Effect of acrylic copolymer dispersants bearing epoxy groups on rheological and dielectric properties of carbon black‐filled epoxy system

In this article, the use of copolymeric dispersants with an acrylic backbone and epoxy side groups for formulating carbon black (CB)‐epoxy composites are described. Six epoxy‐containing acrylic copolymer dispersants were prepared from hexyl methacrylate (HMA), poly(ethylene glycol) ethyl ether methacrylate (PEGMA), and glycidyl methacrylate via a group transfer polymerization technique. The epoxy‐containing acrylic copolymer of the highest concentration of PEGMA showed a desirable passivation effect on CB, and was found to lower the viscosity of the CB‐epoxy paste, leading to the well‐cured composite after heat treatment. The thick composite film prepared by employing the [CB/acrylic dispersant/epoxy] paste was built up on a Cu plate by a screen printing process followed by thermal curing. The dielectric properties of the 3.1 vol % CB‐filled epoxy film showed us high dielectric constant (Dk 4900) and rather low dissipation factor (Df 29%) at 1 MHz. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dielectric properties of epoxy composites with modified multiwalled carbon nanotubes

We report here a high dielectric percolative polymer nanocomposite, fabricated by a combination of triethylene-tetramine (TETA) modified multiwalled carbon nanotube (named as TETA-MWNT) within epoxy resin matrix. In this composite system, with various TETA-MWNT volume fractions, the dielectric constant (K) is well fitted by the scaling law of the percolation theory with the percolation threshold f _c is 0.042 and the critical exponent p is 0.786. At 1,000 Hz of room temperature, the value of the dielectric constant is as high as 421 with the TETA-MWNT content of 4.14vol%, which is almost 60 times higher than that of epoxy resin. In contrast, a simple blend of pristine MWNT in epoxy composite shows evident lower dielectric constant and much higher loss with the same volume fraction.     

Novel polymer–ceramic nanocomposite based on high dielectric constant epoxy formula for embedded capacitor application

Embedded capacitor technology can increase silicon packing efficiency, improve electrical performance, and reduce assembly cost compared with traditional discrete capacitor technology. Developing a suitable material that satisfies electrical, reliability, and processing requirements is one of the major challenges of incorporating capacitors into a printed wiring board (PWB). Polymer–ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the high dielectric constant of ceramics. A novel nanostructure polymer–ceramic composite with a very high dielectric constant (ε_r ～110, a new record for the highest reported ε_r value of a nanocomposite) was developed in this work. A high dielectric constant is obtained by increasing the dielectric constant of the epoxy matrix (ε_r >6) and using the combination of lead magnesium niobate–lead titanate (PMN–PT)/BaTiO₃ as the ceramic filler. This nanocomposite has a low curing temperature (<200°C); thus, it is multichip‐module laminate (MCM‐L) process‐compatible. An embedded capacitor prototype with a capacitance density of 50 nF/cm² was manufactured using this nanocomposite and spin‐coating technology. The effect of the composite microstructure on the effective dielectric constant was studied. This novel nanocomposite can be used for integral capacitors in PWBs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1084–1090, 2002     

Microwave dielectric properties and EMI shielding effectiveness of poly(styrene‐b‐styrene‐ butadiene‐styrene) copolymer filled with PAni.Dodecylbenzenesulfonic acid and carbon black

Conducting composites of polyaniline doped with dodecylbenzenesulfonic acid (PAni.DBSA), carbon black (CB) and poly(styrene‐b‐styrene‐butadiene‐b‐styrene) (STF) as supporting matrix were prepared by in situ polymerization. The influence of components and composition (% w/w) on the electromagnetic properties (dielectric constant ε′ and the dielectric loss ε″) and electromagnetic interference shielding effectiveness (EMI‐SE) of the materials were evaluated with a waveguide, using a microwave network analyzer from 8.2 to 12.4 GHz (X‐band). It was found that CB presence generates adverse effects on PAni.DBSA yield during synthesis, as it can be seen by X‐ray diffraction and TGA analyses. The type of PAni.DBSA formed modifies the composites properties. Dielectric constant, loss factor, and EMI shielding increase with conductive filler loading. Both the fillers, individually and in combination, increase the properties; however, the effect is not additive in nature. POLYM. ENG. SCI., 52:2041–2048, 2012. © 2012 Society of Plastics Engineers     

