Preparation and characterization of epoxidate poly(1,2‐butadiene)–toughened diglycidyl ether bisphenol‐A epoxy composites

By the oxidation of liquid poly(1,2‐butadiene) (LPB) with H₂O₂/HCOOH, epoxidate poly(1,2‐butadiene) (ELPB) was obtained as a toughening agent to prepare diglycidyl ether bisphenol‐A (DGEBA) epoxy composites by using V115 polyamide(PA) as a cross‐linking agent. DGEBA, ELPB, and the composites were effectively cured by PA at 100°C for 2 h followed by postcuring at 170°C for 1 h. Thermal gravimetric analysis results in air and nitrogen atmosphere showed that the thermal stability of composites could be improved by the addition of ELPB. Compared with DGEBA/PA, the composites exhibited a decrease in strength at yield but an increase in strain at break with the increase in ELPB amount. The composite with 10% ELPB exhibited both thermal stability and tenacity superior to those of DGEBA/PA and composites with 5 and 20% ELPB, respectively. The improvements in thermal and mechanical properties of composites depended on the formation of Inter Penetrating Networks (IPN) among DGEBA/PA/ELPB and their distributions in the matrix. At an appropriate ELPB amount, the IPN, mostly made of DGEBA/PA/ELPB, may be distributed more evenly in the matrix; less ELPB resulted in the formation of IPN mainly made of DGEBA/PA; excessive addition of ELPB resulted in the local aggregation of ELPB/PA and phase separations. The toughening mechanism was changed from chemically forming IPN made of DGEBA/PA/ELPB to physically reinforcing DGEBA/PA by ELPB/PA with the increase in ELPB addition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Flexural,compression, chemical resistance,and morphology studies on granite powder‐filled epoxy and acrylonitrile butadiene styrene‐toughened epoxy matrices

Granite powder is an inexpensive material that can reduce the overall cost of a composite if used as a filler in epoxy and acrylonitrile butadiene styrene (ABS)‐toughened epoxy matrices. Epoxy and ABS‐toughened epoxy resins filled with granite powder were cast into sheets. To enhance the properties of these composites, granite powder was treated with triethoxymethyl silane coupling agent. Flexural properties, compression properties, chemical resistance, and morphology of these composites were studied. The filler used varied from 0 to 60 wt %. Composites consisting of ABS‐toughened epoxy with treated granite powder were found to be superior in mechanical properties to composites with treated and untreated granite powder. Composites with 50 wt % of granite powder was found to have maximum mechanical properties in all cases. All the three composites, i.e., untreated, treated and ABS toughened composites showed good resistance toward, acids, alkalis, and solvents. Treating granite powder with silane coupling agent enhances its mechanical properties and improves the interfacial bond between granite powder and the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 171–177, 2007     

Synthesis,phase behaviors,and mechanical properties of biphenyl‐type epoxy resins and composites

Diglycidyl ether of 3,3′,5,5′‐tetramethyl‐4,4′‐biphenyl (TMBPDGE) which has been found great applications in semiconductor packaging was synthesized. The liquid crystalline phases of diglycidyl ether of 4,4′‐dihydroxybiphenol (BPDGE) cured with phenol novolac (PN) were studied by wide angle X‐ray diffraction (WAXD) and polarized optical microscopy (POM). BPDGE was in situ copolymerized with TMBPDGE to improve its thermal and mechanical properties by means of the LC domains retained in the crosslinked networks. The results indicated that a nematic phase was formed and fixed with proper curing schedule when BPDGE was cured with PN that had no neighboring active hydrogens and the LC domains could also be efficiently embedded into the composite systems. Dynamic mechanical properties showed that epoxy networks containing LC domains displayed higher α‐relaxation temperature and linear elastic modulus traces. The impact toughness and T_g were improved with the addition of BPDGE. Scanning electron microscope observation of the fracture surfaces showed that there was a change in failure mechanism in the composite systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The conductivity behavior of multi‐component epoxy,metal particle,carbon black,carbon fibril composites

Following the previous studies of epoxy/silver conductive composites, a detailed investigation of the influence of ethylene glycol on the resulting resistivity of various composites was carried out. Ethylene glycol was found to have a catalytic effect on the curing process of the epoxy resin, verified by differential scanning calorimetry studies. The accelerated curing process diminishes settling of the metal particles and therefore results in better and more uniform conductivities. High temperature curing of the composites was found to have a similar effect on the conductivity. The conductivity behavior of some other composites, such as epoxy/nickel, epoxy/nickel/carbon fibrils, and epoxy/carbon black/carbon fibrils, were also studied. The structure–property relations were better understood through scanning electron microscopy observations. Silver and nickel particles were found to perform differently in the cured epoxy, showing different percolation concentrations and conductivity levels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1706–1713, 2002     

