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1.
Cold-set epoxy-based wood adhesives were investigated for production of exterior plywood. Effective adhesives were composed of bisphenol A diglycidyl ether (BPADGE), polyamidoamine (PAA), and polyethylenimine (PEI). Three-ply plywood panels were prepared with BPADGE–PAA–PEI adhesives and evaluated for their strengths and water resistance in accordance with a standard for exterior plywood. The effect of BPADGE/(PAA + PEI) weight ratio, PAA/PEI weight ratio, the mixing time for preparing the adhesive, and the pressing time for making plywood panels on the water resistance and the shear strengths of the plywood panels was investigated. The pot life of the adhesive was also measured. Plywood panels made with the BPADGE–PAA–PEI adhesives met the industrial requirements for exterior applications. Adhesion mechanisms are discussed in detail. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47741. 相似文献
2.
Thermoset resins have been extensively utilized as an adhesive for electronic devices. In particular, semiconductor packaging materials between chips/substrates require electrical interconnections by using deoxidizing agents along with thermoset adhesives. In this study, a facile combination of hydroxyl‐functionalized epoxy and cyclohexane‐structured cyclic anhydrides produced curable acidic moieties, thereby allowing synchronous deoxidizing and curing without the use of a deoxidizing agent. By contrast, unitary cyclic anhydrides rarely presented acidic moieties, probably due to their rapid networkable reactivity caused by structural flexibility once opened, which was detected and quantified by spectroscopic analyses. This binary system in the absence of additional deoxidizing agents achieved the complete wetting of common Sn‐based solders via chip bonding systems due to the generated acidic moieties. The binary mixture also showed an increased glass transition temperature of 110 °C and enhanced Young's modulus of 1.6 GPa, relative to the ternary mixture (85 °C and 0.8 GPa) comprising a deoxidizing agent. This discovery is beneficial in terms of the simplification of composition design and mechanical robustness of solderable adhesives. Quantification via spectroscopic studies can also help anticipate the deoxidizing capability of binary and ternary systems at different temperatures for various bondable and solderable applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46639. 相似文献
3.
Jiongjiong Li Wenjie Zhu Jizhi Zhang Shifeng Zhang Qiang Gao Jianzhang Li Wei Zhang 《应用聚合物科学杂志》2019,136(12):47229
In this study, sodium carbonate (Na2CO3) was used as a catalyst to prepare high-ortho phenol-formaldehyde (HOPF) resin, and ester and carbonate curing accelerators were used to increase its curing rate. The physicochemical properties of the prepared resins and the mechanism of curing acceleration were investigated. The results showed that, with the addition of Na2CO3, the ortho/para ratio of methylol groups increased from 7.257 to 27.800. The gel time of the cure-accelerated HOPF resins decreased from 620 to 240 s as compared with PF resin. The bonding strength of plywood bonded with the cure-accelerated HOPF resins were all above 0.70 MPa. The curing acceleration was caused by the carbonate ions rather than the metal ions, and a temporary incorporation mechanism apparently occurred for the ester accelerators. The prepared phenolic resin had fast curing rate, low curing temperature, high thermal stability, and favorable mechanical performance, which has potential for industry applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47229. 相似文献
4.
A series of Mannich base curing agents were synthesized by using different structured phenols and amines. The phenols were phenol, o‐cresol, and nonylphenol, and the amines were diethylenetriamine, m‐xylylenediamine, and JEFFAMINE D230 polyetheramine. The chemical structures of Mannich bases were confirmed by 1H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The curing agents had low viscosities in the range of 19.9 to 1549 mPa s. The curing behavior of diglycidyl ether of bisphenol A with these curing agents was studied by differential scanning calorimetry. The mechanical properties and thermal properties of the cured epoxies were also investigated and compared. Lap‐shear adhesion in air and underwater was studied by using stainless steel substrates, and the adhesion after ageing in hot water (80 °C) was also investigated. Adhesive cured with phenol modified m‐xylylenediamine showed the highest underwater adhesion around 5.9 MPa, which was comparable to other ones tested in air. In addition, the high adhesive strength was kept after ageing in hot water for 7 days. The structural influence of the curing agents on mechanical property and adhesive performances were discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45688. 相似文献
5.
