Synthesis and characterization of solvent-free hybrid alkyd resin with hyperbranched melamine core

In this study, a new hybrid alkyd resin was formulated using melamine-based hyperbranched polymer having 24 hydroxyl groups on its structure and relatively low molecular weight alkyd. The alkyd was synthesized using an oil mixture (40% linseed + 60% sunflower). Melamine was used as the core molecule for the hyperbranched polymer due to its excellent properties such as greater hardness, alkali and solvent resistance, and thermal stability. Melamine was first hydroxylated using formaldehyde and changed into hexamethylol melamine. This product was then twice hydroxylated with dimethylol propionic acid to obtain a hyperbranched polymer with 24 hydroxyl end groups. It was then reacted with low molecular weight alkyd resin at different proportions. The product had a low viscosity and could easily flow like oil. It is a solvent-free and water-free liquid. The ‘hyperbranched polymer/alkyd’ ratio affected physical properties of the liquid polymer and also the mechanical properties of the hardened polymer, which can be used for surface coating. The viscosity of the liquid resin decreases from 148 to 8.84 Pa.s as the hyperbranched-polymer-to-alkyd ratio is decreased from 1:3 to 1:24. On the other hand, the hardness of heat-treated resin decreases from 198 Persoz to 43 Persoz, respectively. That is, the increase in the amount of hyperbranched polymer in the resin increases hardness, whereas the increase in the amount of alkyd decreases it. The mechanical tests of hardened resins showed that all specimens passed conical mandrel bending test, and they all depicted high adhesion, and high abrasion and impact resistance. The specimens also had excellent gloss properties.     

Tannic acid-based tough hyperbranched epoxy thermoset as an advanced environmentally sustainable high-performing material

Bio-based resources are progressively replacing those of petroleum-based to address the detrimental impact on environment and health issues. In this regard, hyperbranched epoxy resins with three different compositions were synthesized by simple polycondensation reaction of bio-based branching reactant, diethanolamide of gallic acid with bisphenol-A, and epichlorohydrin. Diethanolamide of gallic acid was obtained from the reaction between tannic acid and diethanol amine in the presence of sodium methoxide catalyst. FTIR, ¹H NMR, and ¹³C NMR spectroscopic analyses were employed to confirm the structure of branching unit and hyperbranched resins. Poly(amido amine)-cured hyperbranched epoxy thermosets exhibited superior properties, such as tensile strength (45–57.2 against 38.5 MPa), elongation-at-break (16.3–24.2 against 5 %), scratch hardness (>10 against 7 kg), toughness (577.8–859.1 against 150.2 MPa), tensile adhesive strength (1647–2086 against 581 MPa), and biodegradability (17.6–31 against 2.2 %), compared with the conventional bisphenol-A-based epoxy, prepared under the same conditions. These results simply indicate the advantageous of the bio-based moiety and hyperbranched architecture on the overall performance of the thermosets. Moreover, good antioxidative response of these thermosets expands their applications as protective coatings and adhesive materials. Thus, diethanolamide of gallic acid-based hyperbranched epoxy thermoset can be used as potent ecofriendly advanced material in multifaceted applications.     

Partially biobased polyamphiphile-bearing reactive epoxy groups in the side chains and its application to the hydrogel

Partially biobased polyamphiphile-bearing reactive epoxy groups in the side chains were obtained in 62–78 % yields by a radical copolymerization of limonene oxide (LO) and PEG methylacrylate (PEGA) with different feed ratios. Degree of LO incorporation into the copolymer was determined as 12–23 % by ¹H NMR spectroscopic analysis. The copolymer having LO unit:PEGA unit = 19:81 formed polymer associates in water, particle diameter of which was ranged mainly from 4 to 66 nm and hydrodynamic mean diameter was 12.3 nm. Its critical micelle concentration was determined as 0.53 g/L by fluorescence spectroscopic analysis. A cross-linking reaction of the epoxy groups in the side chains was conducted with 3.97 mol% (to the epoxy group) of branched poly(ethylene imine) as a cross-linker to give the corresponding hydrogel in 56 % yield. The hydrogel can absorb water as much as 13 times its own mass.     

