Adhesive Bonding of Oil-Contaminated Steel Substrates

Durability of adhesive bonds formed by curing epoxies against oil-contaminated steel substrates using amidoamine curing agents was determined during exposure to boiling water. The most durable bonds were obtained using amidoamine curing agents with relatively low amine numbers and by blending silane coupling agents such as γ-glycidoxypropyltrimethoxysilane (γ-GPS) and N-(2-aminoethyl)-3-aminopropyltrimethoxy silane (AAMS) into the adhesives. When X-ray photoelectron spectroscopy (XPS) was used to characterize the failure surfaces of the adhesive joints after exposure to boiling water, it was determined that adhesives prepared using amidoamine curing agents with low amine numbers were able to displace the oil from the steel surface but adhesives prepared with amidoamine curing agents with high amine numbers were not. Results obtained from XPS also showed that the amino groups on the substrate fracture surfaces of joints prepared using curing agents with low amine numbers were protonated whereas the amino groups in the bulk adhesive were not, indicating that there was a chemical interaction between the curing agent and the hydrated surface of the substrate. It was also shown using infrared spectroscopy that the amidoamine curing agents formed salts with calcium compounds in the oil.     

Adhesive Bonding of Clean and Oil-Contaminated Electrogalvanized Steel Substrates

The performance of two-part, amidoamine-cured epoxy adhesives on clean and oil-contaminated electrogalvanized steel (EGS) was studied using screening and lap shear tests. On exposure to boiling water, the cured epoxy adhesives with amidoamines having higher amine value delaminated from the clean and oil-contaminated EGS surfaces before those cured with amidoamines having low amine value. The results of X-ray photoelectron spectroscopy (XPS) showed that the adhesives cured with amidoamines having high amine value were unable to displace the oil from the EGS substrate. However, the durability and the strength of the adhesive bonds on the oiled EGS could be improved by adding proper amounts of silane or wetting agent to the adhesive. The preferential adsorption of amino curing agents occurred on the clean EGS surface, confirmed by XPS and reflection absorption infrared spectroscopy, and this decreased the durability of the bonds in boiling water. In addition, from XPS analyses of various specimens, different amounts of cured resins were detected in the adhesive/EGS interfacial regions which affecting the durability of the adhesive bonds. In addition, the amidoamine curing agents may form complexes on the EGS surface.     

Molecular Structure of the Interphase Formed by Plasma-Polymerized Acetylene Films and Steel Substrates

The molecular structure of the interphase between plasma-polymerized acetylene films and steel substrates was determined using in situ reflection-absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS). Plasma-polymerized acetylene films were deposited onto polished steel substrates using argon as a carrier gas and inductively coupled, radio frequency (RF)-powered plasma reactors that were interfaced directly to the XPS and Fourier transform infrared (FTIR) spectrometers. RAIR showed that the plasma polymerized films contained large numbers of methyl and methylene groups but only a small number of mono substituted acetylene groups, indicating that there was substantial rearrangement of the monomer molecules during plasma polymerization. Bands were observed near 1020 and 855 cm^-1 in the RAIR spectra that were attributed to skeletal stretching vibrations in C-C-O-Fe groups, indicating that the plasma-polymerized films interacted with the substrate through formation of alkoxide bonds. Another band was observed near 1565 cm^-1 and attributed to carboxylate groups in the interphase between the films and the oxidized surface of the substrate. Results obtained from XPS showed that the surface of the iron substrate consisted mostly of a mixture of Fe₂O₃ and FeOOH and that iron was mostly present in the Fe(III) oxidation state. However, during plasma polymerization of acetylene, there was a tendency for the concentration of FeOOH groups to decrease and for the concentration of Fe(II) to increase, due to the reducing nature of argon/acetylene plasmas. Results from XPS also confirmed the formation of alkoxide and carboxylate groups in the interphase during plasma polymerization of acetylene.     

