Phasex Corporation

Lawrence, MA, United States

Phasex Corporation

Lawrence, MA, United States

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Schmidt R.G.,Dow Corning | Gordon G.V.,Dow Corning | Dreiss C.A.,King's College London | Cosgrove T.,University of Bristol | And 3 more authors.
Macromolecules | Year: 2010

The zero-shear-rate viscosity η 0 of polymer-nanocomposites (PNCs) derived from entangled poly(dimethylsiloxane)s and rigid polysilicate nanoparticles were investigated as a function of molecular size and concentration. Narrow molecular weight fractions of polymer and nanoparticle were obtained by supercritical fluid extraction. Molecular weight properties were analyzed by size exclusion chromatography and the nanoparticle radius of gyration R g was characterized by small-angle neutron scattering. All seven polysilicate fractions were smaller (0.75 ≤ R g,nm ≤ 2.1) than the five polymers (3.0 ≤ R g,nm ≤ 12). Relative to the polymer η 0 the PNC η 0 exhibited either plasticization (viscosity reduction) or reinforcement (viscosity increase). Only reinforcement was observed in PNCs based on the polymer below M c-the critical molecular weight for chain entanglement effects to start influencing η 0-which included an increase in the PNC η 0 by over 3 orders of magnitude using 0.30 volume fraction of the largest nanoparticle. For polymers above M c, the crossover from plasticization to reinforcement behavior could be described by a critical molecular-size ratio based on the unperturbed R g of the nanoparticle and of the polymer. Viscosity reductions of up to 52% were achieved, and were more significant at the higher of the two nanoparticle concentrations studied. The critical nanoparticle-to-polymer R g ratio at 298 K was 0.18 ± 0.006 and 0.13 ± 0.003 for a nanoparticle volume fraction of 0.17 and 0.30, respectively. A generalized form for the concentration dependent crossover ratio is proposed to account for perturbations in the molecular size of the PNC components that can be the basis for future studies. The effects of particle size polydispersity and temperature are discussed. © 2010 American Chemical Society.


Favaloro M.,CompositeTechs LLC | Schonemann H.,Phasex Corporation | Krukonis V.,Phasex Corporation
CAMX 2015 - Composites and Advanced Materials Expo | Year: 2015

The application and value of supercritical fluids are well known and exploited in the chemical processing industry. However, the vast majority of seasoned materials engineers are not aware of the value, or even the technical aspects, of supercritical fluid processing as it relates to their respective industries. This paper provides an overview of the supercritical fluid technology. Advantages and disadvantages are compared with other chemical processes, and specific examples in a variety of industries that utilize supercritical fluids are described. Key examples of supercritical fluid processing in the plastics and composites industries are provided.


Wang Y.,University of Pittsburgh | Williams K.T.,Phasex Corporation | Li L.,University of Pittsburgh
Macromolecular Chemistry and Physics | Year: 2011

For decades, the viscosity (ν)-molecular weight (M) relationship of linear polymer melts has been successfully described by the Debye-Bueche model when M is lower than critical molecular weight (Mc). However, recent studies on diolic perfluoropoly (oxyethylene-ran-oxymethylene) (DPFPO), a linear polymer with polar endgroups, raise uncertainty on the validity of Debye-Bueche model. Experimental results show that the Debye-Bueche model does not hold for DPFPO, which has been attributed to the fact that the strong intermolecular endgroup-endgroup coupling is not considered in original Debye-Bueche model. A modified molecular-level model, in which the endgroup-endgroup coupling is taken into consideration, is proposed to interpret the anomalous ν-M relationship of DPFPO. For decades, the viscosity (ν)-molecular weight (M) relationship of linear polymer melts has been successfully described by the Debye-Bueche model when M is lower than critical molecular weight (Mc). Experimental results show that the Debye-Bueche model does not hold for some polymers with polar endgroups and a modified molecular-level model is proposed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Gordon G.V.,Dow Corning | Schmidt R.G.,Dow Corning | Quintero M.,University of Bristol | Benton N.J.,University of Bristol | And 4 more authors.
Macromolecules | Year: 2010

