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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 …
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.
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 …
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 …
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.
The Effects Of Low Molar Mass Diluents On The Microstructure Of Ionomers, Robert Weiss
The Effects Of Low Molar Mass Diluents On The Microstructure Of Ionomers, Robert Weiss
Robert Weiss
The effect of polar and nonpolar low molar mass diluents on the microstructure of lightly sulfonated polystyrene (SPS) ionomers was studied using electron spin resonance spectroscopy, small-angle x-ray scattering, and dynamic mechanical analysis. Nonpolar diluents primarily affected the hydrocarbon - rich phase, while polar diluents partitioned into the ion-rich regions and disrupted the supramolecular structure. The ionic clusters remained intact, even at elevated temperatures, upon the addition of nonpolar solvents such as dodecane and dioctylphthalate. More polar solvents such as methanol and glycerol swelled the ionic domains and promoted increased mixing of the two phases.
Assessment Of Time-Temperature Superposition Of Linear Viscoelastic Behavior Of Strongly Interacting Polymer Blends: N-Methylated Nylon 2,10 And Lightly Sulfonated Polystyrene Ionomers, Robert Weiss
Robert Weiss
The applicability of time-temperature superposition of dynamic mechanical data for miscible polymer blends that exhibit strong intermolecular interactions was investigated. Blends of the lithium salt of lightly sulfonated polystyrene ionomers (Li-SPS), 9–12 mol% sulfonation, and N-methylated nylon-2, 10 (mPA) were miscible over the composition range studied, 30–70 wt% ionomer. Time—temperature superposition (TTS) of the storage and loss shear moduli measured at frequencies of 0.01–500 rad s−1 was applicable over the temperature range from 95 to 185°C. The molecular-weight distribution of the ionomer had no effect on the applicability of TTS. The success of TTS was attributed to the complexation of …
Studies On A Diphenylether Modified Poly(Phenyl-1,4-Phenylene Terephthalate) Liquid Crystalline Polymer And Its Blends With Polycarbonate And Polysulfone, Robert Weiss
Robert Weiss
Blends of a thermotropic liquid crystalline polymer, LCP, (4,4′-dicarboxy diphenyl ether modified poly(phenyl-1,4-phenylene terephthalate)) with polycarbonate and polysulfone were prepared and characterized with respect to their thermal properties, viscoelastic behavior, processability and mechanical properties. The processability of the thermoplastics was significantly improved by the addition of small amounts of LCP. This was also reflected by decreases in the steady shear viscosities, though the dynamic complex viscosities of the blends were generally similar or higher than those of the individual component polymers. Composite fibers were spun from the blends and the tensile moduli and strengths were consistent with a morphology of …
Strain Induced Crystallization Of Peek, Robert Weiss
Strain Induced Crystallization Of Peek, Robert Weiss
Robert Weiss
Strain-induced crystallization of poly(ether ether ketone) (PEEK) was studied by the use of a parallel plate rheometer. The experimental variables included preheating time, crystallization temperature, and shear rate. The crystallization kinetics were characterized by means of an induction time defined as the time elapsed from the start of shearing to the onset of crystallization. The experimental results showed that the induction time for strain-induced crystallization of PEEK was significantly shorter than that for crystallization under quiescent condition, and that strain-induced crystallization was much less temperature dependent than quiescent crystallization. The activation energy for strain-induced crystallization was found to be 0.035kcal/mole, …
Properties Of Polyethylene Modified With Phosphonate Side Groups I. Thermal And Mechanical Properties, Robert Weiss
Properties Of Polyethylene Modified With Phosphonate Side Groups I. Thermal And Mechanical Properties, Robert Weiss
Robert Weiss
Low-density polyethylene was modified by the inclusion of phosphonate ester pendent groups by using an oxidative chlorophosphonylation reaction followed by esterification of the polyethylene poly(phosphonyl chloride) with an alcohol. Two different types of phosphonate esters were prepared: dimethyl phosphonate from the reaction with methanol and a phosphonate graft copolymer from the reaction with hydroxy-terminated poly(ethylene oxide) (PEO). For the latter, oligomers with molecular weights of 350 and 750 were used. For each type of phosphonate, a series of polymers were prepared with pendent group concentrations ranging from 0 to 9.1 substituents per 100 carbon atoms. The modified polymers were characterized …
Molecular Dynamics Simulation Of Chain Collapse Of Random Ionomers In A Poor Solvent, Robert Weiss, Rue Xie
Molecular Dynamics Simulation Of Chain Collapse Of Random Ionomers In A Poor Solvent, Robert Weiss, Rue Xie
Robert Weiss
Chain collapse and ionic aggregation of sodium salts of lightly sulphonated polystyrene (Na-SPS) in a poor solvent were simulated by molecular dynamics of a single ionomer chain in vacuum. Ionomers with a sulphonation level from 0 to 28 mol% and a polymerisation index of 50 were constructed by virtual copolymerisation of the ionic and nonionic species. Chain collapse occurred by a three-stage process. Local collapse of the ionomer occurred in the first stage, which was marked by sharp decreases in both the radius of gyration (Rg) and the chain end-to-end distance (D). The second stage was a transition to a …
Strength Improvement Of Short Graphite Fiber-Reinforced Polypropylene, Robert Weiss
Strength Improvement Of Short Graphite Fiber-Reinforced Polypropylene, Robert Weiss
Robert Weiss
The Improvement of the tensile strength of discontinuous graphite fiber-reinforced polypropylene is described. Two methods were employed: (1) modification of the polymer backbone by the introduction of acrylic acid grafts and (2) varying the chemistry of the fiber sizing. The strength improvements attained are attributed to intermolecular interactions, such as hydrogen bonding, which improve the adhesion between the fiber and the polymer.
