Reactivity and spectral comparisons of alkylresorcinol laminating resins with phenolic and resorcinolic resins

Two alkylresorcinol-based laminating resins, DFK-14R and FR-100, are compared in reactivity and structure with resorcinol- and phenol-based adhesive resins. The alkylresorcinols, derived from Estonian shale oil, replace costlier, less-reactive resorcinol in adhesives in the USSR. Differential scanning calorimetry quantitates the reactivity advantage. Infrared spectroscopy and proton nuclear magnetic resonance provide spectral patterns to distinguish the alkylresorcinol resins from the families of resorcinol-and phenol-based resins. Structural features are assigned for most of the spectral absorptions, with aid from ¹³carbon nuclear magnetic resonance spectra of the shale oil resins.     

纸塑复合胶粘剂的研究现状和动向

纸塑复合制品是现代包装行业应用较广泛的一种复合材料,而纸塑复合胶粘剂是纸张和塑料薄膜复合工本文综述了溶剂型和水基型两类纸塑复合胶粘剂的研究现状,并提出今后的研究方向是开发环境友好胶粘剂、高固含量乳液和功能性胶粘剂.     

Modification of melamine‐formaldehyde resins by substances from renewable resources

In the present contribution, investigations on the chemical modification of thermosetting melamine formaldehyde resins by natural polyol compounds are presented. As representative agents soluble starch, sucrose, and glycerol were chosen to cover three different classes of polyols. The major aim was to use substances produced from natural bio‐renewable feedstock that are available in large quantities and may serve as environmentally innocuous and bio‐renewable substitutes for petro‐chemically derived and potentially hazardous materials. Different reaction conditions lead to resins with varying technical performance. For soluble starch no reaction conditions could be found that allow the adoption of this substitute for the laminate industry due to insufficient technological performance. Sucrose and glycerol on the other hand yielded impregnation resins with suitable performance. Chemical linkage of the modifying agent into the chain propagation by poly‐condensation however, was only found with glycerol. The covalent incorporation of glycerol in the network was observed with addition of glycerol at different stages during synthesis. The technological performance of the various modified thermosetting resins was assessed by determining flow viscosity, molar mass distribution, the storage stability, and in a second step laminating impregnated paper to particle boards and testing the resulting surfaces according to standardized quality tests. Spectroscopic evidence of chemical incorporation of glycerol was found by applying by ¹H, ¹³C, ¹H/¹³C HSQC, ¹H/¹³C HMBC, and ¹H DOSY methods. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Effect of Different Surface Pretreatment Methods on Nano-adhesive Application in High Strength Steel and Aluminum Bonding

Epoxy adhesives (single and two components) modified with SiO₂ nano-particles were used in this investigation to glue aluminum alloy and also two types of high strength steel (dip-galvanized steel DP 600 and micro-alloyed steel ZStE340). To improve the adhesion between metal surfaces and adhesives, the metal surfaces were pretreated with: a self-indicating pretreatment (SIP^*); corundum blasting; corundum blasting + a SIP coating; and a Pyrosil^® treatment + SurALink^® primer (PG 15 for epoxy adhesive). A single-lap shear tension test, done in accordance to DIN EN 1465, was used to determine the adhesive strength. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) analysis were used to analyze fractures that took place in the samples. The results showed that the adhesion strength of glued samples, containing the nano-particles modified adhesive, had significantly higher strength than unmodified ones. Pretreatment of the metal surfaces affected the adhesion, using nano-adhesives, only slightly. The adhesive strength values for single component epoxy resins were higher than those for two component epoxy resins. It was found that steel samples fractured adhesively at the steel surfaces. Aluminum treated samples indicated after pretreatment an increase in adhesive strength and the fracture occurred adhesively at the aluminum surfaces. Aluminum glued with two-component adhesives and pretreated with corundum blasting plus a SIP coating showed a mixed fracture mode; adhesively at the aluminum surface and cohesively in the adhesive layer.     

Thermal response of composite panels

The thermochemical and flammability characteristics of laminating resins and composites currently in use and others being considered for use as aircraft interior panels are described. The properties studied included: (a) limiting oxygen index of the composite constituents; (b) fire containment capability of the composite; (c) smoke evolution from the composite; (d) thermogravimetric analysis; (e) composition of the volatile products of thermal degradation; and (f) relative toxicity of the volatile products of pyrolysis. The performance of hightemperature laminating resins such as modified phenolics, polyimides and bismaleimides is compared with the performance of epoxies. The relationship of increased fire safety with the use of polymers with high anaerobic char yield is shown. Processing parameters of the state-of-the-art epoxy resin and the advanced resin composites are detailed.     