Interaction of Epoxy/Dicyandiamide Adhesives with Metal Substrates

The molecular structure of the interphase formed by curing a model adhesive system consisting of the diglycidyl ether of bisphenol-A (DGEBA) and dicyandiamide (DDA) against mechanically polished aluminum and electrogalvanized steel (EGS) substrates was determined using reflection-absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS). RAIR analysis suggested that DGEBA/DDA mixtures created an interphase with a different molecular structure from the bulk of the adhesive when cured in contact with aluminum. The formation of this unique interphase was mainly due to interactions between DDA and the Al surface. XPS analysis indicated that aluminum ions exposed by heating the substrate surface were necessary for this interaction. DDA was found to adsorb onto the aluminum surface via the lone pair of electrons on the nitrogen atoms of the nitrile groups. A slight decrease in the nitrile stretching frequency suggested an additional back-bonding interaction between aluminum ions and the nitrile groups. Slight back donation of electrons from the metal to DDA resulted in a reduction product that led to the formation of the carbodiimide form of DDA. This specific reaction caused a decrease in the concentration of nitrile groups in the interphase and changed the extent of the reaction between DDA and DGEBA by inhibiting the formation of oxazolidine structures. The interaction of DDA with EGS surfaces followed a similar trend. However, the effects were much more pronounced with EGS and the extent of the curing reaction and the cross-linking rate near the metal surface were strongly affected by EGS/DDA interactions.     

Physical,mechanical properties,and structural characterization of konjac glucomannan-chitosan-polypeptide adhesive blends

Polypeptide was used to improve the water resistance of konjac glucomannan (KGM)-chitosan-based wood adhesives. With identical solid content, the tensile strength in wet state was increased by the addition of polypeptide and a maximum tensile strength of 2.34 MPa was reached. To examine the physical and chemical changes induced by the addition of polypeptide, the structure, viscoelasticity, morphology, and miscibility of the adhesive blends were determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, rheometry, and scanning electron microscopy. Results indicated improvements in mechanical properties were related to the formation of intermolecular hydrogen bonds and covalent bonds between KGM, chitosan, and polypeptide, which was enhanced by increasing the polypeptide concentration. Good miscibility existed between KGM, chitosan and polypeptide, as well as good wettability between the adhesive blends and wood veneer.     

Interphase Composition in Aluminum/Epoxy Adhesive Joints

Model epoxy/aluminum adhesive joints were constructed with a geometry that allowed cracks to be propagated extremely close to the adhesive/adherend interface. The joints were fractured in air and the fracture surfaces analyzed using angle resolved X-ray photoelectron spectroscopy. Fracture occurred in a manner that left a significant amount of aluminum oxide on the epoxy side of the fracture surface and very little epoxy on the aluminum side. Aliphatic amine curing agent found associated with the aluminum oxide on both the adhesive and the adherend sides of the fracture surface was protonated by the acidic hydroxyls present in the aluminum hydroxide. Moreover, catalysis of the curing reaction by these hydroxyls resulted in an increased degree of crosslinking in the regions of the adhesive very close to the oxide surface. Thus, the aluminum oxide surface modified the structure of the adhesive in the near surface regions and resulted in the formation of a distinct interphase region with a composition different from that of the bulk adhesive.     

Interphase Composition in Aluminum/Epoxy Adhesive Joints

Model epoxy/aluminum adhesive joints were constructed with a geometry that allowed cracks to be propagated extremely close to the adhesive/adherend interface. The joints were fractured in air and the fracture surfaces analyzed using angle resolved X-ray photoelectron spectroscopy. Fracture occurred in a manner that left a significant amount of aluminum oxide on the epoxy side of the fracture surface and very little epoxy on the aluminum side. Aliphatic amine curing agent found associated with the aluminum oxide on both the adhesive and the adherend sides of the fracture surface was protonated by the acidic hydroxyls present in the aluminum hydroxide. Moreover, catalysis of the curing reaction by these hydroxyls resulted in an increased degree of crosslinking in the regions of the adhesive very close to the oxide surface. Thus, the aluminum oxide surface modified the structure of the adhesive in the near surface regions and resulted in the formation of a distinct interphase region with a composition different from that of the bulk adhesive.     

