环氧灌浆材料在莞惠城际轨道工程GZH-5标渗漏水治理中的应用

针对当前聚氨酯灌浆材料在渗漏水治理中存在的问题,提出了依靠堵水环氧灌浆材料和高渗透环氧灌浆材料进行渗漏水治理的新思路。环氧类灌浆材料既能够对混凝土裂缝等缺陷进行修复,也能够封堵渗漏水,希望修复后的缺陷能够保持和恢复混凝土结构的耐久性。     

Mechanical,thermal and morphological behavior of bismaleimide modified polyurethane‐epoxy IPN matrices

An intercrosslinked network of bismaleimide modified polyurethane‐epoxy systems were prepared from the bismaleimide having ester linkages, polyurethane modified epoxy and cured in the presence of 4,4′‐diaminodiphenylmethane. Infrared spectral analysis was used to confirm the grafting of polyurethane into the epoxy skeleton. The prepared matrices were characterized by mechanical, thermal and morphological studies. The results obtained from the mechanical and thermal studies reveal that the incorporation of polyurethane into the epoxy skeleton increases the mechanical strength and decreases the glass transition temperature, thermal stability and heat distortion temperature. Whereas, the incorporation of bismaleimide having ester linkages into polyurethane modified epoxy systems increases the thermal stability, tensile and flexural properties and decreases the impact strength, glass transition temperature and heat distortion temperature. Surface morphology of polyurethane modified epoxy and bismaleimide modified polyurethane‐epoxy systems were studied using scanning electron microscopy. Copyright © 2003 John Wiley & Sons, Ltd.     

A study on the glass transition behavior and morphology of semi-interpenetrating polymer networks

The epoxy resin/polyurethane semi-IPN was prepared and the glass transition behavior of the semi-IPN was discussed with DSC and DMA methods. The results show that the two glass transition temperatures (T_g) referring to epoxy resin and polyurethane respectively get closer. Between the two T_g there exists another T_g related to the interface between the two polymers. SEM indicates that this semi-IPN has a two-phase continuous structure which changes with different weight compositions. This is also proved by testing the Young's modulus. It is found that the IPN system has a cellular structure. Comparatively, the compatibility between the two polymers is the best when the weight ratio of EP/PU is 70/30. © 1996 John Wiley & Sons, Inc.     

Assessment of adhesion between polyurethane liner and epoxy based substrate: Methodology and experiment

A methodology for assessing interfacial adhesion properties between polyurethane liners and epoxy based substrates was sought to optimize manufacturing procedures for polyurethane lined fibre reinforced epoxy piping. The experimental study showed that the blister test is apposite and expedient for this purpose. The employed methodology allowed for quantification of bond toughness by pressurizing a polyurethane overlayer through a central perforation in an epoxy substrate and measuring the height and pressure of the resulting blister during interfacial fracture. Details of sample fabrication, experimental setup and testing procedures are presented. This study demonstrated that specimens with mechanically bonded polyurethane-epoxy interface underwent interfacial fracture. Samples with a strong chemical bond at the interface, on the other hand, did not exhibit interfacial fracture. A chemically bonded interface is, thus, deemed superior to its mechanically bonded counterpart, and manufacturing protocols for polyurethane lined fibre reinforced epoxy pipe should, therefore, be adjusted to promote chemical bonding at the materials' interface.     

Preparation of thermal-enhanced epoxy resin adhesive with organic PCM for applying wood flooring

Epoxy resins are well-known materials that show beneficial properties, such as high tensile strength and modulus, good adhesive properties, low cost, and ease of processing and environmental advantages. However, epoxy resin adhesive has no characteristic of thermal storage. Latent heat storage is one of the favorable kinds of thermal energy storage methods considered for energy saving and thermal efficiency in various fields, such as solar air conditioning systems and buildings. So we prepared thermal-enhanced epoxy resin adhesive by using PCM. This paper addresses the effects of n-hexadecane and sodium lauryl sulfate on the thermal properties and chemical properties of epoxy resin adhesive and HEAC, using differential scanning calorimetry, thermal gravimetric analysis, and Fourier transform-infrared spectroscopy. Also, we evaluated the applicability of composite epoxy resin adhesive to wood-based flooring using n-hexadecane, through measurement of bonding strength from universal testing machine analysis.     

