VARI成型泡沫夹层复合材料界面质量控制方法研究

采用本体树脂涂覆、胶膜和辅助织物粘贴在泡沫加工表面的方法分别改善胶接界面,解决了真空树脂浸渗工艺(VARI)制备的非屈曲碳纤维织物(NCF)/聚甲基丙烯胺(PMI)泡沫夹芯复合材料中泡沫与蒙皮的脱粘问题。结果表明,在相同VARI工艺参数条件下,采用890树脂涂覆的方法可以达到大约80%区域面积的良好粘接界面,对应的抗平拉强度提高了30%;同时胶膜和辅助织物粘贴方法则可达到接近100%改善胶接界面质量的效果,其对应的抗平拉强度则分别提高了76%和56%。     

Effects of epoxy resin liquidity on the mechanical properties of aluminum foam sandwich

Adhesion strength plays an important role in the mechanical properties of glued aluminum foam sandwich (AFS). This study aims to understand the effect of epoxy resin liquidity on the three-point bending performance of AFS. The liquidity of epoxy resin was improved by adding alcohol or acetone diluents. The adhesion strength of seven groups of epoxy resin added with different quantities of alcohol or acetone were tested through single-lap shear test and the mechanical properties of AFS glued by the seven adhesives were investigated through three-point bending test by using WDW-T100 electronic universal tensile testing machine. Results indicated that the liquidity influenced the properties of epoxy resin significantly and then affected the mechanical properties of glued AFS. The adhesion strength went down with the improvement of epoxy resin liquidity in general but when certain quantity of acetone was added into the epoxy resin, its plasticity improved and then the deformation mechanism of AFS changed, especially when 15% of acetone was added into the epoxy resin the energy absorption value of AFS improved by over 100%. This work can not only improve the comprehensive properties of AFS but may make it possible for AFS to be produced by machine because of the improvement of the epoxy resin liquidity.     

Peel strength improvement of silicone rubber film by plasma pretreatment followed by graft copolymerization

Here we discuss the improvement in the peel strength of silicone rubber film by O₂ plasma pretreatment followed by grafting with hydrophilic monomers: acrylamide (AAm) and acrylic acid (AA). The peroxides concentration after O₂ plasma treatment was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. ESCA analysis was carried out to confirm the existence of AAm. The peroxides concentration and hence the peel strength increased with increasing plasma treatment power and time, reached a maximum value, and then decreased with further increasing plasma treatment power and time. Peel strength of the silicone film with 3M-600 tape was observed to increase with grafting time; however, it was found to decrease with overgrafting. The maximum peel strength of 384.4 g/cm was found for the 20 W, 10 min plasma treated, AAm grafted film with maximum peroxides concentration of 4.86 x 10^-9 mol/cm² and also with maximum nitrogen-to-carbon ratio (N/C) of 0.247. Hydrolysis experiments show that -NH₂ provides higher contribution to adhesion than -COOH does and the grafting degree of AA is lower than that of AAm. The relationship between the degree of grafting and peel strength can be well explained by the mechanical interlocking theory of adhesion.     

5231环氧树脂体系/玻璃布复合材料性能研究

一种160℃固化的改性环氧树脂体系5231,该树脂体系粘性适中,具有良好的阻燃性和较高的抗滚筒剥离强度,其预浸料可与Nomex芳纶纸蜂窝直接共固化。另外,其玻璃布复合材料力学性能满足了技术指标要求,耐热性和耐湿热性良好,并已在飞机的结构件上得到应用。     

纳米颗粒对环氧树脂胶粘剂／钢铁附着强度的影响

采用纳米Al2O3、纳米CaCO3、纳米SiO2三种纳米颗粒,机械混合对环氧树脂胶粘剂进行改性,并对纳米颗粒改性的环氧树脂胶粘试样进行了附着强度的检测。结果发现,通过改变纳米颗粒的种类和含量,环氧胶粘剂／钢铁基体之间的附着强度得到不同程度的提高,其中添加2％纳米Al2O3颗粒的环氧胶粘剂与钢铁基体的附着强度提高了4倍左右。通过断面形貌特征和不同基体粗糙度下对添加纳米颗粒环氧胶与钢铁基体之间附着强度的检测,对此现象产生的原因进行了分析和讨论。     

Cone calorimeter testing of foam core sandwich panels treated with intumescent paper underneath the veneer (FRV)

