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Herein, non‐polymeric thin cross‐sectional wires were fabricated by injecting materials into elastomeric hollow fibers with subsequent drawing. Once materials were injected into hollow elastic fibers, cores were drawn as fibers elongated. Solidifying the core and removing polymeric shell could form free‐standing wires with thin cross‐sections. In this work, two different thin wires, metallic wires (gallium), and SiCN ceramic wires, were fabricated. Although mechanical and physical properties of these wires completely differed, fabrication approaches were identical by drawing materials near room temperature. Solidified wires enhanced mechanical properties of fibers. Thus, fibers could store elastic energy and preserve deformed complex shapes with the assist of solidified cores. Although the wires with thin cross sections are inherently brittle, the relatively low melting point of gallium (29.8°C) allows it to heal easily upon body heating. [ABSTRACT FROM AUTHOR]

Flexible and stretchable electrodes have attracted immense attention because of their various electronic applications on the wearable sensing electronics, but challenges regarding robust and sustainable electrical performance under static and dynamic mechanical stresses still need to be overcome. Herein, with a simple effective strategy, a highly serviceable and flexible elastomeric electrode fabricated by utilizing an interpenetrating network between acrylic rubber (AR) and silicone rubber (SR), and silver (Ag) ink to increase electrical conductivity, is introduced. Oxygen (O2) plasma and sodium dodecyl sulfate (SDS) treatment on wrinkle substrate surface lead to robust adhesion of Ag ink layer, results in high electrical conductivity. Wrinkle morphology can help to stably maintain the continuous conductive Ag network during static and dynamic deformation. This stretchable electrode possessing properties such as robust and stable electrical conductivity of ~103 S/cm under 150% static tensile deformations and good sustainability after 1000 cycles of dynamic tensile deformations is a promising candidate for stretchable wearable electronics. [ABSTRACT FROM AUTHOR]

Composites based on brominated isobutylene‐isoprene rubber (BIIR) and 5‐mm short aramid fiber were prepared by varying the fiber content from 1 to 10 phr using 4, 4' bismaleimido diphenyl methane (BMDM) and zinc oxide as the vulcanizing agent. Morphological analysis revealed that the fiber dispersion becomes inferior even at 5 phr loading due to fibrillation during mixing. As a result, the 10 phr fiber‐filled composite showed a brittle failure under a tensile deformation. To solve this problem, maleic anhydride‐grafted polybutadiene (MA‐g‐PB) resin was treated with the aramid fibers in the 1:1 ratio prior to mixing with the rubber matrix. Excellent fiber dispersion could be seen in both the visual image of the molded sheet and the scanning electron microscope image of the fractured surface. The stress–strain curve of the 10 phr fiber‐filled composite after the resin treatment showed a tough deformation behavior with a breaking elongation >100% indicating an enhanced fiber‐matrix adhesion. From the vulcanization studies of the fiber‐filled BIIR before and after the MA‐g‐PB resin treatment, it has been identified that a co‐crosslinking reaction between the MA‐g‐PB‐treated fiber and the BIIR matrix with BMDM via Alder‐ene and Diels‐Alder reactions is responsible for the enhanced fiber–matrix adhesion. POLYM. COMPOS., 40:2993–3004, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

