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The conformational transition behavior of polymer in the amorphous state has been investigated through molecular dynamics simulations across the glass transition temperature (T g ). We find that the conformational transition, a localized and short time dynamics feature, crosses over different barrier heights when the system transforms from the molten state into the glass state and the barrier...
The incorporation of benzoxazine (Ba) or sulfonic acid containing benzoxazine (SBa) as a crosslinking agent in SPEEK proton exchange membrane (PEM) can substantially improve the SPEEK membrane performance. The SPEEK–SBa membranes give higher effective selectivity than corresponding SPEEK–Ba membranes under close crosslinker loading and thus are more suitable to be used in direct methanol fuel cells...
Several poly(pyridinium salt)s containing various organic counterions and oxyethylene unit in their backbones were synthesized by either the ring-transmutation polymerization reaction of 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium tosylate) with 1,2-bis(4-aminophenoxy)ethane on heating in dimethyl sulfoxide or the metathesis reaction of the tosylate polymer with the corresponding lithium or sodium...
Surface properties and structure of an oxygen-plasma-treated thermoplastic fluoroelastomer film under mechanical stretching were investigated using dynamic contact angle, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. The contact angle of water on the surface decreased from 96° to 36° by the plasma treatment. The contact angle increased under uniaxial stretching:...
In this study, water acts as a co-blowing agent to support carbon dioxide (CO 2 ) in the extrusion foaming process of polystyrene (PS) to produce foams with very low density for thermal insulation applications. Herein, we report a simple suspension polymerization method to prepare water expandable polystyrene (WEPS) based on a PS/water containing activated carbon (AC) composite. AC pre-saturated...
Various conducting polymer/hydrophobic insulating polymer (CP/HIP) composite nanofibers have been prepared by electrospinning and vapor deposition polymerization (VDP) with benzoyl peroxide (BPO) as oxidant. BPO is soluble in N,N-dimethylformamide (DMF) and can form homogenous solutions with hydrophobic polymers such as poly(methyl methacrylate) (PMMA) and polystyrene (PS). High-quality nanofibers...
This investigation reports the preparation of a series of well-defined Poly(methyl methacrylate)-b-poly(hexyl acrylate)-b-poly (methyl methacrylate) (PMMA-b-PHA-b-PMMA) triblock copolymers by Atom Transfer Radical Polymerization (ATRP). Their morphology, dynamic mechanical and tensile properties are thoroughly investigated. Phase separation is observed for all the above-mentioned triblock copolymers,...
In polymer nanocomposites, interactions between filler particles and matrix material play a crucial role for their macroscopic properties. Nanocomposites consisting of varying amounts of silica nanoparticles and an epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) have been studied before and during network formation (curing). Rheology and mainly temperature modulated differential scanning...
This paper is concerned with the fabrication of voided polyethylene microstructures by heat melding of plastic microcapillary films (MCFs) to form microcapillary monoliths (MCMs), which are consolidated layers of MCFs forming in two-dimensional arrays of microcapillaries. MCMs were manufactured by heat melding multiple layers of low-voidage MCFs or high-voidage MCFs. The optimal conditions for interface...
Mixtures of cylindrical forming diblock copolymers (DBCPs) and mobile nanorods (NRs) are systematically investigated via dissipative particle dynamics (DPD) simulations. Final morphology of such composites depends not only on the characteristics of the copolymers, but also on the physical or chemical features of NRs, such as NR number, length, and surface adsorption (neutral, A and B attractive)....
Poly(methylmethacrylate) (PMMA) and polystyrene(PS)/PMMA particles with Janus-like morphology were prepared via the internal phase separation followed by extraction of hexadecane (HD) template. The internal phase separation was triggered by evaporation of dichloromethane (DCM) from the polymer/HD/DCM-in-water emulsion droplets, which led to the formation of HD/PMMA or HD/PMMA/PS microparticles. After...
A novel benzoxazine monomer containing diacetylene linkage has been synthesized by applying an oxidative coupling approach. The structure is confirmed by 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) is used to study crosslinking behavior of synthesized material. The benzoxazine...
The morphologies and properties of Polystyrene (PS)/Carbon Nanotube (CNT) conductive electrospun mat were studied in this paper. Nanocomposite fibers were obtained through electrospinning of PS/Di-Methyl Formamide (DMF) solution containing different concentrations and types of CNTs. The dispersion condition of CNTs was correlated to morphologies and properties of nanocomposite fibers. A copolymer...
A series of inorganic–organic nanocomposites containing sulfonated polyimides and silica particles were synthesized. Anhydride-terminated pre-polymers were prepared, followed by introduction of reactive silanes. Casting, curing, and acidification routines lead to nanocomposites with significantly different properties compared to parent sulfonated polyimides. The presence of silica was qualitatively...
We report on the gelation capability of polystyrene/poly(2-vinyl pyridine) amphiphilic heteroarm polyelectrolyte stars in acidic salt-free aqueous media. The star polymers associate through hydrophobic interactions, by retraction of the stretched arms under no interdigitation conditions, in the dilute regime forming colloidal soft nanoparticles comprising about 6 stars, At concentrations significantly...
Moisture is known to accumulate at the interface between polymers and metal oxides, leading to detrimental effects on physical properties such as modulus and adhesion. Direct measurement of the interfacial moisture profile has been carried out with neutron reflectivity, while thickness dependent swelling of a thin film series has also been also utilized to indirectly assess the interfacial moisture...
In this article, thermal behavior of an epoxy based thermoset polymer has been discussed using atomistic molecular dynamics simulations. The simulations were performed on crosslinked network of EPON-862 and curing agent-W (DETDA) using consistent valence force field (CVFF). Thermal conductivity was calculated using both equilibrium as well as non-equilibrium molecular dynamics approaches and the results...
Surface of titania nanoparticles (TiO 2 ) was modified by a coupling agent as 3-(trimethoxysilyl)propyl methacrylate (MPS) to form TiO 2 -MPS polymerizable particles. Methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (MASi) were radically polymerized through the immobilized vinyl bond on the surface in the presence of the reversible addition-fragmentation chain transfer...
Described in this paper is a novel study focused on producing bead-free ultrafine fibers, with narrow fiber diameter distribution, from Poly(ɛ-caprolactone) (PCL) via electrospinning. High quality product is achieved with the use of a new solvent system that involves an acid–base reaction to produce weak salt complexes, which serve to increase the conductivity of the polymer solution. Additionally,...
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