Frequency and voltage dependence of dielectric properties,complex electric modulus,and electrical conductivity in Au/7% graphene doped‐PVA/n‐Si (MPS) structures

In order to increase the capacitance of Au/n‐Si (MS) structure, 7% graphene doped PVA was coated on n‐Si as an interfacial layer. The measured data of capacitance (C) and conductance (G/ω) of Au/7% graphene doped‐PVA/n‐Si (MPS) structure was utilized for the calculation of real and imaginary parts of complex permittivity (ε^* = ε′ − jε″), loss tangent (tanδ), complex electric modulus (M^* = M′ + jM″), and electrical conductivity (σ). The admittance measurements (C and G/ω) were carried out in the frequency range of 0.5 kHz to 1 MHz at room temperature. Frequency dependence of the dielectric constant (ε′), dielectric loss (ε″) and tanδ shows a dispersive behavior at low frequencies. This behavior was explained by Maxwell–Wagner relaxation. Due to the dipolar and the interfacial polarizations, as well as the surface states (N_ss) and the interfacial PVA layer, the parameters exhibited a strong dependence on frequency and applied bias voltage. The σ versus log(f) plot exhibited both low and high frequency dispersion phenomena such that at low frequencies σ value corresponding to the dc conductivity (σ_dc), but at high frequencies it corresponds to the ac conductivity (σ_ac). M′ and M″, both, have low values in the low frequency region. However, an increase is observed with the increasing frequency due to the short‐range mobility of charge carriers. As a result, the change in dielectric parameters and electric modulus with frequency is the result of relaxation phenomena and surface states. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43827.     

Preparation of high‐k composites with low dielectric loss based on the double‐layer coaxial structure of inorganic/polymer

This study presents a novel and simple modification of cladding multiwalled carbon nanotubes (MWCNTs) using organic polymer and inorganic nanoparticles to synthesize a product, which has a double‐cladding coaxial structure and can be applied as filler in the dielectric field. The first layer of MWCNTs was coated with polyaniline (PANI) through the oxidation–reduction reaction mechanism using Ce(NH₄)₂(NO₃)₆ as oxidizing agent and metal precursor of cerium oxide. Cerium ions on the second cladding layer of MWCNTs were directly deposited from the solution to the surface of the PANI layer forming the double‐cladding hybrid (CeO₂/PANI@MWCNTs). The external inorganic layer provides an insulating shell, which can prevent the contact between the conductive particles and hinder the migration of electrons between the MWCNTs. The intermediate layer of PANI provides the bonding between CeO₂ and the conductive core of MWCNTs, which also shows lower conductivity than carbon nanotubes. The CeO₂/PANI@MWCNTs were compounded with epoxy (EP) resin and formed a dielectric material with the advantage of reducing dielectric loss while ensuring high dielectric constant. The dielectric constant of the coated MWCNTs/EP composites was 194.90 at 10³ Hz with the content of fillers reaching 30 wt %, which is 28 times that of the pure EP. Accordingly, the dielectric loss of 30 wt % coated MWCNTs/EP composites was only 0.09 at 10³ Hz, which is only 2.25 times that of the pure EP. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46299.     