Synthesis and properties of multiarm star hydroxyl-terminated polyesters for two-component polyurethane coatings

A series of multiarm star hydroxyl-terminated polyesters (MHPs) were synthesized through a “one-pot” method with di-trimethylolpropane as the core molecule, 2,2-dimethylolpropionic acid as the AB₂-type monomer, ε-caprolactone, and monocarboxylic acids as modifiers. The influence of different monocarboxylic acids on the viscosities of polyesters and their 2K-PU films hardness was studied and it was found that MHPs prepared from lauric acid displayed the higher films hardness and lower viscosities. IR spectra of MHPs disclosed the ring-opening reaction between ε-caprolactone and hydroxyl groups occurred. ¹H NMR spectra demonstrated that the molecular structures of MHPs were irregular due to the multiplicity of reaction processes. The measured number-average molecular weights (M _n) of MHPs were around 715–1854 g/mol with the PDI of 1.45–2.05. MHPs exhibited lower viscosities in the range of 3304–9060 mPa s at 100% solid contents and possessed lower intrinsic viscosities compared with linear polymers of similar molecular weight. The cured films of MHPs exhibited excellent impact resistance, adhesion, flexibility, and high hardness and displayed good thermal stability with 5% weight loss at 280°C. The solution viscosities of MHPs were less than 450 mPa s at 80% solid contents, and the VOC contents of 2K-PU coatings obtained from MHPs were low to 300 g/L.     

Toughening of an epoxy anhydride resin system using an epoxidized hyperbranched polymer

This paper reports on the use of an epoxidized hyperbranched polymer (HBP) as an additive to an epoxy anhydride resin system. The hyperbranched polymer used was an aliphatic polyester with a molecular weight of around 10 500 g mol^?1. The epoxy resin mixture used was a combination of a difunctional diglycidyl ether of bisphenol A (DGEBA) epoxy and an epoxy novolac, and was cured with a catalysed anhydride curing agent. It has been shown that, at a concentration range of 0 to 20 wt% addition, the HBP is able to almost double the fracture toughness, with little evidence of any deleterious effects upon processing and the durability of the cured resin system. The flexural modulus and stress, however, were found to both decrease by about 30% as a result of HBP addition while the T_g was found to decrease by about 10%. The processability of the uncured resin systems has been investigated by using rheological and calorimetric techniques and it was found that the processability window, as determined by the gel time and viscosity changes, was relatively unaffected by HBP addition. The fracture surfaces were evaluated by using scanning electron microscopy which showed that the unique structure of the HBP facilitates an enhanced interaction with the polymer matrix to achieve excellent toughness enhancement of the polymer matrix. The durability of the epoxy network has been investigated via thermogravimetric analysis (TGA) and solvent uptake, and the HBP has been shown to have little systematic deleterious effect upon the degradation temperatures and the total amount of solvent absorbed. Copyright © 2003 Society of Chemical Industry     

Hyperbranched polyurethane/Fe3O4 thermosetting nanocomposites as shape memory materials

Nanocomposites of hyperbranched polyurethane were prepared by the in situ pre-polymerization technique with Fe₃O₄ nanoparticles. The synthesized Fe₃O₄ nanoparticles were characterized by the Fourier transform infrared spectroscopy and the X-ray diffraction study. The transmission electron microscopic study indicates the homogeneous distribution of Fe₃O₄ nanoparticles in the polymer matrix. The mechanical, thermal and shape memory behaviors of the nanocomposites were studied as a function of nanomaterial content. The glycidyl bisphenol-A based epoxy cured thermosetting nanocomposites exhibited significant improvement of tensile strength (5.7–18 MPa), scratch hardness (3.0–6.5 kg) and thermal stability (241–275 °C) with the increase of the content of Fe₃O₄. The nanocomposites possess excellent shape fixity over the repeated cycles of test. They also showed good shape recovery under the application of microwave energy. The shape recovery speed found to increase with the increase of the loading of Fe₃O₄ in the nanocomposites. Thus, the prepared nanocomposites might be utilized as advanced shape memory materials in their potential fields.     