It is well known that the vulcanization of chlorinated isobutylene-isoprene rubber (CIIR) with ZnO alone is very slow and the resulting vulcanizate shows low crosslinking density as well as poor mechanical and thermal properties. For these problems to be addressed, 4,4′-bis(maleimido) diphenylmethane (BMDM) has been applied along with ZnO to cure CIIR. The curing behavior was investigated using oscillating disk rheometer and differential scanning calorimetry analysis. The crosslinking densities, mechanical, dynamic mechanical, and thermal properties of the vulcanizates were also evaluated as a function of BMDM content. From the rheometer and differential scanning calorimetry analysis, it has been confirmed that the rate of curing, as well as the extent of curing between CIIR and ZnO, has remarkably increased in the presence of BMDM. The Diels-Alder reaction between the in situ formed conjugated diene butyl from CIIR/ZnO with the maleic moieties of BMDM has been identified as a primary reason for the higher rate and state of cure. The crosslinking densities of the vulcanizate CIIR/ZnO have significantly increased with increase in the content of BMDM. As a result, the compression set of the vulcanizate was remarkably decreased at elevated temperature. Moreover, the vulcanizates contain BMDM that has exhibited high thermal degradation temperature and good retention of the mechanical properties even after 7 days of thermal ageing. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT The development of thermally stable bromobutyl rubbers has been a challenge in rubber chemistry and engineering. In this circumstance, 4,4′-bismaleimidodiphenylmethane (BMI) was newly applied as a novel crosslinking agent for thermally stable brominated isobutylene-isoprene rubber (BIIR) with a high crosslinking density. With oscillating disk rheometry and differential scanning calorimetry, the curing characteristics of BIIR were systematically investigated with respect to the content of BMI. We found that BMI alone could crosslink BIIR at higher temperature, and a corresponding possible chemical reaction mechanism was proposed. With the introduction of zinc oxide, the curing reaction of BIIR with BMI was significantly accelerated, and the resulting vulcanizate provided a higher state of curing with excellent overcure reversion stability even at a temperature of 190 °C for 2 h. The content of the dicumyl peroxide (DCP) reaction accelerator was also optimized to be BMI/DCP = 1:0.05 on the basis of considerations of the curing rate, scorch safety, maximum rheometric torque, and reversion resistance at 160 °C. Compared with the conventional sulfur-cured BIIR, the BMI-cured BIIR exhibited a higher crosslinking density with a superior low compression set property at elevated temperatures and an excellent thermal stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44092. [ABSTRACT FROM AUTHOR]

ABSTRACT The graphene oxide (GO) was prepared by sonication-induced exfoliation from graphite oxide, which was produced by oxidation from graphite flakes with a modified Hummer's method. The GO was then treated by hydrazine to obtain reduced graphene oxide (rGO). On the basis of the characterization results, the GO was successfully reduced to rGO. Acrylonitrile-butadiene rubber (NBR)-GO and NBR-rGO composites were prepared via a solution-mixing method, and their various physical properties were investigated. The NBR-rGO nanocomposite demonstrated a higher curing efficiency and a change in torque compared to the gum and NBR-GO compounds. This agreed well with the crosslinking density measured by swelling. The results manifested in the high hardness (Shore A) and high tensile modulus of the NBR-rGO compounds. For instance, the tensile modulus at a 0.1-phr rGO loading greatly increased above 83, 114, and 116% at strain levels of 50, 100, and 200%, respectively, compared to the 0.1-phr GO loaded sample. The observed enhancement was highly attributed to a homogeneous dispersion of rGO within the NBR matrix; this was confirmed by scanning electron microscopy and transmission electron microscopy analysis. However, in view of the high ultimate tensile strength, the NBR-GO compounds exhibited an advantage; this was presumably due to strong hydrogen bonding or polar-polar interactions between the NBR and GO sheets. This interfacial interaction between GO and NBR was supported by the marginal increase in the glass-transition temperatures of the NBR compounds containing fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42457. [ABSTRACT FROM AUTHOR]