Bio‐based hyperbranched polyurethane/clay nanocomposites: adhesive,mechanical, and thermal properties

The unison of vegetable oil‐based hyperbranched polymers with nanotechnology can unhook myriad of avant‐garde applications of such materials. Thus Mesua ferrea L. seed oil‐based hyperbranched polyurethane (HBPU)/clay nanocomposites and their performance, with special reference to adhesive strength, are reported for the first time. The nanocomposites of the hyperbranched polyurethane with organically modified nanoclay were obtained by ex situ solution technique and cured by bisphenol‐A‐based epoxy with poly(amido amine) hardener system. The partially exfoliated and well‐distributed structure of nanoclay was confirmed by XRD, SEM, and TEM studies. FTIR spectra indicate the presence of H‐bonding between nanoclay and the polymer matrix. Two times improvement in the adhesive strength and scratch hardness, 10 MPa increments in the tensile strength and 112°C more thermo‐stability have been observed without much affecting the impact resistance, bending, and elongation at break of the nanocomposites compared to the pristine epoxy modified HBPU system. Thus, the resulted nanocomposites are promising materials for different advanced applications including adhesive. Copyright © 2009 John Wiley & Sons, Ltd.     

Epoxy modified polyurethane rigid foams

Rigid IPN foams were prepared by sequential polymerization of polyurethane and epoxy systems. Significantly higher compressive modulus and strength were observed with the IPN foams in comparison to the corresponding polyurethane rigid foams. The IPN foams show one glass transition temperature. The single T_g indicates the very small domain size in the PU-epoxy IPN's.     

Structural investigation of e-beam cured epoxy resins through solid state NMR

In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artefact, are obtained by solid state NMR, carried out at constant room temperature.     

Sol–gel derived hybrid coatings as an environment friendly surface treatment for corrosion protection of metals and their alloys

Sol?Cgel derived organic inorganic hybrid coatings are effective corrosion protective systems for metals. They offer an excellent adhesion to metal as well as to the subsequent coat via strong covalent bond and a three dimensional network of ?CSi?CO?CSi?C linkages which helps to retard the penetration of corrosive medium through the coating. Unlike conventional surface protection methodology, silane based pre-treatment is an environment friendly technology with number of advantages like room temperature synthesis, chemical inertness, high oxidation and abrasion resistance, excellent thermal stability, very low health hazard etc. Further, the hybrid silane provides required flexibility and an increased compatibility with the subsequent coating in multicoat systems. The performance properties of hybrid systems depend on number of parameters like type of silane (mono or bis), degree of hydrolysis, type and dosage of inhibitive/barrier pigments (in case of pigmented system), application techniques, curing temperature and curing schedule, need to be optimized. A guideline formulation for maximum corrosion resistance with low environmental impact consist of a superprimer (a bis-silane with conventional resins, chrome free inhibitive pigments and additives) followed by epoxy or polyurethane top coat as per the exposure conditions.     

Colour development and luminescence phenomena in epoxy glasses

The process of colour development in aromatic-amine cured epoxy resin glasses following exposure to oxygen has been studied using electron spin resonance (ESR) and thermoluminescence (TL). Even short duration exposure to oxygen was found to produce species in glassy epoxy resins which gave rise to TL when heated from room temperature to a temperature just below the cure temperature. In some epoxy samples, oxygen exposure over longer periods was found to produce sample colouration. UV-visible spectrophotometry revealed chromophores which were believed to arise from the diaminodiphenylmethane structural unit found in epoxy systems containing the resin, N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) or the curing agent, 4,4′-diaminodiphenylmethane (DDM). The chromophore produced in TGDDM-based resins appeared to be simlar to the "Wurster's salt'-type structure produced by photo-ionization of these systems. A distinctive ESR spectrum was also noted for samples exposed to oxygen. These results are indicative of both peroxide group formation on the methylene groups as well as the formation of amine centred radical cations, and are consistent with the oxidative sensitivity of these epoxy resins. The TL is believed to result from the thermally induced recombination of the 'Wurster's salt'-like cations with peroxy anions leading to the production of an electronically excited diaminobenzophenone structure © 1998 John Wiley & Sons, Ltd.     