Fabrication of highly refractive barium‐titanate‐incorporated polyimide nanocomposite films with high permittivity and thermal stability

Crystalline nanoparticles of barium titanate (BT) are incorporated into polyimide (PI) to fabricate highly refractive, anti‐UV‐degradable nanocomposite films with high permittivity and thermal stability. For homogeneous incorporation of BT nanoparticles into the PI matrix, the BT nanoparticles are surface modified by phthalimide with the aid of a silane coupling agent as a scaffold. The PI nanocomposites are prepared by in situ polymerization in which a diphthalic anhydride and a diamine are used to form the PI matrix in the presence of the surface‐modified nanoparticles. The refractive index of the transparent nanocomposite films reaches 1.85 at a nanoparticle content of 59 vol% with a high dielectric constant of ε = 37 and thermal stability up to 460 °C. Copyright © 2012 Society of Chemical Industry     

Sensing of damage in carbon nanotubes and carbon black‐embedded epoxy under tensile loading

In situ sensing of damage in epoxy embedded separately with carbon nanotubes (CNTs) and carbon black (CB) microparticles is investigated under quasi‐static uniaxial tensile loading. Three different weight fractions of CNTs (0.1, 0.3%, and 0.5%) and one‐weight fraction of CB (10%) are used to generate a conductive network in epoxy. A modified four circumferential ring probes technique is employed and a constant current was applied through the outer probes. The resulting voltage drop between the inner probes is measured using a high‐resolution electrometer‐based system to determine the resistance change associated with nonlinear deformation, damage initiation, and growth in the material. As the generated conductive network is different with changing weight fractions of CNTs, the resulting electrical response was identified to be significantly different between composites. The nonlinear deformation associated with the unfolding of entangled polymer chains and further straightening of them, decreased the distance between neighboring CNTs, resulting in improved electron hopping. For CB‐embedded epoxy, a very high percentage increase in resistance is noticed when compared to CNTs case owing to induced microcracks associated with agglomerated CB particles. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Surface barrier layer effect in (In + Nb) co‐doped TiO2 ceramics: An alternative route to design low dielectric loss

Giant dielectric permittivity (ε′) with low loss tangent (tanδ) was reported in (In + Nb) co‐doped TiO₂ ceramics. Either of electron‐pinned defect‐dipole or internal barrier layer capacitor model was proposed to be the origin of this high dielectric performance. Here, we proposed an effectively alternative route for designing low‐tanδ in co‐doped TiO₂ ceramics by creating a resistive outer surface layer. A pure rutile‐TiO₂ phase with a dense microstructure and homogeneous dispersion of dopants was achieved in (In + Nb) co‐doped TiO₂ ceramics prepared by a simple sol‐gel method. Two giant dielectric responses were observed in low‐ and high‐frequency ranges, corresponding to extremely high ε′≈10⁶‐10⁷ and large ε′≈10⁴‐10⁵, respectively. After annealing in air, a low‐frequency dielectric response disappeared and could be restored by removing the outer surface of the annealed sample, indicating the dominant electrode effect in the initial sample. Annealing can cause improved dielectric properties with a temperature‐ and frequency‐independent ε′ value of ≈1.9 × 10⁴ and cause a decrease in tanδ from 0.1 to 0.035. High dielectric performance in (In_0.5Nb_0.5)_xTi_1?xO₂ ceramics can be achieved by eliminating the electrode effect and forming a resistive outer surface layer.     

Functionalized graphene sheets‐epoxy based nanocomposite for cryotank composite application

Multifunctional high performance functionalized graphene sheets (FGSs) based epoxy nanocomposites were investigated to understand the feasibility that these FGSs‐epoxy nanocomposites can be applied to cryotank composite applications. The FGSs were successfully synthesized from graphite flakes through preparing graphite oxides by oxidizing graphite flakes first and next, thermally exfoliating the formed graphite oxides. These high performance FGSs were next incorporated into epoxy matrix resin system to generate the uniformly dispersed FGSs reinforced epoxy nanocomposites. The resultant FGSs‐epoxy nanocomposites significantly enhanced resin strength and toughness about 30–80% and 200–700% at room and low temperatures of −130°C, respectively, and reduced the coefficient of thermal expansion (CTE) of polymer resin at both below and above T_g about 25% at loading of 1.6 wt% FGSs, and increased T_g of polymer resin about 8°C at low loading of 0.4 wt% FGSs without deteriorating their good processability. We found that these significantly improved properties of FGSs‐reinforced epoxy nanocomposite were closely associated with high surface area and wrinkled structure of the FGSs. The further optimization will result the high performance FGSs‐epoxy nanocomposite suitable for use in the next generation multifunctional cryotank carbon fiber reinforced polymer (CFRP) composite applications, where better microcrack resistance and mechanical and dimensional stability are needed. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Few‐layer‐graphene/polycarbonate nanocomposites as dielectric and conducting material