ABSTRACT Ethylene-propylene-diene termonomer (EPDM) compounds filled with halogenated (Br and Cl) flame retardants (FRs) and Sb2O3 were prepared via melt mixing, and their thermal stability, weight loss, and elemental composition were investigated as a function of aging conditions (temperature: 120-380°C, period: ∼100 h, and atmosphere: nitrogen and air). The thermal aging was done with thermogravimetic analysis under both isothermal and nonisothermal conditions and a convection oven. Scanning electron microscopy-energy dispersive spectroscopy was used to study the surface morphology and elemental composition of the thermally aged FRs-filled EPDM compounds. For a better precision of compositional analysis, a laser-induced breakdown spectroscopy (LIBS) was employed in this study. The thermal degradation behavior of EPDM compounds containing halogenated FRs was strongly dependent on the aging atmosphere (N2 or air) and type of FRs. The weight loss of the EPDM compounds during thermal aging was found to be quite small in the temperature ranges below 190°C, while it was noticeable above the temperature. The LIBS technique can be an effective and promising analysis tools for analyzing the elemental components in a bulk rubber compound. Two possible mechanisms were proposed for the thermal degradation of the EPDM compounds containing brominated FR and Sb2O3. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41324. [ABSTRACT FROM AUTHOR]

ABSTRACT Graphene oxide-reinforced acrylonitrile-butadiene rubber nanocomposites were prepared via solution mixing. The morphology of the graphene oxide was studied, and its successful dispersion within the rubber matrix was confirmed by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction studies. The strong rubber-to-filler interaction was confirmed by swelling and mechanical reinforcing behaviors and thermal stability. Dielectric spectroscopy test indicated a marked improvement of about five times in the real part of permittivity. The electrical conductivity level was close to that of nonconductive materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40640. [ABSTRACT FROM AUTHOR]

A ribbon-shaped chiral liquid crystalline (LC) dendrimer with photochromic azobenzene mesogens and an isosorbide chiral center (abbreviated as AZ3DLC) was successfully synthesized and its major phase transitions were studied by using differential scanning calorimetry (DSC) and linear polarized optical microscopy (POM). Its ordered structures at different temperatures were further identified through structure-sensitive diffraction techniques. Based on the experimental results, it was found that the AZ3DLC molecule exhibited the low-ordered chiral smectic (Sm*) LC phase with 6.31 nm periodicity at a high-temperature phase region. AZ3DLC showed the reversible photoisomerization in both organic solvents and nematic (N) LC media. As a chiral-inducing agent, it exhibited a good solubility, a high helical-twisting power, and a large change in the helical-twisting power due to its photochemical isomerization in the commercially available N LC hosts. Therefore, we were able to reversibly 'remote-control' the colors in the whole visible region by finely tuning the helical pitch of the spontaneously formed helical superstructures. [ABSTRACT FROM AUTHOR]

ABSTRACT Dielectric elastomers (DEs) have been suggested as generators to harvest electrical energy from natural mechanical energy sources, such as human movements and ocean waves. In this study, a donut-shaped DE generator (DEG) has been fabricated and its performance is characterized depending on the stretch deformation. A simple new stretchable electrode system using multi-walled carbon nanotubes has been suggested. Measurements on the resistance, capacitance, and electrical power generation are made depending on the area expansion. The capacitance and harvested energy are parabolically increased with increased area expansions. The theoretical prediction of energy harvesting is in good agreement with measured values of capacitance changes with stretching. FE analysis is also applied for calculation of strains for the DEG to figure out the distribution of strains. It is suggested that the DEG has promising applications in the field of designing an energy harvesting device depending on the type of energy available. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40076. [ABSTRACT FROM AUTHOR]