The Adhesive Bonding of Steel with Polysulfone

The bonding of cold rolled steel with polysulfone, a thermoplastic adhesive has been studied. The single lap shear strength of bonded samples where the substrate was gritblasted was 40% lower than for the case where the substrate was hydrothermally oxidized. Both surface preparations resulted in diminished lap shear strength on exposure to high humidity conditions. However, the hydrothermally oxidized substrates resulted in more durable bonds.     

Interaction of Epoxy/Dicyandiamide Adhesives with Metal Substrates

The molecular structure of the interphase formed by curing a model adhesive system consisting of the diglycidyl ether of bisphenol-A (DGEBA) and dicyandiamide (DDA) against mechanically polished aluminum and electrogalvanized steel (EGS) substrates was determined using reflection–absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS). RAIR analysis suggested that DGEBA/DDA mixtures created an interphase with a different molecular structure from the bulk of the adhesive when cured in contact with aluminum. The formation of this unique interphase was mainly due to interactions between DDA and the Al surface. XPS analysis indicated that aluminum ions exposed by heating the substrate surface were necessary for this interaction. DDA was found to adsorb onto the aluminum surface via the lone pair of electrons on the nitrogen atoms of the nitrile groups. A slight decrease in the nitrile stretching frequency suggested an additional back-bonding interaction between aluminum ions and the nitrile groups. Slight back donation of electrons from the metal to DDA resulted in a reduction product that led to the formation of the carbodiimide form of DDA. This specific reaction caused a decrease in the concentration of nitrile groups in the interphase and changed the extent of the reaction between DDA and DGEBA by inhibiting the formation of oxazolidine structures. The interaction of DDA with EGS surfaces followed a similar trend. However, the effects were much more pronounced with EGS and the extent of the curing reaction and the cross-linking rate near the metal surface were strongly affected by EGS/DDA interactions.     

Adhesion of Injection Molded PVC to Steel Substrates

Interactions occurring at the interface between injection-molded poly (vinyl chloride) (PVC) and steel substrates that were coated with thin films of aminosilanes were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The silane films were formed by adsorption of γ-aminopropyltriethoxysilane (γ-APS) or N-(2-aminoethyl-3-aminopropyl)trimethoxysilane (γ-AEAPS) from 2% aqueous solutions onto polished steel substrates. PVC was injection molded onto the silane-primed steel substrates and annealed at temperatures up to 170°C for times as long as 30 min. PVC was peeled off of the primed steel substrates using a 90° peel test and the substrate failure surfaces were thoroughly rinsed with tetrahydrofuran (THF) and distilled water to remove PVC and other compounds that were not strongly bonded to the substrates. The PVC failure surfaces were characterized by attenuated total reflection infrared spectroscopy (ATR) and PVC rinsed off of the substrate failure surfaces was characterized by transmission infrared spectroscopy. The resulting transmission and ATR spectra showed an absorption band near 1650 cm^-1 that was attributed to unsaturation in PVC. The substrate failure surfaces were characterized by XPS; curve-fitting of N(1s) and Cl(2p) high-resolution spectra showed the formation of amine hydrochloride complexes by protonation of amino groups of the silanes with HCl that was liberated from PVC during the onset of thermal dehydrochlorination. Furthermore, quaternization or nucleophilic substitution of labile pendent allylic chloride groups by amino groups on the silanes took place, thus grafting PVC onto the aminosilanes. It was determined that PVC that had β-chloroallyl groupings along its chains showed better adhesion with steel primed with aminosilanes and that generation of allylic chloride groups in PVC chains was the rate-limiting step in the reaction between PVC and aminosilane. Moreover, the effect of crosslinking of silane films on adhesion between PVC and aminosilane primed steel was investigated and it was concluded that interdiffusion of the polymer phase and the silane phase was also critical in obtaining good adhesion.     

