺、配方设计,并对材料的密度、力学性能、表面改性剂、粒径匹配、热性能、介电性能和微观形貌进行了实验研究.结果表明:空心玻璃微珠/环氧树脂复合材料密度在0.28～0.8g/cm3之间可调,抗压缩强度达到4.5MPa～120MPa,空心玻璃微珠表面改性剂的加入,明显提高了复合材料的机械性能,在600～9000MHz频率条件下,其介电性能基本不随频率而变化,介电常数为2.01～2.05,介电损耗角正切为2.57×10-3-2.80×10-3,空心玻璃微珠/环氧树脂复合材料具有较高的使用温度,扫描电镜表明表面改性剂改善玻璃微珠的浸润性,并且验证了空心玻璃微珠级配理论.     

空心玻璃微珠填充环氧树脂复合材料压缩性能研究

制备了空心玻璃微珠 (HGM )填充环氧树脂复合材料 ,对材料进行了单轴静态压缩实验。研究了HGM的粒径和体积分数 (Vf)对材料压缩性能的影响 ,研究发现 ,Vf增大 ,材料中HGM外部空气泡的含量增大 ;材料的压缩强度和压缩模量可在 5 0～ 10 0MPa和 1.5 0～ 1.80GPa之间调节 ;材料断裂应变较小 ,用扫描电镜观察了其结构形态和破坏形式 ,断裂面与应力方向约成 45°角 ,破坏主要由HGM的破裂引起 ;HGM粒径减小 ,材料压缩强度增大 ;Vf 增大 ,压缩强度减小 ,压缩模量先增大后减小 ,断裂应变减小。用改进Turcsanyi方程对压缩强度进行了模拟计算 ,材料的密度与计算值基本一致     

改性空心玻璃微珠/环氧树脂复合材料力学性能研究

采用偶联剂对玻璃微珠表面进行改性处理,借助超声波振动,使改性空心玻璃微珠在环氧树脂中均匀、稳定分散,增强了玻璃微珠与环氧树脂之间的相容并探讨了改性空心玻璃微珠对环氧树脂力学性能的影响。结果表明,复合材料中改性空心玻璃微珠添加质量分数为3%时,其拉伸强度达到最大值68.54 MPa,与空白样相比提高了20.3%;冲击强度达到最大值24.42 kJ/m2,比纯环氧树脂提高了166%;KIC(断裂韧性)达到最大值2.338 MPa/m2,是空白试样的2.27倍,增韧效果较为明显。     

空心玻璃微珠改性环氧树脂的制备及其性能研究

以双酚F环氧树脂为基体,以空心玻璃微珠为填料,制备环氧树脂绝缘复合材料。用硅烷偶联剂KH-570对空心玻璃微珠进行表面改性,并研究改性后的空心玻璃微珠对复合材料力学性能、热机械性能以及电绝缘性能的影响。实验结果表明:随着填料含量的增加,力学性能表现出先增加再降低的趋势,并在空心玻璃微珠含量为4%时,性能达到最优;热机械性能和介电性能均随填料含量的增加而呈现降低的趋势,并在空心玻璃微珠含量为8%时,介电常数最低。     

环氧树脂/空心玻璃微珠泡沫材料性能研究

以高强度环氧树脂为基体,表面改性处理的空心玻璃微珠(HGB)为填料,经高温固化制备了环氧树脂/HGB泡沫材料,并研究了HGB类型、HGB含量和固化剂用量对泡沫材料压缩性能的影响。研究发现,随着HGB填充量的增大,泡沫材料的密度和压缩强度均下降。当固化剂与环氧树脂物质的量比为0.85时,泡沫材料的抗压性能最好,压缩强度为40.19 MPa。偶联剂改性HGB可以有效改善HGB和基体树脂的粘合效果。当改性HGB质量分数为80%时,与未改性环氧树脂相比,环氧树脂/改性HGB泡沫材料压缩强度提高了5.0%,吸水率下降40.6%。     

空心玻璃微珠/环氧复合材料的制备及性能研究

制备了空心玻璃微珠/环氧复合材料。通过力学性能、固化收缩率、热性能等测试考察了空心玻璃微珠粒径、填充量、硅烷偶联剂处理对树脂及固化物性能的影响。结果表明,硅烷偶联剂改善了空心玻璃微珠与树脂基体的相容性。复合材料的力学性能随着空心微珠粒径减小而增大。随着空心微珠填充量的加大,固化物拉伸强度有所降低,冲击强度和弯曲强度在空心玻璃微珠质量分数为2%时达到最大值,比纯树脂分别提高了30%和34.2%,同时材料的固化收缩率和密度降低,玻璃化转变温度升高。     