ABSTRACT At glass transition temperature, Tg the rubber compound becomes stiff and brittle and it loses all its rubbery characteristics. This article deals with the changes in Tg of rubber blends based on natural rubber and polybutadiene rubber of varying vinyl content having different types and content of plasticizers, different curing systems and its effect on physico-mechanical properties to improve its freezing resistance. The plasticizers used were dioctylphthalate (DOP), tricrecylphosphate (TCP), dioctyladipate (DOA), and oil type plasticizers like parafinic oil (P#2) and aromatic oil (A#2). Among the plasticizers, when DOP and DOA content was high, an appreciable decrease of Tg was found compared to TCP. Moreover, there was a remarkable decrease of Tg using DOA plasticizer, which shows more effective on freezing resistance. However, there was not much change in Tg with oil-type plasticizers with high oil content compared to TCP plasticizer. The effect of cross-linking systems such as conventional sulfur vulcanization (CV), efficient sulfur vulcanization (EV), and dicumyl peroxide (DCP) and rubber blends with varying vinyl content in polybutadiene rubber were also carried out. It was found that Tg in different cross-linking system decreased in this order: CV < EV < DCP. It reveals that DCP cross-linking system affect more for improving freezing resistance. Physico-mechanical properties such as tensile strength, tear strength, hardness were also measured. The ratio of initial slope ( M0) to steady-state slope ( M1), M0/ M1 in tensile curves of different blends were verified, which in turn related to the physico-mechanical properties and freezing resistance of rubber compounds. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39795. [ABSTRACT FROM AUTHOR]