Improvement of the Durability of Zinc-Coated Steel/Epoxy Bonded Joints

The durability properties of bonded lap shear joints made from an epoxy/dicyandiamide adhesive and hot-dipped galvanized (G2F) or electroplated-phosphated (EZ2) steel have been investigated. The degradation mechanisms have been studied after three accelerated ageing tests: the “cataplasme humide” (“C.H.T.”), immersion (“I.T.”), and salt spray (“S.S.T.”) tests. X-ray photoelectron spectroscopy (XPS) analysis of fracture surfaces after ageing have shown that anodic dissolution of the zinc-coating is responsible for debonding in all cases and that intergranular corrosion phenomena account for poorer performances of the hot-dipped galvanized substrate during “C.H.T.” and “I.T.” Silane coupling agents were successfully used as primers on both substrates to increase the hydrolytic stability of the metal/adhesive interface. XPS results indicate that both the interfacial dissolution of the phosphate coating of EZ2 and intergranular corrosion of G2F are delayed for silane-primed specimens. The observed improvements do not appear to depend on the nature of the silane coupling agents. Alkylsilanes have been found to perform as well as silanes having a group capable of reacting with the epoxy/dicyandiamide system.

Additional tests were carried out in view of the possible application of organosilane reagents as additives in corrosion-protective oils. Good durability properties have been obtained by priming the metal coupons with a standard oil/silane mixture prior to bonding.

When corrosion was the controlling degradation mechanism as is the case during the salt spray test, silane treated specimens did not generally perform better than control specimens.     

Improvement of the Durability of Zinc-Coated Steel/Epoxy Bonded Joints

The durability properties of bonded lap shear joints made from an epoxy/dicyandiamide adhesive and hot-dipped galvanized (G2F) or electroplated-phosphated (EZ2) steel have been investigated. The degradation mechanisms have been studied after three accelerated ageing tests: the “cataplasme humide” (“C.H.T.”), immersion (“I.T.”), and salt spray (“S.S.T.”) tests. X-ray photoelectron spectroscopy (XPS) analysis of fracture surfaces after ageing have shown that anodic dissolution of the zinc-coating is responsible for debonding in all cases and that intergranular corrosion phenomena account for poorer performances of the hot-dipped galvanized substrate during “C.H.T.” and “I.T.” Silane coupling agents were successfully used as primers on both substrates to increase the hydrolytic stability of the metal/adhesive interface. XPS results indicate that both the interfacial dissolution of the phosphate coating of EZ2 and intergranular corrosion of G2F are delayed for silane-primed specimens. The observed improvements do not appear to depend on the nature of the silane coupling agents. Alkylsilanes have been found to perform as well as silanes having a group capable of reacting with the epoxy/dicyandiamide system.

Additional tests were carried out in view of the possible application of organosilane reagents as additives in corrosion-protective oils. Good durability properties have been obtained by priming the metal coupons with a standard oil/silane mixture prior to bonding.

When corrosion was the controlling degradation mechanism as is the case during the salt spray test, silane treated specimens did not generally perform better than control specimens.     