Bio‐based high‐performance waterborne hyperbranched polyurethane thermoset

Tannic‐acid‐based low volatile organic compound‐containing waterborne hyperbranched polyurethane was prepared. In order to improve the performance, it was modified in an aqueous medium using a glycerol‐based hyperbranched epoxy and vegetable‐oil‐based poly(amido amine) at different wt%. The combined system was cross‐linked by heating at 100°C for 45 min. Fourier transform infrared spectroscopy and swelling study were used to confirm the curing. A dose‐dependent improvement of properties was witnessed for the thermoset. Thermoset with 30 wt% epoxy showed excellent improvements in mechanical properties like tensile strength (~3.4 fold), scratch hardness (~2 fold), impact resistance (~1.3 fold), and toughness (~1.7 fold). Thermogravimetric analysis revealed enhancement of thermal properties (maximum 70°C increment of degradation temperature and 8°C increment of T_g). The modified system showed better chemical and water resistance compared with the neat polyurethane. Biodegradation study was carried out by broth culture method using Pseudomonas aeruginosa as the test organism. An adequate biodegradation was witnessed, as evidenced by weight loss profile, bacterial growth curve, and scanning electron microscope images. The work showed the way to develop environmentally benign waterborne polyurethane as a high‐performance material by incorporating a reactive modifier into the polymer network. Use of benign solvent and bio‐based materials as well as profound biodegradability justified eco‐friendliness and sustainability of the modified system. Copyright © 2015 John Wiley & Sons, Ltd.     

Nanocomposites based on silicon dioxide. Preparation and properties

The literature devoted to the preparation of nanocomposites based on polyurethane and epoxy polymers and silicon dioxide is reviewed. The main methods for their production are summarized, and the properties of resulting materials are presented. The synthesis, properties, and structure of the polymers obtained by the sol-gel technique are described in detail.     

环氧改性水性聚氨酯乳液的制备及其膜性能

以聚己内酯二元醇(CAPA)为软段,异佛尔酮二异氰酸酯(IPDI)和六亚甲基二异氰酸酯(HDI)为硬段,环氧树脂E-44为大分子交联剂,经相转化法合成了一系列环氧树脂改性负离子水性聚氨酯(EPPU)自乳化乳液,并制备了改性水性聚氨酯的固化膜.通过FTIR、TGA及接触角、力学性能测试对聚合物结构及其膜性能进行了研究.通过原子力显微镜(AFM)观察膜表面形态和表面粗糙度.乳液粒径及粒径分布通过动态激光光散射法(DLLS)测定.FTIR分析表明环氧树脂的羟基和环氧基都参与了发应.TGA表明,环氧树脂的加入可以提高聚氨酯的热稳定性.随着w(E-44)增大,改性聚氨酯膜的拉伸强度得到改善,断裂伸长率减小.随着w(E-44)增大,乳液粒径增大,薄膜的接触角增大,改性后的PU膜表面光滑度下降,拒水性增强.     

New low viscous polyisocyanates for VOC compliant systems

Since 1961, aliphatic polyisocyanates based on HDI-biurets are used as light stable hardeners for 2-K polyurethane coatings. The market introduction of the HDI-isocyanurates or simply 'trimers' in the early 1980's was driven by their lower viscosity and their better monomer stability. The most recent development in HDI-polyisocyanate research are the iminooxadiazinediones (asymmetric trimers). In this paper, a new product based on that technology with a very low viscosity (700 mPas@23°C) and a NCO-functionality of more than 3 is presented. Because of its low viscosity, this hardener can be easily incorporated into aqueous systems and is the solution for high and full solids coatings as well.     

Study on the sorption of water into epoxy resins by means of electrochemical impedance spectroscopy

In this work the relationship between structure and water sorption for epoxy films was studied using electrochemical impedance spectroscopy. It is shown that the electrochemical impedance spectroscopy can be applied to obtain information about the amount of water absorbed by the epoxy film and the water permeation through the film, while only the amount of water absorbed is obtained from the “sorption method”. The free volume is the decisive factor for both the amount of water in the cured epoxy film and water permeation through the film.     