A phthalic allyl ester having a hydroxyl group [2‐(2‐hydroxy‐3‐allyloxypropanocarbonyl)‐allylphthalate (HDAP)] was synthesized by the reaction of phthalic monoallyl ester with allyl glycidyl ether. HDAP was added to a diallyl phthalate resin to a concentration of 30 wt % to improve the adhesive properties. These blends were cured with dicumyl peroxide. The lap shear strength of joints was measured to evaluate the adhesive properties of the modified diallyl phthalate resin to steel and copper. The lap shear strength of the diallyl phthalate resin was increased by modification with HDAP. By modification with HDAP, the lap shear strength to steel increased up to about 2.5 times that of the diallyl phthalate resin. Moreover, the lap shear strength to copper was about 3.0 times larger than that of the diallyl phthalate resin upon the addition of 30 wt % HDAP. These results suggested that the secondary hydroxyl group of HDAP (used as a modifier) formed a hydrogen bond to a hydroxyl group of water existing on the metal surface, and as a result, the adhesive strength to metals such as steel and copper increased. The thermal decomposition temperature of the modified diallyl phthalate resin was almost the same as that of the diallyl phthalate resin; on the other hand, the glass‐transition temperature of the modified diallyl phthalate resin decreased with an increasing concentration of HDAP. The electrical properties of the modified diallyl phthalate resin were almost the same as those of the diallyl phthalate resin. On the other hand, water absorption after boiling increased with an increasing concentration of HDAP. This result led to the conclusion that the secondary hydroxyl group of HDAP (used as a modifier) formed a hydrogen bond to water. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
6.
Amy Philbrook Scott Earnshaw Christopher J. Easton Max A. Keniry Melissa J. Latter 《应用聚合物科学杂志》2013,128(5):3375-3381
1H‐15N‐13C correlation NMR spectroscopy techniques developed to identify and characterize co‐polymer fragments in melamine‐urea‐formaldehyde (MUF) and phenol‐urea‐formaldehyde (PUF) model systems have been applied to industrially prepared MUF, PUF, and phenol‐melamine‐formaldehyde (PMF) resins. The NMR data confirm that co‐polymers form in a commercially prepared MUF resin manufactured by Momentive Specialty Chemicals Pty. Ltd. Spectra from PUF model reactions were compared with those from a PUF resin and it was determined that PUF co‐polymers did not form in the resin prepared using typical temperature and pH. Finally, NMR spectroscopy was used to identify and characterize PMF co‐polymer bonds in a phenol‐melamine‐urea‐formaldehyde (PMUF) resin prepared using a procedure from Momentive Specialty Chemicals Pty. Ltd. With these NMR techniques in hand, it is now possible to relate co‐polymer structures to properties of commercial thermosets. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
7.
Ana Maria Ferreira João Pereira Margarida Almeida João Ferra Nádia Paiva Jorge Martins Luísa H. Carvalho Fernão D. Magalhães 《应用聚合物科学杂志》2019,136(17):47389
Combination of urea–formaldehyde (UF) resins with technical lignins has been often reported in the literature. However, the actual implications of this approach have not been effectively addressed yet. In this work, unmodified thick spent sulfite liquor (TSSL) and hydroxymethylated TSSL (TSSLH) were incorporated in a standard UF resin in different amounts (10 and 20%) and at different stages. When 10% of TSSLH was incorporated after the synthesis, the produced particleboards performed equivalently to when 90% of UF resin was used. In all other cases tested, combining UF resin with TSSL/TSSLH actually led to lower internal bond strengths. The results evidence that addition of TSSL or TSSLH does not have a beneficial effect on UF bonding performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47389. 相似文献
8.
Yawen Huang Quanli Zhang Qiuxia Peng Huan Hu Hongtao Yu Junxiao Yang Lili Liu 《应用聚合物科学杂志》2019,136(20):47465
Organosilicon resins have been demonstrated to be promising materials for low-dielectric-constant (low-k) related applications. In this study, we proposed a method to further reduce the dielectric constant (k) value of organosilicon resins with [1,1-dimethyl,1-(4′-benzocyclobutenyl)silyl] cyclotetrasiloxane (BCB-D4) as a building block. This building block was prepared by the hydrosilylation reaction of tetravinyl cyclotetrasiloxane with dimethyl–benzocyclobutene–silane. The reaction of benzocyclobutene on BCB-D4 by bulk polymerization in modules directly produced a highly crosslinked resin (poly{[1,1-dimethyl,1-(4′-benzocyclobutenyl)silyl] cyclotetrasiloxane) [poly(BCB-D4)]). Poly(BCB-D4) exhibited a low k of about 2.70; this value was greatly lower than the k (~3.0) of conventional benzocyclobutene–organosilicon resins obtained by the curing of linear polysiloxane. The low k was possibly due to the porous structure, which was constructed from multifunctionalized and cyclic building blocks. In addition, poly(BCB-D4) also exhibited a relatively high modulus (5.0 GPa) without a sacrifice in the thermal resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47465. 相似文献
9.