The Influence Of Intermolecular Interactions On The Melt Rheology Of A Propylene-Acrylic Acid Copolymer And Its Salts., Robert Weiss
The Influence Of Intermolecular Interactions On The Melt Rheology Of A Propylene-Acrylic Acid Copolymer And Its Salts., Robert Weiss
Robert Weiss
Ionomers based on propylene–acrylic acid copolymer have been prepared and their rheological behavior studied. With different cations the melt viscosity at any shear rate increases as tributylamine salt < acid < zinc salt < sodium salt. Similarly, the activation energies for viscous flow follow the order polypropylene ∼ tributylamine salt < acid ∼ zinc salt < sodium salt. These results are a consequence of intermolecular interactions between salt groups for the metal acrylate derivatives and hydrogen bonding for the acid derivatives. Strong ionic interactions are absent in the tributylamine salt because of steric hindrance of the bulky amine substituents. The glass transition temperatures for these …
The Synthesis Of Sulfonated Polymers By Free Radical Copolymerization. (Poly(Butadiene-Co-Sodium Styrene Sulfonate)., Robert Weiss
The Synthesis Of Sulfonated Polymers By Free Radical Copolymerization. (Poly(Butadiene-Co-Sodium Styrene Sulfonate)., Robert Weiss
Robert Weiss
The copolymerization of butadiene with sodium styrene sulfonate was studied and the copolymer products characterized. In general these copolymers contain 0.5–4 mole% of sulfonated monomer. The effects of the following reaction variables are described: emulsifier type and concentration, monomers feed ratio, chain transfer agent concentration, and reaction conversion. The products were heterogeneous with regard to composition, molecular weight, and solubility behavior. Copolymers prepared under certain conditions exhibited strong intermolecular interactions derived from associations of the ionic species as observed in other ionomers.
Improvement Of The Processability Of Poly(Ether Ketone Ketone) By The Addition Of A Liquid Crystalline Polymer, Robert Weiss
Improvement Of The Processability Of Poly(Ether Ketone Ketone) By The Addition Of A Liquid Crystalline Polymer, Robert Weiss
Robert Weiss
The addition of a thermotropic liquid crystalline, wholly aromatic copolyester, TLCP, improved the melt processability of poly(ether ketone ketone), PEKK. The tensile strength and modulus of the blends also improved with increasing TLCP, but the elongation at break decreased significantly. The blends were phase-separated, but the polymers were partially miscible as evident from shifts of the glass transition temperature (Tg) of each component towards that of the other component in the blend. Similarly, the melting points (Tm) of both components were depressed by blending. When the crystallization temperature was above Tm of the TLCP, the PEKK crystallization rate in the …
Synthesis, Properties, And Structure Of Sulfonate Ionomers, Robert Weiss
Synthesis, Properties, And Structure Of Sulfonate Ionomers, Robert Weiss
Robert Weiss
The unique mechanical and rheological properties of ionomers are sources of growing academic and industrial interest. The relationship between the complex properties that ionomers exhibit and their microstructure has been the subject of numerous studies. A greater understanding of this relationship is necessary if one wishes to manipulate the ionic interactions in order to control the properties of the polymer.