Exploration of ionic modification in dual‐layer hollow fiber membranes for long‐term high‐performance protein separation

Two types of ionic modification approaches (i.e., sulfonation and triethylamination) were applied with the aid of dual‐layer hollow fiber technology in this work to fine tune the pore size and pore size distribution, introduce the electrostatic interaction, and reduce membrane fouling for long‐term high‐performance protein separation. A binary protein mixture comprising bovine serum albumin (BSA) and hemoglobin (Hb) was separated in this work. The sulfonated fiber exhibits an improved BSA/Hb separation factor at pH = 6.8 compared with as‐spun fibers but at the expense of BSA sieving coefficient. On the other hand, the triethylaminated fiber reveals the best and most durable separation performance at pH = 4.8. Its BSA/Hb separation factor is maintained above 80 for 4 days and maximum BSA sieving coefficient reaches 33%. Therefore, this study documents that an intelligent combination of both size‐exclusion and electrostatic interaction can synergistically enhance protein separation performance in both purity and concentration. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Preparation and characterization of siliconized epoxy/bismaleimide (N,N′‐bismaleimido‐4,4′‐diphenyl methane) intercrosslinked matrices for engineering applications

Novel hybrid intercrosslinked networks of hydroxyl‐terminated polydimethylsiloxane‐modified epoxy and bismaleimide matrix systems have been developed. Epoxy systems modified with 5, 10, and 15 wt % of hydroxyl‐terminated polydimethylsiloxane (HTPDMS) were developed by using epoxy resin and hydroxyl‐terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane (γ‐APS) as compatibilizer and dibutyltindilaurate as catalyst. The reaction between hydroxyl‐terminated polydimethylsiloxane and epoxy resin was confirmed by IR spectral studies. The siliconized epoxy systems were further modified with 5, 10, and 15 wt % of bismaleimide (BMI). The matrices, in the form of castings, were characterized for their mechanical properties. Differential scanning calorimetry and thermogravimetric analysis of the matrix samples were also performed to determine the glass‐transition temperature and thermal‐degradation temperature of the systems. Data obtained from mechanical studies and thermal characterization indicate that the introduction of siloxane into epoxy improves the toughness and thermal stability of epoxy resin with reduction in strength and modulus values. Similarly the incorporation of bismaleimde into epoxy resin improved both tensile strength and thermal behavior of epoxy resin. However, the introduction of siloxane and bismaleimide into epoxy enhances both the mechanical and thermal properties according to their percentage content. Among the siliconized epoxy/bismaleimide intercrosslinked matrices, the epoxy matrix having 5% siloxane and 15% bismaleimide exhibited better mechanical and thermal properties than did matrices having other combinations. The resulting siliconized (5%) epoxy bismaleimide (15%) matrix can be used in the place of unmodified epoxy for the fabrication of aerospace and engineering composite components for better performance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 38–46, 2001     

Preparation and properties of aluminum nitride‐filled epoxy composites: Effect of filler characteristics and composite processing conditions

Polymer‐matrix composites based on brominated epoxy as the matrix and aluminum nitride (AlN) particle as the filler were prepared. Effects of AlN size and content as well as composite processing conditions on the preparation and properties of the composites had been investigated. At the same processing conditions, Young's modulus (E) and dielectric constant (D_k) of the composites increase, whereas coefficient of thermal expansion decreases when increasing AlN content or decreasing AlN size; tensile strength and elongation at break first increase then decrease with AlN content, and they reach maximum values at lower AlN content with decreasing AlN size; glass transition temperature (T_g) also exhibits a trend of first increase then decrease with AlN content, and it decreases with decreasing AlN size, especially at high AlN content; dissipation factor (D_f) generally decreases with AlN content except for the composites filled with 50 nm‐AlN, and it increases with decreasing AlN size. Comparing the composites prepared at different processing conditions, the properties of the composite are relatively poor at low vacuum conditions during removal of solvent and bubble. The scanning electron microscope and Fourier transform infrared analyses indicate that the properties of the composites are related to the aggregation of AlN filler and voids in the composites as well as the crosslink density of epoxy matrix. The preparation of the composites is also found to be affected by AlN size and content as well as vacuum conditions, indicating that increase of viscosity of system and/or the solvent evaporation during curing results in poor formability of the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Core–shell particles to toughen epoxy resins. I. Preparation and characterization of core–shell particles

