Toughening of aromatic diamine-cured epoxy resins by poly(butylene phthalate)s and the related copolyesters

Aromatic polyesters, prepared by the reaction of aromatic dicarboxylic acids and 1,4-butanediol, were used to improve the toughness of bisphenol-A diglycidyl ether epoxy resin cured with p,p′-diaminodiphenyl sulfone. These polyesters contained poly(butylene phthalate)s (PBP), poly(butylene phthalate-co-butylene isophthalate)s, poly(butylene phthalate-co-butylene terephthalate)s, and poly(butylene phthalate-co-butylene 2,6-naphthalene dicarboxylate)s. All aromatic polyesters used in this study were soluble in the epoxy resin without solvents and were found to be effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt % PBP (MW 16,300) led to a 120% increase in the fracture toughness (K_IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism was discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system. © 1996 John Wiley & Sons, Inc.     

Preparation of novel soluble poly(ester imide)s containing a trimellitimide moiety and their use as modifiers for aromatic diamine‐cured epoxy resin

Poly(ester imide)s, prepared by the reaction of phthalic anhydride, N‐(4‐carboxyphenyl) trimellitimide and 1,2‐ethanediol, were used to improve the toughness of bisphenol‐A diglycidyl ether epoxy resin cured with 4,4′‐diaminodiphenyl sulfone (DDS). The poly(ester imide)s include poly(ethylene phthalate‐co‐ethylene N‐(1,4‐phenylene) trimellitimide dicarboxylate)s (PESIs) having 10, 20 and 30 mol% trimellitimide (TI) units, respectively. PESIs having 10 and 20 mol% TI units were effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt% of PESI (20 mol% TI unit, M _W 19300 g mol^?1) led to a 55% increase in the fracture toughness (K_IC) of the cured resin (with an increase in flexural strength and modulus) and the modified resin had a particulate morphology. PESI having 30 mol% TI units was not effective because of degradation of the modifier by DDS. The toughening mechanism is discussed in terms of morphological and dynamic viscoelastic behaviour of the modified epoxy resin system. © 2001 Society of Chemical Industry     

Synthesis,characterization, and properties of a novel epoxy resin containing both binaphthyl and biphenyl moieties

A new epoxy resin containing both binaphthyl and biphenyl moieties in the skeleton (BLBPE) was synthesized and confirmed by electrospray ionization mass spectroscopy, ¹H‐nuclear magnetic resonance spectroscopy, and infrared spectroscopy. To evaluate the combined influence of two moieties, one epoxy resin containing binaphthyl moiety and another containing biphenyl moiety were also synthesized, and a commercial biphenyl‐type epoxy resin (CER3000L) was introduced. Thermal properties of their cured polymers with phenol p‐xylene resins were characterized by differential scanning calorimetry, dynamic mechanical, and thermogravimetric analyses. The cured polymer obtained from BLBPE showed remarkably higher glass transition temperature and lower moisture absorption, as well as comprehensively excellent thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Reaction kinetics,thermal properties of tetramethyl biphenyl epoxy resin cured with aromatic diamine

Epoxy resins, 4, 4′‐diglycidyl (3, 3′, 5, 5′‐tetramethylbiphenyl) epoxy resin (TMBP) containing rigid rod structure as a class of high performance polymers has been researched. The investigation of cure kinetics of TMBP and diglycidyl ether of bisphenol‐A epoxy resin (DGEBA) cured with p‐phenylenediamine (PDA) was performed by differential scanning calorimeter using an isoconversional method with dynamic conditions. The effect of the molar ratios of TMBP to PDA on the cure reaction kinetics was studied. The results showed that the curing of epoxy resins contains different stages. The activation energy was dependent of the degree of conversion. At the early of curing stages, the activation energy showed the activation energy took as maximum value. The effects of rigid rod groups and molar ratios of TMBP to PDA for the thermal properties were investigated by the DSC, DMA and TGA. The cured 2/1 TMBP/PDA system with rigid rod groups and high crosslink density had shown highest T_g and thermal degradation temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