Weibull analysis of stiffness and strength in bulk epoxy adhesives reinforced with particles

The mechanical and statistical behaviour of aerospace structural adhesives has been investigated by performing tensile tests on moulded samples and applying Weibull theory to results. Effects of loading rate, sample size and process parameters have been studied. The experimental design method has been employed in an attempt to extend the experimental results to other combinations of parameters. Three kinds of structural adhesive have been characterised, viz, Hysol^® EA9321, Hysol^® EA9394 and Hysol^® EA9395, which are particle reinforced epoxy adhesives, all of them containing voids with statistically distributed sizes (partially dependent on bonding technique). These highly heterogeneous, but natural, microstructures explain the dispersion of measured strength and Young’s modulus of the materials. These two quantities are demonstrated not to be correlated. With these results, simple fibre bundle theory is used to evaluate the mean value and variance of the failure stress of a bonded joint loaded in tension.     

Phenolic resin adhesives based on chestnut (Castanea sativa) hydrolysable tannins

Chestnut hydrolysable tannins are phenolic materials that have been considered too unreactive to compete in the phenolic resin adhesives market for exterior boards for the building industry. However, an article in 1973 describing 3?years industrial application of chestnut hydrolysable tannins during the first oil crisis indicated that this was not the case. We have extended this old work by using superior phenolic resins formulations and producing phenol–formaldehyde–chestnut tannin adhesives where a substitution of up to 80% of the phenol is possible with remarkably good results. The reactions involved were clarified by ¹³C NMR and MALDI-TOF mass spectrometry.     

水性材料在医药包装行业中的应用

目前国内在医药包装行业普遍使用溶剂型凹版油墨、OP/VC剂、复合胶粘剂,具有毒性大、成本高、易燃易爆、溶剂残留影响药物质量等缺陷,在医药包装行业中应用水性材料已是大势所趋。主要介绍了水性凹版油墨、水性OP/VC剂、水性复合胶粘剂的研究进展,及在医药包装行业中的应用,并对未来的发展做出了展望。     

水性丙烯酸酯类纸塑复膜胶的研究进展

水性纸塑复膜胶是包装行业应用广泛的胶粘剂.目前,研究和应用最为广泛的是丙烯酸酯类纸塑复膜胶.综述了丙烯酸酯类纸塑复膜胶的研究进展,并对其存在的问题及今后的研究方向进行了讨论.     

An aliphatic amine cured rubber modified epoxide adhesive: 1. Preparation and preliminary evaluation using a room temperature cure

Methods of preparing epoxy resins capable of being cured at room temperature to yield adhesives of high shear and peel strengths are examined. The preferred formulation consists of reacting the diglycidyl ether of bisphenol A with a dicarboxy-terminated butadiene—acrylonitrile (CTBN) rubber (10–15 phr) at 150°C for a minimum period of 2 h. These materials may be cured with diethyleneglycol bis-propylamine at room temperature for 3 days to yield adhesives which have shear and peel strengths of about 32 MN/m² and 5 kN/m respectively at 10 phr CTBN and about 26 MN/m² and 8 kN/m at 15 phr CTBN.     

Flame retardant investigations on carbon fibre-reinforced polyurethane resin parts for aircraft applications produced by wet compression moulding

Epoxy resins are widely used in composite materials for aircraft applications. However, they are difficult to recycle, thus posing an increasing challenge to the aviation sector. By contrast, polyurethane resins (PUR) can be easily chemically recycled by solvolysis, but structural parts made of carbon fibre-reinforced polyurethanes (CF-PURs) are currently not in use in aircraft applications. This is due to a lack of knowledge about the properties of CF-PURs, especially during exposure to higher temperatures and to fire. To increase the recyclability of aircraft parts, for example interior structures like seats, there is a need for CF-PUR components which are able to fulfil the flame retardant regulations as well as the quality and production cycle time requirements of the aviation industry. It was found that a CF-PUR formulation processed by wet compression moulding containing 9 wt% of a phosphorous polyol is able to fulfil these requirements for aviation interior applications.     

