Vinyl‐containing silicone resin as the crosslinking agent of heat‐curable silicone rubber

Heat‐curable silicone rubber (HCSR) was prepared by using vinyl‐containing silicone resin (VSR) as the crosslinking agent instead of polyvinylsilicone oil (C gum). Mechanical properties and crosslink density of the vulcanizates were measured. The results indicate that VSR is a good crosslinking agent for HCSR. The tensile strength, tearing strength, elongation at break, and hardness of the vulcanizate can reach 10.2 MPa, 29.1 kN/m, 720%, and 58 SHA, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3123–3127, 2002; DOI 10.1002/app.10054     

Thermosetting resin system based on novolak and bismaleimide for resin‐transfer molding

A thermosetting resin system for resin‐transfer molding based on novolak and bismaleimide (BMI) was developed. The novolak resin was allylated and BMI was used as the curing agent, and allyl phenyl ether, as the diluent. The viscosity–temperature curve and the viscosity–time curve were used to characterize the processing property of the resin system. The resin system had a long pot life at the injection temperature. Based on the DSC data, a regime for the curing and postcuring cycles was established. The cured resin showed outstanding heat resistance and good flexural properties. Composites based on the resin system and woven glass fabric were fabricated using RTM technology. The composites showed very good flexural properties at room temperature and high retention rates at 200 and 300°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1651–1657, 2002     

Diethyl ketone‐based imine as efficient latent hardener for epoxy resin

Several imines were synthesized and evaluated as water‐initiated hardener for epoxy resin. Imines with a lower electron density on the C=N carbon showed a faster hydrolysis rate. Diethyl ketone‐based imines were the most efficiently hydrolyzed among the imines examined, and the adhesive properties of epoxy resin with diimines used as the hardeners were evaluated. A novel diethyl ketone‐based diimine, N,N′‐di(1‐ethylpropylidene)‐m‐xylylenediamine (10), served as an efficient latent hardener of epoxy resin. Epikote 828 containing 10, filler, and dryer increased the adhesive strength faster than Epikote 828 containing filler and dryer with methyl isobutyl ketone‐based imine. The mixed system of epoxy resin and 10 showed good storage stability at room temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1744–1749, 2002     

A novel bio‐based phthalonitrile resin derived from catechin: synthesis and comparison of curing behavior with petroleum‐based counterpart

The development of bio‐based thermosetting resins with good thermal stability can potentially afford sustainable polymers as replacements for petroleum‐based polymers. We report a practical route to a novel catechin‐based phthalonitrile resin precursor (CA‐Ph), which contains free phenolic hydroxyl groups that result in ‘self‐curing’ at elevated temperatures to afford a thermostable polymer. Comparison of the performance of this CA‐Ph resin with that of a conventional petroleum‐based bisphenol A phthalonitrile resin (BPA‐Ph; containing 5 wt% of the curing agent 4,4′‐diaminodiphenylsulfone) revealed that CA‐Ph exhibits a lower melting point and curing temperature. Cured CA‐Ph resin retains 95% of its weight at 520 °C under a nitrogen atmosphere, which compares favorably with results obtained for BPA‐Ph resin that retains 95% of its weight at a lower temperature of 484 °C. Kinetic results indicated that the curing reactions of both CA‐Ph and BPA‐Ph systems follow an autocatalytic mechanism. These results suggest that catechin is a useful bio‐based feedstock for the preparation of self‐curing and thermally stable phthalonitrile resins for advanced technological applications. © 2017 Society of Chemical Industry     

Preparation and performance of high refractive index silicone resin‐type materials for the packaging of light‐emitting diodes

A novel high refractive index and highly transparent silicone resin‐type material for the packaging of high‐power light‐emitting diodes (LEDs) is introduced, which was synthesized by hydrosilylation of vinyl end‐capped methylphenyl silicone resin and methylphenyl hydrosilicone oil catalyzed by Karstedt's catalyst. The vinyl end‐capped methylphenyl silicone resins were prepared by hydrolysis?polycondensation method from methylphenyl diethoxysilane (MePhSi(OEt)₂), phenyl triethoxysilane (PhSi(OEt)₃), and vinyl dimethylethoxy silane (Me₂ViSiOEt) in toluene/water mixture catalyzed by cation‐exchange resin. The vinyl end‐capped methylphenyl silicone resins were characterized by ¹H‐NMR and Fourier‐transform infrared. The performances of the cured silicone resin‐type materials for LED packaging have been examined in detail. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Morphology of epoxy resin modified with silyl‐crosslinked urethane elastomer