UV and corrosion protective behavior of polymer hybrid coating on mild steel

Poly[(pyridine‐4‐yl‐methyl)methacrylate‐co‐butyl methacrylate] [poly(PyMMA‐co‐BMA)] and its ZnO nanocomposites [poly(PyMMA‐co‐BMA)/ZnO] were coated on the mild steel substrate (MS) to improve the corrosion resistance by blocking the destructive ultraviolet radiation (UV‐radiation) and corrosive ions as well. The optical and anticorrosive properties of poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (1.0, 1.5, and 2.5 wt %) coatings were evaluated. The surface characterization techniques like UV visible spectroscopy and scanning electron microscope were taken to confirm the formation of poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (2.5 wt %) coating on MS. The optical studies revealed that the poly(PyMMA‐co‐BMA)/ZnO (2.5 wt %) coating displays excellent UV blocking properties than other nanocomposite coatings (1.0 and 1.5 wt %). The potentiodynamic polarization and electrochemical impedance spectroscopy studies show that the poly(PyMMA‐co‐BMA) and poly(PyMMA‐co‐BMA)/ZnO (1.0, 1.5, and 2.5 wt %) coated MS in 3.5% (w/v) NaCl provides better protection against corrosion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46175.     

Temperature‐sensitive poly(N‐tert‐butylacrylamide‐co‐acrylamide) hydrogels bonded on cotton fabrics by coating technique

Different from the conventional method of developing stimuli‐sensitive textiles by graft copolymerization of environmental responsive polymers onto the fabric, the coating technique was applied to bond temperature‐sensitive hydrogels with cotton fabric through chemical covalent in our work. A temperature‐sensitive linear copolymer of N‐tert‐butylacrylamide (NTBA) and acrylamide (AAm) was prepared in methanol. Then, the cotton fabrics were coated using an aqueous solution of this copolymer containing 1,2,3,4‐butanetertracarboxylic acid as a crosslinker and sodium hypophosphite (SHP) as a catalyst, followed by drying and curing. The surface of the cotton fabrics was bonded on more or less coatings of poly (NTBA‐co‐AAm) hydrogels, as verified by Fourier transform infrared spectroscopy and scanning electron microscopy images. The poly(NTBA‐co‐AAm) hydrogels‐coated fabrics exhibited temperature sensitive, and the temperature interval of the deswelling transition was higher than lower critical solution temperature of linear copolymer solution. The coated fabrics presented good water‐impermeable ability because of the swelling of hydrogels bonded, especially when the add‐on was as high as 14.14%. Environmental scanning electron microscopy images revealed that coating hydrogels swelled and covered on the surface as a barrier to prevent water from penetrating once the coated fabric came into contact with water. The findings demonstrate that the temperature‐sensitive hydrogels can be covalently bonded on the cotton fabrics by coating technique and the coated fabrics have potential on immersion fabrics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Nanostructures and thermomechanical properties of epoxy thermosets containing reactive diblock copolymer

Polystyrene‐block‐poly(glycidyl methacrylate) reactive diblock copolymer (PS‐b‐PGMA) was synthesized via atom transfer radical polymerization (ATRP). The diblock copolymer was characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The cured epoxy thermosets with 10–20 nm PS particles were prepared by blending the diblock copolymer with epoxy resin. The nanostructures were examined by means of transmission electronic microscopy (TEM) and small angle X‐ray scattering (SAXS). The formation of the nanostructures was caused by the reaction‐induced microphase separation mechanism. It is significant that the glass transition temperatures (T_gs) of these epoxy thermosets were increased by the addition of PS‐b‐PGMA reactive block copolymer as revealed by both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of bio‐based epoxy montomorillonite nanocomposites derived from polyglycerol polyglycidyl ether and ε‐polylysine

Glycerol polyglycidyl ether (GPE) and polyglycerol polyglycidyl ether (PGPE) were cured with ε‐poly(L ‐lysine) (PL) using epoxy/amine ratios of 1 : 1 and 2 : 1 to create bio‐based epoxy cross‐linked resins. When PGPE was used as an epoxy resin and the epoxy/amine ratio was 1 : 1, the cured neat resin showed the greatest glass transition temperature (T_g), as measured by differential scanning calorimetry. Next, the mixture of PGPE, PL, and montomorillonite (MMT) at an epoxy/amine ratio of 1 : 1 in water was dried and cured finally at 110°C to create PGPE‐PL/MMT composites. The X‐ray diffraction and transmission electron microscopy measurements revealed that the composites with MMT content 7–15 wt % were exfoliated nanocomposites and the composite with MMT content 20 wt % was an intercalated nanocomposite. The T_g and storage modulus at 50–100°C for the PGPE‐PL/MMT composites measured by DMA increased with increasing MMT content until 15 wt % and decreased at 20 wt %. The tensile strength and modulus of the PGPE‐PL/MMT composites (MMT content 15 wt %: 42 and 5300 MPa) were much greater than those of the cured PGPE‐PL resin (4 and 6 MPa). Aerobic biodegradability of the PGPE‐PL in an aqueous medium was ～ 4% after 90 days, and the PGPE‐PL/MMT nanocomposites with MMT content 7–15 wt % showed lower biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of poly(1,4‐cyclohexylenedimethylene phthalate)s and their use as modifiers for aromatic diamine‐cured epoxy resin