环氧树脂/空心玻璃微珠复合浮力材料制备及性能

采用硅烷偶联剂KH–550改性空心玻璃微珠(S38HS),并通过旋转脱泡–浇注–模压成型法制备了环氧树脂/空心玻璃微珠复合浮力材料。研究了空心玻璃微珠表面处理、体积分数对复合浮力材料压缩强度和密度的影响。结果表明,表面处理有利于改善环氧树脂和空心玻璃微珠之间的界面,从而提高复合浮力材料的压缩强度。添加高体积分数的空心玻璃微珠有利于降低复合浮力材料的密度,而材料的压缩强度随着空心玻璃微珠体积分数的增加而降低,应该综合考虑空心玻璃微微珠的含量,以获取所需的密度和压缩强度。当空心玻璃微珠体积分数为60%时,复合浮力材料的压缩强度和密度分别为61.41 MPa和0.66 g/cm³。     

聚丙烯/空心玻璃微珠复合材料流变性能的研究

分别讨论了空心玻璃微珠(HGB)的添加量对聚丙烯(PP)和硅烷偶联剂KH550对PP/HGB复合材料流变性能的影响。结果表明:增加HBG的添加量和KH550改性HGB都能增加复合材料复合黏度、储能模量和损耗模量,但损耗角正切轻微减小。     

国内空心玻璃微珠/环氧树脂基固体浮力材料研究进展

从提高压缩强度、降低吸水率、降低密度三个方面对国内空心玻璃微珠/环氧树脂基固体浮力材料的研究进展进行综述,并对空心玻璃微珠/环氧树脂基固体浮力材料的未来发展方向进行了展望。     

Mechanical and thermal properties of graphite platelet/epoxy composites

Anhydride-cured diglycidyl ether of bisphenol A (DGEBA) reinforced with 2.5-5% by weight graphite platelets was fabricated. The structural, mechanical, viscoelastic and thermal properties of these composites were studied and compared. XRD studies indicated that the processing of composites did not change the original d-spacing of pure graphite. Tensile property measurements of composites indicated higher elastic modulus and tensile strength with increasing concentration of graphite platelets. The storage modulus and glass transition temperatures (T_g) of the composites also increased with increasing platelet concentration, however, the coefficient of thermal expansion decreased with the addition of graphite platelets. The thermal stability was determined using thermogravimetric analysis. The composites showed higher thermal stability in comparison with pure epoxy and increased char concentration for higher graphite concentration. The effects of reinforcement on the damage mechanisms of these composites were investigated by scanning electron microscopy.     

丙烯酸酯改性双环戊二烯酚型环氧树脂及其性能研究

通过FT－IR光谱表征了丙烯酸酯改性的DCPD酚型环氧树脂／DDM体系结构，并通过测定改性体系的凝胶时间和分析凝胶时间的影响因素，研究了该体系的反应特性，同时，对改造前后DCPD酚型环氧树脂体系的性能做了分析。     

Quantitative structure-property relationships for composites: prediction of glass transition temperatures for epoxy resins

The glass transition temperatures of nine stoichiometric resin systems of tetraglycidyl-4,4′-diamino-diphenylmethane (TGDDM), triglycidyl p-amino phenol and diglycidyl ether of bisphenol A with 4,4′-diaminodiphenylsulphone (DDS), diethyl-toluenediamine and dimethylthiotoluenediamine were calculated using group interaction modelling (GIM) and atomic additivity (AA) methods. The input parameters were generated from kinetics simulation, which outputs the structure information for the cured systems. The modelling parameters were also applied to four non-stoichiometric systems of TGDDM and DDS. The predicted values from GIM were in good quantitative agreement with measured results from temperature modulated differential scanning calorimetry for all systems studied. Compared to GIM, the AA method gave inferior predictions for the highly crosslinked systems, especially for those, where epoxy was in excess.     

Sialon陶瓷材料的结构、性质及应用

系统地评述了不同种类单相Sialon陶瓷的结构特征和物理、化学性质,并介绍了Sialon在冶金工业等方面的应用.单相Sialon陶瓷中,β'-Sialon强度和韧性最高,α'-Sialon硬度和耐磨性最好,O'-Sialon抗氧化性最佳.     

An impact study of epoxy resin composites reinforced with glass fiber fabrics

The impact properties of epoxy resin composites reinforced with three types of fabrics which are welf-knitted structural fabrics (WKSF), three-dimensional fabrics (3D-3A & 3D-5A) and plain-weave structural fabrics (2D-2A) have been investigated. The results of experiments show that WKSF composite has total impact energy about 1.5 and 3.5 times those of 3D and 2D fabrics composite respectively. The ductility index of WKSF is about 2.2 times of those of 3D and 2D. WKSF composites are very ductile materials and can absorb much more impact energy than 3D and 2D composites. The pushed-out volume of WKSF composites after the impact test was calculated from the photographs and the results show that the volume of the pushed-out zone is proportional to impact energy.     