Silyl‐crosslinked urethane elastomer modifying epoxy resin has drawn much interest. Here the triethoxysilyl‐terminated polycaprolactone elastomer (PCL‐TESi) modifying diglycidylether of bisphenol A epoxy resins (DGEBA) system was chosen, and then the effect of the type of curing agent on the phase structure of the studied epoxy resin system was investigated. The modified systems were obtained with different phase structures by varying the formulations of the curing agent. It was experimentally shown that with the addition of aminosilane (KBE‐9103), the crosslinked density was greatly increased. The cured system also showed from SEM and TEM analysis that addition of KBE‐9103 increased the compatibility between the PCL‐TESi and DGEBA, which made the ductility of the system decrease, but also indicated from TEM that addition of much KBE‐9103 made the reacted silicone particles coagulate each other. The state of phase separation from TEM in the cured system was theoretically explained. These would serve the deeper studies of the mechanism of silyl‐crosslinked urethane elastomer modifying epoxy resin in the future. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 611–619, 2005     

High‐retention properties for Hg(II) ions of a resin containing ammonium and pyridine groups

The metal‐ion uptake behavior of the chelating resin poly([(3‐(methacryloylamino)propyl] trimethyl ammonium chloride‐co‐4‐vinyl pyridine) has been investigated. The resin is obtained by radical copolymerization in a yield of 99.6%. The hydrophilic resin shows a high retention capacity and selectivity toward Hg(II) ions in the presence of Cu(II), Pb(II), Cd(II), Zn(II), and Cr(III) ions. A retention of Hg(II) higher than 99% is observed after 5 min. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2595–2599, 2002     

ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C₁₄H₇O⁺, CHO⁺, CH₃O⁺, and C₂₁H₂₄O₄⁺ showed variance related to the completion of the curing reaction. Relative intensities of C_xH_yN_z⁺ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Curing characteristics of epoxy resin systems that include a biphenyl moiety

The curing characteristics of epoxy resin systems that include a biphenyl moiety were investigated according to the change of curing agents. Their curing kinetics mainly depend on the type of hardener. An autocatalytic kinetic reaction occurs in epoxy resin systems with phenol novolac hardener, regardless of the kinds of epoxy resin and the epoxy resin systems using Xylok and DCPDP (dicyclopentadiene‐type phenol resin) curing agents following an nth‐order kinetic mechanism. The kinetic parameters of all epoxy resin systems were reported in terms of a generalized kinetic equation that considered the diffusion term. The fastest reaction conversion rate among the epoxy resin systems with a phenol novolac curing agent was obtained in the EOCN‐C epoxy resin system, and for systems with Xylok and DCPDP hardeners, the highest reaction rate values were obtained in NC‐3000P and EOCN‐C epoxy resin systems, respectively. The system constants in DiBenedetto's equation of each epoxy resin system with different curing agents were obtained, and their curing characteristics can be interpreted by the curing model using a curing agent as a spacer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1942–1952, 2002     

Synthesis and analytical application of a chelating resin based on a crosslinked styrene/maleic acid copolymer for the extraction of trace‐metal ions

A new chelating polymer sorbent was synthesized through the copolymerization of styrene and maleic anhydride in the presence of divinyl benzene as the crosslinking agent, followed by hydrolysis. This polymeric resin, bearing O donor groups, had the advantage of being stable in basic and saline media, unlike its linear analogue. This newly developed chelating matrix has a high resin capacity for metal ions such as Cr, Fe, Ni, Cu, and Pb. Various physicochemical parameters, such as the pH, volume, and flow rate, and the interference effect on metal uptake were studied. The sorption capacities of the crosslinked resin for Cr(III), Fe(III), Ni(II), Cu(II), and Pb(II) were 10.2, 14.3, 14.2, 15.4, and 8.8 mg/g, respectively. A high recovery of 98% was obtained for all the metal ions with 2N HCl as the eluting agent. The chelating resin was characterized by swelling studies, Fourier transform infrared, elemental analysis, X‐ray studies, and thermal analysis. The Langmuir and Freundlich adsorption isotherms were used to validate the metal‐uptake data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1771–1779, 2004     

Bismaleimide resin modified with diallyl bisphenol A and diallyl p‐phenyl diamine for resin transfer molding

