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Articles 1 - 30 of 149
Full-Text Articles in Engineering
Ftir Studies Of Ionic Interactions In Blends, Robert Weiss
Ftir Studies Of Ionic Interactions In Blends, Robert Weiss
Robert Weiss
No abstract provided.
Supercritical Carbon Dioxide Aided Preparation Of Conductive Polyurethane-Polypyrrole Composites, Robert Weiss
Supercritical Carbon Dioxide Aided Preparation Of Conductive Polyurethane-Polypyrrole Composites, Robert Weiss
Robert Weiss
Conductive polyurethane (PU) foams were prepared using a two-step procedure. First, PU foams were impregnated with the oxidant I2 from a scCO2 solution. Subsequently, the foams were subjected to pyrrole vapor, which polymerized within the foam in the presence of the oxidant. The reduced form of iodine as a result of the oxidative polymerization of pyrrole functions as a dopant. The conductivities of the foams ranged from 10−7 to 10−2 S/cm and the foams were flexible and not brittle. The concentration of conductive polypyrrole, i.e. the PPy–I2 charge-transfer complex, needed to achieve a conductivity of 10−4–10−3 S/cm was about 22% …
Supercritical Carbon Dioxide Aided Preparation Of Conductive Polyurethane-Polypyrrole Composites, Robert Weiss
Supercritical Carbon Dioxide Aided Preparation Of Conductive Polyurethane-Polypyrrole Composites, Robert Weiss
Robert Weiss
Conductive polyurethane (PU) foams were prepared using a two-step procedure. First, PU foams were impregnated with the oxidant I2 from a scCO2 solution. Subsequently, the foams were subjected to pyrrole vapor, which polymerized within the foam in the presence of the oxidant. The reduced form of iodine as a result of the oxidative polymerization of pyrrole functions as a dopant. The conductivities of the foams ranged from 10−7 to 10−2 S/cm and the foams were flexible and not brittle. The concentration of conductive polypyrrole, i.e. the PPy–I2 charge-transfer complex, needed to achieve a conductivity of 10−4–10−3 S/cm was about 22% …
Development Of Miscible Blends Of Bisphenol-A Polycarbonate And Sulfonated Polystyrene Ionomers From Intrapolymer Repulsive Interactions, Robert Weiss
Robert Weiss
Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the phase behavior and interactions of blends of the free acid derivative and lithium and sodium salts of lightly sulfonated polystyrene (MSPS) with Bisphenol A polycarbonate (PC). The blends exhibited upper critical solution temperature (UCST) phase behavior and a miscibility window with respect to the sulfonation level. At a fixed blend composition, a minimum in the cloud point temperature occurs at the sulfonation level marking the middle of the miscibility window. The miscibility window depended on the sulfonate cation used. No interactions involving either the carbonate …
Rheological Behavior Of Liquid Crystalline Polymer/Polymer Blends, Robert Weiss
Rheological Behavior Of Liquid Crystalline Polymer/Polymer Blends, Robert Weiss
Robert Weiss
This paper reviews the literature on the rheological behavior of liquid crystalline polymer/polymer blends. The advantages of blending a LCP with a thermoplastic polymer is that the LCP serves as a processing aid and can also form a reinforcing phase. Rheology plays an important role in determining the morphology and hence the mechanical properties of these blends. This review also discusses the slow behavior of neat liquid crystalline polymers.
Synthesis And Thermal Properties Of Telechelic Poly(Lactic Acid) Ionomers, Robert Weiss
Synthesis And Thermal Properties Of Telechelic Poly(Lactic Acid) Ionomers, Robert Weiss
Robert Weiss
Telechelic poly(lactic acid) (PLA) ionomers were synthesized using a chemical recycling process. A transesterification reaction between a commercial PLA and 2-hydroxyethyl methacrylate or ethylene glycol was used to produce a hydroxy-terminated PLA. The hydroxy-terminated PLA was then reacted with itaconic anhydride to produce terminal carboxylic acid groups, which were neutralized with appropriate metal acetates to produce Na-, Li-, K-, Zn-, Ca- and Y-ω- and α,ω-telechelic PLA ionomers. 1H NMR spectroscopy was used to confirm the presence of the itaconic acid end-groups and FTIR spectroscopy was used to quantify the extent of neutralization. The addition of the ionic groups increased the …
Sulfonated Polystyrene Ionomers Prepared By Emulsion Copolymerization Of Styrene And Sodium Styrene Sulfonate, Robert Weiss
Sulfonated Polystyrene Ionomers Prepared By Emulsion Copolymerization Of Styrene And Sodium Styrene Sulfonate, Robert Weiss
Robert Weiss
Sulfonated polystyrene (S–PS), which is of considerable scientific and technological interest, has been traditionally prepared by the sulfonation of preformed polystyrene. This report describes the preparation and properties of S–PS prepared by emulsion copolymerization of styrene and sodium styrene sulfonate. S–PS prepared by copolymerization gave solubility, solution behavior and thermal characteristics that are consistent with an ionomeric structure. The solubility characteristics indicated some chain-to-chain sulfonate heterogeneity. Thermal analysis studies indicated that the glass transition does not increase with increasing sulfonate content. This is contrary to what has been observed for S–PS prepared by sulfonation and suggests that the S–PS prepared …
New Design Of Shape Memory Polymers: Mixtures Of An Elastomeric Ionomer And Low Molar Mass Fatty Acids And Their Salts, Robert Weiss
New Design Of Shape Memory Polymers: Mixtures Of An Elastomeric Ionomer And Low Molar Mass Fatty Acids And Their Salts, Robert Weiss
Robert Weiss
No abstract provided.
