Microgelation of unsaturated polyester resins in the presence of poly(vinyl acetate) by static and dynamic light scattering

The partially cured unsaturated polyester (UPE)/styrene resins with various degrees of conversion lower than gel conversion blended with PVAc and 2‐fluorotoluene solvent were investigated using both static and dynamic light scattering (SLS and DLS). The solvent (i.e., 2‐fluorotoluene) is isorefractive with PVAc; thus, one sees only primary and partially cured UPEs in light‐scattering experiments. DLS was used to follow the variations of primary UPE and UPE microgel particle sizes, and SLS was used to follow the variations of UPE molecular weight, second virial coefficient (A₂), anisosymmetry (ρ_v), and differential index refraction (dn/dC) with degree of UPE conversion and PVAc concentration. The experimental data showed that, at a fixed degree of UPE/styrene conversion, increasing PVAc concentration in the UPE/styrene system caused decreases in dn/dC, A₂, ρ_v, and particle sizes of UPE microgels. These results suggest that mixing PVAc into UPE/styrene resins causes an increase in the compactness of UPE coils and favors intramolecular UPE/styrene cyclization in the early stage of curing. Thus A₂, ρ_v, and particle sizes of microgels decreased with increasing PVAc concentration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1439–1449, 2001     

High glass transition temperature bismaleimide‐triazine resins based on soluble amorphous bismaleimide monomer

A novel bismaleimide (DOPO‐BMI) with unsymmetrical chemical structure and DOPO pendant group has been prepared. The particular molecular structure makes DOPO‐BMI show an intrinsic amorphous state with a T_g about 135°C and excellent solubility in most organic solvents, which is beneficial to the processability of bismaleimide composite materials. A series of bismaleimide‐triazine (BT) resins have been prepared based on DOPO‐BMI and 2,2‐bis(4‐cyanatophenyl)propane at various weight ratios. The prepared BT resins show outstanding solubility in organic solvent and low viscosity about 10–671 mPa s at 180°C. The cured BT resins exhibit high glass transition temperature (T_g) over 316°C. As the weight ratio of DOPO‐BMI increases to 80% (BT80), the T_g can rise to 369°C (tan δ). The cured BT resins also show good thermal stability with the 5% weight loss temperature over 400°C under both nitrogen and air atmosphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42882.     

Acrylated epoxidized soybean oil as a styrene replacement in a dicyclopentadiene‐modified unsaturated polyester resin

Nonvolatile and nonhazardous acrylated epoxidized soybean oil (AESO) was investigated as a replacement for hazardous styrene in a commercial unsaturated polyester (UPE) resin [a mixture of styrene and a dicyclopentadiene (DCPD)‐modified UPE (DCPD–UPE)]. DCPD–UPE was prepared from ethylene glycol, diethylene glycol, maleic anhydride, and DCPD. Mixtures of AESO and DCPD–UPE [AESO–(DCPD–UPE) resins] were found to be homogeneous, easily pourable solutions at room temperature. The glass‐fiber‐reinforced composites from the AESO–(DCPD–UPE) resins were comparable or even superior to those from the mixture of styrene and DCPD–UPE in terms of the flexural and tensile strengths. The viscoelastic properties of the cured AESO–(DCPD–UPE) resins and the corresponding glass‐fiber‐reinforced composites were characterized by dynamic mechanical analysis. The viscosities and pot lives of the AESO–(DCPD–UPE) resins as a function of the temperature were studied. The curing mechanism of the AESO–(DCPD–UPE) resins is discussed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46212.     