Surfaces of novel foam core sandwich panels were adhered with intumescent fire‐retardant paper underneath the veneers (FRV) to improve their flammability properties. The panels were evaluated by means of cone calorimeter test (ASTM E 1354). Variables tested were different surface layer treatments, adhesives used for veneering, surface layer thicknesses, and processing conditions, having the objective of obtaining similar or better flammability as that of solid particle boards. Previous research showed that sandwich panels without FRV compared to panels with FRV generally had much higher heat release rates, somewhat higher heat of combustion and much higher smoke production due to the polymeric foam component of tested panels. The present study shows that using FRV adhered to the surface layer of sandwich panels dramatically improved flammability properties; the best FRV performance resulted from panels produced with thicker face layer (5 mm) and lower press temperature (130°C) and adhered with an acrylic thixotropic adhesive. Such protected foam core particleboard has heat release rate profiles as low as that is typical of commercially available fire‐retardant–treated plywood, thus implying a low flammability rating when tested in accordance with both single burn item (Euro Class B anticipated) and steiner tunnel (North America Class A anticipated) tests.     

Effect of resin impregnation methods at the early stage of densification on the impregnation efficiency,microstructure, and thermal stability of carbon–carbon composites

The effect of impregnation methods and heat‐treatment temperature at the early stage of densification on the impregnation efficiency, microstructure, and thermal stability of carbon–carbon composites prepared from carbon–phenolic green composites was studied. The results suggest that simultaneous application of pressure and heat provides better impregnation performance during densification at the early stage of carbon–carbon composite fabrication than ultrasonic impregnation and vacuum infiltration impregnation. Also, optical microscopic examination strongly supports the result of the impregnation efficiency obtained using three different resin impregnation methods. An additional heat‐treatment at 2000 °C after carbonization results in better thermal stability and a denser microstructure of the fiber and matrix of the composite. For the carbonized composites, including a fully cured furfuryl alcohol resin impregnant, the weight loss measured by a thermogravimetric method quantitatively agrees with the weight loss occurred in a carbonization furnace at the corresponding temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 183–192, 2002     

Two-step vs. one-step conditioning systems and adhesive interface of glass ceramic surface and resin systems

The effect of two-step and one-step ceramic surface conditioning/priming, and subjecting to exposure with boiling water on adhesion strength of resin cements was evaluated. Rectangular shaped specimens were cut from CAD blocks of E-max (Ivoclar Vivadent) and Mark II (VITA Zahnfabrik) and randomly assigned to two main study groups. Group one specimens’ surfaces were conditioned using the two-step conditioning/priming procedure and group two specimens were treated using the one-step conditioning/priming system. After treating, 3 mm thick resin cement layer was applied onto the surface using a split stainless steel mold. Each group was further divided into four subgroups (n = 10) depending on type of resin cement applied and subjecting to exposure in boiling water. Adhesion strength of all the specimens was measured using the universal material testing machine, results were tabulated and subjected to statistical analysis at a significance level of p < 0.05. Adhesive resin showed higher values of 22.05 and 18.65 MPa with E-max and Mark II respectively, and resin composites showed 18.13 and 15.13 MPa with E-max and Mark II respectively, when two-step conditioning system was employed. Majority of the adhesive resin specimens showed cohesive failure in cement. Subjecting the specimens to exposure in boiling water for 24 h not only showed adhesive failure but also significantly reduced adhesion strength of adhesive resin and resin composite. The significance of the study is that, the traditional two-step ceramic surface conditioning is more effective than the one-step conditioning and unfilled adhesive resin provides better adhesion strength.     

环氧树脂的加入对水性聚氨酯性能的影响

以聚丙二醇、异佛尔酮二异氰酸酯、2,2-二羟甲基丁酸、环氧树脂E51等为主要原料,通过丙酮法制备环氧树脂改性聚氨酯乳液.探究了环氧树脂E51的用量对聚氨酯贮存稳定性、力学性能、热稳定性的影响.结果表明,环氧树脂E51的最佳用量为6％(质量分数).通过傅里叶红外光谱分析证明了环氧树脂E51成功的连接到了聚氨酯的主链上.     

木质素筛余物对物料黏度及聚氨酯合成革剥离强度的影响

木质素是聚氨酯合成革中优良的填充剂,其赋予了聚氨酯合成革特殊的物理性能和加工性能,可降低成本。不同的木质素筛余物对木质素/聚氨酯共混体的黏度及聚氨酯合成革的剥离强度有一定的影响,当木质素筛余物质量分数控制在5.5%～6.5%,能得到较佳的作用效果。     

Influence of chopped strand fibres on the flexural behaviour of a syntactic foam core system

The comparative performance in a three point bending test of syntactic foam comprising epoxy resin and glass microballoons with and without the inclusion of glass fibre in the form of chopped strands is reported. Test samples having a span‐to‐depth ratio of 16:1 were used. The data show that the glass fibre reinforced foam system had a higher strength compared to the unreinforced system. Resorting to light macroscopic and scanning electron microscopic examinations on mechanically tested samples expanded the scope of the work for a structure–property correlation to emerge. © 2000 Society of Chemical Industry     