Influence of Nano-Inorganic Particles on Properties of Epoxy Nanocomposites

Solution polymerization of Bisphenol-A and Epichlorohydrine gives epoxy resin. Spray pyrolysis technique was found to be promising method for synthesis of nanomaterials like CaCO₃ of different sizes (10, 15, and 18 nm). The nanomaterial (2 to 10 mass % loading) was added at the time of resin formation. Mechanical stirring as well as an ultrasonication technique were used for uniform distribution of nanomaterials inside the resin. The effect of nanomaterials on thermal behaviors like curing time and glass transition temperature (Tg) were studied. Addition of nanomaterials accelerates the rate of curing of epoxy resin during composite formation. Moreover, addition of nanomaterial doesn't show any consequent change in Tg of epoxy composite but cross-linking density changes linearly. The rheological parameters like viscosity and torque were recorded on a Brookfield viscometer and correlated with M = CS^α and τ = κ(γ)ⁿ.     

Enhanced thermal and mechanical properties of epoxy composites by addition of hyperbranched polyglycerol grown on cellulose fibers

We reported a novel approach for epoxy composites by incorporation of hyperbranched polyglycerol (HPG) grafted sisal cellulose fibers (SCF). In this work, we have synthesized SCF wrapped HPG shell (SCF-g-HPG) by a “grafting from” strategy for the strong interfacial interaction between fillers and matrix. It was found that the thermal and mechanical properties of epoxy composites were greatly improved by incorporating SCF-g-HPG. For example, the impact strength, flexural strength, tensile strength, Young’s modulus and toughness of the composites with 3.0 wt% SCF-g-HPG loading were 38.35 KJ/m², 123.40 MPa, 86.62 MPa, 151.7 MPa, and 417.84 MJ/m³, significantly increased by 119.1 %, 55.2 %, 45.6 %, 43.1 %, and 166.1 % respectively, as compared with neat epoxy. In addition, thermal stability of SCF-g-HPG/epoxy composites also showed an obvious enhancement compared with neat epoxy.     

Synthesis and Comparative Physico-chemical Study of Polyester Polyols Based Polyurethanes of Bisphenol-A and Bisphenol-C Epoxy Resins

Polyester polyols of epoxy resins of bisphenol-A and bisphenol-C were synthesized by reacting corresponding 0.02 mol epoxy resin, and 0.04 mol ricinoleic acid by using 1,4-dioxane (30 ml) as a solvent and 0.5 g triethyl amine as a catalyst at reflux temperature for 4–5 hr. Polyurethanes have been synthesized by reacting 0.0029 mol of polyester polyols with 0.004 mol toluene diisocyanate at room temperature and their films were cast from solutions. The formation of polyester polyols and their polyurethanes are supported by IR spectral data (1732.9–1730.0 cm^?1 ester and urethane and 3440.8–3419.6 cm^?1 OH and NH str). The densities of polyurethane of bisphenol-A (PU-A) and polyurethane of bisphenol-C (PU-C) were determined by a floatation method. The observed densities of PU-A and PU-C are 1.2190 and 1.2308 g/cm³, respectively. Slightly high density of PU-C is due to structural dissimilarity of two bisphenols. The tensile strength, electric strength, and volume resistivity of PU-A and PU-C are 34.7, 18.7 MPa; 80.7, 44.4 kv/mm; and 1.7 × 10¹⁵, 2.2 × 10¹⁵ ohm cm, respectively. PU-A and PU-C are thermally stable up to about 182–187°C and followed three step degradation. Incorporation of cyclohexyl cardo group in polyurethane chain did not impart any change in thermal properties but it caused drastic reduction in tensile and electric strength due to rigid nature of PU-C chains. PU-C has excellent chemical resistance over PU-A. Both polyurethanes possess good resistance against water, 10% each of aqueous acids (HCl, HNO₃, and H₂SO₄), alkalis (NaOH and KOH) and NaCl. Good thermo-mechanical, excellent electrical properties, and good chemical resistance of polyurethanes signify their usefulness in coating and adhesive, electrical and electronic industries.     