Preparation and analysis of a flexible curing agent for epoxy resin

A kind of novel aromatic amine bis(4‐nonyl‐2,5‐diamine‐penoxyl)alkylate (RA_n) as curing agents for epoxy resins were prepared through three steps of reactions using nonyl phenol and dibromoalkylate as materials. Dynamic mechanical analysis (DMA) indicated that the secondary relaxation for the resins cured by RA_n were generated by the nonyls in RA_n molecules when temperature was below ?50°C. Comparing with other reference resins, the enhancement for toughness of RA_n cured‐resins were at least 15%, which were contributed by such secondary relaxation. Furthermore, stiffness of the networks and thermal properties of the resins were not influent by the flexible groups (nonyl) in RA_n after curing, since the groups were located only in the branched chains of the networks. The mechanical and thermal properties of the new material have been significantly enhanced. The relevant method and procedure developed through this research have been granted Chinese patent recently (Yang and Gong, Chin. Pat. CN1978483A, 2007). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biobased composite resins design for electronic materials

Biobased materials developed from triglycerides contain a large variety of structures, which makes it difficult to predict their properties. In this study, we used a structure–property relation to design biobased materials, both theoretically and experimentally. A general equation to predict the crosslink density in terms of the level of chemical functionalities of the triglycerides was derived and used as a design rule for high‐crosslinked polymer materials. The twinkling fractal theory and the Clausius–Mossotti equation were used to guide two approaches of synthesis to improve the properties of the biobased thermosets: the biobased resin acrylated epoxidized soybean oil (AESO) was either crosslinked with divinylbenzene (DVB) or chemically modified by phthalic anhydride. The DVB‐crosslinked resins had a 14–24°C increase in their glass‐transition temperatures (T_g′s), which was dependent on the crosslink densities. T_g increased linearly as the crosslink density increased. Phthalated acrylated epoxidized soybean oil (PAESO) had an 18–30% improvement in the modulus. The dielectric constants and loss tangents of both DVB‐crosslinked AESO and PAESO were lower than conventional dielectrics used for printed circuit boards (PCBs). These results suggest that the new biobased resins with lower carbon dioxide footprint are potential replacements for commercial petroleum‐based dielectric materials for PCBs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Adhesion potential of relining materials to polyamide and PMMA-based denture base materials: effect of surface conditioning methods

This study evaluated the bond strength of relining materials to different denture base materials polyamide and polymethylmethacrylate denture base materials after various surface conditioning methods. Denture base resin specimens (N?=?128; n?=?8 per group) (10?×?10?×?2.5?mm³) were fabricated out of injection-moulded thermoplastic polyamide resin (POL) (Deflex) and heat-polymerized polymethylmethacrylate (PMMA, Dura Dent) (HC). The specimens were randomly divided into 4 main groups according to different surface conditioning methods: (a) No conditioning, control (C), (b) grinding with green stone (G), (c) application of primer (V), (d) silica coating with Al₂O₃ particles coated with SiO₂ (Rocatec) (R). Half of the specimens in each group received auto-polymerized hard relining resin (GC, GC Reline Hard) and the other half PMMA based relining resin (SC, Dura Dent). After thermocycling (×5000), the bonded specimens were tested under tensile forces (0.5?mm/min). Data (MPa) were analyzed using Mann–Whitney U and Kruskal–Wallis tests (alpha = 0.05). Bond strength of relining resins were significantly higher to PMMA than to POL, regardless of the conditioning method (p?<?0.05). While R positively affected the bond strength results (p?<?0.05) (4.99?±?1.65–3.27?±?1.31), application V or G did not show significant effect to POL-relining resin adhesion. After R conditioning, bond strength values were significantly higher in HC-GC group (7.48?±?2.32) than POL-GC group (3.27?±?1.31) (p?<?0.05). Adhesion of auto-polymerized relining materials to thermoplastic polyamide or polymethylmethacrylate denture resins could be improved after surface conditioning with silica-coating.     

Replacement of styrene with acrylated epoxidized soybean oil in an unsaturated polyester resin from propylene glycol,isophthalic acid,and maleic anhydride

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.     