Fabrication of novel antimicrobial poly(vinyl chloride) plastic for automobile interior applications

With the fast development of auto industry, more and more new functional materials are developed to satisfy our life. Auto interior materials are usually suffered from the attack of bacteria and therefore affect people. In this work, we reported on the fabrication of novel antimicrobial poly(vinyl chloride) plastic (PVCP-I, PVCP-II) with antimicrobial halloysite nanotubes and SiO₂/ZnO/ZnS/Ag₂S nano-composites as additives, respectively, and then these two kinds of novel antimicrobial poly(vinyl chloride) PVC materials were applied to automobile interior. Firebrake^® ZB was used as the fire retardant and the results showed that the prepared PVC materials have excellent non-flammability properties. The oxygen indexes of traditional PVCP, PVCP-I and PVCP-II were 30.1, 31.9 and 32.5 %, respectively. PVC antimicrobial materials were prepared by coating on the special paper. PVCP-I and PVCP-II could kill more than 99 % of Escherichia coli and Staphylococcus aureus with concentration of about 7 × 10⁷ and 4 × 10⁷ CFU mL^?1, respectively. Mechanical properties and thermal stability were also investigated to study the physical characteristics of the prepared PVC plastic. The formation of nano-additives was confirmed by X-ray diffraction and transmission electron microscopy techniques. Antimicrobial capacity was used as a probe to evaluate the potential applications of prepared PVC-I and PVC-II materials in antimicrobial automobile interiors. Also, the material was characterized by thermo-gravimetric analysis; the result showed that PVCP-I and PVCP-II have excellent thermo-stability. What counts is the simple processing and outstanding characteristic of the PVCP material and great application potential may have in store for the obtained antimicrobial PVC-I and PVCP-II.     

Cure kinetics of a glass/epoxy prepreg by dynamic differential scanning calorimetry

Dicyandiamide (DICY)‐cured epoxy resins are important materials for structural adhesives and matrix resins for fiber‐reinforced prepregs. Dynamic differential scanning calorimetry (DSC) with heating rates of 2.5, 5, 10, and 15°C/min was used to study the curing behavior of the epoxy prepreg Hexply 1454 system, which consisted of diglycidyl ether of bisphenol A, DICY, and Urone reinforced by glass fibers. The curing kinetic parameters were determined with three different methods and compared. These were the Kissinger, Ozawa, and Borchardt–Daniels kinetic approaches. The lowest activation energy (76.8 kJ/mol) was obtained with the Kissinger method, whereas the highest value (87.9 kJ/mol) was obtained with the Borchardt–Daniels approach. The average pre‐exponential factor varied from 0.0947 × 10⁹ to 2.60 × 10⁹ s⁻¹. The orders of the cure reaction changed little with the heating rate, so the effect of the heating rate on the reaction order was not significant. It was interesting that the overall reaction order obtained from all three methods was nearly constant (≅2.4). There was good agreement between all of the methods with the experimental data. However, the best agreement with the experimental data was seen with the Ozawa kinetic parameters, and the most deviation was seen with the Borchardt kinetic parameters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

软包装用无溶剂型聚氨酯复膜胶的发展概况

综述了国内外软包装用无溶剂型聚氨酯(PU)复膜胶的发展概况,并针对其面临的主要问题提出了今后的发展方向。随着人们对环保要求日趋严格,绿色环保的无溶剂型复膜胶必将在复合软包装行业中得到迅速而广泛的应用。     

Analysis of adhesively-bonded T-joints by experimentation and cohesive zone models

Within the scope of adhesively-bonded joints, one of the joint types having industrial application is the T-joint, for example, in marine applications (joining of panels to the hull and connecting the glass-fibre composite hull with anti-flood panels) and aeronautical applications (wing panels, fuselage sections). This work aims to experimentally and numerically study, by cohesive zone models (CZM), the behaviour of T-joints under peel loads. The experimentally evaluated adhesives are the Araldite^® AV138 (high ultimate strength but brittle) and Araldite^® 2015 (less stress to failure but ductile and more flexible). The joint strength is evaluated with different L-shaped adherends’ thickness (t_P2). With the numerical analysis, the stress distributions, damage evolution and strength are studied. Additionally, a purely numerical study compared joints with or without adhesive filling at the curvature of the L-shaped adherends, and an extremely ductile adhesive (Sikaforce^® 7752) was additionally evaluated. The experimental tests validated the numerical results and showed that CZM is an accurate technique for the study of T-joints. It was also shown that the geometry of the L-parts, the presence of filler adhesive and the type of adhesive have a direct influence on the joint strength. In fact, in this particular joint configuration, the ductile but with lower ultimate strength adhesive Sikaforce^® 7752 clearly outperforms the two adhesives with higher mechanical properties but less ductility.     