Compatibilization Of Syndiotactic Polystyrene And A Thermotropic Liquid Crystalline Polymer Blend With A Zinc Salt Of A Sulfonated Polystyrene Ionomer, Robert Weiss
Robert Weiss
A zinc salt of a lightly sulfonated (4.5 mol %) polystyrene ionomer was used to compatibilize a 3/1 (w/w) blend of syndiotactic polystyrene and a wholly aromatic thermotropic liquid-crystalline polymer (TLCP). The addition of the ionomer significantly reduced the dispersed TLCP domain size and improved the tensile strength, ultimate elongation, and flexural toughness of the blend
Microstructure Of Block Copolymers Of Polystyrene And Poly(Ethylene-Alt-Propylene), Robert Weiss
Microstructure Of Block Copolymers Of Polystyrene And Poly(Ethylene-Alt-Propylene), Robert Weiss
Robert Weiss
The microstructure and microphase behaviour of diblock (Ma ≈ 27 and 50 kg mol−1) and triblock (Ma ≈ 50kg mol−1) copolymers of polystyrene (PS) and poly(ethylene-alt-propylene) (PEP) were studied by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and dynamic mechanical thermal analysis (DMTA). The composition was varied from 10 wt.% to 50 wt.% PS. The morphology of solution-cast and compression-moulded samples was compared. The common packing arrangements of body-centred-cubic (BCC) spheres, hexagonal-close-packed (HCP) cylinders and alternating lamellae were observed for the PS microdomains using SAXS and TEM. A microphase texture of PS spheres with a liquid-like packing (LLP) …
Analysis Of Caprolactam Polymerization, Robert Weiss
Analysis Of Caprolactam Polymerization, Robert Weiss
Robert Weiss
No abstract provided.
Characterization Of The Block Microstructure In Block Copolymer Ionomers Using Small Angle X-Ray Scattering, S. Mani, Robert Weiss, C. E. Williams, S. F. Hahn
Characterization Of The Block Microstructure In Block Copolymer Ionomers Using Small Angle X-Ray Scattering, S. Mani, Robert Weiss, C. E. Williams, S. F. Hahn
Robert Weiss
The block microstructure of a series of diblock copolymer ionomers was investigated using synchrotron small-angle x-ray scattering (SAXS). The base materials used were poly[styrene-b-(ethylene/propylene)] (SEP) diblock copolymers with a constant total molecular weight of ca. 50 kg/mol, but three different compositions : 20.3 wt%, 35.6 wt% and 50.4 wt% polystyrene (PS). The polystyrene microphase structures for these unmodified diblock copolymers were cylindrical, lamellar and lamellar, respectively. Ionomers were synthesized from the block copolymers by lightly sulfonating the PS blocks, followed by neutralization to the sodium and zinc salts. The introduction of ionic species into the PS blocks perturbed the block …
Comparisons Of Styrene Ionomers Prepared By Sulfonating Polystyrene And Copolymerizing Styrene With Styrene Sulfonate, Robert Weiss
Comparisons Of Styrene Ionomers Prepared By Sulfonating Polystyrene And Copolymerizing Styrene With Styrene Sulfonate, Robert Weiss
Robert Weiss
As part of a continuing study of ion-containing polymers, a comparison has been made on styrene-based sulfonate ionomers obtained by two different processes. Copolymers of styrene with sodium styrene sulfonate (SSS) have been compared with corresponding polymers obtained by the sulfonation/neutralization of preformed polystyrene (S–PS). The former system covered a range of sulfonate level from 1 to 30 mol %, while the latter ranged from about 1 to 7 mol %. The characterization of these materials has been conducted using solubility behavior, dilute solution viscometry, thermal mechanical analysis, density measurements, and water adsorption studies. At low (ca. 1%) levels the …
Time Dependent Characteristics Of Sulfonated Epdm Containing Zinc Stearate I. Thermal Behavior, Robert Weiss
Time Dependent Characteristics Of Sulfonated Epdm Containing Zinc Stearate I. Thermal Behavior, Robert Weiss
Robert Weiss
The crystallization and melting of zinc stearate (ZnSt) in ZnSt-plasticized compositions of ethylene–propylene–diene terpolymer (EPDM) and sulfonated EPDM (S-EPDM) have been studied by differential scanning calorimetry. While immiscible in both EPDM and S-EPDM, ZnSt is compatible with the latter. This compatibility presumably arises from either electrostatic or dipole–dipole interactions between the carboxylate functionality of ZnSt and the sulfonate groups of the polymer. The crystallization behavior of ZnSt is significantly perturbed when the material is added to S-EPDM, and the crystalline ZnSt phase that results is strongly time dependent. ZnSt first crystallizes as small imperfect crystals when the compositions are cooled …
The Effect Of Aging On The Thermal Behavior Of Sulfonated Polystyrene, Robert Weiss
The Effect Of Aging On The Thermal Behavior Of Sulfonated Polystyrene, Robert Weiss
Robert Weiss
The thermal properties of an ionomer glass, lightly sulfonated polystyrene, was studied as a function of aging at room temperature after being cooled from the melt. An anomalous endothermic event below Tg was observed by differential scanning calorimetry; the intensity of this excess enthalpy was a function of time and sulfonate concentration. It is suggested that the origin of this relaxation may be due in part to morphological changes that occur as a consequence of electrostatic interactions of the sulfonate groups.