Glass‐transition temperature based on dynamic mechanical thermal analysis techniques as an indicator of the adhesive performance of vinyl ester resin

Vinyl ester resins are being used extensively as matrices in fiber‐reinforced polymer composite materials, but their use as a structural adhesive has been limited. Initial studies investigating the durability of a vinyl ester as a wood adhesive showed unsatisfactory performance in comparison with other adhesives. In this work, the glass‐transition temperatures (T_g's) of a vinyl ester and a E‐glass/vinyl ester composite material, fabricated by the Composites Pressure Resin Infusion System, were determined with dynamic mechanical thermal analysis. The results indicated that the resin cured under ambient conditions had a much lower T_g (～60°C) than the postcured material (～107°C). This suggested undercuring, that is, incomplete crosslinking, of the resin when it was cured at room temperature. E‐glass/vinyl ester samples, however, showed virtually no difference in T_g between room‐temperature‐cured and postcured samples. The exact reasons for this are not currently known but are thought to be both mechanical and chemical in nature. On the basis of the findings presented in this article, it can be concluded that if this vinyl ester resin is to be used as a structural adhesive, postcuring or formulation to ensure a high degree of crosslinking under ambient conditions is necessary. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2221–2229, 2005     

Influence of alumina content and thermal treatment on the thermal conductivity of UPE/Al2O3 composite

Ultra high molecular weight polyethylene/alumina (UPE/Al₂O₃) microcomposites with high loading micro alumina (Al₂O₃, 20 to 100 phr) were prepared by casting method. The composites were thermal treated (cooled slowly) and then the thermal properties were studied at temperatures from 25 to 125°C. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) proves the homodispersion of Al₂O₃ microparticles in UPE. TGA indicates that the temperature of 5% weight loss of UPE/Al₂O₃ (100 phr) composite is 467.0°C, 10.5°C higher than that of pure UPE. Differential scanning calorimetry (DSC) shows that the melting point and the real degree of crystal (X_rc) of treated UPE/Al₂O₃ composite (100 phr) are 141.4°C and 65.7%, respectively, all higher than that of untreated composite, which can be described by crystal bridge mechanism. The density of the composite is also be enhanced because of crystal volume shrinkage induced by thermal treatment. The thermal conductivity of the treated UPE/Al₂O₃ composite (100 phr) is 1.920 W (m K)^?1 at 25°C, 23.6% higher than that of the untreated composite. Crystal bridge thermal conduction mechanism is proposed. The thermal conductivity of UPE/Al₂O₃ composite has some dependency on the increasing Al₂O₃ content and also thermal treatment. These results can give some advice to design formulations for practical applications in pipe area and other wear area. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40528.     

Adhesives,syntactics and laminating resins for aerospace repair and maintenance applications from Ciba Specialty Chemicals

Ciba Specialty Chemicals, Performance Polymers Division, has been a leading supplier of materials to the aerospace industry for the fabrication, repair and assembly of interior and exterior aircraft components for many year. Araldite^®, Epibond^® and Epocast^® epoxy adhesives, syntactics and laminating resins in addition to Uralane^®, polyurethane adhesives have long been associated with quality, reliability and innovative chemistry. The majority of these systems are qualified to aircraft manufacturer’s specifications and are included as approved repair materials in structural repair manuals and serivce bulletins. Many of the adhesives, syntactics and laminating resins are self-extinguishing and exhibit the low flame, smoke and toxicity (FST) characteristics required to comply with industry legislation such as FAR (Federal Aviation Regulation) 25.853 which governs the requirements for materials used in aircraft interior applications. The aim of this paper is to review a number of newly developed Ciba materials for repair and maintenance with a specific emphasis on technical performance and novel methods of application which can increase cost effectiveness and reduce labour when compared to conventional methods.     

Novel Flower-Like ZnO Hybridized with Acrylic Ester Resin for Enhanced Oil Absorption Properties

The acrylic ester resins have potential applications in for treatment of oily wastewater due to their high oil retention capacity and excellent cycle performance. Herein, a novel acrylic ester hybrid resins composed by poly(n-butylacrylate-co-styrene) resins and flower-like ZnO clusters were prepared using a combination of hydrothermal and suspension polymerization. The hybrid resins can remove a broad variety of oils from water with the maximum oil absorption performance of 30.87?g/g. More importantly, the hybrid resins are reversible and maintain high oil absorption properties after oils absorption-regeneration, making them promising candidates for treatment of oily wastewater.     

