Fragility and cooperativity concepts in hydrogen-bonded organic glasses

Delpouve, Nicolas; Vuillequez, A.; Saiter, Allisson; Youssef, B.; Saiter, Jean‐Marc

doi:10.1016/j.physb.2012.05.024

Cited by 13 publications

(9 citation statements)

References 60 publications

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“…These are quite comparable to the values reported previously for PLA and its composites and other bio‐based polymers . This is, by the way, a classical behavior for macromolecules with Van der Walls or hydrogen bonds interactions between chains . PLA composites seem to be more fragile compared to neat PLA.…”

Section: Resultssupporting

confidence: 88%

Mechanical, thermal, and dielectric properties of poly(lactic acid)/chitosan nanocomposites

Elsawy

Saad

Sayed

2016

Polymer Engineering & Sci

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Poly(lactic acid) (PLA) loaded with various levels of chitosan nanoparticles (CsNP) (0-5.0%) were prepared by twinscrew extrusion. The nanocomposites were investigated based on their morphology, thermal, mechanical and dielectric properties. The SEM morphology showed that CsNP was dispersed uniformly in the PLA matrix. Thermal analysis through DSC revealed that the cold crystallization temperature of PLA in the case of nanocomposites slightly decreased with increasing content of CsNP; indicating a limit nucleating effect of CsNP. TGA analysis revealed that the incorporation CsNP slightly decreased the thermal stability of the PLA matrix. The mechanical analysis indicated that the incorporation of the CsNP in the PLA matrix improved the elongation and the impact strength, but decreased the tensile strength. The dielectric properties of these materials have been investigated for the a-relaxation process as a function of the temperature and frequency. The a-relaxation process was analyzed with Vogel-Fulcher-Tamman and Havriliak-Negami models and fitting parameters and their evolution were obtained. POLYM. ENG. SCI., 00:000-000, 2016.

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Section: Resultssupporting

confidence: 88%

Mechanical, thermal, and dielectric properties of poly(lactic acid)/chitosan nanocomposites

Elsawy

Saad

Sayed

2016

Polymer Engineering & Sci

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“…This decrease supports the decrease of CRR size of plasticized PLA observed at T g and is concordant with the idea developed by several authors that the cooperativity volume is related to the number and the nature of inter‐chains bonds. This includes in particular the studies evidencing an increase of cooperativity length with the increase of hydrogen bonds in the system . Nakanishi et al even proposed to express the cooperativity, the fragility index, and the glass transition temperature as a function of the number of hydroxyl groups for homologous structure series of molecules.…”

Section: Resultsmentioning

confidence: 99%

Molecular mobility and physical ageing of plasticized poly(lactide)

Dobircau

Delpouve

Herbinet

et al. 2014

Polymer Engineering & Sci

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Molecular mobility and physical ageing of amorphous plasticized polylactide (PLA) with two different contents of mesolactide are studied with the help of thermal analysis. Used plasticizers are acetyl tributyl citrate (ATBC) and triacetin (TA), two molecules with established miscibility and plasticizing efficiency. Lower plasticizer permanence of TA compared with ATBC is found. The plasticizer molecules decreased the size of the cooperativity domains at the glass transition temperature Tg and likely in the glassy state by decreasing intermacromolecular interactions and notwithstanding the mesolactide content of PLA and the chemical identity of the plasticizer. The recovery function is given and shows a significant effect of the plasticizer on the physical ageing. The supplementary free volume brought by the plasticizer enhances molecular mobility in the glassy state and increases structural relaxation at one order of magnitude. The comparison between different plasticizers reveals that the structural relaxation is however independent from the type of plasticizer and the percentage of mesolactide in PLA. POLYM. ENG. SCI., 55:858–865, 2015. © 2014 Society of Plastics Engineers

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“…The variation of ln|b C | as a function of 1/T 0 f is thus supposed to be linear, and the slope of the corresponding curve is proportional to the fragility index [20,21].…”

Section: Introductionmentioning

confidence: 99%

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Dhôtel

Rijal

Delbreilh

et al. 2015

J Therm Anal Calorim

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New experimental results focused on Flash DSC, DSC and broadband dielectric spectroscopy investigations are reported in this work. The fictive temperatures and fragility indexes are estimated from Flash DSC experiments and compared to values obtained from classical DSC. The consistency of the Tool-NarayanaswamyMoynihan model and fragility concept is then investigated over a large range of cooling rates. Indeed, the Flash DSC allows exploring thermal properties of materials over a continuous and broad range of heating and cooling rates, complementary to rates usually available with DSC. The reliability of investigations is also demonstrated by comparing results obtained from two model amorphous polymeric systems: polystyrene and poly(ethylene terephthalate)-glycol. The temperature dependence of the cooling rate obtained by Flash DSC and DSC is also compared to the temperature dependence of the relaxation times obtained from broadband dielectric spectroscopy, experiment considered as the reference concerning the fragility measurements. The comparison of these two dependencies implies a better understanding about the origin of the temperature dependence of the cooling rate.

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Fragility and cooperativity concepts in hydrogen-bonded organic glasses

Cited by 13 publications

References 60 publications

Mechanical, thermal, and dielectric properties of poly(lactic acid)/chitosan nanocomposites

Mechanical, thermal, and dielectric properties of poly(lactic acid)/chitosan nanocomposites

Molecular mobility and physical ageing of plasticized poly(lactide)

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

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