| 1. |
- Carlberg, Magnus, et al.
(författare)
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Ethylene-propylene-rubber (EPR)/polydimethylsiloxane (PDMS) binary polymer blends: Morphology and viscoelastic properties
- 2004
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 94:5, s. 2240-2249
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Tidskriftsartikel (refereegranskat)abstract
- Melt mixed blends of ethylene-propylenerubber (EPR) and polydimethylsiloxane (PDMS) were studied with regard to the composition dependence of the dynamic viscoelastic properties in relation to their morphology. Differential scanning calorimetry, scanning electron microscopy, and dynamic mechanical analysis (DMA) were used together with theoretical predictions to characterize the blends. The investigation of the viscoelastic properties showed significant improvement of the mechanical properties of the blends following the increase of the EPR content. The association of DMA results and theoretical predictions indicated that the studied blends consisted of dispersed PDMS in a matrix of EPR over the whole composition range. The microscopy study of the blends also supports these morphological conclusions. (C) 2004 Wiley Periodicals, Inc.
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| 2. |
- Chenal, J M, et al.
(författare)
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Influence of the process on phase separation induced by radical copolymerization of styrene and divinylbenzene in the presence of reactive polyurethane network precursors
- 2006
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 99:6, s. 2989-2996
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Tidskriftsartikel (refereegranskat)abstract
- Interpenetrating polymer systems based on crosslinked polyurethane (PU) and polystyrene (PS) were prepared at room temperature by a one-shot (in situ) method, starting from an initial homogeneous mixture of reagents via noninterfering mechanisms. Both polymerizations were performed either simultaneously or one after the other. True simultaneity at every stages of the process is not possible. Despite the difference in refractive index of the components, hazy or optically clear films were obtained, thus indicating various levels of phase separation, also confirmed by glass transition temperature (T-g) measurements. The results suggest that controlling the chemistry and process (crosslink density, composition, and time sequence of events) of in situ interpenetrating network formation will give various morphologies, and hence properties, ranging from microphase separated materials to larger macrophase separated materials.
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| 3. |
- Colombini, Didier, et al.
(författare)
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Direct and reverse mechanical modeling of an alkyd acrylic hybrid system: A morphological study
- 2004
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 37:7, s. 2596-2602
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical modeling and dynamic mechanical analysis were associated to investigate the viscoelastic properties of an alkyd acrylic hybrid system in connection with its morphology, which was characterized by transmission electron microscopy. Theoretical predictions based on the interlayer model used in direct mode were successfully combined with the experimental viscoelastic data to lead to relevant additional information about the complex particulate morphology of the hybrid system. Thus, using direct mechanical modeling, it was concluded that the experimental response of the alkyd acrylic hybrid system to a sinusoidal mechanical stress corresponds to the mechanical response of a sample whose morphology involves a acrylic-rich interphase between continuous and dispersed alkyd-rich domains. For the very first time, the interlayer model was then used in reverse mode in order to separate the actual viscoelastic properties of such a acrylic-rich interphase from those experimentally obtained for the alkyd acrylic hybrid system. The differences in these extracted viscoelastic properties, when compared to those of the pure latex film, were presented as reflecting the changes in the molecular mobility of the macromolecules resulting from the mutual influence of the phases in the multiphase hybrid material.
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| 4. |
- Colombini, Didier, et al.
(författare)
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Effects of thermal annealing on the viscoelastic properties and morphology of bimodal hard/soft latex blends
- 2005
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Ingår i: Journal of Polymer Science. Part B, Polymer Physics. - : Wiley. - 0887-6266 .- 1099-0488. ; 43:17, s. 2289-2306
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Tidskriftsartikel (refereegranskat)abstract
- The effects of thermal annealing on the viscoelastic properties and morphology of films prepared from bimodal latex blends containing equal weight fractions of soft and hard latex particles with controlled sizes were investigated. The thermal and viscoelastic properties of as-dried and annealed samples were investigated with differential scanning calorimetry and dynamic mechanical analysis (DMA). Throughout the thermal annealing, the latex blend morphologies were also followed with atomic force microscopy and transmission electron microscopy (TEM). A particulate morphology, consisting of hard particles evenly dispersed in a continuous soft phase, was observed in the TEM micrographs of the as-dried latex blends and resulted in an enhancement of the mechanical film properties at temperatures between the a relaxations of the soft and hard phases in the DMA thermograms. As soon as the thermal annealing involved temperatures higher than the glass-transition temperature of the hard phase, the hard particles progressively lost their initial spherical shape and formed a more or less continuous phase in the latex blends. This induced coalescence of the hard particles was confirmed by the association of the experimental viscoelastic data with theoretical predictions, based on self-consistent mechanical models, which were performed by the consideration of either a particulate or cocontinuous morphology for the bimodal latex blends. (c) 2005 Wiley Periodicals, Inc.