Adhesion of Injection Molded PVC to Steel Substrates

Interactions occurring at the interface between injection-molded poly (vinyl chloride) (PVC) and steel substrates that were coated with thin films of aminosilanes were investigated by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The silane films were formed by adsorption of γ-aminopropyltriethoxysilane (γ-APS) or N-(2-aminoethyl-3-aminopropyl)trimethoxysilane (γ-AEAPS) from 2% aqueous solutions onto polished steel substrates. PVC was injection molded onto the silane-primed steel substrates and annealed at temperatures up to 170°C for times as long as 30 min. PVC was peeled off of the primed steel substrates using a 90° peel test and the substrate failure surfaces were thoroughly rinsed with tetrahydrofuran (THF) and distilled water to remove PVC and other compounds that were not strongly bonded to the substrates. The PVC failure surfaces were characterized by attenuated total reflection infrared spectroscopy (ATR) and PVC rinsed off of the substrate failure surfaces was characterized by transmission infrared spectroscopy. The resulting transmission and ATR spectra showed an absorption band near 1650 cm^?1 that was attributed to unsaturation in PVC. The substrate failure surfaces were characterized by XPS; curve-fitting of N(1s) and Cl(2p) high-resolution spectra showed the formation of amine hydrochloride complexes by protonation of amino groups of the silanes with HCl that was liberated from PVC during the onset of thermal dehydrochlorination. Furthermore, quaternization or nucleophilic substitution of labile pendent allylic chloride groups by amino groups on the silanes took place, thus grafting PVC onto the aminosilanes. It was determined that PVC that had β-chloroallyl groupings along its chains showed better adhesion with steel primed with aminosilanes and that generation of allylic chloride groups in PVC chains was the rate-limiting step in the reaction between PVC and aminosilane. Moreover, the effect of crosslinking of silane films on adhesion between PVC and aminosilane primed steel was investigated and it was concluded that interdiffusion of the polymer phase and the silane phase was also critical in obtaining good adhesion.     

提高环氧树脂黏钢胶机械性能的研究

研究目的在于提高建筑用环氧树脂黏钢胶的机械性能,以符合建筑行业使用的要求.通过采用自制酚醛胺为固化剂,并采用复配技术优化环氧树脂胶黏剂的组成,达到了调节胶黏剂刚性和韧性平衡的目的.考察了环氧树脂和填料的种类及用量对环氧树脂胶黏剂拉伸、弯曲和压缩强度的影响.当主树脂为E-51,添加100％比例为1:3的滑石粉与细砂复配填...     

Cathodic Debonding of Neoprene from Steel

X-ray photoelectron spectroscopy (XPS) has been used to determine the failure mechanisms in neoprene/steel adhesive bonds during cathodic delamination or during immersion in aqueous solutions of NaOH to simulate the effects of cathodic delamination at the bondline. Delamination of the rubber from substrates that had been pretreated by acid-etching began at the edges of the bonds and proceeded slowly inward. The centers of the bonds were always intact except for every long times when complete delamination of the rubber was observed. Failure was near the primer/oxide interface but with islands of rubber remaining on the substrate and islands of oxide remaining on the rubber. The failure mechanism was associated with degradation of the phenolic primer and with dehydrohalogenation of chlorinated rubber in the adhesive and primer. Dehydrohalogenation resulted in the formation of inorganic salts which could dissolve during exposure to water at high pH values, leading to large osmotic pressures at the interface. Debonding of rubber from polished substrates was much faster, leaving little rubber on the substrate failure surfaces and little oxide on the rubber failure surfaces, and indicating that mechanical interlocking of the rubber with the substrate has an important effect on the environmental stability of rubber-to-metal bonds.     

LBA钢木结构防盗门胶粘剂

介绍了钢木结构防盗门用LBA胶粘剂所用材料及配制工艺,讨论和评价了有关性能,进行简单的经济分析。     

冷轧薄钢板磷化发蓝问题的原因及对策

冷轧薄钢板在使用时出现三种形态的磷化发蓝缺陷；点状，条状及整个磷化面蓝色，其原因主要有以下几种，钢板的化学活性高，催化剂的浓度高以及磷化段入口处磷化液流量小等，通过作相应的调整，获得了合格的磷化膜。     

Comparison of the Degradation Mechanisms of Zinc-Coated Steel, Cold-Rolled Steel, and Aluminium/Epoxy Bonded Joints

The durability properties of bonded lap shear joints made from an epoxy/dicyandiamide adhesive and zinc, zinc-coated steel, two different aluminium alloys or cold-rolled steel metal coupons have been investigated. The influence of the dicyandiamide content of the adhesive on the durability properties-has been assessed by salt spray testing or by storing the joints in water at 70°C or 90°C for periods of time up to five weeks. The degradation products formed during ageing of the epoxy adhesive in water have been investigated using high performance liquid chromatography (HPLC) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). The degradation mechanisms of aluminium/epoxy bonded joints have been thoroughly studied using X-ray photoelectron spectroscopy.