国内外民机用胶黏剂的应用概况及展望

自航空工业诞生以来胶黏剂就成为了飞机制造中非常重要的材料之一,而自己设计制造大飞机是我国人民和几代航空人的梦想。国内现有的胶黏剂制造和胶接制件的生产水平达不到大飞机的生产需要。综述了国内外民机用胶黏剂的应用现状,分析了差距,指出了我国民机用胶黏剂的发展方向。     

Investigation of soy protein-kymene<Superscript>®</Superscript> adhesive systems for wood composites

This study investigated a new adhesive system, consisting of soy protein isolate (SPI) and Kymene^® 557H (simply called Kymene) (a commercial wet-strength agent for paper), that was prepared by mixing SPI and Kymene. Wood composites bonded with SPI-Kymene adhesive preparations had shear strengths comparable to or higher than those bonded with commercial phenol formaldehyde resins. Wood composites bonded with the new adhesive system had high water resistance and retained relatively high strength even after they had undergone a boiling-water test. The new adhesive system is formaldehyde-free, easy to use, and environmentally friendly. Kymene was proposed to serve as a curing agent in SPI-Kymene adhesives.     

Use of sustainable glucose and furfural in the synthesis of formaldehyde-free phenolic resole resins

Sustainable resol-type resins [phenol–furfural–glucose (PFuG), phenol–furfural (PFu), and phenol–glucose resins] were synthesized via alkali catalysis. The chemical structures of the PFuG resins, which had different molar ratios of glucose to furfural, were analyzed by ¹H-NMR and Fourier transform infrared spectroscopy. A possible mechanism for formation of the PFuG resin was proposed. The crosslinking curing behaviors of the PFuG resins were examined by differential scanning calorimetry analysis. The performance of the PFuG resins as wood adhesives was studied. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47732.     

Toughening of epoxy resins by hydroxy‐terminated,silicon‐modified polyurethane oligomers

Epoxy resins are among the most versatile engineering structural materials. A wide variety of epoxy resins are commercially available, but most are brittle. Several approaches have been used to improve the toughness of epoxy resins, including the addition of fillers, rubber particles, thermoplastics, and their hybrids, as well as interpenetrating polymer networks (IPNs) of acrylic, polyurethane, and flexibilizers such as polyols. This last approach has not received much attention; none of them have been able to suitably increase resin toughness with out sacrificing tensile properties. Therefore, in an attempt to fill this gap, we experimented with newly synthesized hydroxy‐terminated silicon‐modified polyurethane (SiMPU) oligomers as toughening agents for epoxy resins. SiMPU oligomers were synthesized from dimethyl dichlorosilane, poly(ethylene glycol) (weight‐average molecular weight ～ 200), and toluene 2,4‐diisocyanate and characterized with IR, ¹H‐NMR and ¹³C‐NMR, and gel permeation chromatography. The synthesized SiMPU oligomers, with different concentrations, formed IPNs within the epoxy resins (diglycidyl ether of bisphenol A). The resultant IPN products were cured with diaminodiphenyl sulfone, diaminodiphenyl ether, and a Ciba–Geigy hardener under various curing conditions. Various mechanical properties, including the lap‐shear, peel, and impact strength, were evaluated. The results showed that 15 phr SiMPU led to better impact strength of epoxy resins than the others without the deterioration of the tensile properties. The impact strength increased continuously and reached a maximum value (five times greater than that of the virgin resin) at a critical modifier concentration (20 phr). The critical stress intensity factor reached 3.0 MPa m^1/2 (it was only 0.95 MPa m^1/2 for the virgin resin). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1497–1506, 2003     

Performance of MUF resins for particleboard before and after spray-drying

Melamine-urea-formaldehyde (MUF) resins can be spray-dried to obtain resins in powder form and indefinite shelf-life. Application as particleboard adhesives of such resins after redissolving in water yield resins of excellent performance as particleboard adhesives if the natural advancement caused by the heat in the spray-drier chamber is taken into account. Solid-state cross-polarization/magic angle spinning ¹³C nuclear magnetic resonance (CP–MAS ¹³C NMR) analysis of the spray-dried resin in powder form and thermomechanical analysis (TMA) has shown some difference in behavior in relation to MUF resins of the same level of water tolerance which have not been spray-dried. These small but significant differences can be ascribed to differences in resin structure.