A two-stage, multistep soapless emulsion polymerization was employed to prepare various sizes of reactive core–shell particles (CSPs) with butyl acrylate (BA) as the core and methyl methacrylate (MMA) copolymerizing with various concentrations of glycidyl methacrylate (GMA) as the shell. Ethylene glycol dimethacrylate (EGDMA) was used to crosslink either the core or shell. The number of epoxy groups in a particle of the prepared CSP measured by chemical titration was close to the calculated value based on the assumption that the added GMA participated in the entire polymerization unless it was higher than 29 mol %. Similar results were also found for their solid-state ^13C-NMR spectroscopy. The MMA/GMA copolymerized and EGDMA-crosslinked shell of the CSP had a maximum glass transition temperature (T_g) of 140°C, which was decreased with the content of GMA at a rate of −1°C/mol %. However, the shell without crosslinking had a maximum T_g of 127°C, which decreased at a rate of −0.83°C/mol %. The T_g of the interphasial region between the core and shell was 65°C, which was invariant with the design variables. The T_g of the BA core was −43°C, but it could be increased to −35°C by crosslinking with EGDMA. The T_g values of the core and shell were also invariant with the size of the CSP. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2069–2078, 1998     

Preparation and characterization of UV‐curable ZnO/polymer nanocomposite films

A series of novel nano‐ZnO/polymer composite films with different ZnO contents was prepared through incorporation of pre‐made colloidal ZnO particles into monomer mixtures of urethane‐methacrylate oligomer and 2‐hydroxyethyl methacrylate, followed by ultraviolet (UV) radiation‐initiated polymerization. The colloidal ZnO nanoparticles with a diameter of 3–5 nm were synthesized from zinc acetate and lithium hydroxide in ethanol via a wet chemical method. In order to stabilize and immobilize the ZnO particles into the polymer matrix, the ZnO nanoparticles were further capped using 3‐(trimethoxysilyl)propyl methacrylate. Thermogravimetric analyses show that the ZnO nanoparticles were successfully incorporated into the polymer matrix and these ZnO/polymer composites have a good thermal stability. Transmission electron microscopy studies indicate the ZnO nanoparticles were uniformly dispersed in the polymer and they remained at the original size (3–5 nm) before immobilization. All nanocomposite films with ZnO particle contents from 1 to 15 wt% show good transparency in the visible region and luminescent properties. In addition, composite films with high ZnO content (>7 wt%) are able to absorb UV irradiation below 350 nm, indicating that these composite films exhibit good UV screening effects. Copyright © 2006 Society of Chemical Industry     

Preparation,morphology, and properties of silane‐modified MWCNT/epoxy composites

Both epoxy resin and acid‐modified multiwall carbon nanotube (MWCNT) were treated with 3‐isocyanatopropyltriethoxysilane (IPTES). Scanning electron microscopy (SEM) and transmission electronic microscope (TEM) images of the MWCNT/epoxy composites have been investigated. Tensile strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 41% comparing to the neat epoxy. Young's modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 52%. Flexural strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 145% comparing to neat epoxy. Flexural modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 31%. Surface and volume electrical resistance of MWCNT/epoxy composites were decreased with IPTES‐MWCNT content by 2 orders and 6 orders of magnitude, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal analysis and mechanical characterization of maleimide‐functionalized benzoxazine/epoxy copolymers

Maleimide‐functionalized benzoxazine is copolymerized with epoxy to improve toughness and processibility without compromising the thermal properties. The incorporation of maleimide functionality into the benzoxazine monomer results in a high performance polymer. All three possible polymerization reactions are confirmed using Fourier transform infrared (FT‐IR) spectroscopy. While maleimide‐functionalized benzoxazine has a glass transition temperature, T_g, of 252°C, a further 25°C increase of T_g is observed when copolymerized with epoxy. The flexural properties are also measured, and the copolymers exhibit a flexural modulus of 4.2–5.0 GPa. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1670–1677, 2006     

Preparation and characterization of hybrid thiol‐ene/epoxy UV–thermal dual‐cured systems