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| 5. |
- Colombini, Didier, et al.
(författare)
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Influence of morphological and conformational changes on the molecular mobility in poly(ethylene naphthalene-2,6-dicarboxylate)
- 2004
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Ingår i: Macromolecular Symposia. - : Wiley. - 1521-3900 .- 1022-1360. ; 212, s. 479-484
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic electric (DEA) and mechanical (DMA) analyses were combined to explore the relaxational processes in amorphous and semicrystalline poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) samples. Differential scanning calorimetry measurements were carried out to investigate the crystallinity of the samples following isothermal annealing treatment at 443 K. The two secondary relaxations beta and beta*, the main alpha relaxation, as well as the rho-relaxational process, were revealed by both electric and mechanical viscoelastic responses of the PEN samples. DMA results clearly identified the above T-alpha loss factor peak, rho, as a probe of the cold crystallization. However, the association of both DMA and DEA investigations pointed out that electric and non-electric aspects might govern the rho-process.
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| 6. |
- Colombini, Didier, et al.
(författare)
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Influence of the particle size and particle size ratio on the morphology and viscoelastic properties of bimodal hard/soft latex blends
- 2004
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 37:18, s. 6865-6873
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Tidskriftsartikel (refereegranskat)abstract
- The morphology and viscoelastic properties of films prepared from bimodal latex blends containing equal weight fractions of soft and hard latex particles were investigated as a function of the particle sizes and the particle size ratio (soft particle diameter/hard particle diameter). Minimum film formation temperature (MFT) measurements were associated with transmission electron microscopy (TEM) to emphasize the particle size ratio dependence of the film formation properties. A significant increase of the MFT values with the soft/hard particle size ratio was observed. As long as the particle size ratio was low, TEM micrographs showed that the film forming soft particles, undergoing complete coalescence, clearly act as the continuous phase where the non film forming hard particles are found evenly dispersed while keeping their initial spherical shape. At higher values of the particle size ratio, TEM micrographs pointed out that the soft particles are prevented from coming into contact with each other by the surrounding hard particles, therefore dramatically increasing the MFT of the sample and resulting in a non film forming latex blend. The existence of a critical volume fraction of hard particles that is directly related to the soft/hard particle size ratio was then established on the basis of geometrical arguments involving the percolation theory. The higher the particle size ratio, the lower the critical volume fraction of hard particles that leads to a macroscopic phase inversion resulting in a non film forming bimodal latex blend. Subsequently, the mechanical film properties were investigated by solid-state dynamic mechanical analysis. The size of the dispersed hard phase was found to affect the final viscoelastic film properties. The smaller the size of the hard particles, the better the mechanical enhancement of the mechanical film properties. Last, the experimental viscoelastic thermograms were compared with some theoretical predictions based on self-consistent mechanical modeling. The final film properties of the bimodal hard/soft latex blends were then directly connected to the film formation properties.
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| 7. |
- Colombini, Didier, et al.
(författare)
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Interfacially induced additional damping peaks in dynamic mechanical spectra - micromechanical transitions in multipolymeric materials
- 2003
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Ingår i: Macromolecular Symposia. - : Wiley. - 1521-3900 .- 1022-1360. ; 198:1, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- The viscoelastic properties of several hypothetical multiphase polymeric materials were investigated in relation to their phase-property dependencies and microstructures. Theoretical mechanical considerations based on the self-consistent interlayer model were performed to point out that specific geometrical arrangements into phases of a set of properties of the pure constituents can lead to interfacially induced damping peaks in dynamic mechanical spectra (DMS). Such additional contributions in DMS were referred to micromechanical transitions to distinguish them from ordinary molecular transitions
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| 8. |
- Colombini, Didier, et al.
