新型耐高温无溶剂环氧胶粘剂的研制

采用DTGM53、DDRS3521这2种多官能环氧树脂,以低黏度的甲基四氢苯酐为固化剂,在促进剂E-24作用下,制备了综合性能优异的新型耐高温无溶剂环氧胶粘剂。同时,对该环氧胶粘剂的黏度、凝胶化时间、粘接性能、活化能等作了系统的研究。结果表明,该胶粘剂具有优异的高温拉伸剪切强度,200℃时高达16.1 MPa。     

耐高温有机胶粘剂的研究进展

对当前国内外耐高温胶粘剂进行了综述。介绍了环氧树脂、酚醛树脂、有机硅、聚酰亚胺、聚苯并咪唑和聚苯基喹嗯啉等耐高温胶粘剂的物理化学性能,以及提高耐高温胶粘剂耐高温性能的一些技术途径和改性方法,并对耐高温胶粘剂的发展趋势进行了展望。     

耐高温热固性树脂胶粘剂的研究动态

综述了耐高温热固性树脂胶粘剂的发展过程与研究现状,介绍了近年来国内外几种性能优异的热固性树脂胶粘剂,提高其高温性能的一些主要途径和改性方法,并介绍了新型功能填料在树脂中的应用情况,最后对耐高温热固性树脂胶粘剂的总体发展趋势进行了展望。     

The preparation and performance of high-temperature adhesives for graphite bonding

Two kinds of high-temperature adhesives (HTAs) were prepared. One was composed of phenol-formaldehyde (PF) resin and boron carbide (PF+B₄C), the other was composed of PF resin, B₄C and fumed silica (PF+B₄C+SiO₂). Graphite materials were bonded by the above adhesives and heat-treated at temperatures ranging from 200 to 1500 °C. The joining strength was tested at room temperature. The results show that the graphite joints exhibit satisfactory bonding strength and that ceramics fillers show a marked property modification effect. The strength of graphite joints bonded by PF+B₄C and PF+B₄C+SiO₂ adhesive and treated at 1500 °C are 9.3 and 17.1 MPa, respectively. The property modification mechanism of ceramics fillers is also discussed in this paper. A strong chemical bonding force is introduced at the bonding interface and the volume shrinkage is restrained, which can be responsible for the good adhesive properties of HTAs for graphite bonding.     

有机硅改性酚醛环氧树脂耐高温胶粘剂的研制

采用甲基苯基硅树脂对酚醛环氧树脂进行改性,硼酚醛树脂与自制固化促进剂作为固化剂,辅以纳米蒙脱土、绢云母粉作为填料,制备出一种能在300℃条件下长期使用的耐高温胶粘剂。在不同的配方及固化工艺条件下測定了有机硅改性酚醛环氧树脂体系的剪切强度,分析了甲基苯基硅树脂／酚醛环氧树脂比例关系、硼酚醛树脂与自制固化促进剂比例关系、固化剂用量、固化工艺条件、纳米蒙脱土的加入量对体系的影响。     

In vitro degradation and cytotoxicity of alkyl 2‐cyanoacrylate polymers for application to tissue adhesives

To investigate the in vitro degradability and cytotoxicity of long alkyl cyanoacrylate polymers [polycyanoacrylates (PCAs)], we synthesized five kinds of alkyl cyanoacrylates (ethyl, 2‐octyl, n‐octyl, ethylhexyl, and ethyl cyanoacryloyllactate). In vitro degradation in buffer solutions and cell cultures for cytotoxicity were performed with PCAs prepared by various polymerization methods. Lower alkyl homologues such as ethyl cyanoacrylate revealed a higher tissue toxicity than higher alkyl homologues. The amounts of formaldehyde released from various PCAs were not proportional to the rate of degradation. The apparent form of the cyanoacrylate polymers greatly affected the degradation rate, as the powdery polymers degraded much more quickly than the films. A new biodegradable polymer, prepared from ethyl 2‐cyanoacryloyllactate, degraded more quickly than the others. The amount of formaldehyde released from the polymer degradation was high because it degraded rapidly. It was observed from cell culture experiments that the viability of the cells was higher with a lower release of formaldehyde because the alkyl side groups were bigger. Therefore, octyl cyanoacrylate polymers demonstrated lower amounts of formaldehyde by degradation and higher cell viability, and these monomers may be desirable for use as tissue adhesives. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3272–3278, 2003     

Novel rapid‐cure adhesives for low temperature using thiirane compound

We investigated improvement of workability (viscosity), storage stability, and curing ability of thiirane resin for adhesive applications. The viscosity of bisphenol‐F thiirane resin was lower than that of bisphenol‐A thiirane resin, especially at low temperatures, thus improving ease of handling. Addition of diphenyl decyl phosphite improved its storage stability to a level similar to that of bisphenol‐A epoxy resin. The curing of bisphenol‐F thiirane resin increased three times faster by adding 2,4,6‐tris(dimethylaminomethyl)phenol (DMP‐30) as a tertiary amine. In applications of this new thiirane resin as civil and architectural adhesives, a superior curing ability at low temperature was attained. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2953–2957, 2001     