An experiment was conducted to investigate the effects of the resin solid content, catalyst content, and pH value obtained by the addition of two kinds of catalysts on the gel time of a urea–formaldehyde (UF) resin. Upon the addition of ammonium chloride, the pH value of the resin mixture decreased to 7 but not significantly further because of the limited free formaldehyde in the system. The pH values of the critical points, at which the resin‐curing rate dramatically increased and the gel time was reduced, were above 7 for both catalysts. To achieve the same gel time, the required pH value of the UF resin adjusted with ammonium chloride was higher than that of the resin modified by hydrochloric acid. This indicated that the main effects of ammonium chloride on the UF‐resin cure included both the release of hydrochloric acid and the catalysis of the reactants in the UF‐resin system. The gel time of the UF resin obviously decreased with increasing catalyst and resin solid contents and with decreasing pH. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1566–1569, 2007 相似文献
10.
A novel polyacetylene-terminated silicone (PTS) resins possessing low curing temperature and high heat resistance has been prepared by Grignard reaction using m-diacetylenylbenzene (DEB), 1,3,5-triacetylenylbenzene(TEB), and dichlorosilane as original materials. The reaction of the functional groups was characterized by in situ Fourier transform infrared spectrometer. The experimental results indicated that Si─H and C≡CH bonds are almost exclusively involved in the crosslinking reaction, while ─C≡C─ bonds only partially react. Further, Si─H and C≡CH bonds can participate in the curing reaction at relatively low temperatures, but ─C≡C─ bonds require higher temperature, indicating the higher activity of Si─H and C≡CH bonds than ─C≡C─ bonds. As determined by differential scanning calorimetry, PTS resins have low peak exothermic temperature at 184.5 °C, which is lower than MSP resin (~ 210 °C); in addition, rheological test showed that PTS resins have a very wide processing window from 40 to 163.3 °C, indicating that the PTS resins have excellent processability with a low curing temperature and wide processing window. What is more, TGA results of thermal-cured PTS resins revealed that Td5 (5% weight loss temperature) of PTS-H10 reached the highest of 684.4 °C. Compared with PTS-H0 resin, there is an increase of 124.2 °C and the remarkably increased heat resistance correlated with a higher m-DEB input ratio. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48783. 相似文献
11.
The curing reaction of different mixtures of an epoxy resin (diglycidyl ether of bisphenol A type) and a phenolic resin (resole type) cured with different amine concentrations (triethylene tetramine) was studied with thermal scanning rheometry under isothermal conditions from 30 to 95°C. The gel time, defined by several criteria, was used to determine the apparent activation energy of the process. Moreover, with an empirical model used to predict the change in the complex viscosity versus time until the gel time was reached, and under the assumption of first‐order kinetics, the apparent rate constant and the apparent activation energy for the curing process were calculated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 818–824, 2005 相似文献
12.
The water‐soluble phenolic resin (PF) and the poly(vinyl alcohol) (PVA) modified phenolic resin (PPF) were synthesized by alkali catalysis method. Both were used as curing agents to blend with the polyvinyl acetate (PVAc) emulsion. The obtained PF, PPF and blending emulsion were characterized by FT‐IR, DSC, DLS, TEM, and viscosity analysis. The thermal stability of latex films was enhanced after blending. When the PF and PPF content was up to 15 wt %, the peel strength of the blending emulsion increased from 17.89 N/25 mm to 21.32 N/25 mm and 23.37 N/25 mm and the shear impact strength were 1.4 and 1.6 times that of unmodified emulsion adhesive, respectively. Moreover, the modification effect of PPF was better than PF due to its tough crosslinked network. Finally, layer cohesion played an increasingly important role in bonding forces with the increment of the PPF content by the glue residue analysis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46448. 相似文献
13.
