Multifunctional epoxy resins: Synthesis and characterization

The tetrafunctional epoxy resins were prepared starting from diaminodiphenylmethane, diaminodiphenylether, and diaminobibenzyl. The obtained resins were characterized by IR and ¹H‐NMR spectroscopy, rheological and thermal techniques. The polymerization reaction was investigated by viscosimetry. The flow activation energy and the polymerization activation energy were evaluated from the rheological data and from the critical parameters (critical time and critical viscosity at gel point). The viscosity measurements and gel time determination showed slight differences between the synthesized resins. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2430–2436, 2000     

Synthesis,characterization, and thermal properties of tris (3‐aminophenyl) phosphine oxide‐based nadimide resins

This article describes the synthesis, characterization, and thermal properties of nadimides obtained by reacting endo‐5‐norbornene‐2,3‐dicarboxylic acid anhydride (nadic anhydride) (NA), 4,4′‐oxodiphthalic anhydride (ODA), 1,4,5,8‐naphthalene tetra carboxylic dianhydride (NTDA) in glacial acetic acid/DMF. Structural characterization of the resins was done by elemental analysis, IR, ¹H‐NMR, and ¹³C‐NMR. The DSC scan showed the endothermic transition in the temperature range of 120–270°C. Multistep decomposition was observed in the TG scan of uncured resins in nitrogen atmosphere. Isothermal curing of the resins was done at 250 and 300°C for 1 h in an air atmosphere. These cured resins were stable to (350 ± 30)°C and decomposed in a single step above this temperature. This may be due to the retro Diels Alder (RDA) reaction. The char yield of the resins increased significantly on curing. The char yield was highest for P‐2N resin and this could be due to the presence of rigid skeleton i.e. naphthalene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of resorcinol-cinnamaldehyde resins

The mechanisms and kinetics of the reaction between resorcinol and cinnamaldehyde were studied by means of ¹³C-NMR spectroscopy, HPLC, and GPC. In the first step the addition of resorcinol to the double bond and to the carbonyl group of cinnamaldehyde takes place. In the second step of reaction the lower molecular weight oligomers form compounds with groups with molecular weights between 1500 and 2500. The red coloured resin reacts at temperatures above 150°C with crosslinking agents to form an insoluble and highly crosslinked product.     

对苯二酚-果糖树脂的合成与表征

在碱性条件下,使用果糖代替甲醛与对苯二酚反应,成功地制备出环境友好型的对苯二酚-果糖树脂。利用红外、GPC、TGA等对所合成的树脂进行了表征。同时使用响应面优化法优化了反应条件,最优反应条件为:催化剂用量3.99%、反应温度69.97℃、反应时间9.03h、n果糖:n对苯二酚=9.29:1。最优条件时的黏度为222.808mPa?s,拉伸强度15.71～23.61MPa。     

Synthesis and characterization of the epoxyfumarate resins

The synthesis and properties of the new epoxyfumarate and epoxymaleate resins obtained by the addition of acidic allyl maleate to the commercially available resin Epidian 5 are presented. The resins were synthesized in one‐ and two‐step procedures and properties of the obtained resins are compared. It should be noted that the use of allyl alcohol in the synthesis of unsaturated resins has an advantageous influence on their properties. Glass‐transition temperatures of the epoxyfumarate resins exceed 100°C, whereas those of epoxymaleates are higher than 70°C. The resins are also characterized by good chemical resistance. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 716–722, 2002; DOI 10.1002/app.10067     

Synthesis and characterization of MQ silicone resins

MQ silicone resins, which represent a broad range of hydrolytic condensation products of monofunctional silane (M) and tetrafunctional silane (Q), were synthesized by reaction of water glass with hexamethyldisiloxane. The optimum reaction time and the optimal reaction temperature is 30 min and 30–40°C, respectively. Concentrated hydrochloric acid is the best one among those catalysts tested. In large-scale experiments (420–1680 mL), the favorable feeding order is catalyst first, and then water glass, the mixture of hexamethyldisiloxane and ethanol last and most MQ silicone resin was observed. The structure of MQ silicone resin was characterized by FT-IR and GPC spectra. The MQ silicone resin shows narrow molecular weight distribution and the number average molecular weight of MQ silicone resin is 2917. The silicone pressure sensitive adhesive prepared from as-synthesized MQ resin has good tack (29#) and 180° peel adhesion (5.630N/20 mm). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of novel dihydrobenzoxazine resins

Three dihydrobenzoxazines are synthesized from bisphenol A (BPA), 4,4′‐biphenol (BIP), and dicyclopentadiene phenol adduct (DCPD). Polydihydrobenzoxazine containing 4,4′‐biphenol (BIPDB) had the most rigid structure of the three and was found to possess the best mechanical and thermal properties. The glass transition temperature of BIPDB was 206°C, and that of BPA‐type polydihydrobenzoxazine (BPADB) and dicyclopentadiene type polydihydrobenzoxazine (DCPDDB) were 184 and 183°C, respectively. DCPDDB, with a rigid hydrophobic cycloaliphatic structure, was found to possess excellent properties such as low moisture absorption, low dielectric constant, low polarization. The resulted polymer from DCPDDB had a dielectric constant of 2.94U, which was better than that of polymers derived from BPA (3.31U), BIP (3.45U), and traditional phenolic resin (3.9–4.0U). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 342–347, 2006     