Development Of An Ionomer Tracer For Extruder Residence Time Distribution Experiments, Robert Weiss
Development Of An Ionomer Tracer For Extruder Residence Time Distribution Experiments, Robert Weiss
Robert Weiss
A polymeric tracer was developed from the tributylamine salt of lightly sulfonated polystyrene. The residence time distribution (RTD) measured for the extrusion of polystyrene with this tracer was compared with that measured using conventional particulate tracers, In general, the particulate tracers had a longer mean residence time and a broader RTD, which were attributed to increased mixing of the particulates.
Protonation Of Polyaniline With Lightly Sulfonated Polystyrene, Robert Weiss
Protonation Of Polyaniline With Lightly Sulfonated Polystyrene, Robert Weiss
Robert Weiss
Protonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such as dimethyl sulfoxide (DMSO) and N-methyl pyrrolidone (NMP) was investigated by UV-Vis absorption spectroscopy. The isosbestic point clearly shows that quinoid unit and semiquinoid unit are in equilibrium and is a function of the sulfonic acid concentration. The protonation of polyaniline is retarded in NMP compared to DMSO due to prevalent hydrogen bonding.
Development Of Miscible Blends Of Polyamide-6 And Manganese Sulfonated Polystyrene Using Specific Interactions, Robert Weiss
Development Of Miscible Blends Of Polyamide-6 And Manganese Sulfonated Polystyrene Using Specific Interactions, Robert Weiss
Robert Weiss
No abstract provided.
Examining Elastomer Blends' Phase Behavior, Z. J. Chen, N. G. Remediakis, M. T. Shaw, Robert Weiss
Examining Elastomer Blends' Phase Behavior, Z. J. Chen, N. G. Remediakis, M. T. Shaw, Robert Weiss
Robert Weiss
No abstract provided.
The Effect Of Deformation History On The Morphology Of Blends Of Polycarbonate And A Liquid Crystalline Polymer, Robert Weiss
The Effect Of Deformation History On The Morphology Of Blends Of Polycarbonate And A Liquid Crystalline Polymer, Robert Weiss
Robert Weiss
The effect of deformation history on the morphology and properties of liquid crystalline polymers (LCP) blended with polycarbonate resin was assessed. The addition of an immiscible LCP phase was found to improve the melt processability of the host thermoplastic polymer. In addition, by employing a suitable deformation history, the LCP phase may be elongated and oriented such that a microfibrillar morphology can be retained in the solid state.
Development Of Miscible Blends Of Bisphenol A Polycarbonate And Lightly Sulfonated Polystyrene Ionomers From Intrapolymer Repulsive Interactions, Xinya Lu, Robert Weiss
Development Of Miscible Blends Of Bisphenol A Polycarbonate And Lightly Sulfonated Polystyrene Ionomers From Intrapolymer Repulsive Interactions, Xinya Lu, Robert Weiss
Robert Weiss
Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the phase behavior and interactions of blends of the free acid derivative and lithium and sodium salts of lightly sulfonated polystyrene (MSPS) with Bisphenol A polycarbonate (PC). The blends exhibited upper critical solution temperature (UCST) phase behavior and a miscibility window with respect to the sulfonation level. At a fixed blend composition, a minimum in the cloud point temperature occurs at the sulfonation level marking the middle of the miscibility window. The miscibility window depended on the sulfonate cation used. No interactions involving either the carbonate …
Synthesis Of Conductive Polypyrrole/Polyurethane Foams Via A Supercritical Fluid Process, Yueping Fu, Daniel R. Palo, Can Erkey, Robert Weiss
Synthesis Of Conductive Polypyrrole/Polyurethane Foams Via A Supercritical Fluid Process, Yueping Fu, Daniel R. Palo, Can Erkey, Robert Weiss
Robert Weiss
No abstract provided.