环氧树脂改性聚氨酯耐热性能的研究

端异氰酸酯基聚氨酯预聚体与环氧树脂E-51形成了互穿网络,通过热重分析仪(TGA)研究了完全固化后的互穿网络的热分解行为、透射电镜研究了IPN的相分离行为,及拉伸强度、硬度等对其进行了表征。结果表明,经过环氧树脂改性的聚氨酯的耐热性能比纯聚氨酯得到了提高,且力学性能也有所改善,并对其机理进行了阐述。     

Influence of different surface treatments on zirconia/resin shear bond strength using one-bottle universal adhesive

ABSTRACT

This study was designed to evaluate the effect of different treatments on the zirconia/resin shear bond strength (SBS) using commercial one-bottle universal adhesive. Zirconia discs with different surface treatments (blank control; airborne-particle-abrasion; glazing) were bonded to the bovine enamel surfaces using one-bottle universal adhesive. All specimens were tested for SBS (MPa) before and after 10000 thermocycles. Statistically analysis were conducted by using one-way analysis of variance and multiple-comparison least significant difference tests (α = 0.05). Airborne-particle-abrasion group showed higher SBS (36.19 ± 11.86) than control group (14.98 ± 5.90) and glazing group (10.63 ± 5.39) (p < 0.05). After thermocycling test, the SBS significantly decreased for control group (8.84 ± 2.55) and glazing group (6.18 ± 2.78) while not for airborne-particle-abrasion group (41.5 ± 7.95). One-bottle universal adhesives combined with airborne-particle-abrasion showed quite high SBS of zirconia/resin, which was appropriate for bonding of zirconia restoration.     

封闭型环氧改性水性聚氨酯的合成研究

以4,4’-二苯基甲烷二异氰酸酯（MDI）、聚醚二元醇N210、交联剂三羟甲基丙烷（TMP）、环氧树脂E44、二羟甲基丙酸（DMPA）、封闭剂己内酰胺（ε-CL）为主要原料,采用自乳化法合成出封闭型环氧改性的水性聚氨酯乳液。对其进行了FT—IR红外表征,研究了DMPA用量、中和度对乳液的外观和稳定性的影响。结果表明,通过环氧改性并交联的水性聚氨酯乳液稳定性及成膜的耐水性和力学性能大大提高。     

Effect of surface conditioning methods,adhesive systems and resin composite on repair strength of dimethacrylate and silorane resin composites

This study evaluated the effect of surface conditioning methods and adhesive systems on the repair bond strength of resin composites. Specimens (FLS: Filtek LS) (N = 144) were prepared using a silicone matrix. The specimens were stored in distilled water and then were randomly divided into the twelve groups (n = 12) according to the surface conditioning method (unground or diamond bur) and adhesive system (no adhesive, LS: Filtek LS, AS: Adper Scotchbond SE Plus) and resin composite (FLS: Filtek LS; FS: Filtek Supreme). The specimens were fixed in an hourglass-shaped silicone matrix and the other half of the specimen was restored. Hourglass-shaped specimens (n = 12) were used as positive control to measure the cohesive strength of the resin composite (Filtek LS). Microtensile bond test was performed (0.5 mm/min) and failure types were analyzed. Data were analyzed using two-way analysis of variance, Tukey’s and Dunnett’s tests (α = 0.05). Adhesive protocol and resin composite significantly affected the results (p < 0.05). For the FS composite, the highest results were obtained using LS adhesive with (18.4 ± 7.7) and without (18.8 ± 4.8) bur roughening. For FLS composite, the highest results were obtained using AS adhesive with (33.2 ± 7.1) and without (25.7 ± 3.6) bur roughening. Without the use of adhesive resin, significantly lower bond strength results were observed with both LS (5 ± 2.1, 4.5 ± 1.5) and FLS (2.2 ± 1.2, 4.4 ± 1.1) for unground and diamond bur roughened groups, respectively (p < 0.0001). Cohesive strength of the FLS (52.3 ± 7.6) was significantly higher than any of the repaired groups (p < 0.0001). FS–LS combination and the groups repaired without adhesive presented more adhesive (Type I) failures.     