改性耐高温胶粘剂的研究进展

综述了近年来国内外改性耐高温胶粘剂的发展现状,对环氧树脂(EP)、酚醛树脂(PF)、有机硅、含氮杂环以及无机耐高温胶粘剂的性能、应用和改性方法进行了详细的论述,主要介绍了提高各种胶粘剂耐高温性能的改性方法和技术途径,并对今后改性耐高温胶粘剂的发展趋势作了展望。     

Geometrical study of mixed adhesive joints for high-temperature applications

The use of adhesives for high-performance structural applications has significantly increased in the last decades. However, the use of adhesive joints in adverse environmental conditions is still limited due to the reduced capability of adhesives to withstand large thermal gradients. Dual adhesive joints, which contain two adhesives with remarkably different mechanical behaviours, are a technique suitable for being used in extreme temperatures. The object of this study is a ceramic–metal joint, representative of the thermal protection systems of some aerospace vehicles. In this paper, several joint-mixed joint geometries are presented, studied with recourse to finite element analysis. In a first phase, the three-dimensional finite element models and the material properties are validated against experimental data. In a second phase, the model geometry is modified, with the aim of understanding the effect of several changes in the joints’ mechanical behaviour and comparing the merits of each geometry. The models’ presented good agreement was found between experimental and numerical data and the alternative geometries allowed the introduction of additional flexibility on the joint but at the cost of lower failure load.     

Epoxy-based composite adhesives with improved lap shear strengths at high temperatures for steel-steel bonded joints

High-performance room temperature-cure epoxy structural adhesives utilizing simplified formulation are developed. The developed structural adhesive consists of diglycidyl ether of bisphenol A (DGEBA) and novolac epoxy blend as a base resin, micrometer-sized silica particles as a reinforcing filler, and triethylenetetramine as a curing agent. The developed ambient temperature-cure epoxy structural adhesive with optimized formulation exhibits outstanding properties including high glass transition temperature of 95°C, high thermal stability with degradation temperature at 5% weight loss of 364°C, exceptionally high rubbery plateau modulus of 320 MPa, good flame-retardant characteristics with limiting oxygen index of 40, and high single lap shear strength for single lap steel-steel bonded joint of 548 MPa at the temperature of 80°C. The silica-filled DGEBA/novolac epoxy composite adhesive is a potential candidate for applying as a structural adhesive for construction with long-term durability.     

Preconditioning of epoxy film adhesives for bond strength improvement

The moisture level of two commercial overaged epoxy film adhesives has been controlled by drying under vacuum and/or exposure to humid atmosphere. Shear and peel bond strengths of the conditioned adhesives were evaluated. Predrying of the uncured adhesive under vacuum (3–5 mm Hg) at room temperature is shown to be very effective for bond strength enhancement. Additional humidifying/drying circles show the same effect but some irreversible degradation occurs and only partial improvement of adhesive bond strength is achieved.     

Characterization of thermally reworkable thermosets: materials for environmentally friendly processing and reuse

In recent years, several research groups have created reworkable thermoset systems. A prominent use of such materials is in microelectronics packaging areas to enable the repair or reprocessing of electronic components. A wider implication of such an application is that it may facilitate the future recycling or reuse of older computer systems. Recent studies indicate millions of computers are discarded each year due to obsolescence or other factors. The research presented here involves studies of thermosets incorporating a cycloaliphatic epoxy monomer that contains a tertiary ester linkage. When part of a fully crosslinked network, the reworkable epoxy unit will disconnect the network under predetermined thermal conditions. We studied the chemical and thermo-mechanical breakdown mechanisms of the monomer and resulting polymer networks as a function of their rework conditions. Via analytical chemistry techniques, the materials were found to degrade in a controlled fashion consistent with prior polyester degradation studies. Monitoring the change in glass transition temperature of the materials under rework conditions yielded both kinetic and mechanistic data of the degradation process, as well as providing insight into the materials' mechanical strength.     

Investigation of mechanical and thermal properties of nanostructure-doped bulk nanocomposite adhesives

ABSTRACT

In recent years, findings in nanoscience and nanotechnology have deeply influenced many disciplines including the material and mechanical sciences. Polymers including nanostructures have attracted attention as their adoptions in general engineering composites have yielded efficient results. In this study, three different two-component (epoxy-hardener) adhesives were doped with graphene nanoplatelets, graphene oxide nanoplatelets, carbon nanotube, and fullerene C60 at three different rates (0.5%, 1%, and 2% by weight) and the mechanical and thermal properties of the nanocomposite adhesives were examined. The nanocomposite adhesives’ mechanical properties were analyzed via tensile tests and thermal properties were analyzed via Differential Scanning Calorimeter (DSC) thermograms and Fourier Transform Infrared Spectroscopy (FT-IR) spectra. Results showed that doping nanostructures improve the stress-strain capacity of the adhesives. Both mechanical and thermal properties of the nanocomposite adhesives seem to change depending on the amount of nanostructure. Additionally, DSC and FT-IR curves showed an agreement with these improvements in the adhesives’ mechanical properties.     