The performances of the bonded joints under a pure corrosive environment have been found to be little influenced by the quantity of dicyandiamide in the adhesive. When the bonded joints were aged in hot water, the stability of the interface toward an excess of dicyandiamide directly followed the sensitivity of the oxide layer at high pH values. Optimal durability properties without peel strength losses of the adhesive were aehieved both with zinc and aluminium-coated substrates by reducing the quantity of dicyandiamide in the epoxy adhesive by 20% (the initial dicyandiamide content in the commercial adhesive being ca. 9%, with respect to the epoxy resin).     

Determination of the Molecular Structure of Interphases Between Epoxy/4,4'-Diaminodiphenylsulfone Adhesives and Silver Substrates Using SERS and XPS

The molecular structure of interphases formed by curing an epoxy/4,4'-diaminodiphenylsulfone (DADPS) adhesive against rough silver substrates was determined using surface-enhanced Raman scattering (SERS) and x-ray photoelectron spectroscopy (XPS). SERS spectra obtained from the adhesive deposited onto silver island films were very similar to SERS spectra obtained from the DADPS curing agent spun onto silver island films, indicating that DADPS in the adhesive system segregated to the interphase and was preferentially adsorbed onto the silver substrate. Differences in the relative intensity of several bands in the normal Raman and SERS spectra of DADPS were observed. For example, the band near 1603 cm^-1 was stronger in SERS spectra of DADPS than in normal Raman spectra. The band near 1150 cm^-1 was weaker in SERS spectra of DADPS than in normal Raman spectra. These results implied that DADPS was adsorbed through one of the NH groups with an end-on conformation. Consistent results were also obtained from XPS spectra. C(ls) spectra of the adhesive and silver fracture surfaces of specimens prepared by curing the adhesive against silver substrates were more similar to the C(ls) spectra of DADPS than to those of the bulk adhesive. These results confirmed the preferential adsorption of DADPS onto the silver substrate from the adhesive system. The similarity of the C(ls) spectra obtained from adhesive and silver fracture surfaces indicated that a thin DADPS-rich interphase was formed between the bulk adhesive and the silver substrate and that the locus of failure was partially within this layer. However, less nitrogen and sulfur were detected on the silver fracture surface than on the adhesive fracture surface. A large amount of silver was observed on the substrate fracture surface and a trace was found on the adhesive fracture surface. These results indicated that failure of the adhesive joints was within the interphase but near the silver substrate. No evidence of chemisorption of DADPS onto the substrate was observed.     

Molecular structure of interfaces between plasma-polymerized acetylene films and steel substrates

Plasma-polymerized films of acetylene were deposited onto steel substrates in an inductively coupled reactor by exciting the plasma in an argon carrier gas and then injecting the monomer into the afterglow region. The molecular structure of the film/substrate interface was determined using reflection–absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS) to characterize the films as a function of thickness. RAIR showed that thick (∼ 900 Å) as-deposited plasma-polymerized acetylene films had a complicated molecular structure and contained methyl and methylene, mono- and disubstituted acetylene, vinyl, and cis- and trans-disubstituted olefin groups. Evidence of oxidation resulting from the reaction of trapped radicals with atmospheric oxygen and moisture to form O—H and C=O groups was also obtained. The molecular structure of thin films (∼ 60 Å) was similar although evidence was obtained to indicate that acetylide groups (H—C≡C⁻) were present at the film/substrate interface. Results obtained using angle-resolved XPS analysis showed that carbonaceous contamination was removed from the substrate and that oxides and hydroxides on the substrate surface, especially FeOOH, were chemically reduced during deposition of the films. XPS also confirmed that plasma-polymerized acetylene films deposited on steel substrates contained groups. Preliminary results also showed that films deposited in an inductively coupled reactor were good primers for rubber-to-metal bonding, whereas films deposited in a capacitively coupled reactor were not. The differences may be due to the wide variety of functional groups found in the former type of films but not in the latter. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1283–1298, 1998