Synthesis and characterization of novel poly(phenylene sulfide) containing a chromophore in the main chain

A kind of novel poly(phenylene sulfide)s (PPSs) containing a chromophore group were synthesized by the reaction of dihalogenated monomer and sodium sulfide (Na₂S.xH₂O) via nucleophilic substitution polymerization under high pressure. The polymers were characterized by Fourier transform infrared spectroscopy, ultraviolet spectroscopy, fluorescence spectroscopy, XRD, DSC, TGA, mechanical testing and dissolvability experiments. The intrinsic viscosity of the polymers obtained with optimum synthesis conditions was 0.22 ? 0.38 dl g^?1 (measured in 1‐chloronaphthalene at 208 °C). These polymers were found to have good thermal performance with a glass transition temperature (T_g) of 90.5 ? 94.6 °C and initial degradation temperature (T_d) of 475–489 °C, showing improved thermal properties compared with homo‐PPS. At the same time the resultant resins had a high tensile strength of 67.5 ? 74.1 MPa and compressive strength of 70.7 ? 85.4 MPa. Additionally, these polymers exhibited a weak UV ? visible reflectivity minimum at 450–570 nm, and the fluorescence spectra of the polymers showed maximum emission around nearly 370 nm. Also they showed excellent chemical resistance and another special property ? bright shiny colors changed into different colors in acid solution. © 2014 Society of Chemical Industry     

Studies of fluorine‐containing bismaleimide resins part I: Synthesis and characteristics of model compounds

A series of fluorine‐containing bismaleimide (FBMI) monomers are synthesized by a 3‐step reaction for using as the applications of low‐k materials. The synthesized FBMI monomers are characterized by the ¹H, ¹³C, ¹⁹F nuclear magnetic resonance (NMR) spectroscopy and element analysis. These FBMI monomers react with free radical initiator or self‐cure to prepare FBMI‐polymers. All the self‐curing FBMI resins have the glass transition temperatures (T_g) in the range of 128–141°C and show the 5% weight loss temperatures (T_5%) of 235–293°C in nitrogen atmosphere. The higher heat resistance of self‐curing FBMI resin relative to FBMI‐homopolymer is due to its higher crosslinking density. The FBMI resins exhibit improved dielectric properties as compared with commercial bismaleimide (BMI) resins with the dielectric constants (D_k) lower than 2.49, which is related to the low polarizability of the C? F bond and the large free volume of CF₃ groups in the polymers. Besides, the flame retardancy of all these FBMI resins could be enhanced via the introduction of Br‐atom. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of melamine–formaldehyde resin grafted by (3-aminopropyl) triethoxysilane for high-performance hydrophobic materials

Aiming at meeting the specific market demands and expanding the downstream application of melamine–formaldehyde (MF) resins, a series of (3-aminopropyl) triethoxysilane (APTES) grafted MF (MF-Si) resins were synthesized via an effective method that minimized the hydrolysis of APTES and overcame the polarity discrepancy of APTES with MF resin matrix. The structure of MF-Si resins was characterized by FTIR spectroscopy, Raman spectroscopy, ¹H nuclear magnetic resonance (NMR), and solid state ¹³C NMR. It was found that APTES moieties in MF-Si materials afforded increased hydrophobicity, water resistance, and the thermal stability was not affected. With the increasing amount of APTES, the water contact angle of MF-Si films increased from 70.56 to 105.92°and the surface free energy decreased from 46.8 to 23.5 mN/m. The temperature of maximum weight loss rate (T_dmax) of MF-Si materials decreased slightly from 371.15 to 353.70 °C and the ultimate residual weight of MF-Si materials increased from 12.51 to 30.04% at 800 °C under N₂. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48664.     