Complexing Blends Of An Ionomer And A Rigid Rod Polymer, L. Shao, Robert Weiss, R. D. Lundberg
Complexing Blends Of An Ionomer And A Rigid Rod Polymer, L. Shao, Robert Weiss, R. D. Lundberg
Robert Weiss
A unique, molecular architecture was developed based on a hydrocarbon soluble backbone with a liquid crystalline side group. Lightly sulfonated polystyrene (SPS) ionomer was complexed with poly(y-benzyl-L-glutamate) (PBLG), an amine terminated synthetic polypeptide, by solution blending in either THF or chloroform. Complexation first occurred by proton transfer from the pendent acid to the amine terminal group. A secondary interaction involved hydrogen-bonding between the sulfonic acid and the carbonyl group on the PBLG chain. This material will have the potential as a molecular composite and unusual solution behavior was observed when the interaction occurred.
Phase Behavior And Specific Interactions Of Poly(Ethylene Glycol)/Poly(Acrylic Acid) Blends: Effect Of Neutralization, Robert Weiss
Phase Behavior And Specific Interactions Of Poly(Ethylene Glycol)/Poly(Acrylic Acid) Blends: Effect Of Neutralization, Robert Weiss
Robert Weiss
No abstract provided.
Small Angle X-Ray Scattering Studies Of Zinc Stearate Filled Sulfonated Epdm, D. A. Jackson, J. T. Koberstein, Robert Weiss
Small Angle X-Ray Scattering Studies Of Zinc Stearate Filled Sulfonated Epdm, D. A. Jackson, J. T. Koberstein, Robert Weiss
Robert Weiss
The crystallization, melting, and dissolution behavior of zinc stearate (ZnSt) in ZnSt-filled sulfonated poly(ethylene-co-propylene-co-ethylidene norbornene) (SEPDM) ionomers was studied by synchrotron small-angle X-ray scattering (SAXS). The melting temperature of ZnSt in the ionomer was considerably lower than in the pure state, which was consistent with the existence of very small ZnSt crystalline domains and a specific interaction between the metal sulfonate groups of the SEPDM and the metal carboxylate groups of ZnSt. Temperature-resolved SAXS showed that, on melting, some or all of the ZnSt rapidly dissolved into the ionomer. Ionic aggregates in the neat ionomer persisted up to 300°C. Microphase …
Properties Of Polyethylene Modified With Phosphonate Side Groups. Ii. Dynamic Mechanical Properties, Robert Weiss
Properties Of Polyethylene Modified With Phosphonate Side Groups. Ii. Dynamic Mechanical Properties, Robert Weiss
Robert Weiss
The viscoelastic behavior of phosphonate derivatives of phosphonylated low-density polyethylene (LDPE) was studied by dynamic mechanical techniques. The polymers investigated contained from 0.2 to 9.1 phosphonate groups per 100 carbon atoms and included the dimethyl phosphonate derivative and two derivatives for which the phosphonate ester group was an oligomer of poly(ethylene oxide) (PEO). The temperature dependences of the storage and loss moduli of the dimethyl phosphonate derivatives were qualitatively similar to those of LDPE. At low phosphonate concentrations, the α, β, and γ dispersion regions characteristic of PE were observed, while at concentrations greater than 0.5 pendent groups per 100 …
Morphology And Phase Behavior Of Blends Of A Styrenic Block Copolymer Ionomer And Poly(Caprolactone), Robert Weiss
Morphology And Phase Behavior Of Blends Of A Styrenic Block Copolymer Ionomer And Poly(Caprolactone), Robert Weiss
Robert Weiss
No abstract provided.
Morphology Development In Polymer Blends Exhibiting Strong Intermolecular Interactions, Robert Weiss, Y. Feng, C. C. Han, A. Karim
Morphology Development In Polymer Blends Exhibiting Strong Intermolecular Interactions, Robert Weiss, Y. Feng, C. C. Han, A. Karim
Robert Weiss
He et al. measured the spinodal decomposition (SD) kinetics of a blend of poly(butyl methacrylate) with a polystyrene modified with 1.5 mol% of a hydroxy-containing comonomer that exhibited intermolecular hydrogen bonding, who studied blends. For small excursions into the spinodal region, multiple structures developed in the blend, which suggested that multiple mechanisms may be involved in the phase separation process. For most cases, however, the kinetics of phase separation followed Cahn-Hilliard theory in the early stage of spinodal decomposition and a self-similar mechanism in the later stages, similar to non-associating polymer blends such as PS/PVME. The failure to observe an …
Microphase Separation In Sulfonated Polystyrene Ionomers, Robert Weiss
Microphase Separation In Sulfonated Polystyrene Ionomers, Robert Weiss
Robert Weiss
Small- and wide-angle x-ray scattering results for a series of un-neutralized and neutralized sulfonated polystyrenes are presented for the range of sulfonation from 0 to 7.26 mol %. From the small-angle scattering it is shown that above the 3 mol % level for both the zinc and sodium salts, a Bragg spacing (37 Å) and diameter (6.9–8.4 Å) of the scattering unit can be calculated. When the concentration of salt is increased, there is no appreciable change in the latter two measurements. The wide-angle data indicate that the cations do not influence to any large extent the basic intramolecular and …
Aromatic Polyamides Of 3,8-Diamino-6-Phenylphenanthridine And Their Molecular Complexes With Sulfonated Polystyrene Ionomers, Robert Weiss
Aromatic Polyamides Of 3,8-Diamino-6-Phenylphenanthridine And Their Molecular Complexes With Sulfonated Polystyrene Ionomers, Robert Weiss
Robert Weiss
No abstract provided.