Influence of surface energy parameters of dental self-adhesive resin cements on bond strength to dentin

The purpose of this study was to determine the surface energy parameters of dental self-adhesive resin cements (SRCs) and to measure their bond strength to dentin. Six dental SRCs (RelyX Unicem Clicker, RU; Maxcem Elite, ME; BisCem, BC; Clearfil SA Luting, SA; Multilink Speed, MS; seT PP, SP) and one resin-modified glass ionomer cement (RelyX Luting 2, RL; control) were tested. Smear layer-covered bovine dentin was used as bonding substrate. Using the dynamic sessile drop method, surface energy, surface energy components, degree of hydrophobicity/hydrophilicity (expressed as ΔG _sws using thermodynamic notation), and apparent surface energies for each material were calculated. The luting cements were bonded to the dentin and stored in water at 37?°C for 24?h prior to shear bond strength test (n?=?10). Pearson correlation analysis was applied to detect possible correlations between surface energy parameters and measured shear bond strength (α?=?0.05). RU, SA, and MS produced negative ΔG _sws values (hydrophobic), whereas ME, BC, SP, and RL yielded positive ones (hydrophilic). RU had the highest value among all six SRCs tested, the value for MS being statistically equivalent (p?=?0.785). The base component, ΔG _sws, and surface energy determined with water showed significant negative linear correlations with dentin bond strength (r/p?=??0.801/0.030, ?0.900/0.006, and ?0.892/0.007, respectively). These results suggest that bonding to smear layer-covered bovine dentin was governed by the base component and the hydrophobicity/hydrophilicity of the SRCs.     

Effect of bio-alkyd resin oil content and viscosity on the adhesion of EPDM to polyester fabric

Three types of bio-alkyd resins varies in their oil content and viscosity were added to EPDM rubber mix loaded by three bonding system consisting of Hexamethylenetetramine, Resorcinol and Hydrated silica (HRH). The mixes were charged by certain amount of thermal carbon black. Rubber dough was spread on polyester sheet fabric. The peel strength was used to measure the adhesion strength. The rubber-proofed fabric subjected to UV irradiation at different period of times. The dielectric constant, volume resistivity, thermal stability, water and air permeability of the various rubber coated fabric were examined. The addition of the bio-alkyd resin improved the various mechanical and physical properties of the rubber coated fabric materials. The suggested mechanism of bio-alkyd resin between EPDM and polyester fabric was also studied.     

Influence of the fiber surface properties on the mechanical strength of unidirectional fiber composites

The influence of the thermodynamic adhesion between fibers and matrix on the mechanical properties of a continuous fiber reinforced composite is studied for two systems: carbon fiber reinforced poly(ether ether ketone) and glass fiber reinforced poly(ether imide). The fibers are modified chemically and characterized by measuring the contact angle formed by molten resin on the fibers. Various fiber treatments yield a wide range of contact angles, which are determined optically. Unidirectional fiber reinforced laminates are manufactured and transverse flexural strength is measured with the values reported as a function of the specific work of adhesion. It is shown that adhesion at the fiber-resin interface correlates with both the composite strength and the void morphology within the laminate after consolidation.     

Surface modification of ultra-high strength polyethylene fibers for enhanced adhesion to epoxy resins using intense pulsed high-power ion beam

The effects of intense pulsed high power ion beam (HPIB) treatment of ultra-high strength polyethylene (UHSPE) fibers on the fiber/epoxy resin interface strength were studied. For this study, argon ions were used to treat Spectra? 1000 (UHSPE) fibers in vacuum. Chemical and topographical changes of the fiber surfaces were characterized using Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), dynamic wettability measurements, and scanning electron microscopy (SEM). The fiber/epoxy resin interfacial shear strength (IFSS) was evaluated by the single fiber pull-out test. The FTIR-ATR and XPS data indicate that oxygen was incorporated onto the fiber surface as a result of the HPIB treatment. The wettability data indicate that the fibers became more polar after HPIB treatment and also more wettable. Although the total surface energy increased only slightly after treatment, the dispersive component decreased significantly while the acid-base component increased by a similar amount. SEM photomicrographs revealed that the surface roughness of the fibers increased following the HPIB treatment. The single fiber pull-out test results indicate that HPIB treatment significantly improved the IFSS of UHSPE fibers with epoxy resin. This enhancement in IFSS is attributed to increased roughness of the fiber surface resulting in mechanical bonding and in increased interface area, increased polar nature and wettability, and an improvement in the acid-base component of the surface energy after the HPIB treatment.     

有机硅环氧树脂对聚氨酯防水涂料结构和耐水性能的影响

以二甲基硅油和环氧树脂对聚氨酯进行复合改性,制备改性聚氨酯防水涂料。通过红外光谱和扫描电镜对改性聚氨酯涂膜进行了表征,研究了n(─NCO)/n(─OH)比值、二甲基硅油和环氧树脂质量分数对涂膜吸水率的影响。结果表明,当n(─NCO)/n(─OH)=2:1、二甲基硅油和环氧树脂含量分别为8%和7%(均为质量分数)时,所制备的有机硅环氧改性聚氨酯涂料的耐水性能最佳,涂膜的拉伸强度为12.02 MPa,抗冲击强度50 kg.cm,吸水率11.37%,附着力1级。