An attempt is taken to develop a flexible and light weight polycarbonate‐based nanocomposite system which could be successfully used as a dielectric material below percolation and as conducting material beyond percolation. The nanocomposite system has been prepared by solution mixing method in which few layer graphene was incorporated as conductive filler. X‐ray diffractometry, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy techniques were employed for characterization studies. The dielectric constant and conductivity were evaluated using precision impedance analyzer. Percolation threshold has been observed to occur at 3.5 wt % of few layer graphene. Dielectric constant of the nanocomposite system, in the smearing region, has been found to increase from ～3.3 (without filler) to ～70 (at 5 wt % FLG) with a dissipation factor of 0.07. The conductivity of the system was increased from 10^?9 S/cm without FLG to 10^?2 S/cm with 7 wt % of few layer graphene. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42443.     

High‐frequency dielectric characterization for liquid crystalline polyimide/SiO2 nanocomposites

In this study, we investigated the influence of frequency, film thickness, and SiO₂ content on the dielectric constant (K) and loss tangent (tan δ) of liquid crystalline polyimide (LCPi) and liquid crystalline polyimide/SiO₂ (LCPi/SiO₂) nanocomposites in a high frequency environment. We tested the loss tangent of the LCPi and LCPi/SiO₂ nanocomposites within the high frequency 1 MHz to 3 GHz range, and determined its value to be between 0.01 and 0.001. In addition, we found a formant for frequencies ranging from 0.5 GHz to 1 GHz. We also inferred from the dielectric loss graphs of films with different thicknesses that the formants of the loss tangent shifted toward higher frequencies with increasing thicknesses. When measuring the dielectric constant at high frequencies, we found that the dielectric constant decreased markedly with increased SiO₂ contents. Using the dielectric constant of high‐frequency circuit board materials as the standard, the dielectric constant of the LCPi/SiO₂ nanocomposites at the frequency range from 1 MHz to 3 GHz was found to be as high as 2.2–3.4, thereby confirming the viability of LCPi/SiO₂ nanocomposites as candidate materials for high‐frequency circuit board. In addition, the volume resistivity (ρ_V) of the LCPi and LCPi/SiO₂ nanocomposites also increased with increased SiO₂ contents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Material characterization of a high‐dielectric‐constant polymer–ceramic composite for embedded capacitor for RF applications

Embedded capacitor technology can improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Polymer–ceramic composites have been of great interest as embedded capacitor materials because they combine the processability of polymers with the desired electrical properties of ceramics. We have developed a novel nanostructure polymer–ceramic composite with a very high dielectric constant (ε_r ≈ 150, a new record for the highest reported ε_r value of a nanocomposite) in a previous work. RF applications of embedded capacitors require that the insulating material have a high ε_r at a high frequency (in the gigahertz range), low leakage current, high breakdown voltage, and high reliability. A set of electrical tests were conducted in this study to characterize the electrical properties of the novel high‐ε_r polymer–ceramic nanocomposite developed in‐ house. The results show that this material had a fairly high ε_r in the RF range, low electrical leakage, and high breakdown voltage. An 85°C/85% thermal humidity aging test was been performed, and it showed that this novel high‐K material had good reliability. An embedded capacitor prototype with a capacitance density of 35 nF/cm² was manufactured with this nanocomposite with spin‐coating technology. This novel nanocomposite can be used for the integral capacitors for RF applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2228–2231, 2004     