Poly(1,4‐cyclohexylenedimethylene phthalate) s, prepared by the reaction of phthalic anhydride and 1,4‐cyclohexane dimethanol (35/65 or 73/27 mol % cis/trans or trans alone), have been used to improve the toughness of bisphenol‐A diglycidyl ether epoxy resin cured with 4,4′‐diaminodiphenyl sulfone. The aromatic polyesters include poly(cis/trans‐1,4‐cyclohexylenedimethylene phthalate) (PCP) based on a commercial cyclohexanedimethanol, poly(trans‐1,4‐cyclohexylenedimethylene phthalate) (trans‐PCP) and poly(cis/trans‐1,4‐cyclohexylenedimethylene phthalate) (cis‐rich PCP) prepared from a cis‐rich diol. The polyesters used were soluble in the epoxy resin without solvents and were effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt% of PCP (MW 6400 g mol⁻¹) led to an 80% increase in the fracture toughness (K_IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism is discussed in terms of morphological and dynamic viscoelastic behaviours of the modified epoxy resin system. © 2000 Society of Chemical Industry     

Syntheses,characterization, and antibacterial activity of chitosan grafted hydrogels and associated mica‐containing nanocomposite hydrogels

Chitosan (CS) grafted poly[(acrylic acid)‐co‐(2‐hydroxyethyl methacrylate)] (CS‐g‐poly(AA‐co‐HEMA)) at different molar ratios of AA and HEMA, and the associated nanocomposite hydrogels of CS‐g‐poly(AA‐co‐HEMA)/mica were synthesized by radical copolymerization. The grafting positions at the amino or hydroxyl groups in the CS were identified by Fourier transform infrared spectroscopy. CS‐g‐poly(AA‐co‐HEMA) hydrogels were intercalated in the mica and the amount of hydrogel insertion did not affect the spacing of the silicate layers in mica. The higher mica loadings produced a rougher surface of the nanocomposite hydrogel. The water absorbency of the CS‐g‐poly(AA‐co‐HEMA)/mica nanocomposite hydrogels decreased with increasing levels of mica loading to a lower level than those of the CS‐g‐poly(AA‐co‐HEMA) hydrogels. Both CS‐g‐poly(AA) and CS‐g‐poly(AA‐co‐HEMA)/mica nanocomposite hydrogels exhibited a higher antiproliferative activity against Staphylococcus aureus than did the neat CS hydrogel with CS‐g‐poly(AA) revealing a very pronounced minimum inhibition concentration (MIC) of 1.56 mg mL^?1. The extent of mica loading in the CS‐g‐poly(AA‐co‐HEMA) nanocomposite hydrogels did not affect the MIC (12.5 mg mL^?1). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Shape‐memory property and characterization of epoxy resin‐modified Mesua ferrea L. seed oil‐based hyperbranched polyurethane

Modification of existing polymers leads to enhancement of many desirable properties. So, a hyperbranched polyurethane (HBPU) of monoglyceride of Mesua ferrea L. seed oil, poly(ε‐caprolactone)diol (M_n = 3000 g mol^?1), 2,4‐toluene diisocyanate, and glycerol with 30% hard segment (NCO/OH = 0.96) has been modified with different amounts of bisphenol‐A based epoxy resin. The system is cured by poly(amido amine) hardener at 120°C for specified period of time. Improvement of thermostability, scratch hardness, and impact strength are observed by this modification of HBPU. The differential scanning calorimetry (DSC) results show improvement of melting temperature of the modified systems. The enhancement of tensile strength is about 2.4 times compared with that of the unmodified one. The morphology and structural changes due to variation of epoxy content was studied by scanning electron microscopy (SEM) analysis and Fourier transform infrared (FTIR) spectroscopy. The rheological properties of the epoxy‐modified HBPU show the dependence on the amount of epoxy resin. Shape memory study of the crosslinked HBPUs shows 90–98% thermoresponsive shape recovery. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether)/poly(styrene acrylate) core–shells and SiO2 nanocomposite films via a solution mixing method

