Glass‐formation kinetics of miscible blends of atactic polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Robertson, Christopher G.; Wilkes, Garth L.

doi:10.1002/polb.1186

Cited by 15 publications

(14 citation statements)

References 69 publications

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“…Hence, fragility of a liquid was proposed to be a measure of structural stability, 3 and thus an important parameter to characterize glass formation. Fragility in polymers has been related and/or correlated to the nonexponentiality (breadth) of segmental relaxation function, [4][5][6] rates of physical aging 7,8 and peculiarity of the fast dynamics. 9,10 It has been realized that behavior of structural (segmental) relaxation in many polymers deviates from regularities known for structural (R-) relaxation in small molecular liquids.…”

Section: Introductionmentioning

confidence: 99%

Role of Chemical Structure in Fragility of Polymers: A Qualitative Picture

et al. 2008

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Understanding microscopic parameters that control steepness of the temperature variations of segmental relaxation (fragility) and the glass transition phenomenon remains a challenge. We present dielectric and mechanical relaxation studies of segmental dynamics in various polymers with different side groups and backbone structures. The results have been analyzed in terms of flexibility of backbone and side groups of polymeric molecules, as suggested by the recent theoretical works by Dudowicz et al. A comparison of structures with identical backbones and varying side groups and identical side groups but different backbones reveals that the flexibility of side groups relative to the flexibility of the backbone is the most important factor controlling fragility in polymers, while the glass transition temperature T g depends primarily on the backbone flexibility and the side group bulkiness (occupied volume). Based on these results and analysis of literature data we formulated a modified approach to understand the role of chemical structure in segmental dynamics: (i) Polymers with stiff backbones always have high T g and fragility, while (ii) polymers with flexible backbones and no side groups are the strongest; (iii) however, for the most common type of polymeric structure, C-C or Si-O backbone with side groups, fragility increases with increasing "relatiVe" stiffness of side groups versus the backbone. In this class of polymers, lowest fragility is expected when the side groups are of similar chemical structure (or flexibility) as the backbone, as in the case of polyisobutylene, one of the strongest polymers known.

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Section: Introductionmentioning

confidence: 99%

Role of Chemical Structure in Fragility of Polymers: A Qualitative Picture

et al. 2008

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“…It is especially useful for the estimation of the effect of addition of compatibilizers in incompatible blends, to obtain satisfactory mechanical properties 7–9. Besides multiphase systems, DMTA can also be used successfully in the study of miscible blends 10–12…”

Section: Introductionmentioning

confidence: 99%

Blends of polymers with similar glass transition temperatures: A DMTA and DSC study

Bikiaris

Prinos

Botev

et al. 2004

J of Applied Polymer Sci

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ABSTRACT:The miscibility of different polymer blends was studied with dynamic mechanical thermal analysis (DMTA) in conjunction with differential scanning calorimetry (DSC). The blends were prepared by melt mixing polymers having similar glass transitions such as polyglutarimide (PGI), styrene-co-maleic anhydride random copolymers (SMA), and polystyrene (PS). In PGI/SMA blends, there is only one glass transition detected with DMTA. In the case of PGI/SMA14 blends, the single glass transition temperature is due to their full miscibility. However, PGI/SMA8 blends are immiscible throughout the whole composition range as was verified by optical observation (opaque appearance), DSC, and scanning electron microscopy. The observation of only one glass transition by DMTA was attributed to weak interactions that take place between the two polymers, leading to partial mutual solubility and bringing the slightly different T g temperatures of the pure polymers even closer. In SMA8/SMA14 blends, there are two glass transitions detected with DSC as well as with DMTA, indicating that the two copolymers are immiscible. However, in all compositions, shifts of the glass transitions were observed with DMTA, which is evidence of partial miscibility. The observation of immiscibility was easiest in PS/SMA blends by both techniques, because of the bigger difference in glass transition temperatures of the initial polymers.

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“…As expected, structural features of the polymer backbone (polarity, symmetry and steric hindrance) are reflected in the coupling constant. The cooperativity analysis has also been utilized for characterizing intermolecular interactions in polymer blends (Roland and Ngai 1992;Robertson and Wilkes 2001). The cooperativity analysis has also been utilized for characterizing intermolecular interactions in polymer blends (Roland and Ngai 1992;Robertson and Wilkes 2001).…”

Section: Introductionmentioning

confidence: 99%

“…In general, polymers built upon smooth, regular and flexible repeat units display low coupling constants while polymers with less flexible repeat units, sterically-hindering pendant groups and high polarity exhibit a broader distribution of relaxation times and greater intermolecular cooperativity (Ngai and Roland 1993). One such study demonstrates the validity of the cooperativity analysis on miscible blends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) for detecting specific interactions between the components (Robertson and Wilkes 2001). One such study demonstrates the validity of the cooperativity analysis on miscible blends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) for detecting specific interactions between the components (Robertson and Wilkes 2001).…”

Section: Introductionmentioning

confidence: 99%

Cooperativity analysis of the in situ lignin glass transition

Laborie¹,

Salmén²,

Frazier³

2004

Holzforschung

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This paper demonstrates the applicability of cooperativity analysis for the glass transition of lignin in wood. In ethylene glycol plasticized wood, the coupling model of relaxation proposed by Ngai allows for quantifying intermolecular coupling associated with the lignin glass transition. The method utilizes Time-Temperature Superposition of viscoelastic properties measured by submersion dynamic mechanical analysis. It is shown that the coupling model by Plazek and Ngai adequately describes segmental relaxation above the lignin glass transition temperature only. No significant difference in intermolecular coupling was found between spruce and yellowpoplar.

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Glass‐formation kinetics of miscible blends of atactic polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Cited by 15 publications

References 69 publications

Role of Chemical Structure in Fragility of Polymers: A Qualitative Picture

Role of Chemical Structure in Fragility of Polymers: A Qualitative Picture

Blends of polymers with similar glass transition temperatures: A DMTA and DSC study

Cooperativity analysis of the in situ lignin glass transition

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