Stephanie Weiss Regina Seidl Waltraud Kessler Rudolf W. Kessler Edith M. Zikulnig-Rusch Andreas Kandelbauer 《应用聚合物科学杂志》2021,138(27):50635
During curing of thermosetting resins the technologically relevant properties of binders and coatings develop. However, curing is difficult to monitor due to the multitude of chemical and physical processes taking place. Precise prediction of specific technological properties based on molecular properties is very difficult. In this study, the potential of principal component analysis (PCA) and principal component regression (PCR) in the analysis of Fourier transform infrared (FTIR) spectra is demonstrated using the example of melamine-formaldehyde (MF) resin curing in solid state. FTIR/PCA-based reaction trajectories are used to visualize the influence of temperature on isothermal cure. An FTIR/PCR model for predicting the hydrolysis resistance of cured MF resin from their spectral fingerprints is presented which illustrates the advantages of FTIR/PCR compared to the combination differential scanning calorimetry/isoconversional kinetic analysis. The presented methodology is transferable to the curing reactions of any thermosetting resin and can be applied to model other technologically relevant final properties as well. 相似文献
14.
Commercial unsaturated polyester (UPE) resins typically contain a high amount of volatile toxic styrene. A non‐volatile acrylated epoxidized soybean oil (AESO) was found to be an excellent replacement of styrene in a commercially available UPE resin [designated as Styrene‐(PG‐IPA‐MA)] that is derived from propylene glycol (PG), isophthalic acid (IPA), and maleic anhydride (MA) in terms of the mechanical properties of the resulting kenaf fiber‐reinforced composites. The AESO‐(PG‐IPA‐MA) resins had low viscosity and long pot life below 70°C for a typical fiber‐reinforced composite application. AESO and PG‐IPA‐MA were not able to form a strong polymer matrix individually for fiber‐reinforced composites. However, a combination of AESO and PG‐IPA‐MA saw strong synergistic effects between them. The flexural, tensile, and water absorption properties of kenaf fiber‐reinforced composites made from AESO‐(PG‐IPA‐MA) resins were comparable with or even superior to those from the Styrene‐(PG‐IPA‐MA) resin. The AESO/(PG‐IPA‐MA) weight ratio was investigated for maximizing the mechanical properties of the kenaf fiber‐reinforced composites. The curing mechanism of the AESO‐(PG‐IPA‐MA) resins is discussed in detail. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43052. 相似文献
15.
Succinic acid was presented as a small molecule low shrinkage additive (LSA) in unsaturated polyester resin (UPR). The effects of succinic acid on the volume shrinkage and the flexural strength of UPR cured at 80 ± 1°C were investigated and compared with those of macromolecule LSAs, including polyvinyl acetate (PVAc), polymethyl methacrylate (PMMA), and polystyrene (PS). The results indicated that the volume shrinkage of succinic acid/UPR specimen was significantly lower than those of specimens with macromolecule LSAs. The flexural strength of succinic acid/UPR specimen was improved. The optimal time of pre‐esterification between succinic acid and the excess dihydric alcohol in UPR was 3.0 h, and the optimal addition of succinic acid was 20 g per 100 g UPR. Compared with 2,2‐dimethyl malonic acid we put forward before, succinic acid was a cheaper and more commercial LSA, which obviously accelerated the pre‐esterification process and presented excellent antishrinkage effect. DSC showed that with the addition of succinic acid, the polymerization of UPR was distinctive. The two‐stage polymerization of UPR glue including the cross‐polymerization of UPR and the homopolymerization of polyester was changed to a one‐stage polymerization with lower exotherm and slower polymerization rate, which was optimal for UPR. FTIR and high resolution magic angle spinning nuclear magnetic resonance (HR/MAS NMR) were applied for the quantitative characterization of pre‐esterification caused by succinic acid. Succinic acid performed better effects on the polymerization of UPR as compared to previous LSAs, and finally the homogeneous micro‐structure of cured succinic acid/UPR formed and was demonstrated by SEM. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41276. 相似文献
16.
Phenol formaldehyde reaction solution (PFS) was used to synthesize urea–formaldehyde resins (PFSUF resins) with low formaldehyde content. In addition, the prepared PFSUF resins were used as adhesives to bond bamboo particleboards. Mechanical properties, fracture morphology, water absorption ratio, and dimensional stability of bamboo particleboards have been studied by tensile tests, SEM tests, water absorption analysis, and swelling ratio analysis, respectively. The results demonstrate that the main ingredient of PFS is phenol formaldehyde intermediate 2,4,6‐trimethylolphenate and proper amount of PFS can be used to reduce the formaldehyde content of UF resins effectively. The results also show that bamboo particleboards bonded with PFSUF resins exhibit better mechanical properties, water resistance, and dimensional stability than that bonded with pure UF resin. However, the results of TG and mechanical properties analysis exhibit that alternative curing agents to ammonium chloride should be studied to improve the curing properties of the PFSUF resins with low formaldehyde content. Taken together, this work provides a method of preparing environment‐friendly PFSUF resins with low phenol and low formaldehyde content and the prepared resins have potential application in wood industry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42280. 相似文献
17.