Assessment of morphological,thermal, and viscoelastic properties of epoxy vinyl ester coating composites: Role of glass flake and mixing method

In this work, glass flake (GF)/epoxy vinyl ester resin composites were fabricated with various compositions and mixing methods. The effect of GF on thermal and mechanical behavior of these composites was investigated using different techniques such as differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and thermogravimetric analysis (TGA). The results showed that the presence of GF in epoxy vinyl ester formulation could obviously affect the cure temperature, reaction enthalpy value, and degradation temperature. DMTA results also exhibited that the tan δ peak area decreased and storage modulus increased with increasing GF content and this effect seemed to be different depending on the initial epoxy vinyl ester compositions. The scanning electron microscopy (SEM) images showed that mixing method had a strong effect on the surface morphology, size, and distribution of glass flake. The effect of mixing method on properties of produced composite was also studied.     

Effect of non-ionic surfactants on thermomechanical properties of epoxy/multiwall carbon nanotubes composites

Epoxy/multiwall carbon nanotubes (MWCNTs) composites were investigated using three different non-ionic surfactants (BYK-110, Tween-80 and Nonidet-P40) separately as a modifier. The role of surfactants in dispersion of MWCNTs in the epoxy matrix was studied. Among three surfactants used, performance of Nonidet-P40 was found to be the best in improving the thermomechanical properties of the epoxy resin and achieving good dispersion of MWCNTs. The good dispersion of Nonidet-P40 modified MWCNT in the epoxy matrix is a result of the π–π interaction between π electrons of the Nonidet-P40 and π electron clouds of MWCNTs as well as H-bonding interaction between of Nonidet-P40 and the epoxy matrix. This type of interaction does not disturb the π electron clouds of MWCNTs as opposed to chemical functionalization strategy.     

Preparation and properties of LDHs/epoxy nanocomposites

Layered double hydroxides (LDHs)/epoxy nanocomposites were prepared by mixing the amino laurate intercalated LDHs, EPON 828 resin, and Jeffamine D400 as a curing agent. The organo-modified LDHs with hydrophobic property easily disperse in epoxy resin, and the amino laurate intercalated LDHs with large gallery space allow the epoxy molecules and the curing agents to easily diffuse into the LDHs galleries at elevated temperature. After the thermal curing process, the exfoliated LDHs/epoxy nanocomposites were formed. X-ray diffraction was used to detect the formation process of the exfoliated LDHs/epoxy nanocomposites. TEM was used to observe the dispersed behavior of the LDHs nanolayers, and the LDHs nanolayers were exfoliated and well dispersed in these nanocomposites. Owing to the reaction between the amine groups of the intercalated amino laurate and epoxy groups, the adhesion between the LDHs nanolayers and epoxy molecules makes these LDHs/epoxy nanocomposites more compatible. Consequently, the tensile properties from tensile test and the mechanical properties from DMA were enhanced, and the T_g of these nanocomposites from DMA and TMA were increased. Coefficients of thermal expansion (CTEs, below and above T_g) of these nanocomposites from TMA decreased with the LDHs content. The thermal stability of these nanocomposites was enhanced by the well dispersed LDHs nanolayers.     

An original epoxy-stamp on glass-disc specimen exhibiting stable debonding for identifying adhesive properties between glass and epoxy

An original axisymmetric specimen composed of a concave epoxy-stamp bonded on a glass-disc, which exhibits stable decohesion under traction, is proposed for identifying the adhesive properties, namely the adhesion surface energy, the adhesion peak stress and the decohesion rupture gap between glass and epoxy. Debonding stability is obtained by combining two stabilizing effects of the epoxy-stamp geometry: axisymmetry and concavity. This stamp design is believed to be an important discovery since stable crack propagation is the exception rather than the rule in fracture mechanics. The increasing graph of the traction force vs. the specimen elongation enables to measure the adhesion surface energy upon unloading, calculate the adhesion peak stress and deduce the decohesion rupture gap. Preliminary experiments confirm the stability of the debonding process and show excellent reproducibility.     

Dielectric properties of epoxy composites with modified multiwalled carbon nanotubes

We report here a high dielectric percolative polymer nanocomposite, fabricated by a combination of triethylene-tetramine (TETA) modified multiwalled carbon nanotube (named as TETA-MWNT) within epoxy resin matrix. In this composite system, with various TETA-MWNT volume fractions, the dielectric constant (K) is well fitted by the scaling law of the percolation theory with the percolation threshold f _c is 0.042 and the critical exponent p is 0.786. At 1,000 Hz of room temperature, the value of the dielectric constant is as high as 421 with the TETA-MWNT content of 4.14vol%, which is almost 60 times higher than that of epoxy resin. In contrast, a simple blend of pristine MWNT in epoxy composite shows evident lower dielectric constant and much higher loss with the same volume fraction.