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     

Comprehensive study of metal on the characteristic properties of epoxy resins

A series of different type of epoxy resins containing metal(s) have been prepared by the using cobalt acrylate (CoA₂), nickel acrylate(NiA₂),bismuth acrylate (BiA₃) during resinification. The values of epoxide equivalent weight, chlorine content increases whereas hydroxyl content, refractive index decreases in the presence of metal acrylate(s). The influence of complex formation of metal acrylate with ether linkage of epoxy resins were investigated by spectroscopy. Epoxy resins containing cobalt acrylate which was cured by p‐acetylbenzilidinetriphenylarsoniumylide (p‐ABTAY) shows better conducting properties in comparison to NiA₂ and BiA₃ containing epoxy resins. The dispersion of metal(s) in epoxy resins matrix was confirmed by scanning electron microscope (SEM). The glass transition temperature of epoxy resins containing CoA₂ is lower than that of blank epoxy resins and epoxy resins containing bismuth and nickel acrylate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermally reversible and self‐healing novolac epoxy resins based on Diels–Alder chemistry

The modified novolac epoxy resins with furan pendant groups were prepared by novolac epoxy resin and furfuryl alcohol and then crosslinked by bifunctional maleimide via Diels–Alder (DA) chemistry to obtain the thermally reversible and self‐healing novolac epoxy resins. The as‐prepared crosslinked novolac epoxy resins were characterized by FT‐IR, NMR, TGA, and DMA. The results indicate that the novel crosslinked novolac epoxy resins present higher storage modulus (2.37 GPa at 30°C) and excellent thermal stability (348°C at 5% mass loss). Furthermore, the thermal reversible and self‐healing properties were studied in detail by DSC, SEM, thermal re‐solution, and gel–solution–gel transition experiments. All the results reveal that the crosslinked novolac epoxy resins based on DA reaction can be used as smart material for the practical application of electronic packaging and structural materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42167.     

Physical aging of linear and network epoxy resins

Network and linear epoxy resins principally based on the diglycidyl ether of bisphenol-A and its oligomers have been prepared and studied. Both diamine and anhydride crosslinking agents were utilized. In addition, some rubber modified epoxies and a carbon fiber reinforced composite was investigated. All of these materials display time-dependent changes in many of their properties when they are stored (following quenching) at temperatures below their glass transition temperature (sub-T_g annealing). For example, the degree of stress relaxation for a given time period is observed to decrease in a linear fashion with the logarithm of time during sub-T_g annealing. Young's modulus and yield stress were also found to increase ire physical aging. Solvent sorption experiments initiated after different sub-T_g annealing times have demonstrated that the rate of solvent uptake can be indirectly related to the free volume of the epoxy resins. The effect of water on the physical aging of these epoxy resins was not found to be a significant variable. Residual thermal stresses were also found to have little effect on the physical aging process, although this variable was not studied in detail. Finally, the physical aging process also affected the sub-T_g properties of uniaxial carbon fiber reinforced epoxy material and the effects were as expected. The importance of the recovery or physical aging phenomenon, which affects the durability of epoxy glasses, is considered in view of the widespread applications for these resins as structural materials.     

A low onset voltage WORM type polymer memory based on functional PES

A high‐performance polymer polyethersulfone (CN‐Azo‐PES), with a flexible ethoxyl linkage between the azobenzene chromophore side chain and the PES backbone, has been designed and successfully synthesized for an application in a WORM type memory device as an active polymer layer. CN‐Azo‐PES has excellent thermal properties with T_g of 151°C and the degradation temperature higher than 373°C, which can contribute to a better performance of the device. The device based on CN‐Azo‐PES exhibits a write‐once read‐many (WORM) type memory performance with an onset voltage as low as ?1.0 V and an ON/OFF current ratio higher than 10² at a reading voltage of 0.4 V. Moreover, the data can be maintained for longer than 4 × 10⁵ s once written and can be read for more than 400 cycles under a reading voltage of 0.4 V. Thus CN‐Azo‐PES can serve as an energy saving memory material in the data storage field of next generation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42644.