O,O′‐diallyl bisphenol A (DBA) and N,N′‐diallyl p‐phenyl diamine (DPD) were used for the reactive diluents of 4,4′‐bismaleimidodiphenol methane (BDM). The objective was to obtain a modified BDM resin system suitable for resin transfer molding (RTM) process to prepare the advanced composites. The processing behavior was determined by time–temperature–viscosity curves, gel characteristics, and differential scanning calorimetry (DSC). The injection temperature of the resin system in RTM could be 80°C, at which its apparent viscosity was only 0.31 Pa/s, and the apparent viscosity was still less than 1.00 Pa/s after the resin was held at 80°C for 16 h. The gel time test result indicated that at low temperatures, the reactivity of the resin system is low, whereas at high temperatures, the resin could cure very fast, which was beneficial to RTM. The postcure of the cured resin at a given temperature was necessary because the resin had a wide and flat cure exothermic peak, observed by DSC curve. The cured resin displayed both high heat and hot/wet resistance and high mechanical properties, especially tensile strength, tensile modulus, and flexural strength at room temperature, which reached 96.2 MPa, 4.8 GPa, and 121.4 MPa, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2245–2250, 2001     

The effect of hydroxyl‐terminated polybutadiene‐grafted carbon fiber on the impact performance of carbon fiber–epoxy resin composites

Carbon fiber (CF) containing 1.4 and 2.1 mmol/g of —COOH and —OH groups, respectively, was functionalized by using an excess of tolylene‐2,4‐diisocyanate. The NCO‐modified CF was submitted to a graft reaction with hydroxyl‐terminated polybutadiene (HTPB). The HTPB‐grafted carbon fiber was employed as reinforcing agent for epoxy resin‐based composites. The presence of the flexible HTPB at the interface between the fiber and the matrix resulted in a substantial improvement on impact strength. Additional improvement on toughness was achieved by using epoxy matrix containing dispersed phase of HTPB. The composite morphology was also studied by scanning electron microscopy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1424–1431, 1999     

Cure kinetics and rheology characterization of soy‐based epoxy resin system

A novel soy‐based epoxy resin system was synthesized by the process of transesterification and epoxidation of regular soy bean oil, which has the potential to be widely usable in various composite manufacturing processes. Cure kinetics and rheology are two chemical properties commonly required in process modeling. In this work, the cure kinetics and rheology of the soy‐based resin system were measured by means of differential scanning calorimetry (DSC) and viscometer. DSC was used to measure the heat flow of dynamic and isothermal curing processes. The cure kinetics models of the different formulations were thus developed. A Brookfield viscometer was used to measure the change in viscosity under isothermal conditions. A novel neural network‐based model was developed to improve modeling accuracy. The models developed for cure kinetics and rheology for soy‐based epoxy resin system can be readily applied to composite processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3168–3180, 2006     

Dynamic mechanical characterization of a soy based epoxy resin system

Epoxidized allyl soyate (EAS), a novel soy based epoxy resin, has been prepared by the process of transesterfication and epoxidation of regular food grade soybean oil. Two types of crosslinking agents were employed in this study. The effects of the concentration of EAS and the type of crosslinking agent on the dynamic mechanical behavior of the soy based resin system have been investigated. The room temperature storage moduli (E′) and the glass transition temperatures (T_g) increased for the anhydride cured and decreased for the amine cured resins. The loss tangent maximum (tan δ)_max decreased for anhydride cured resins and increased for amine cured resins. The effect of frequency on the storage modulus was also studied. Master curves were constructed by the time‐temperature superpositioning technique (TTS) to predict the storage modulus at times and temperatures that are not experimentally feasible. The results indicate that soy based epoxy resins with appropriate concentrations hold great potential as a replacement for petroleum based materials in noise and vibration attenuation applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1772–1780, 2005     

Preparation and characterization of epoxy resin modified with alkoxysilane‐ functionalized poly(urethane‐imide) by the sol–gel process

The sol–gel process has been frequently employed for preparation of high performance silica/polymer composites. In this paper, novel sol–gel precursor triethoxysilane‐terminated poly(urethane‐imide) (PUI‐Si), combining the advantages of polyurethane (PU) and polyimide, was synthesized and characterized. Then PUI‐Si was incorporated into the epoxy resin matrix to prepare a series of EP/PUI‐Si organic‐inorganic hybrids through an in situ sol–gel process and crosslinking reactions. The thermal stability of EP/PUI‐Si hybrids was evaluated by thermogravimetric analysis and the results show that the PUI‐Si could significantly improve the thermal properties of epoxy resin. The initial decomposition temperature of composites with 50 wt% PUI‐Si reached 347.1 °C, 157.3 °C higher than that of neat epoxy resin. Furthermore, the tensile strength and breaking elongation can also be clearly improved by adding a suitable amount of PUI‐Si. Similarly, the water contact angle increased to 97.4° with 70 wt% PUI‐Si, showing a hydrophobic surface. The morphology was investigated by transmission electron microscopy and the results reveal that the silica particles are smaller than 20 nm and have a strong interaction with the epoxy resin matrix, resulting in the above‐mentioned high performance properties. Copyright © 2011 Society of Chemical Industry     