Effect of Hyperbranched Poly (Trimellitic Anhydride Ethylene Glycol) Epoxy (HTME) on Thermal Degradation Activation Energies of HTME/Diglycidyl Ether of Bisphenol-A Epoxy Hybrid Resin by Kissinger and Flynn–Wall–Ozawa Method

The thermal degradation behavior and kinetics of hyperbranched poly (trimellitic anhydride ethylene glycol) epoxy (HTME)/diglycidyl ether of bisphenol-A epoxy (DGEBA) hybrid resin was investigated with thermogravimetric analysis (TGA) by using Kissinger method and Flynn–Wall–Ozawa method. The results show that the thermal degradation activation energies of DGEBA, 9 wt% HTME-1/91wt% DGEBA, 3 wt% HTME-2/97 wt% DGEBA, 9 wt% HTME-2/91 wt% DGEBA, 15 wt% HTME-2/85 wt% DGEBA, and 9 wt% HTME-3/91wt% DGEBA are 152.5, 144.4, 135.4, 133.2, 121.8 and 143.0 kJmol^?1, respectively, by Kissinger method. and the activation energies are 173.3, 165.0, 163.2, 151.7, 137.7 and 159.7 kJmol^?1, respectively by Flynn–Wall–Ozawa method. With the increase of HTME content, the activation energies of HTME/DGEBA hybrid resin decrease. Although molecular weight or generation of hyperbranched epoxy resins (HTME) has little effect on the thermal degradation activation energies and other kinetics data.     

Optical,Electrochemical, and Structural Properties of Spray Coated Dihexyl Substituted Poly (3,4 Propylene Dioxythiophene) Film for Optoelectronics Devices

The dihexyl substituted poly (3,4-propylenedioxythiophene) (PProDOT-Hx₂) thin films uniformly deposited by cost effective spray coating technique on transparent conducting oxide coated substrates. The electro-optical properties of PProDOT-Hx₂ films were studied by UV-Vis spectroscopy that shows the color contrast about 45% with coloration efficiency of ～ 185 cm²/C. The electrochemical properties of PProDOT-Hx₂ films were studied by cyclic voltammetry and AC impedance techniques. The cyclic voltammogram shows that redox reaction of films are diffusion controlled and ions transportation will be faster on the polymer film at higher scan rate. Impedance spectra indicate that polymer films are showing interface charge transfer process as well as capacitive behavior between the electrode and electrolyte. The XRD of the PProDOT-Hx₂ thin films revealed that the films are in amorphous nature, which accelerates the transportation of ions during redox process.     

Biodegradable and thermostable synthetic hyperbranched poly(urethane-urea)s as advanced surface coating materials

Aliphatic hyperbranched poly(urethane-urea)s with different weight percentages of branch generating moiety were synthesized by a one pot A₂ + BC₂ approach. Isophorone diisocyanate was used as the A₂ type monomer, while a tri-functional dihydroxyamine compound synthesized from ?-caprolactam and diethanol amine acted as the BC₂ monomer. Evidence supporting the hyperbranched structure of the synthesized poly(urethane-urea) was obtained from ¹H NMR spectra. FTIR study confirmed the nature and extent of hydrogen bonding present in this novel macromolecule. A Gaussian band fitting procedure of the IR band at amide-I region showed that the extent of hydrogen bonding increases with the increase of weight percentage of the tri-functional compound. The tensile strength, elongation at break, impact resistance, scratch hardness and gloss followed an increasing trend with the same. The thermal degradation of the hyperbranched poly(urethane-urea) was found to be dependent on the weight percentage of the BC₂ type moiety. The kinetics of thermal degradation studied by the Ozawa method showed that the activation energy required for thermal degradation of hyperbranched polymer is higher than its linear polyurethane analog. The synthesized polymer was found to be biodegradable by Pseudomonas aeruginosa bacteria. The study showed superiority of the hyperbranched structure over the linear one. Thus the results indicated the potential usage of the studied hyperbranched poly(urethane-urea) as an advanced surface coating material.     