Introducing hard spherical polysilicate nanoparticles up to 0.30 volume fraction into narrow molecular weight (M) fractions of poly(dimethylsiloxane) (PDMS) that spanned its unentangled and entangled polymer chain regimes produced transparent and colorless polymer nanocomposites (PNCs) with zero-shear-rate viscosities η0 either greater or less than the polymer matrix. Below the PDMS critical molecular weight for chain entanglements to start influencing η0 (Mc), nanoparticle inclusion increased the PNC η0 consistent with the reinforcement mechanism from traditional fillers of much larger particle sizes. Conversely, PNCs using entangled PDMS (M > Mc) exhibited a reduction in η0 within a certain concen tration range of nanoparticles. The reduction in η0 was proposed to be primarily due to the dilution of the entanglement density of polymer chains as evidenced by a shift to higher M c that was a function of the volume fraction of polymer chains, ℙ1 -0.56, and an increase in the translational motion manifested through an increase in the polymer self-diffusion coefficient. In contrast to the ℙ1 -1 dependence of Mc in concentrated polymer solutions, the dilution effect of the polysilicate nanoparticle on the polymer chain entanglement density was moderated by polymer adsorption, hydrodynamic effects and to some extent by free volume. Above M c, the PNC η0 scaled as ℙ2M w 3.5 where Mw is the polymer weight-average molecular weight. Nuclear magnetic resonance T2 spin-spin relaxation measurements found that the increase in polymer mobility due to the nanoparticles became evident only above 2Mc. In contrast to the η0 results, the transition to a stronger Mw dependence by 1/T2 shifted to lower M with increasing nanoparticle concentration. © 2010 American Chemical Society.


Rheaume R.,Phasex Inc.
54th Annual British Conference of Non-Destructive Testing, NDT 2015 | Year: 2015

In our modern world, learning has become an essential part of our working life. We need to maintain our existing skills as well as acquire new ones just to cope we the technological changes. The way we learn NDT has more or less been the same since the beginning: a teacher at the front of the room transmit his knowledge to a group of people. Although this approach has been proven, new learning methods must be implemented to cope with the requirements of productivity and continuous learning. Online training has already proven its efficiency in many sectors of activity. An overview of the challenges faced by online training in NDT and their associated solutions will be presented.


Patent
U.S. Smokeless Tobacco Co. and Phasex Corporation | Date: 2010-09-15

Methods of selectively reducing constituents in tobacco as well as the tobacco obtained by such methods are disclosed. Subcritical fluids, e.g., liquid carbon dioxide, serve as the reduction media.


Patent
Phasex Corporation and U.S. Smokeless Tobacco Company LLC | Date: 2013-10-11

Methods of selectively reducing constituents in tobacco as well as the tobacco obtained by such methods are disclosed. Subcritical fluids, e.g., liquid carbon dioxide, serve as the reduction media.


The present invention relates to the energy efficient and selective extraction of dilute concentrations of biomolecules, e.g., small organic compounds, e.g., one or more C2-C6 alcohols, one or more C3-C5 carboxylic acids, one or more C8-18 fatty alcohols, one or more C1-C18 dicarboxylic acids, one or more furfurals, one or more furans, one or more butanediols, one or more butadienes, and mixtures thereof, from an aqueous solution using liquid phase dimethyl ether (DME).


Patent
Phasex Corporation and U.S. Smokeless Tobacco Company | Date: 2011-03-09

Methods of selectively reducing constituents in tobacco as well as the tobacco obtained by such methods are disclosed. Subcritical fluids, e.g., liquid carbon dioxide, serve as the reduction media.


The present invention relates to the energy efficient and selective extraction of dilute concentrations of C2-C6 alcohols from an aqueous solution using liquid phase dimethyl ether.

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