Nanodiamond tethered epoxy/polyurethane interpenetrating network nanocomposite: Physical properties and thermoresponsive shape-memory behavior

In this study, a novel blend of polyurethane and diglycidyl 1,2-cyclohexanedicarboxylate epoxy was prepared and reinforced with various content of functional nanodiamond (0.1–5 wt%). According to morphological analysis, diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond nanocomposite revealed beaded-twine network structure due to entrapment of nanodiamond aggregates into epoxy/polyurethane interpenetrating networks. Exclusive self-assembled nanodiamond-tethered interpenetrating network was due to physical inter-linking of nanodiamond with blend components. There was a 47% rise in tensile strength and an 80% increase in Young’s modulus of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 nanocomposite relative to neat polymer. The original shape of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 was 95% recovered using heat-induced shape-memory effect.     

Flame retardancy and heat resistance of phenol-biphenylene-type epoxy resin compound modified with benzoguanamine

The flame retardancy and heat resistance of a phenol-biphenylene-type epoxy resin compound, which forms a self-extinguishing network structure, were increased by the inclusion of a benzoguanamine-modified phenol biphenylene resin. The benzoguanamine-modified phenol biphenylene resin contains a benzoguanamine unit to release non-flammable nitrogen substances during ignition and to increase the resin's reactivity toward epoxy resins, and biphenylene units to keep the resin's thermal degradation and water resistance. The addition of the benzoguanamine-modified phenol biphenylene resin in the epoxy resin compound improved the epoxy resin compound's flame retardancy and heat resistance, and also increased its glass transition temperature while maintaining its water resistance and mechanical properties. Copyright © 2003 John Wiley & Sons, Ltd.     

聚氨脂改性环氧树脂注浆材料的研究

本研究是以聚醚型聚氨酯改性环氧树脂作为混凝土裂缝修补注浆材料。这种改性的环氧树脂注浆材料不仅弹性、韧性得到大大提高,而且仍具有较高的抗压与抗拉强度、高粘结性。本文讨论了该浆材不同溶剂、不同交联剂用量对浆液性能的影响,并用红外光谱对改性环氧树脂注浆材料进行了结构分析。     

Ball milling: An effective technique for the preparation of exfoliated clay filled unsaturated polyester toughened epoxy nanocomposite

This paper investigates the possibility of improving the mechanical and thermal properties of epoxy and unsaturated polyester toughened epoxy resins through the dispersion of octadecyl ammonium ion-exchanged montmorillonite (organoclay) through exfoliated mechanism. The nanocomposites prepared are characterized for their structural change and studied for their crystallite size, mechanical, thermal and water absorption (hydrophilicity) properties. The mechanical data indicates significant improvement in the flexural and tensile properties over the neat epoxy and UP-epoxy matrix according to the percentage content of organoclay. The thermal behavior too shows noticeable enhancement in glass transition temperature T _g and high thermal stability. Hydrophilicity of all the composites decreases irrespective of the concentration of organoclay on the epoxy and UP-epoxy matrices. The homogeneous morphology of epoxy and UP toughened epoxy nanocomposite hybrid systems is ascertained using scanning electron microscope (SEM). X-ray results point out that the cetyl ammonium modified clay filled composites exhibited the exfoliated structure.     

Transient deformation and heat generation of solid polyurethane under impact compression

This investigation examines the transient deformation and heat generation of a solid polyurethane subjected to dynamic compression. A special method is presented to prepare the solid polyurethane from raw materials which are commonly used to make polyurethane foams. Testing methods including infrared spectrum, differential scanning calorimetry, quasi-static and dynamic compression were applied to study the basic physical properties of the solid polyurethane. High-speed optical and infrared imaging systems are used to obtain visual and thermo-graphic images during impact tests. Under quasi-static compression, the solid polyurethane presents a good performance in toughness. This is confirmed by its Poisson's ratio. Under impact compression, the adiabatic heat generation are identified statistically. Temperature distribution confirms the fact of transient heat generation in specimens. Adiabatic self-heating mechanism provides a consideration to understand the negative strain-rate effect and post-yield softening effect found in the solid polyurethane. Mechanical properties including quasi-static and dynamic responses are related with the composition of molecular and structure of polymer.