Synthesis and second-order nonlinear optical properties of hyperbranched polymers containing pendant azobenzene chromophores

Two hyperbranched polymers with methyl ester (P1) and epoxy (P2) terminal groups containing pendant azobenzene chromophores were prepared through an “A₂ + B₃” approach used for second-order nonlinear optical materials. Their chemical structures were characterized by NMR and GPC analyses. The polymers have good solubility in common organic solvents and film-forming ability. The pure films were fabricated successively without doping into other matrices. The poled films exhibit high second-harmonic generation coefficients (>50 pm/V) due to the three-dimensional spatial isolation effect resulting from their highly branched structures. The optical nonlinearity of the poled P2 film is thermally more stable than that of P1 due to the cross-linking of epoxy groups with carboxylic acid groups in the former during poling. The onset decay temperature of SHG intensity of P2 was determined to be at around 155 °C, which was 20 °C higher than that of P1.     

Synthesis and Characterization of NiS/MnS Core-Shell Embedded Conducting Polyaniline Composite for Photovoltaic Application

Conducting polyaniline (Pani) films embedded with Co²⁺ doped, PVA-capped NiS/MnS core-shell particles as photoluminescent boosters have been developed and reported. The absorption and photoluminescence characteristics of the core-shell Pani have increased significantly. Film of the core-shell-Pani composite is n-type semiconductor with a band gap of 2.34 eV. Periodic arrangement of the nanoclusters of the core-shell in the continuous conductive polymer matrix with high carrier density (3.99 × 10¹⁶) rates this material for photoelectrochemical applications. Solid-state photovoltaic cells with NiS/MnS-Pani as the electron conductor shows a I_sc of 0.14 mA/cm², V_oc of 382 mV and photo conversion efficiency of 1.25%.     

Hyperbranched poly(arylene ether phosphine oxide)s

Summary New AB₂ and A₂B monomers, bis(4-fluorophenyl)-4'-hydroxyphenylphosphine oxide and bis(4-hydroxyphenyl)-4'-fluorophenyl-phosphine oxide were prepared and converted to corresponding hyperbranched poly(arylene ether phosphineoxide)s with hydroxyphenyl and fluorophenyl end functional groups. While the dihydroxy monomer gave a low molecular weight polymer, the difluoro monomer produced a high molecular weight hyperbranched polymer. The glass transition temperature of the obtained polymers was 266°C and 230°C, and 5% weight loss temperature was 491 °C and 391 °C, respectively. The fluorophenyl-terminated hyperbranched polymer was soluble in CHCl₃, but the hydroxyphenyl-terminated polymer was not soluble in CHCl3 even though it has lower molecular weight than the fluorophenyl-terminated polymer, indicating that properties of the hyperbranched polymers markedly depend on end functional groups as well as their molecular weight. Received: 23 August 2000/Revised version: 19 October 2000/Accepted: 31 October 2000     

Thermal and electrical properties of epoxy composites at high alumina loadings and various temperatures

Epoxy microcomposites with high loading micro alumina (Al₂O₃, 100–400 phr) were prepared by casting method and their thermal and electrical properties were studied at temperatures from 25 to 150 °C. The electric resistance device and the dielectric electrode device were designed to measure the electrical properties of the composites. Thermogravimetric analysis (TGA) and scanning electron microscopic proves the homodispersion of Al₂O₃ microparticles in epoxy. TGA indicates that the temperature of 5 % weight loss of epoxy/Al₂O₃ (100 phr) composite is 366 °C, 34 °C higher than that of pure epoxy. Differential scanning calorimetry shows that the glass transition temperature of epoxy/Al₂O₃ composite (400 phr) increases to 114.7 °C, 9.2 °C higher than that of pure epoxy. Thermal conductivity test demonstrated that with increasing Al₂O₃ content at 25 °C, thermal conductivity of epoxy/Al₂O₃ composites increased to 1.382 W/(m K) which is 5.62 times that of pure epoxy. Electrical tests demonstrate that by increasing of Al₂O₃ content and temperature, the electric resistance and dielectric properties of the composites show great dependencies on them. Resistivities of all the specimens decreased with the increasing of temperature owing to the increasing molecular mobility in the higher temperature. Resistivity of pure epoxy at 25 °C is about 9.56 × 10¹⁶ Ω cm, about one order of magnitude higher than that of pure epoxy at 125 °C and two orders of magnitude higher than that of pure epoxy at 150 °C. These results can give some advice to design formulations for practical applications in power apparatus.     

