Effects of molecular weight distribution on the spinodal temperature of polymer mixtures

Jw, Kim; Kim, Y; Ck, Kim

doi:10.1002/pi.1628

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…At a low conversion (before gelation), the molecular weight of the growing thermoset epoxy–anhydride n ‐mers is distributed with a Poisson distribution28, 29 and increases with conversion 29. The additional degree of freedom due to the molecular weight distribution results in the destabilization of the polymer mixture 30. It has been found that the monodisperse assumption gives a reasonable approximation when macroscopic separation is considered, although the effect of polydispersity must be taken into account to realize a more exact analysis 14.…”

Section: Resultsmentioning

confidence: 99%

Effects of the molecular weight of poly(ether imide) on the viscoelastic phase separation of poly(ether imide)/epoxy blends

Gan

Wei

et al. 2009

J of Applied Polymer Sci

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ABSTRACT:The phase separation of diglycidyl ether of bisphenol A/methyl tetrahydrophthalic anhydride blends modified with three poly(ether imide)s (PEIs) of different molecular weights was investigated with scanning electron microscopy (SEM) and time-resolved light scattering (TRLS). The morphologies observed by SEM for the three blends were all close to a cocontinuous structure with different periodic distances. The results of TRLS indicated that the phase separation for the PEI-modified epoxy blends took place according to the spinodal decomposition mechanism and the onset time of phase separation, with the periodicity of the phase structure depending on the PEI molecular weight and cure temperature. The time-dependent peak scattering vector was simulated with a Maxwell-type viscoelastic relaxation equation, indicating that the coarsening process of epoxy droplets was mainly controlled by the viscoelastic flow. Relaxation times obtained at different temperatures for the three blends could be described by the Williams-Landel-Ferry equation. The effects of the PEI molecular weight on the processes of viscoelastic phase separation were investigated, and the observed trends could be explained qualitatively through thermodynamic analysis.

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Section: Resultsmentioning

confidence: 99%

Effects of the molecular weight of poly(ether imide) on the viscoelastic phase separation of poly(ether imide)/epoxy blends

Gan

Wei

et al. 2009

J of Applied Polymer Sci

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“…The MW distribution influenced the phase stability of a polymer mixture. A polymer blend of mixed polymers having a narrow MW distribution was reported to show phase stability compared to polymers with a broad MW distribution [ 20 ]. A recent report described that the thermo-responsive transition of poly(N-isopropylacrylamide) was affected by MW and the distribution of MW [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Fractionation of Regenerated Silk Fibroin and Characterization of the Fractions

Aoki

Ishikawa

et al. 2021

Molecules

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The molecular weight (MW) of regenerated silk fibroin (RSF) decreases during degumming and dissolving processes. Although MW and the MW distribution generally affect polymer material processability and properties, few reports have described studies examining the influences of MW and the distribution on silk fibroin (SF) material. To prepare different MW SF fractions, the appropriate conditions for fractionation of RSF by ammonium sulfate (AS) precipitation process were investigated. The MW and the distribution of each fraction were found using gel permeation chromatography (GPC) and SDS-polyacrylamide electrophoresis (SDS-PAGE). After films of the fractionated SFs formed, the secondary structure, surface properties, and cell proliferation of films were evaluated. Nanofiber nonwoven mats and 3D porous sponges were fabricated using the fractionated SF aqueous solution. Then, their structures and mechanical properties were analyzed. The results showed AS precipitation using a dialysis membrane at low temperature to be a suitable fractionation method for RSF. Moreover, MW affects the nanofiber and sponge morphology and mechanical properties, although no influence of MW was observed on the secondary structure or crystallinity of the fabricated materials.

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Compatibility of Statistical Aromatic Copolycarbonates in Polystyrene and Poly(carbonate of Bisphenol A) Blends

Penco

Sartore

Sciucca

et al. 2006

International Journal of Polymeric Materials and Polymeric Biom

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In this work the compatibility of aromatic copolycarbonates containing\ud bisphenol A (BPA) and tetramethyl bisphenol A (TMBPA) with polystyrene (PS) was\ud investigated. Miscibility prediction data were used to select copolycarbonates of\ud potential interest for developing highly compatible blends. Statistical\ud copolycarbonates (CPCs) containing different BPA/TMBPA molar ratios were\ud synthesized by polycondensation reaction and the effect of copolymer composition\ud on the PS/CPC miscibility was studied. The blends were prepared by casting from\ud chloroform solutions and/or melt mixing. The compatibility was evaluated by\ud optical microscopy (OM), calorimetric (DSC), and dynamic-mechanical thermal (DMTA)\ud analyses. Two glass transition temperatures were found for all the prepared PS/CPC\ud blends, but an improvement of compatibility was obtained increasing TMBPA content\ud in CPC copolymer. On the other hand, blends of polycarbonate of bisphenol A (PCPA)\ud and CPCs were characterized by a single glass transition temperature and\ud transesterification reaction was noticed. Finally, a compatibilization effect of\ud CPCs and polycarbonate of tetramethyl-bisphenol A (PCTMP) was highlighted in\ud PS/PCPA/CPCs and PS/PCPA/PCTMP three components blends

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Effects of molecular weight distribution on the spinodal temperature of polymer mixtures

Cited by 3 publications

References 26 publications

Effects of the molecular weight of poly(ether imide) on the viscoelastic phase separation of poly(ether imide)/epoxy blends

Effects of the molecular weight of poly(ether imide) on the viscoelastic phase separation of poly(ether imide)/epoxy blends

Fractionation of Regenerated Silk Fibroin and Characterization of the Fractions

Compatibility of Statistical Aromatic Copolycarbonates in Polystyrene and Poly(carbonate of Bisphenol A) Blends

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