Hybrid thiol‐ene/epoxy coatings were prepared by combining thiol‐ene photo‐curable formulations with epoxy monomers, through a dual UV–thermal curing process. An increase in glass transition temperature and in storage modulus was observed for the hybrid thiol‐ene/epoxy coatings when compared with the pristine thiol‐ene UV‐cured system. Also, the bisphenol A moieties introduced into the hybrid networks during the dual‐curing process induced an increase in thermal stability of the cured materials. It has been demonstrated that the addition of epoxy monomer to the thiol‐ene photo‐curable system is a good strategy to follow in order to improve the final properties of thiol‐ene‐based coatings leading to a wide range of possible applications for the hybrid materials. Copyright © 2010 Society of Chemical Industry     

Preparation and pH‐sensitivity of polyacrylonitrile (PAN) based porous hollow gel fibers

Polyacrylonitrile based porous hollow gel fibers were prepared from PAN hollow fibers by oxidation and subsequent alkaline treatment. Fourier‐transform infrared (FTIR), X‐ray diffraction, and scanning electron microscope (SEM) analyses showed that the PAN porous hollow gel fiber was a kind of amphoteric fiber due to the combination of cationic groups of pyridyl and anionic groups of carboxyl; after gelation the hollow channel and finger‐like pores on the fiber walls were conserved. The effects of cyclization reaction degree, alkaline solution concentration, and alkaline treatment time on the mechanical properties or pH‐sensitive behavior of the porous hollow gel fibers were investigated. The elongation/contraction behavior was studied in detail. It was found that the gel fiber exhibited a large swelling in an alkaline solution and contracting in an acid solution; the swelling change in length was above 90%; the responsive time of elongation/contraction was less than 20 s; the maximum contraction force was 20 N/cm²; and pH‐sensitivity was reversible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal pressure coefficient of a polyhedral oligomeric silsesquioxane (POSS)‐reinforced epoxy resin

The thermal pressure coefficients of a neat, unfilled, epoxy resin and a 10 wt % POSS (polyhedral oligomeric silsesquioxane)‐filled epoxy nanocomposite have been measured using a thick‐walled tube method. It is found that just below the glass transition temperature the thermal pressure coefficient is ～ 20% smaller for the polymer composite containing 10% POSS than for the neat, unfilled resin. The thermal expansion coefficient and thermal pressure coefficient of the uncured POSS itself are also reported. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of composites of polyaniline and polyurethane‐modified epoxy

A toughened, semiconductive polyaniline/polyurethane (PANI/PU)‐epoxy nanocomposite was prepared using a conductive polymer, PANI, and a PU prepolymer‐modified diglycidyl ether of bisphenol A (DGEBA) epoxy. The formation of a nanostructure was confirmed by Fourier transform infrared spectroscopy and SEM. The mechanical properties of the composites were evaluated and compared with those of the corresponding matrix. The improvement in impact strength of the composites (especially in the PANI/PU(PPG2000)‐epoxy system) was explained after fracture surface analysis using SEM. DSC and TGA studies indicated that the thermal properties of these composites were comparable to those of DGEBA epoxy. A conductivity in the range 10^?9–10^?3 S cm^?1 was obtained, depending on the testing frequency (10³–10⁷ Hz) and the PANI content incorporated. Copyright © 2006 Society of Chemical Industry     

Thermal and mechanical characterization of amine‐epoxy/Kevlar fibre composites

Experimental results of dynamic‐mechanical measurements and differential scanning calorimetry are compared for a pure diglycidyl‐type epoxy/tetrafunctional aliphatic amine system and for a composite containing Kevlar fibres as reinforcement. The presence of fibres had marked effects on the curing reaction, depending on the curing temperature. At low curing temperatures, the extent of the reaction was lower for reinforced than for neat formulations. For higher curing temperatures, the thermograms shifted to shorter times as the fibre content increased. In dynamic curing, an increase in the fibre content affected the curing kinetics by slightly shifting the heat flow curves to higher temperatures, and resulted also in a reduction of the glass transition temperature of the matrix if postcuring was not applied. The dependence of the dynamic‐mechanical spectra of the samples on fibre content was satisfactorily modelled with the aid of Takayanagi's block model. An analysis of the main relaxation master curve shows that relaxation broadens as fibre content increases. © 1999 Society of Chemical Industry     

Preparation and properties of TiO2‐filled poly(acrylonitrile‐butadiene‐styrene)/epoxy hybrid composites