Newly proposed polymer electrolyte membranes (PEMs) composed of an electrospun poly(vinylidene fluoride) (PVDF) fibrous mat embedded in a poly(4-vinylpyridine) (P4VP) matrix were successfully fabricated in order to improve the mechanical and dimensional stabilities and ionic conductivity of membranes in lithium rechargeable batteries. Fourier transform infrared spectroscopic analysis showed that as a result of the use of a high voltage during electrospinning the crystalline structure of PVDF changed partially from α-phase to β-phase. Energy-dispersive X-ray spectroscopy confirmed the existence of crosslinked P4VP in the PVDF fibrous mat. The electrolyte uptakes of PVDF and PVDF/P4VP composite mats were higher than that of PVDF cast film. The tensile properties of PVDF/P4VP composite mat were considerably improved compared to those of the pristine PVDF fibrous mat under both dry and wet (soaked with electrolyte) conditions. In addition, the mechanical and dimensional stabilities of the PVDF/P4VP composite PEM were further enhanced due to crosslinking between the P4VP chains. Furthermore, the PVDF/P4VP composite PEM exhibited an ionic conductivity that was an order of magnitude higher than that of traditional PVDF film. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Wax in a rubber article migrates to the surface and plays the role of an antidegradant by formation of an impervious barrier on the surface. Wax solubility of a rubber article is important for understanding migration behaviors and film formation of wax as well as for determining the proper content of wax in a rubber compound. Wax solubilities of natural rubber composites reinforced with carbon black were measured using wax solution in toluene. A variation of the wax solubility with the carbon black content was investigated. Raw wax solubility decreased with the increase of carbon black content. Solvent swell-corrected wax solubility also decreased with the carbon black content. The raw wax solubilities were corrected with the rubber fractions, total bound rubber contents, and tightly bound rubber contents as well as the solvent swelling ratio to investigate the influencing parameters on wax solubility. It was found that the unbound and loosely bound rubber fractions as well as the solvent swelling enhanced the wax solubility while the tightly bound rubber fraction reduced it. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Zinc methacrylate (ZMA) and carbon black (CB) are incorporated into natural rubber/butadiene rubber matrix by direct mixing in a Banbury mixer. Tensile and tear tests showed that CB has a great reinforcing effect on rubber matrix. The results show that the amount of ZMA also plays an important role in mechanical properties. The addition of ZMA resulted in a significant increase of the optimum cure time even at lower loading. Incorporation of ZMA improved mechanical properties, such as tensile modulus and cure reinforcing parameter. The extraordinary improvement in properties is due to the formation of covalent and ionic crosslink. The composite containing only CB shows higher elongation at break, superior tensile strength, and tear strength than ZMA-filled composites. Reinforcing effect of different composites has also been evaluated using different theoretical model. It has been observed that blowout time became slower and blowout temperature became higher as the ZMA content of the specimen increased. This represents multiple interactions between ZMA and rubber matrix. On the basis of the experimental results, possible mechanisms for reinforcement and microstructure of ZMA/rubber composites have been proposed. Both ZMA and CB provide better thermal stability especially for the composites, where the highest reinforcement effect is observed by mechanical analysis. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Formation of porous films from poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) using the breath figures (BF) method was investigated by evaporating solutions in chloroform in humid air and examining film structure using optical and scanning electron microscopy (SEM). BF films were successfully fabricated from PHB ( Mw = 486,000 g/mol) and displayed hexagonal arrays of pores, which varied in diameter ( D = 7-2 μm) with solution concentrations (0.5-2.00%). SEM of fractured films also showed subsurface closed nano-pores ( D = 500-700 nm). BF films cast from PHBV (5% HV) formed arrays with smaller pores and apparent surface defects. Differential scanning calorimetry showed that porous PHB and PHBV films produced using the BF method were more crystalline than nonporous solvent cast films of PHB and PHBV. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Utilizing polymer electrospinning technology, novel electrolyte membranes based on poly(vinylidene fluoride) (PVDF)/organomodified clay (OC)/tripropyleneglycol diacrylate (TPGDA) composite nanofibers with a diameter of 100-400 nm were fabricated for application in lithium batteries. Ultraviolet photo-polymerization of electrospun PVDF/OC/TPGDA nanofibers generated chemically crosslinked TPGDA-grafted PVDF/OC nanofibers exhibiting robust mechanical and electrochemical properties. The prepared fibrous PVDF/OC/TPGDA electrolytes were characterized in terms of morphology, crystallinity, electrochemical stability, ionic conductivity and cell cycleability. Based on differential scanning calorimetry analysis, the crystallinity of PVDF decreased by ca 10% on employing the OC and TPGDA. Compared with pure PVDF film-based electrolyte membranes, the TPGDA- and OC-modified PVDF electrolyte membranes exhibited improved mechanical properties and various electrochemical properties. The OC- and TPGDA-modified microporous membranes are promising candidates for overcoming the drawbacks of the lower mechanical stability of fibrous-type electrolytes with further improvement of electrochemical performance. Copyright © 2009 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Polymer nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) have been newly introduced for semiconducting layers of high-voltage electrical power cables. Homogeneity of the MWCNT-reinforced polymer nanocomposites was achieved by solution mixing, and their mechanical, thermal and electrical properties were investigated depending on the type of polymer. By changing the polymer matrix, the volume resistance of the MWCNT-reinforced polymer nanocomposites could be varied by more than four orders of magnitude. Through systematic experiments and analysis, two possible factors affecting the volume resistance were found. One is the degree of crystallinity of the polymer used and the other is the change of MWCNT morphology under strain. By increasing the degree of crystallinity above a certain level, the volume resistance linearly increased. The MWCNTs embedded in the nanocomposites gradually protruded through the surface on stretching the sample and reversibly returned back to the original positions at a relatively small strain (below 20%). Based on the criteria of tensile properties and volume resistance, a poly[ethylene- co-(ethyl acrylate)]/MWCNT nanocomposite was selected as the best candidate for the semiconducting layers of high-voltage electrical power cables. Copyright © 2009 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The article discusses a research study on determining fibre diameter changes and morphology development of electrospun fibres during electrospinning based on polyacrylonitrile (PAN/poly(methyl methacryalate) (PMMA) blends. Researchers used scanning electron microscopy in observing the decrease in fibre diameter with increase in content of PMMA at 50 percentage weight (wt%). Conclusions indicated a microphase-separation fibre morphology occuring in electrospinning of incompatible PAN/PMMA.

The article presents a study which suggested novel gel polymer electrolytes (GPE) based on poly(vinylidene fluoride)-graft-poly(tert-butyl acrylate) (PVDF-g-tBA) microporous mats. The researchers noted that much interest has been shown in improving the performance of lithium-ion polymer batteries with GPE due to a rapid expansion in industrial demand. They concluded that tBA-grafted PVDF microporous electrolytes are promising candidates for enhancing the performance of lithium-ion polymer batteries.