Addition‐cure‐type phenolic resin based on alder‐ene reaction: Synthesis and laminate composite properties

A maleimide‐functional phenolic resin was reactively blended with an allyl‐functional novolac in varying proportions. The two polymers were coreacted by an addition mechanism through Alder‐ene and Wagner–Jauregg reactions to form a crosslinked network system. The cure characterization was done by differential scanning calorimetry and dynamic mechanical analysis. The system underwent a multistep curing process over a temperature range of 110–270°C. Although the cure profiles were independent of the composition, the presence of maleimide led to a reduced isothermal gel time of the blend. Increasing the allylphenol content decreased the crosslinking in the cured matrix, leading to enhanced toughness and improved resin‐dominant mechanical properties of the resultant silica laminate composites. Changing the reinforcement from silica to glass resulted in further amelioration of the resin‐reinforcement interaction, but the resin‐dominant properties of the composite remained unaltered. Increasing the maleimide content resulted in enhanced thermal stability. Integrating both the reactive groups in a single polymer and its curing led to enhanced thermal stability and T_g, but to decreased mechanical properties of the laminate composites. This can be attributed to a brittle matrix resulting from enhanced crosslinking facilitated by interaction of the reactive groups located on the polymer of an identical backbone structure. The cured polymers showed a T_g in the range of 170–190°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 737–749, 2001     

Synthesis and characterization of a novel silicon‐containing polytriazole resin

4,4′‐Diazidomethylbiphenyl (DAMBP) and poly(dimethylsilylene‐ethynylenephenyleneethynylene) (PDMSEPE) were thermally polymerized to form a novel silicon‐containing polytriazole resin (PDMSEPE‐DAMBP) by 1,3‐dipolar cycloaddition. Differential scanning calorimetry, FTIR, and ¹³C‐NMR were used to characterize the curing behaviors of PDMSEPE‐DAMBP resins. The results indicated that the resins could cure at temperatures as low as 80°C. Dynamic mechanical analysis showed that there was a glass transition at 302°C for the cured PDMSEPE‐DAMBP resin. The carbon fiber (T700) reinforced PDMSEPE‐DAMBP composites exhibited excellent mechanical properties at room temperature and high property retention at 250°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Resol‐type phenolic resin from liquefied phenolated wood and its application to phenolic foam

A liquefied wood‐based resol resin was prepared with excellent yield by a reaction of liquefied wood and formaldehyde under alkaline conditions. The effects of various reaction parameters on the extent of the yield of the resol resin, unreacted phenol content, and viscosity were investigated. Milder resol resinification conditions were required as compared to those used in conventional methods. The liquefied wood‐based resol resin was successfully applied to produce phenolic foam using appropriate combinations of foaming agents. Diisopropyl ether with a relatively higher boiling temperature was suitable for the foaming of liquefied wood‐based resol resin. Hydrochloric acid and poly(ethylene ether) of sorbitan monopalmitate were used as a catalyst and a surfactant, respectively. The obtained foams showed satisfactory densities and compressive properties, comparable to those of foams obtained from conventional resol resin. Foams with low density were obtained by the blending of liquefied wood‐based resol resin and conventional resol resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 468–472, 2002; DOI 10.1002/app.10018     

Merrifield resin and 1,6‐hexanediol diacrylate‐crosslinked polystyrene resin for solid‐phase peptide synthesis: A comparative study

Three short peptides were synthesized on Merrifield resin (PS–DVB) and on polystyrene crosslinked with 1,6‐hexanediol diacrylate resin (PS–HDODA) to compare their efficiencies in solid‐phase peptide synthesis (SPPS). A 2% crosslinked polymeric system having almost equal capacity was used in both cases. The peptides were synthesized using standard solid‐phase methodology. In the case of the PS–HDODA resin, all the couplings were completed by the first coupling and the peptides were obtained in > 90% yield and > 95% purity. But in the case of the PS–DVB resin, most of the attachments require two to three couplings and the peptides were obtained in about a 65% yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1933–1939, 1999