The Influence Of Thermal History On The Microstructure Of Sulfonated Polystyrene Ionomers, Robert Weiss
The Influence Of Thermal History On The Microstructure Of Sulfonated Polystyrene Ionomers, Robert Weiss
Robert Weiss
No abstract provided.
Novel Reinforced Polymers Based On Blends Of Polystyrene And A Thermotropic Liquid Crystalline Polymer, Robert Weiss
Novel Reinforced Polymers Based On Blends Of Polystyrene And A Thermotropic Liquid Crystalline Polymer, Robert Weiss
Robert Weiss
A thermotropic liquid crystalline polymer (LCP), when added to polystyrene (PS), can function as both a processing aid and a reinforcing filler. Thermal, rheological, and mechanical properties of the pure components and blends containing up to 10 percent LCP are reported. The LCP used is immiscible with PS, and when an extensional component of flow is present during processing, the LCP forms an elongated fibrous phase oriented in the flow direction. This oriented phase lubricates the melt, substantially lowering the viscosity. When the processed blend is cooled, the dispersed fibrous LCP phase is preserved in the solidified material. The LCP …
A New Rheo-Light-Scattering Instrument For The Study Of The Phase Behavior Of Polymer Blends Under Simple-Shear Flow, Robert Weiss
A New Rheo-Light-Scattering Instrument For The Study Of The Phase Behavior Of Polymer Blends Under Simple-Shear Flow, Robert Weiss
Robert Weiss
A rheo‐light‐scattering instrument for investigating the influence of shear on the phase behavior of polymer blends was constructed from a commercial parallel‐plate rheometer. Laser light scattering from the sample plane formed by the flow and vorticity directions was projected on a screen, and a combination of a camera lens and a charge‐coupled device detector was used to record the scattering pattern. The rheometer, which can generate angular velocities of up to 100 rad/s and measure torque and normal forces up to 9.8×103 N m and 9.8×105 N, respectively, is suitable for studying polymer melts at stresses up to 9.1 kPa. …
Liquid Crystalline Ionomers: 2. Synthesis And Characterization Of A Main-Chain Liquid Crystalline Polymer Containing Terminal Sulfonate Groups, Robert Weiss
Robert Weiss
Liquid crystalline ionomers containing sulfonate groups on the terminal unit of the chain were synthesized by an interfacial condensation reaction of 4,4′-dihydroxy-α,α′-dimethyl benzalazine, the monofunctional dye fast yellow (FY), and a 50/50 mixture of sebacoyl and dodecanedioyl dichlorides. The weight-average molecular weights were estimated from inherent viscosity measurements to be between 6000–11,000 and the sodium sulfonate concentrations ranged from 0–18.4 meq/100 g polymer. Elemental analyses, however, indicated much higher molecular weights, which suggested that there was a distribution of chains with one, two, or no FY endgroups. The polymers were semicrystalline and melted at ca. 140°C to form nematic mesophases …
Synthesis And Characterization Of Poly(Styrene-Co-Vinyl Phosphonate) Ionomers., Robert Weiss
Synthesis And Characterization Of Poly(Styrene-Co-Vinyl Phosphonate) Ionomers., Robert Weiss
Robert Weiss
Poly(styrene-co-diethyl vinylphosphonate) copolymers were synthesized by free radical copolymerization. The ester groups of the copolymers were hydrolyzed to phosphonic acid groups, and the sodium and zinc salts ionomers were obtained by neutralization. The structure and the thermal and viscoelastic properties of the copolymers and ionomers were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and small-angle X-ray scattering. The phosphonate ester lowered the glass transition temperature (Tg) of polystyrene. The free acid derivatives and metal phosphonates increased Tg and produced a rubbery plateau region in the viscoelastic properties due to the formation of …
Synthesis Of Conductive Elastomeric Foams By An In Situ Polymerization Of Pyrrole Using Supercritical Carbon Dioxide And Ethanol Cosolvents, Robert Weiss
Robert Weiss
Electrically conductive polyurethane (PU) foams were prepared by first impregnating a PU foam with ferric trifluoromethane sulfonate (ferric triflate) using supercritical carbon dioxide (scCO2) containing 0.2–1.3 vol.% ethanol as a cosolvent, and then exposing the foam to pyrrole vapor. Polypyrrole (PPy) was formed in situ by an chemical oxidative polymerization. The conductivity of the composite foams ranged from 10−7 to 10−2 S/cm, depending on the amount of ethanol and impregnation time used. The amount of PPy produced depended on the amount of oxidant absorbed by the foam. For low ethanol concentrations and/or short impregnation time, the PPy produced was concentrated …