Synthesis and properties of fluorinated biphenyl‐type epoxy resin

A novel fluorinated biphenyl‐type epoxy resin (FBE) was synthesized by epoxidation of a fluorinated biphenyl‐type phenolic resin, which was prepared by the condensation of 3‐trifluoromethylphenol and 4,4′‐bismethoxymethylbiphenyl catalyzed in the presence of strong Lewis acid. Resin blends mixed by FBE with phenolic resin as curing agent showed low melt viscosity (1.3–2.5 Pa s) at 120–122°C. Experimental results indicated that the cured fluorinated epoxy resins possess good thermal stability with 5% weight loss under 409–415°C, high glass‐transition temperature of 139–151°C (determined by dynamic mechanical analysis), and outstanding mechanical properties with flexural strength of 117–121 MPa as well as tensile strength of 71–72 MPa. The thermally cured fluorinated biphenyl‐type epoxy resin also showed good electrical insulation properties with volume resistivity of 0.5–0.8 × 10¹⁷ Ω cm and surface resistivity of 0.8–4.6 × 10¹⁶ Ω. The measured dielectric constants at 1 MHz were in the range of 3.8–4.1 and the measured dielectric dissipation factors (tan δ) were in the range of 3.6–3.8 × 10^?3. It was found that the fluorinated epoxy resins have improved dielectric properties, lower moisture adsorption, as well as better flame‐retardant properties compared with the corresponding commercial biphenyl‐type epoxy resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Novel high‐performance wave‐transparent aluminum phosphate/cyanate ester composites

Advanced wave‐transparent composites are the key materials for many cutting‐edge industries including aviation and aerospace, which should have outstanding heat resistance, low dielectric constant and loss as well as good mechanical properties. A novel kind of high‐performance wave‐transparent composites based on surface‐modified aluminum phosphate AlPO₄(KH‐550) and cyanate ester (CE) was first developed. The dielectric and dynamic mechanical properties of AlPO₄(KH‐550)/CE composites were investigated intensively. Results show that AlPO₄(KH‐550)/CE composites have decreased dielectric loss and higher storage moduli than pure CE resin; in addition, the composites with suitable AlPO₄(KH‐550) concentration remain the outstanding thermal property and low dielectric constant of pure CE resin. The reasons attributing to these results are discussed from the effects of AlPO₄(KH‐550) on the key aspects such as morphology, curing mechanism, and interfacial adhesion of composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dielectric and electric properties of plasticized PEO‐AgCF3SO3‐SiO2 nanocomposite polymer electrolyte system

The effect of plasticizer poly(ethylene glycol) (PEG) on dielectric and electrical properties of an ionically conducting polymer nanocomposite electrolyte PEO: AgCF₃SO₃: SiO₂: PEG has been investigated. The variation of relative dielectric constant and tangent loss peak with frequency have been discussed. The ionic and polymer segmental motions have been analyzed by electrical modulus and dielectric permittivity. The electrical modulus formalism is used to study the ionic relaxation process in these composites in terms of conductivity relaxation time. On addition of plasticizer, the modulus peak shifts toward higher frequency side suggesting the speeding up of the relaxation time. The frequency dependence of AC conductivity follows the universal power law. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

The effects of polymer‐nanofiller interactions on the dynamical mechanical properties of PMMA/CaCO3 composites prepared by microemulsion template

We prepared novel poly(methyl methacrylate) (PMMA)/CaCO₃ nanocomposites by using reverse micelle as a template. The nanoparticles of CaCO₃ were prepared by the reverse microemulsion with functional monomer, methyl methacrylate (MMA) as oily phase, and the PMMA/CaCO₃ nanocomposite was obtained via polymerization of MMA monomer. The SEM image showed that the nanoparticles of CaCO₃ were dispersed in the polymer matrix. Dynamic mechanical analysis (DMTA) was performed to investigate the interaction between the nanoparticles and the polymer chains. In the low‐temperature ripening process, two tan δ peaks were observed in the nanocomposite, corresponding to the glass transitions of the matrix and the interface layer. In the high‐temperature ripening process, only one tan δ peak was observed, suggesting that the interface layer forms a continuous phase. The nanoparticles behave as a physical crosslinker in the interface layer. Modification of the surface of nanoparticles with polyacrylamide and poly(N,N′‐methylenedisacrylamide) in the nanocomposite did not show an appreciable effect on the interaction of nanoparticles with the matrix. Upon removal of the aqueous phase around the nanoparticles, we obtained surface‐capped nanoparticles by using an improved reverse microemulsion technique. Another PMMA/CaCO₃ nanocomposite was also obtained with these modified nanoparticles. DMTA analysis of this nanocomposite demonstrated that the aqueous phase layer around the nanoparticles does not significantly affect the interaction between the nanoparticles and the polymer chains. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2739–2749, 2004     