Tris(3-aminophenyl)Phosphine oxide-based nadimide resins. II

A series of phosphorus-containing nadimide end-capped resins having different backbones was prepared by reacting endo-5-norbornene-2-3-dicarboxylic acid anhydride (nadic anhydride), pyromellitic dianhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6F) and tris(3-aminophenyl)phosphine oxide (TAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, FTIR, and ¹H-NMR. Thermogravimetric studies revealed a multistep decomposition reaction for uncured resins. Residual weight at 800°C in nitrogen was found to be 50–60%. Resins cured at 300°C for 1 h in air atmosphere were stable up to 440 ± 20°C and decomposed in a single step above this temperature. The char yields of cured resins were in the range 63–71.5%. © 1992 John Wiley & Sons, Inc.     

Synthesis and characterization of epoxy resins containing bismuth

The synthesis of epoxy resins in the presence of Bi as bismuth acrylate (BiA₃) showed that the properties such as epoxide equivalent weight (eq/100 g), molecular weight, and viscosity (η_sp) increased; whereas hydrolyzable chlorine content, hydroxyl content, and refractive index decreased in the presence of BiA₃. The metal forms a complex with ether linkage of epoxy resins, as evidenced from infrared spectroscopy. The presence of Bi in epoxy resins has been confirmed by scanning electron microscopy (SEM) and qualitative analysis. The glass transition temperature (T_g) of epoxy resins containing 1.18 × 10⁻⁵ and 2.8 × 10⁻⁵ molar equivalent of BiA₃ is 131.58 and 190°C, respectively, and is greater than that of blank (130°C). The heat of reactions for epoxy resins containing 1.18 × 10⁻⁵ molar equivalent of BiA₃, calculated by differential scanning calorimetry, is 4.75 J g. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1359–1365, 1997     

Synthesis and characterization of thermosetting polyacetylene-terminated silicone resins

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 T_d5 (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.     

On the toughening of unsaturated polyester resins using nadimide end-functionalized polyether telechelics

Copoly-propylene glycol (terephthalate–maleate) based unsaturated polyester resin (UPER) was modified with nadimide end-capped polyether telechelics namely, polypropylene glycol (PPG with molecular weight 2000, 1000, 400 g/mol), polytetramethylene oxide (PTMO with molecular weight 2000 g/mol) and polyethylene glycol (PEG with molecular weight 2000 g/mol) (NPPG/NPTMO/NPEG). The telechelic NPPG/NPTMO/NPEG were synthesized from the corresponding polyols (hydroxy telechelics) by reaction with 4-nadimido benzoyl chloride. These derivatives were characterized by chemical and spectral methods. Blends of UPER with varying amounts of NPPG/NPTMO/NPEG were prepared. Blending boosted the cohesive energy through enhanced crosslinking as reflected in the gel content of the cured matrices done in separate studies. It increased the fracture characteristics tremendously. The addition of 2.5 phr of the nadimide end functional polyether gave the maximum toughness. The crosslink density showed an initial increase on blending, but further addition of the telechelics did not make any change. The properties of the prepared blends were compared with maleimide end-capped polyether toughened UPE resins. It was concluded that the toughening effect of the polyether additive depends not only on its concentration but also on its distribution in the matrix as dictated by its reactivity ratio with styrene. The high reactivity of the nadimide groups did not create an ambiance good enough to get an acceptable distribution of the polyether segments conducive for a tough matrix. Whereas the maleimide end-capped polyether provides better toughening efficiency.     

Synthesis and characterization of resins from urea and acrolein

The reactions of urea with acrolein in neutral and acidic media were studied by means of ¹H- and ¹³C-NMR spectroscopy. The addition of aldehyde groups to urea seems to be the first step of the reaction. In the second step in neutral medium the groups and the double bonds react with the amide groups. In the acidic medium the condensation of as second step was dominant. In the further course of the reaction highly crosslinked resins are formed which are insoluble and unmeltable. Chemical shifts of individual compounds are given. On the basis of these data, it was possible to set up tentative reaction schemes. The determination of the concentrations of reaction products as functions of reaction time allowed to establish the kinetics of individual reactions.     