Nanocomposite particles of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether) [poly(CTFE‐co‐EVE)]/poly(styrene acrylate) (PSA)/SiO₂ were prepared with poly(CTFE‐co‐EVE)/PSA [CS(FS); core–shell (CS) fluoro surfactant (FS)] and hydrophilic SiO₂ nanoparticles by a solution mixing method. This method yielded a homogeneous dispersion of hydrophilic SiO₂ nanoparticles in the CS(FS) matrix. The nanocomposite particle composition was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. A slight improvement in the thermal stability was observed and the glass‐transition temperature of the nanocomposite particles increased compared with the CS(FS) matrix. A remarkable enhancement was observed in the mechanical properties with an increase in the tensile strength from 1.1 to 6.2 MPa and with an increase in the elongation at break from 209.6 to 350.1% for the films with 15 wt % SiO₂. The presence of a wettable PSA shell on the fluorocore made interaction possible with SiO₂; this made it more hygroscopic with a decent water uptake capacity and an enhanced water contact angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

A novel amide and imide copolymer as matrix resin for UV photoresist

A novel amide and imide copolymer, poly(N‐phenylmethacrylamide‐co‐N‐(p‐hydroxyphenyl)maleimide) was synthesized for the matrix resin of ultraviolet (UV) photoresist. Elemental analysis and self‐polymerization experiment verified that this copolymer was very close to 1:1 (molar ratio) in composition and was predominately alternating. It was able to dissolve in various organic solvents and form uniform curing film when spin‐coating. Its differential scanning calorimetry and thermogravimetry analysis test showed good thermal stability and its glass transition temperature (T_g) was about 280°C. Photolithographic experiment indicated that the UV photoresist formulated with this copolymer as matrix resin was achieved the resolution of about 5 μm, the contrast of 3.001, and the sensitivity of 32 mJ/cm². With good plasma etching resistance, the photoresist studied was able to bear 250°C for 30 min without thermal deformation during the thermal resistance test. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Effect of cobalt on the electrical conductive property of epoxy resins

Cobalt acrylate (CoA₂) has been treated with bisphenol‐A and epichlorohydrin to modify epoxy resins. It was cured with p‐acetylbenzilidene triphenyl arsonium ylide. The properties such as epoxide equivalent weight (equiv/100 g), molecular weight, hydrolyzable chlorine content increases whereas hydroxyl content, refractive index decreases in the presence of CoA₂. The cured epoxy resins shows improve electrical conductivity due to the incorporation of CoA₂ with epoxy resins. The influence of complex formation of CoA₂ with either linkage of epoxy resins were investigated by spectroscopy. The decrease in T_g from differential scanning calorimetry support the improve in flexibility. The dispersion of cobalt in epoxy resins matrix was confirmed by scanning electron microscope. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Multilayer‐coated NPK compound fertilizer hydrogel with controlled nutrient release and water absorbency

A novel trilayered controlled‐release nitrogen, phosphorous, and potassium (NPK) fertilizer hydrogel was prepared by dipping the NPK fertilizer granules sequentially in 7% w v^?1 poly(vinyl alcohol) (PVA) and 2% w v^?1 chitosan (CS) solutions and then cross‐linking the CS layer (cross‐CS) via glutaraldehyde vapor deposition. Different NPK fertilizer hydrogels were then synthesized by inverse suspension polymerization of the dried PVA/cross‐CS bilayer‐coated fertilizer granules in various molar ratios of acrylamide (AM) and acrylic acid (AA) monomers, and polymerization with varying molar ratios of ammonium persulfate, N,N,N′,N′‐tetramethylethylenediamine and N,N′‐methylenebisacrylamide (N‐MBA). The water dissolution time of the obtained PVA/cross‐CS/poly (AA‐co‐AM) trilayer‐coated NPK fertilizer hydrogel granules was prolonged, while the water absorbency increased with increasing AA contents, and decreased with increasing N‐MBA contents in the outer poly(AA‐co‐AM) coating. The optimal trilayer‐coated NPK fertilizer hydrogel obtained released 84 ± 18, 63 ± 12, and 36 ± 15% of the N, P, and K nutrients, respectively, after a 30‐day immersion in water. The release phenomena of the N, P, and K nutrients of the fertilizer hydrogel obeyed both the Korsmeyer‐Peppas and Ritger‐Peppas models with a pseudo‐Fickian diffusion mechanism. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41249.     

