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In this study we present experimental results and a constitutive model for predicting the nonlinear viscoelastic response of polyoxymethylene (POM). Relaxation and creep tests under relatively low strains are conducted at room temperature. The nonlinearity is analyzed by conducting the aforementioned tests at several stress or strain levels at higher temperatures. To complete the characterization,...
Percolating carbon conduction network is not only a long-time pursued scientific topic but also becomes more and more technologically important. Yet no established diagnostic tool is available. A simple two-wire transmission line (TL) model with symmetric boundary condition is suggested as working equivalent circuit model for the percolating carbon network in the insulating matrix such as polymer...
The present work explores a facile route to synthesize nanocomposite based on graphene and Polypyrrole nanofiber using a biopolymer, sodium alginate. The synthesis procedure of composite is simple, inexpensive and ecofriendly. The possible interaction between graphene and PPy nanofiber has been characterized by FTIR analysis. Morphological study confirmed the fiber like morphology of PPy and the presence...
Necking is a well known phenomenon in uniaxial extension of filled and unfilled semi-crystalline polymers as well as amorphous polymers below their glass transition temperature; however, necking has not been observed for elastomers. For the first time necking is observed for a lightly cross-linked poly(dimethylsiloxane) elastomer filled with 30 phr or more of high surface area (≥300 m 2 /g)...
Hollow microspheres were synthesized using an oil in water suspension system. The oil droplets were comprised of ethylene glycol dimethacrylate (EGDMA) and n-butyl acetate. Upon radical polymerization and gel formation, the polymer phase-separated from the solution and precipitated on the interface between water and organic solvent. The solvent n-butyl acetate was found to be crucial in the process...
To elucidate a difference of micelles formed from AB di- and ABA tri-block copolymers, PMOVE–PNIPAM–PMOVE triblock copolymers were synthesized by both living cationic polymerization of MOVE and RAFT polymerization of NIPAM using a dicarboxylic RAFT agent, where MOVE is 2-methoxyethyl vinyl ether, NIPAM is N-isopropylacrylamide. The ABA triblock copolymers consist of cationically polymerizable monomer...
We report the pH-controlled surface behavior of amphiphilic PS n (P2VP-b-PAA) n heteroarm star block terpolymers, (n = number of arms, 9 and 22), bearing amphoteric diblock arms with varying polyvalent ionic charges (i.e. negative, positive, and zwitterionic) at the air–water and air–solid interfaces. We investigated the assembly of these pH-sensitive star terpolymers in Langmuir and...
The swelling of a commercial thiol-ene adhesive and surfactant dispersed single wall carbon nanotubes (swCNTs) nanocomposites is investigated in a variety of organic solvents. These nanocomposites can be used to form well-defined microstructures via soft lithography. swCNTs are flocculated in suspension using a novel surfactant based on poly(fluorooxetane-block-polyethylene oxide-block-fluorooxetane);...
A series of hyperbranched polyethylene imine (PEI) polymers functionalized with long aliphatic chains has been prepared and characterized. Their self-organization as a function of temperature has been investigated using differential scanning calorimetry, thermogravimetry and X-ray diffraction. Both lamellar (SmA, SmB) and columnar (rectangular) mesophases have been identified. From the detailed study...
The morphology of polymeric self-assembled structures can be changed by environmental conditions, including pH, temperature, and various additives such as ions, cosolvents, nanoparticles (NPs), and so on. Studies have focused on the size and shape of NPs to investigate the effect of NP incorporation into polymeric structures. In this study, qualitative NP effect is experimentally investigated in terms...
This study describes the synthesis of three triphenylamine-based linear conjugated polyfluorenes, differing in the proton (PFH), aldehyde (PFCHO), and 4′-(4-vinylphenyl)-2,2′:6′,2″-terpyridine (PFTPY) pendant groups that attach to the para position relative to 4,4′-dibromotriphenylamine monomer, by using Suzuki coupling polymerization. The structural effect on optical properties and the effect of...
This report describes the surface morphology and wetting behavior of one aryl and three fluorous polyphosphazenes: poly[bis(2,2,2-trifluoroethoxy)phosphazene], PTFEP, 1, poly[bis(para-fluorophenoxy)phosphazene] 2, poly[bis(meta-trifluoromethylphenoxy)phosphazene] 3, and poly(diphenoxyphosphazene) 4. Thermal analysis confirms high thermal stability for these polyphosphazenes. With phenyl side chains,...
Mechanical property of semicrystalline polymer with large-size spherulites is rather poor, and needs to be improved by adding nucleating agent to make spherulites smaller. However, the nucleating agent causes many problems limiting its applications. In this paper, we report a method to simultaneously improve the toughness and tensile strength of isotactic polypropylene (iPP) with large-size spherulites...
Polymer crystals of monodisperse poly (9,9-dioctylfluorene)s (PFOs, named as Fn) on mixing both components (F16 and F64) in different ratios are grown from chloroform/ethanol solutions. In these crystals, lamellar thicknesses corresponding to relevant components can be observed by utilizing atomic force microscopy (AFM). Crystallization of these polymers is accompanied by fractionated crystallization...
β phase isotactic polypropylene (β-iPP) with the β phase lamellae oriented parallel to the melt extrusion direction, was employed to investigate the deformation-induced structure evolution at various temperatures (25, 80, 110, 130 and 140 °C). The orientation change of β phase during deformation greatly influences the β to α phase transformation and its temperature dependence. At temperatures lower...
Mixture quality plays a crucial role in the physical properties of multi-component immiscible polymer mixtures including nanocomposites and polymer blends. Such complex mixtures are often characterized by hierarchical internal structures, which have not been accounted for by conventional mixture quantifications. We propose a way to characterize the mixture quality of complex mixtures with hierarchical...
Nylon 13,6 was successfully synthesized and its chemical composition, thermal properties, crystal structure, and moisture absorption characterized. Melting temperature and glass transition temperature were determined to be 206 °C and 60 °C, respectively, while the equilibrium melting temperature was determined to be 248 °C. Characterization of the crystallization kinetics showed that nylon 13,6 exhibits...
The influence of aspect ratio of multiwalled carbon nanotube (MWCNTs) on rheological and electrical properties of MWCNT/polypropylene (PP) composites has been studied. Owing to the pre-grinding for MWCNTs and the efficient twin-extruder mixing, the dispersion of MWCNTs of different aspect ratios in the PP matrix is all uniform and homogeneous. With incorporation of 10 wt% MWCNTs with an aspect ratio...
Highly transparent polyimide (PI) with a low coefficient of thermal expansion (CTE), comparable to that of copper foil (17 ppm/K), has been developed in conjunction with a relatively rigid and symmetrical monomer, trans-cyclohexyl diamine (CHDA), and in so doing we clarified the effectiveness of a multi-block copolymer system in terms of maximizing the degree of CTE reduction as well as mechanical...
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