Synthesis and characterization of petroleum and biobased epoxy resins: a review

Petroleum based epoxy resins exhibit various excellent properties such as adhesion, mechanical performance, electrical insulation and chemical resistance. There is wide concern towards depletion of non‐renewable resources, climate change and finding renewable alternatives for petroleum based materials to reduce the emission of greenhouse gases. This review mainly draws attention towards the utilization of renewable resource based epoxy resin derived from lignocellulosic biomass, furan, tannins, itaconic acid, rosin acid and bio‐oil etc. Without altering the mechanical and thermal properties much, epoxy resins derived from renewable materials have been widely investigated. The last two decades have witnessed an exponential growth in using bio‐derived products, which has been driven by the need to replace petroleum based materials, reduce fuel consumption and lower the overall environmental impact. © 2018 Society of Chemical Industry     

Synthesis and characterization of epoxy resins containing arsenic acrylate

The properties of epoxy resins containing arsenic acrylate have been compared with that of a blank epoxy resin (DGEBA). The values of epoxide equivalent, hydroxyl content, hydrolyzable chlorine content, and specific gravity increased, whereas refractive index decreased in the epoxy resins containing arsenic acrylate (AsA₃). This is attributed to a complex formation between an As and an oxygen atom in the resin, as evidenced from IR spectroscopy. The reaction is first order (ER₃) with an activation energy of 53 kJ/mole. The epoxy resin with As cured with polyamide at 30°C, showed chemical resistance and excellent thermal stability compared with blank epoxy resin (epoxy resin without As).     

Synthesis and characterization of poly(tetramethyldisiloxane-ethynylenephenyleneethynylene) resins

Poly(tetramethyldisiloxaneethynylenephenyleneethynylene) resins were synthesized by polycondensation reactions of the bismagnesium derivative of p- or m-diethynylbenzene with 1,3-dichlorotetramethyldisiloxane. The molecular weights of the resins were determined by gel permeation chromatography. The structures of the resins were verified by ¹H, ¹³C, and ²⁹Si NMR as well as FT-IR spectroscopy. The thermal behavior of the resins was traced by differential scanning calorimetry (DSC). The resins can be thermally crosslinked through the acetylene groups to produce highly crosslinked resins which were thermally stable up to 539 °C in both nitrogen and air. Hard, black, and glassy ceramics were obtained after the sinter of the crosslinked resins at 1,450 °C. The polymers have a potential application as matrix materials for advanced composites and ceramic precursors.     

Synthesis and characterization of resins from 4-ethylphenol and cinnamaldehyde

The mechanisms of the reaction between 4-ethylphenol and cinnamaldehyde were studied by means of HET 2DJ ¹³C-NMR spectroscopy, ¹H-NMR spectroscopy and GPC. In the first step of the reaction the addition of 4-ethylphenol to carbonyl group and to double bond of cinnamaldehyde takes place. In the second step of the reaction the ? CH(OH)-group reacts with 4-ethylphenol to form branched products of red coloured resins with an average molecular weight of 600. The reaction takes place at temperatures above 100°C in strong acid medium.     

Synthesis,characterization and self-crosslinking of glycidyl carbamate functional resins

Multifunctional glycidyl carbamate functional resins were synthesized, characterized, and self-crosslinked coatings were prepared and characterized. Coatings based on glycidyl carbamate (GC) functional oligomers are attractive because they combine polyurethane properties with epoxide reactivity. The glycidyl carbamate functional resins were synthesized via reactions of the biuret adduct and isocyanurate trimer of hexamethylene diisocyanate (HDI) with glycidol. Resins were characterized using gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy and ¹³C NMR spectroscopy. Coatings were prepared to study the self-crosslinking reaction without additional hardener. Self-crosslinked coatings had an excellent combination of solvent resistance, good hardness and high impact resistance. The glycidyl carbamate resin from the biuret isocyanate adduct (BGC) was found to be more reactive during cure than glycidyl carbamate from the isocyanurate isocyanate trimer (IGC) as determined by hardness, solvent resistance, and T_g measurements. Thermogravimetric analysis (TGA) of the resins did not show thermal decomposition below 250 °C.     

Synthesis,characterization, and curing of o-and p-chlorophenol-furfural resins

Polycondensation of furfural, respectively, with o- and p-chlorophenols has been carried out under various reaction conditions. All the resin samples have been characterized by spectral studies, viscometric measurement and by the estimation of the number-average molecular weight. Thermogravimetric analysis (TGA) of selected resin samples has been carried out. The kinetics of curing reaction of selected resin samples has been investigated by differential scanning calorimetry (DSC). The properties of the glass laminates prepared using each of the two types of resins showed that the latter are much less suitable than phenol-furfural resin as matrices for the fabrication of laminates.     

Synthesis and characterization of aniline-doped mixed copolymer resins. II

Copolymer resins were synthesized by the mixed condensation of resorcinol–CH₂O, resorcinol–aniline–CH₂O, resorcinol–aniline–thiourea–CH₂O, and resorcinol–aniline–urea–thiourea–CH₂O with a view to develop synthetic resins having improved properties and performance like toughness, mechanical properties, thermal resistance, chemical inertness, and adhesion. The resins were characterized by IR and TG analyses. The thermal analysis showed that the mixed copolymer resins have significantly better thermal stability than that of the simple phenol–CH₂O, aniline–CH₂O, urea–CH₂O, and thiourea–CH₂O resins. At 600°C, only a 50% weight loss is observed, and even at 800°C, the weight loss is about 70%. The resins are insoluble in most of the organic solvents including DMSO-d₆. They too are unaffected by diluted HNO₃, but dissolve in concentrated HNO₃. © 1996 John Wiley & Sons, Inc.