We obtained lignin‐based wood adhesives satisfying the requirements of relevant international standards for the manufacture of wood particleboard. These were based on two different low‐molecular‐mass lignins. These lignin‐based wood adhesives did not use any formaldehyde in their formulation; formaldehyde was substituted with a nonvolatile nontoxic aldehyde, namely, glyoxal. The last formaldehyde present, contributed by a fortifying synthetic phenol–formaldehyde resin, was also eliminated by the substitution of the phenol–formaldehyde resin with a natural, vegetable polyflavonoid tannin extract to which no aldehyde was added. This substitution brought the total content of natural material up to 80 wt % of the total adhesive. The adhesives yielded good internal bond strength results of the panels, enough to pass relevant international standard specifications for interior‐grade panels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
18.
A polyurethane‐modified epoxy resin system with potential as an underfill material in electronic packaging and its preparation procedure were studied. The procedure enabled the practical incorporation of an aliphatic polyurethane precursor, synthesized from poly(ethylene glycol) and hexamethylene diisocyanate without a solvent, as a precrosslinking agent into a conventional epoxy resin. With a stoichiometric quantity of the polyurethane precursor added to the epoxy (ca. 5 phr), the polyurethane‐modified epoxy resin, mixed with methylene dianiline, exhibited a 36% reduction in the contact angle with the epoxy–amine surface, a 31% reduction in the cure onset temperature versus the control epoxy system, and a viscosity within the processable range. The resultant amine‐cured thermosets, meanwhile, exhibited enhanced thermal stability, flexural strength, storage modulus, and adhesion strength at the expense of a 5% increase in the coefficient of thermal expansion. Exceeding the stoichiometric quantity of the polyurethane precursor, however, reduced the thermal stability and modulus but further increased the coefficient of thermal expansion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
19.
The characterization of film adhesives is challenging because they required freezer storage, contain an inseparable filler—thermoplastic knit or fiber‐reinforcement, and are heat activated systems with a pre‐cure and unknown chemistry. A testing protocol that eliminates these sources of error is proposed. This study presents a method to generate time–temperature‐transformation (TTT) diagrams of epoxy film adhesives via differential scanning calorimetry (DSC). Non‐isothermal and isothermal DSC scans are used to capture the reaction and the glass transition temperature. The use of an initial fast ramp—up to 500 K/min—in the isothermal scans is explored for the first time. This technique shows the potential to produce a quasi‐isothermal cycle, eliminating the loss of data in the initial stage of the reaction. The total heat released, the activation energy, and the fractional kinetic parameter, are estimated via model‐free methods. The Kamal–Sourour model and the formal kinetic model are fit to model the rate of cure. The simplest model that accurately captures the reaction, a parallel two‐step model, A , is outlined. The glass transition temperature is modeled via DiBenedetto's equation to include the diffusion‐controlled mechanism. The TTT‐diagrams of two commercial adhesives, DA 408 and DA 409, are shown with an analysis of processing optimization. The use of quasi‐isothermal scans with initial fast ramps combined with the correction for filler, moisture, and pre‐curing history can be applied to characterize fast curing thermosets, complex B‐stage resins, and thermosetting composites. The modeling results can also be used in numerical studies of residual stresses and dimensional stability in the manufacturing of thermosetting composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45791. 相似文献
20.
We propose an original method to determine the temperature and time required for additional curing of physically aged partially cured glass-shaped systems, based on the example of epoxy amine systems. The approach consists of the plotting of temperature–time–transformation (TTT) diagrams, supplemented with lines, which illustrate the shift in glass transition temperature (Tg) as a result of the processes of physical aging (enthalpy relaxation) and with isoconversion curves. Then we should determine Tg of partially cured and aged sample at a certain temperature. Having known this Tg value, the position of the isoconversion curve at a given point and Tg,∞ as well, we can determine the postcuring time at T = Tg,∞ + 5 K. Thus, the method provides information about the temperatures and the duration of these two consecutive steps. The TTT diagrams are based on experimental results obtained by differential scanning calorimetry in dynamic mode with preliminary heated samples in an external thermostat. The proposed approach based on epoxy amine systems allows the prediction of the optimal curing mode for thermosetting systems to provide the highest degree of cure. Our method is applicable to a wide range of thermosetting polymer systems that complete transition to a glassy state before full conversion is achieved. 相似文献