双马来酰亚胺/环氧树脂胶粘剂增韧改性的研究

以双马来酰亚胺（ＢＭＩ）、环氧树脂、芳香二胺和液体橡胶为主要原料,综合ＢＭＩ的耐高温性能、环氧的良好粘接性能和液体橡胶的增韧作用,制作成一种性能优异的胶粘剂。重点讨论了两种橡胶对胶粘剂性能（尤其是高温强度和温度冲击强度）的影响,并用热重分析（ＴＧ／ＴＧＡ）的扫描电镜（ＳＥＭ）对胶进行了表征。     

Synthesis,Characterization, and Antimicrobial Properties of p-Chloroacetophenone Oxime-Based Furan Resins

A copolymer resin, p-chloroacetophenone oxime-furfuraldehyde (CAOFU), and a terpolymer resin, p-chloroacetophenone oxime-formaldehyde-benzoic acid (CAOFUBA), were synthesized in the presence of hydrochloric acid as catalyst. The structures of copolymer and terpolymer were established by FT-IR and ¹H NMR techniques. Molecular weight and polydispersity index were determined by gel permeation chromatography. The thermal stability was evaluated by thermogravimetric analyses (TGA). Softening temperatures (T_s) of these polymers were obtained from differential scanning calorimetry (DSC). All the synthesized polymers have shown reasonably good antimicrobial activities.     

Synthesis and properties of vinyltrimethoxysilane–EPDM–styrene graft terpolymer

The graft copolymerizations of vinyltrimethoxysilane (VTMO) and styrene (St) onto ethylene–propylene–diene terpolymer (EPDM) were carried out with benzoyl peroxide (BPO) as an initiator in toluene. The effects of EPDM concentration, mole ratio of VTMO to St, reaction time, reaction temperature, and initiator concentration on the graft copolymerizations were examined. The synthesized VTMO–EPDM–St graft terpolymers (VES) were confirmed by infrared and ¹H-NMR spectroscopies. The molecular weight, thermal stability, light resistance, and weatherability of the graft terpolymer were investigated by gel permeation chromatography, thermogravimetric analysis, and Fade-o-Meter. The number-average molecular weight was 109,000. It was found that the heat resistance and light resistance as well as weatherability of VES are considerably better than those of acrylonitrile–butadiene–styrene terpolymer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1345–1352, 1998     

样品制备工艺对石材干挂胶性能测试结果的影响

探讨了石材干挂胶性能测试中样品制备工艺对钢/钢拉剪强度和冲击强度测试结果的影响。结果表明,制备钢/钢拉剪样品时用垫丝控制胶层厚度的方法,控厚更精确,测试结果重复性好;相比于硅胶模具,钢模具制2备的试样冲击强度要高出0.5~0.8 k J/m,样品制备中不同的表面找平方法对冲击强度的影响相对较小。     

碱水易溶聚酯热降解动力学研究

利用热重分析法(TGA)对自制的碱水易溶聚酯(ASHPET)的热降解动力学进行了研究,并与常规PET和国外某公司碱水易溶聚酯(K-COP)进行了比较。结果表明:几种ASHPET的热稳定性略低于常规PET;三种自制的ASHPET的热稳定性不低于国外某公司的K-COP。     

聚醋酸乙烯酯乳液胶粘剂的改性研究进展

介绍了聚醋酸乙烯酯(PVAc)乳液的特点,并对醋酸乙烯胶粘剂的改性研究的最新状况进行了综述。     

Novel pyridinium derivatives as very efficient photoinitiators for UV-activated synthesis of acrylic pressure-sensitive adhesives

During the development of synthesis of acrylic pressure-sensitive adhesives, newly synthesized pyridinium derivatives were used by the UV-initiated polymerization quarantines of new polymer design for the synthesized self-adhesive acrylics with excellent performance, for which tack, peel adhesion, shear strength and shrinkage were measured. For example, the best tack and peel adhesion performances were achieved after 30 and 60 s UV radiation for 3.0 wt% pyridinium photoinitiator PPP, after 60 and 90 s UV exposure for 4.0 wt% pyridinium photoinitiator HPP and after 90 s UV-crosslinking in the case of 5.0 wt% pyridinium photoinitiator OPP. An increase of novel pyridinium photoinitiators concentration causes in an increase of the monomers conversion. For high photoinitiator content, characterized for each investigated photoinitiator, ranging from about 3.0 (PPP) to 5.0 wt% (OPP), the degree of monomer conversion reaches a maximum value of about 99.6 wt%.Preliminary results are reported illustrating the effectiveness of the acrylic PSA development.