A novel UV‐curable epoxy acrylate resin containing arylene ether sulfone linkages: Preparation,characterization, and properties

UV‐curing processes are used in industrial applications because of their advantages such as high‐speed applications and solvent‐free formulations at ambient temperature. UV‐curable epoxy acrylate resins containing arylene ether sulfone linkages (EAAES) were synthesized through the condensation of bis(4‐chlorophenyl)sulphone and bisphenol‐A, followed by end‐caping of epichlorohydrin and subsequently acrylic acid. UV‐cured coatings were formulated with epoxy acrylates, reactive diluents such as pentaerythritol tri‐acrylate and pentaerythritol dia‐crylate and photoinitiator. Fourier transfer infrared, ¹H NMR, and thermal gravimetrical analysis were employed to investigate the structures and thermal properties of the EAs films. The introduction of EAAES into epoxy acrylate substantially improves its thermal properties and thermo‐oxidative stability at high temperatures. In addition, the acrylate containing arylene ether sulfone linkages can also improve pencil hardness and chemical and solvent resistance of the epoxy acrylate. The obtained UV‐curable epoxy acrylate containing arylene ether sulfone linkages is promising as oligomer for UV‐curable coatings, inks, and adhesives in some high‐tech regions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41067.     

Synthesis and performance application of self-crosslinking water-borne epoxy resin for cementing

Aiming at the problem of high brittleness of cement stone, we have studied the self-emulsificating and self-crosslinking modification of epoxy resin (EP) (E54), and the modified EP was used in oil well cement to improve the cement ring toughness and reduce the cement ring cracked. Using 2-acrylamide-2-methyl propane sulfonic acid and acrylamide as modified monomers, benzoyl peroxide as initiator, and grafting modification method by free radical polymerization to obtain water-borne epoxy resin (WBE). Fourier transform infrared spectrometer and ¹H NMR were used to characterize the modified product, which showed that the WBE contained ─SO₃H and ─CONH₂ hydrophilic groups, and the connecting method of the hydrophilic side chain was clarified. WBE can achieve good dispersion in an aqueous solution, it can be stabilized for 30 min without stratified at a centrifugal speed of 6000 rpm; when the temperature is >80°C, it can be self-curing. The addition of WBE can increase the flexural strength of cement stone by 48.3%, the compressive strength by 38.4%, and reduce the modulus of elasticity by 45.3%. Scanning electron microscope analyzed the mechanism of WBE to improve the toughness of cement stone, and found that after WBE cross-linking, polymer films and three-dimensional network structures are formed in the cement stone, making the cement structure more compact. WBE can effectively improve the mechanical properties of cement rings and can be used to improve cementing quality.     

Ferrocene-Decorated Hyperbranched Poly(aroxycarbonylphenylene)s: Synthesis, Light Refraction, Photopatterning and Precursor to Magnetic Ceramics

Ferrocene-decorated hyperbranched poly[1,3,5-tri(aroycarbonyl)phenylene]s (hb-PTACPs) are prepared in moderate yields with high molecular weights by one-pot polycyclotrimerization of 4,4′-isopropylidenediphenyl bipropiolate with 4-(ferrocenylmethyl)phenyl propiolate in reflux dimethylformamide. All the polymers are soluble and film-forming. They enjoy high thermal stability and lost little of their weight when heated to 300 °C under nitrogen. Thin solid films of the organometallic polymers shows high refractive indices (RI = 1.7038–1.6295) in the wavelength region of 400–1,700 nm. Ceramization of the organometallic hb-PTACPs at high temperature under inert atmosphere gives iron nanoparticles with high magnetizabilities. The organometallic polymers are readily crosslinked under UV irradiation and pyrolysis of the patterned polymer films produces magnetic ceramic patterns with good shape retention.