(författare)
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Origin of additional mechanical transitions in multicomponent polymeric materials
- 2002
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 35:15, s. 5891-5902
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Tidskriftsartikel (refereegranskat)abstract
- The viscoelastic properties of several multicomponent materials (including both particulate multipolymeric materials and multilayer polymer blends) were investigated in relation to their microstructures and phase-property dependencies. Theoretical considerations based on mechanical modeling were used to explore the origin of additional mechanical transitions in experimental viscoelastic spectra. The major part of this work was devoted to particulate multicomponent systems, and especially to the further exploration of the characteristics of the so-called micromechanical transition (MMT). Although such an additional phenomenon is clearly explained as a result of a specific interphase, our investigation also provides evidence that the occurrence of a MMT in dynamic mechanical spectra reflects the contribution of the geometrical arrangement into phases of a set of properties of the pure components, rather than a molecular relaxational process within the interfacial area. Finally, on the basis of an equivalent approach, the influence of the geometrical arrangement of phases on the viscoelastic response of multilayer polymer blends was pointed out as a relevant argument to justify the existence of "spurious" additional damping peaks in some experimental dynamic mechanical spectra reported in the literature.
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| 9. |
- Colombini, Didier, et al.
(författare)
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The effect of the polymerization route on the amount of interphase in structured latex particles and their corresponding films
- 2005
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861. ; 46:4, s. 1295-1308
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Tidskriftsartikel (refereegranskat)abstract
- Three series of hard/soft styrene-acrylic latex based systems with equivalent compositions were prepared either by blending of homopolymer latexes or by preparing structured latex particles having core shell (CS) or inverted core shell (ICS) morphologies. Transmission electron microscopy (TEM) was used to investigate the particle morphologies, which were correlated to the calculated fractional radical penetration for the propagating species during the reactions. The thermo-mechanical properties as well as the morphology of the resulting latex films were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and TEM. The viscoelastic properties of the interphase between the first and second-stage polymers formed in the structured hard/soft latex films, as well as its qualitative amount and also the film morphologies were found to depend on the interplay between thermodynamic and kinetic parameters during the synthesis of the samples. (C) 2004 Elsevier Ltd. All rights reserved.
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| 10. |
- Karlsson, Ola, et al.
(författare)
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The effect of first-stage polymer Tg on the morphology and thermomechanical properties of structured polymer latex particles
- 2003
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Ingår i: Comptes Rendus. Chimie. - : Elsevier BV. - 1631-0748. ; 6:11-12, s. 1233-1244
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Tidskriftsartikel (refereegranskat)abstract
- A series of heterogeneous latexes having stage ratios of 40:60 between the first and second stage polymers were prepared by emulsion polymerization. The first-stage polymers were non-polar S-BuA with Tgs ranging from + 100 °C to + 20 °C and the second stage polymer was polar MMA–BuA–MAA having a Tg of 20 °C. The latex particle morphologies were studied using TEM and the thermomechanical properties of the resulting latex films were studied with DSC and DMA. Calculated diffusion rates for propagating species during the reactions were correlated to the observed morphologies and to the amount of interphase in the latex particles.
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| 11. |
- Ljungberg, Nadia, et al.
(författare)
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Plasticization of poly(lactic acid) with oligomeric malonate esteramides: Dynamic mechanical and thermal film properties
- 2005
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 96:4, s. 992-1002
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Tidskriftsartikel (refereegranskat)abstract
- Two oligomeric malonate esteramides and an oligomeric malonate ester were synthesized with the intention to plasticize poly(lactic acid), PLA. The synthesis was performed by reacting diethyl bishydroxymethyl malonate (DBM) with adipoyl dichloride and one of two diamines, that is, triethylene glycol diamine (TA) and polyoxypropylene glycol diamine (PA), or triethylene glycol (TEG), giving three platicizing agents denoted as DBMATA, DBMAPA, and DBMAT, respectively. The synthesis products were characterized by size exclusion chromatography and Fourier transform infrared spectroscopy, and blended with PLA at a concentration of 15 wt %. Dynamic mechanical analysis, differential scanning calorimetry, and tensile testing were used to investigate the physical properties of films from the resulting blends. All three plasticizers decreased the glass transition temperature of PLA, and the largest decrement was observed for PLA/DBMATA. Films of DBMATA and DBMAT showed enhanced flexibility in strain at break as compared to neat PLA. Subsequently, it was found that thermal annealing of the plasticized materials (4 h at 100 degrees C) encouraged cold crystallization, inducing phase separation in the blends, and caused them to regain the brittleness of neat PLA. On the other hand, by aging (6 weeks) the blends at ambient conditions, cold crystallization could be avoided and the flexibility in the films maintained. (c) 2005 Wiley Periodicals, Inc.
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