The Mechanical Properties Of Polypropylenes Reinforced With Short Graphite Fibers, Robert Weiss
The Mechanical Properties Of Polypropylenes Reinforced With Short Graphite Fibers, Robert Weiss
Robert Weiss
The Mechanical properties of injection molded and compression molded graphite fiber-reinforced polypropylenes are discussed. In general, the tensile properties of polypropylene are significantly improved by reinforcement with graphite fibers and to a greater extent than achieved by glass fiber reinforcement. The failure mechanism of these materials involved a combination of matrix fracture and debonding of the fiber-polymer interface. The use temperature of these materials is shown to increase with increasing fiber content and the notch sensitivity is reduced.
Mechanical Behavior Of Double Network Hydrogels Composed Of A Physical Network And A Chemical Network, Robert Weiss
Mechanical Behavior Of Double Network Hydrogels Composed Of A Physical Network And A Chemical Network, Robert Weiss
Robert Weiss
A facile method is developed to fabricate nanocomposite double-network (DN) gels with excellent mechanical properties, which do not fracture upon loading up to 78 MPa and a strain above 0.98, by compositing of carbon nanotubes (CNTs) without organic modification. Investigations of swelling behaviors, and compressive and tensile properties indicate that equilibrium swelling ratio, compressive modulus and stress, fracture stress, Young’s modulus, and yield stress are significantly improved in the presence of CNTs. Scanning electron microscopy (SEM) reveals that the pore size of nanocomposite DN gels is decreased and some embedded micro-network structures are observed on the fracture surface in comparison …
Effect Of Solvents On The Microstructure Of Sulfonated Polystyrene Ionomers, Robert Weiss, J. J. Fitzgerald, D. Kim
Effect Of Solvents On The Microstructure Of Sulfonated Polystyrene Ionomers, Robert Weiss, J. J. Fitzgerald, D. Kim
Robert Weiss
No abstract provided.
Flow-Induced Mixing Of Blends Of Poly(Ethylene-Vinyl Acetate) And Solution Chlorinated Polyethylene, Robert Weiss
Flow-Induced Mixing Of Blends Of Poly(Ethylene-Vinyl Acetate) And Solution Chlorinated Polyethylene, Robert Weiss
Robert Weiss
No abstract provided.
Characterization Of Blends Of An Amorphous Polyamide With Lightly Sulfonated Polystyrene Ionomers, Robert Weiss
Characterization Of Blends Of An Amorphous Polyamide With Lightly Sulfonated Polystyrene Ionomers, Robert Weiss
Robert Weiss
Improved compatibility of blends of polystyrene and an amorphous polyamide was achieved by lightly sulfonating the polystyrene. Hydrogen bonding between amide groups and either sulfonic acid or metal sulfonate groups lowered the interfacial tension between the two polymers, which led to a much finer dispersed phase size in blends involving the sulfonated polystyrene. At relatively high sulfonate to amide ratios, the two polymers formed a miscible blend. Improved mixing of the phases was verified by shifts in the glass transitions, and the specific interactions that occurred were characterized by Fourier transform infrared spectroscopy.
Physically Crosslinked Alkyl Acrylamide Hydrogels: A Sans Analysis Of The Microstructure, Robert Weiss
Physically Crosslinked Alkyl Acrylamide Hydrogels: A Sans Analysis Of The Microstructure, Robert Weiss
Robert Weiss
No abstract provided.
Flow-Induced Phase Changes Of Ps/Pib Blends, R. Wu, M. T. Shaw, Robert Weiss
Flow-Induced Phase Changes Of Ps/Pib Blends, R. Wu, M. T. Shaw, Robert Weiss
Robert Weiss
No abstract provided.