Effects of nanoclay on the properties of cardanol‐modified‐resol‐epoxy‐novolac composite material

A nanocomposite based on nanoclay and resol that was modified with cardanol, a natural alkyl phenol, shows improvement for the glass‐fiber‐reinforced epoxy‐composite system. Dispersion of the nanocomposite was investigated by X‐ray, showing good results obtained by the in situ polymerization method. The mechanical properties of the final composites were improved by doping a 6 wt% of nanoclay in cardanol‐modified‐resol (CMR) into the epoxy matrix. The results show that a 15 wt% of CMR in epoxy is a most suitable ratio. Using polyamide as a curing agent instead of other traditional systems, such as anhydrides or amines for epoxy resin, overcame important limitations, further allowing for improved processability. The overall composite performance was enhanced. Additionally, the thermal stability of the system was investigated by thermal gravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3238–3242, 2007     

Composition dependence of dielectric properties,elastic modulus,and electroactivity in (carbon black‐BaTiO3)/silicone rubber nanocomposites

The dielectric properties, elastic modulus, and electromechanical responses of dielectric elastomers (DEs) consisting of silicone rubber and carbon black (CB) incorporated with BaTiO₃ (BT) were studied. When compared with single filler/rubber composites, the resulting three‐component nanocomposites yielded very abnormal phenomena. They might be attributed to the interactions between the two kinds of fillers. The increase in concentration of CB (BT) would play a destructive role to the network structure formed by BT (CB) particles. The maximum electromechanical strain of the nanocomposites achieved at mass fraction m_CB = 0.03 and m_BT = 0.06. The resultant electromechanical strain would be attributed to the large dielectric permittivity in the three‐component nanocomposites, in which the BT particles themselves have a high dielectric permittivity and the electrical networks of CB particles have a contribution on the increase in dielectric permittivity of the three‐component nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of poly(styrene‐co‐butyl acrylate)/montmorillonite nanocomposite by emulsion polymerization: Characterization and nanoscratch behavior

Organic–inorganic hybrid poly(styrene‐co‐butyl acrylate)/organically modified montmorillonite (PSBA/organo‐MMT) latex particles have been prepared by in situ emulsion polymerization. The effects of modifier variety and the level of organo‐MMT have been investigated on the basis of the characteristics and mechanical properties of the resulting hybrid emulsion polymers. Although the more hydrophilic intercalated organic modifiers increased the latex particle size, the hydrophobic ones decreased the particle size. A more heterogeneous copolymer chain intercalation was seen by widespread XRD reflection as the organo‐MMT (organoclay) level increases. The tapping mode atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to determine the dispersion state of organoclay particles inside the nanocomposite copolymer films. Dynamic mechanical thermal analysis (DMTA) showed that adding the organoclay to the copolymer decreased the maximum loss tangent (tanδ) value and caused the shift to a lower temperature. Interestingly, the incorporation of organoclay decreased the glass storage modulus of the copolymer, while increased the rubbery storage modulus to some extent. In addition, a standard indenter for the nanoscratching of copolymer nanocomposite films was used under low applied loads of 150 and 250 μN. The nanoscratch results showed that incorporation of a 3 wt % hydrophobic organoclay, e.g., Closite15A, in the copolymer matrix enhanced considerably the near‐surface hardness and grooving resistance of the nanocomposite film at room temperature. In fact, copolymer nanocomposite films with higher near‐surface hardness and tanδ curve broadening exhibited more nanoscratch resistance through a specific variety of viscoelastic deformation, which did not create a bigger groove. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012