Preparation and characterization of composites of polyethylene with polypyrrole‐coated wollastonite

Composite sheets of polyethylene and polypyrrole‐coated wollastonite were prepared by extrusion and compression molding. Four compatibilizers were also evaluated, poly(ethylene‐co‐methyl acrylate) (EMA), maleated polyethylene (MAPE), poly(ethylene‐co‐vinyl alcohol) (EVOH), and poly(vinyl alcohol) (PVOH). The composite materials were characterized using X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy (SEM), Raman spectroscopy, and mechanical properties determined by tensile tests. SEM micrographs showed that significantly improved interactions occurred between the PE matrix and polypyrrole‐coated wollastonite particles in the presence of EMA, MAPE, and EVOH. Raman spectroscopy confirmed that the polypyrrole coating on the wollastonite particles was not thermally degraded during melt processing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flexible epoxy novolac coatings: Use of cardanol‐based flexibilizers

Flexible epoxy novolac coatings were developed by reacting an epoxy novolac resin, poly[(phenylglycidyl ether)‐co‐formaldehyde] (PPGEF) with an amine curing agent, 4,4′‐diamino‐3,3′‐dimethyldicyclohexyl methane (BMCHA), cardanol based reactive diluent (Cardolite NC‐513) and two different cardanol‐based flexibilizers (Cardolite NC‐514 and Cardolite NC‐547). The flexibilizer content was varied from 5 to 10% by weight of the resin. These resins were coated onto the stainless steel panels and tested for their gloss, cross‐hatch adhesion, falling weight impact resistance, flexibility, abrasion, scratch hardness, solvent scrub resistance, and chemical resistance. The thermo‐mechanical properties of these coatings were determined by TGA, DSC, DMTA, and tensile strength measurements. The cryofractured specimens were subjected to SEM analysis. The influence of structural differences of two flexibilizers on the coating properties was investigated. These coatings exhibited excellent properties and have great potential in industrial applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44920.     

Modification of bismaleimide resin by soluble poly(ester imide) containing trimellitimide moieties

Poly(ester imide)s containing trimellitimide moieties have been used to reduce the brittleness of the bismaleimide resin composed of 4,4′‐bismaleimidediphenyl methane and o,o′‐diallyl bisphenol A. The poly(ester imide)s include poly[ethylene phthalate‐co‐ethylene N‐(1,4‐phenylene)trimellitimide dicarboxylate]s containing 20–40 mol% trimellitimide (TI) unit, and poly[trimethylene phthalate‐co‐trimethylene N‐(1,4‐phenylene)trimellitimide dicarboxylate]s (PESIP) containing 20 mol% TI unit. The poly(ester imide)s are effective modifiers for reducing the brittleness of the bismaleimide resin. For example, when using 30 wt% of PESIP (20 mol% TI unit, M_w 13 500 g mol^?1), the fracture toughness (K_IC) for the modified resin is increased by 80% with retention in flexural properties and a slight loss of the glass transition temperature, compared with the values of the unmodified cured bismaleimide resin. Microstructures of the modified resins have been examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified bismaleimide resin system. © 2004 Society of Chemical Industry     

Thermal properties and fire behaviour of materials produced from curing mixed epoxy and phenolic resins

Thermal stability and fire behaviour of materials obtained from curing mixed epoxy and phenolic resins have been studied, the decomposition processes being compared with those for the pure resins. Samples were cured by triethylenetetramine or p‐toluenesulphonic acid by isothermal pressing at 90^°C, and decompositions were carried out under nitrogen and air environment from 50 to 1000^°C. Only for mixtures with higher proportion of epoxy resin, the decomposition process goes through a unique step as for the pure resin. Results from fire tests indicated that mixtures are classified as M3 and F1. Copyright © 2008 John Wiley & Sons, Ltd.     

Curing behavior,thermal, and mechanical properties of epoxy resins cured with a novel liquid crystalline dicarboxylic acid curing agent

A novel di‐carboxylic acid curing agent (DACA) was successfully synthesized and cured with three different epoxy resins: glycidyl end‐capped poly(bisphenol‐A‐co‐epichlorohydrin) (pDGEBA, M_n = 377), N,N‐diglycidyl‐4‐glycidyloxyaniline (TGAP), and 4,4′‐methylenebis(N,N‐diglycidylaniline) (TGDDM). The cured epoxy exhibited excellent thermal stability, which was indicated by high initial degradation temperature (T_id) and char yield. The T_id values of cured epoxy were in the range of 327–338°C, and the char yields increased with increasing epoxy functionality. The char yields of cured DACA/pDGEPA, DACA/TGAP, and DACA/TGDDM samples were 21.1, 60.4, and 66.9%, respectively. In addition, the cured epoxy samples also showed low coefficients of thermal expansion and high storage moduli (E′), which were around 60 ppm/°C and 2800 MPa, respectively. The failure surfaces were ductile and rough, so the cured epoxy samples are expected to have high fracture toughness and impact strength. POLYM. ENG. SCI., 54:695–703, 2014. © 2013 Society of Plastics Engineers