Poly (acrylonitrile‐butadiene‐styrene) (ABS) was used to modify diglycidyl ether of bisphenol‐A type of epoxy resin, and the modified epoxy resin was used as the matrix for making TiO₂ reinforced nanocomposites and were cured with diaminodiphenyl sulfone for superior mechanical and thermal properties. The hybrid nanocomposites were characterized by using thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), universal testing machine (UTM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The bulk morphology was carefully analyzed by SEM and TEM and was supported by other techniques. DMA studies revealed that the DDS‐cured epoxy/ABS/TiO₂ hybrid composites systems have two T_gs corresponding to epoxy and ABS rich phases and have better load bearing capacity with the addition of TiO₂ particles. The addition of TiO₂ induces a significant increase in tensile properties, impact strength, and fracture toughness with respect to neat blend matrix. Tensile toughness reveals a twofold increase with the addition of 0.7 wt % TiO₂ filler in the blend matrix with respect to neat blend. SEM micrographs of fractured surfaces establish a synergetic effect of both ABS and TiO₂ components in the epoxy matrix. The phenomenon such us cavitation, crack path deflection, crack pinning, ductile tearing of the thermoplastic, and local plastic deformation of the matrix with some minor agglomerates of TiO₂ are observed. However, between these agglomerates, the particles are separated well and are distributed homogeneously within the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of high‐selectivity hollow fiber composite nanofiltration membrane by two‐way coating technique

A novel coating technique, named as two‐way coating (TWC), was explored to prepare hollow fiber composite (HFC) nanofiltration (NF) membrane through interfacial polymerization from piperazine (PIP) and trimesoyl chloride (TMC) on the lumen side of hollow fiber polysulfone ultrafiltration membrane with an effective membrane area of 0.4 m². The optimum preparation conditions were systematically investigated and obtained as follows: PIP 0.023 mol/L, TMC 0.0057 mol/L, air blowing rate 2.7 m/s for 30 min after aqueous coating, aqueous coating pressure 0.1 MPa, organic solution flowing rate 0.32 m/s, and heat treating time 3 min. The resultant HFC membrane showed a high selectivity of divalent ion and monovalent ion. Salt rejections of MgSO₄ and NaCl were 98.13 and 18.6% with the permeate flux of 32.6 and 40.2 L m^?2 h^?1 at 0.7 MPa, respectively. Field emission scanning electron microscopy images indicated that composite membrane prepared by TWC technique had a uniform active layer from the upper end to the bottom of the hollow fiber. And the salt rejection and permeate flux showed almost no difference between different membrane sections. Stability results suggested that good reproducibility could be obtained by TWC technique for the preparation of high‐performance HFC NF membrane. The resultant NF membrane showed a high removal rate of chemical oxygen demand and chroma of landfill leachate which were approximately 100%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41187.     

Polyaniline–rhodium composites: Preparation,physicochemical characterization,and catalytic properties

In this work, polyaniline (PANI)–rhodium composites have been obtained for the first time. Their preparation procedure has involved reduction of Rh³⁺ ions in RhCl₃ aqueous solutions with NaBH₄ in the presence of PANI. Using UV–vis spectroscopy, it has been found that the reduction process is fast. X‐ray diffraction and Rh3d XPS studies have confirmed that metallic rhodium is incorporated into PANI matrix. SEM and TEM investigations allowed to establish that the sizes of Rh crystallites formed depend on the amount of metal in the composite as well as on the preparation conditions. It has been demonstrated that the composites containing Rh nanoparticles whose size is predominantly below 10 nm can be obtained. IR spectroscopy has proved that PANI chain is protonated in the Rh³⁺ reduction process. Catalytic properties of PANI–Rh composites have been investigated using isopropyl alcohol conversion as the test reaction. It has been found that the composites containing Rh nanoparticles show high redox activity. Catalytic activity of the composites in which larger, agglomerated metal particles have been present is about three times lower. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization core‐shell particles and application for E‐Ink

the core‐shell particles were prepared by dispersion copolymerization. The core‐shell particles were characterized with Fourier‐transform infrared spectroscopy, Transmission electron microscope and scanning electron microscope. The dispersion stability and electrophoretic performance of core‐shell particles were studied in the mixed medium of tetrachloroethylene and cyclohexance. Microcapsules containing the core‐shell particles were prepared by coacervation. Results showed that the core‐shell particles had good dispersion stability and it had no electric response, which could be used as grounding particles for E‐Ink. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1195–1199, 2007