Miscibility, crystallization kinetics and real-time small-angle X-ray scattering investigation of the semicrystalline morphology in thermosetting polymer blends of epoxy resin and poly(ethylene oxide)

Guo, Qipeng; Harrats, Charef; Groeninckx, Gabriël; Koch, Michel H. J.

doi:10.1016/s0032-3861(00)00813-2

Cited by 110 publications

(86 citation statements)

References 37 publications

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“…Moreover, an increase in the glass transition temperature is expected due to the stiffening of the amorphous phase by reinforcement from PEO spherulites. 7 This agrees with several calorimetric results 2,8,15 and appears independent of the type and content of the hardener. It is clear, though, from the data included in Figure 3b that the exact threshold is highly dependent on the nature of the curing agent, spanning the range between ∼50 17 and 80 11,41 wt % PEO.…”

Section: Thermal Characteristics Of the Er-i-peo Networksupporting

confidence: 91%

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Nanoscale Confinement Effects on the Relaxation Dynamics in Networks of Diglycidyl Ether of Bisphenol-A and Low-Molecular-Weight Poly(ethylene oxide)

et al. 2007

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Thermoplastic poly(ethylene oxide) (PEO) (M w(PEO) ≈ 4000) has been used to prepare thermosetting nanocomposites incorporating diglycidyl ether of bisphenol A (DGEBA) epoxy oligomer. Blends with various PEO/DGEBA weight ratios were cured using stoichiometric portions of 4,4′-diaminodiphenylmethane. The resulting semi-interpenetrating polymer networks were studied by several techniques. Nanoscale confinement effects, thermal (glass transition, melting and crystallization temperatures) and structural features of our materials are similar to those for networks with much higher M w(PEO) and different curing agents; however, the polyether crystallization onset occurs in our case at a lower PEO concentration; shorter PEO chains organize themselves more easily into crystalline domains. Very low estimates of the k parameter of the Gordon-Taylor equation, used to fit the compositional dependences of the dielectric and calorimetric glass transition temperatures, and a strong plasticization of the motion of the glyceryl segments ( -relaxation) in the epoxy resin were observed. These illustrate an intensified weakening in the strength of the intermolecular interactions in the modified networks, as compared to the high strength of the self-association of hydroxyls in the neat resin. The significance of hydrogen-bonding interactions between the components for obtaining structurally homogeneous thermoseti-thermoplastic networks is discussed.

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Section: Thermal Characteristics Of the Er-i-peo Networksupporting

confidence: 91%

“…[12][13][14][15][16] Figure 3a shows the glass transition temperatures, T g , the melting temperatures, T m , and crystallization temperatures, T c , as a function of composition. Deviations of the T g curve on the right-hand side from a simple concave shape will be a subject of a separate publication.…”

Section: Thermal Characteristics Of the Er-i-peo Networkmentioning

confidence: 99%

Nanoscale Confinement Effects on the Relaxation Dynamics in Networks of Diglycidyl Ether of Bisphenol-A and Low-Molecular-Weight Poly(ethylene oxide)

et al. 2007

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“…where DH m o is 136 J/g, which is the theoretical heat of fusion for 100% crystalline PCL, 42,43 and m PCL is the mass fraction of PCL in the nanocomposite fibers (m PCL = 1 for PCL fibers and m PCL = 0.9 for PCL-10% Nanoclay). For TGA, samples were heated in a ceramic pan at the rate of 10°C/min from 50°C to 600°C under a constant stream of nitrogen at a flow rate of 20 mL/min.…”

Section: Chemical and Thermal Characterizationsmentioning

confidence: 99%

Nanoclay-Enriched Poly(ɛ-caprolactone) Electrospun Scaffolds for Osteogenic Differentiation of Human Mesenchymal Stem Cells

Gaharwar

Mukundan²,

Karaca³

et al. 2014

Tissue Engineering Part A

138

122

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Musculoskeletal tissue engineering aims at repairing and regenerating damaged tissues using biological tissue substitutes. One approach to achieve this aim is to develop osteoconductive scaffolds that facilitate the formation of functional bone tissue. We have fabricated nanoclay-enriched electrospun poly(e-caprolactone) (PCL) scaffolds for osteogenic differentiation of human mesenchymal stem cells (hMSCs). A range of electrospun scaffolds is fabricated by varying the nanoclay concentrations within the PCL scaffolds. The addition of nanoclay decreases fiber diameter and increases surface roughness of electrospun fibers. The enrichment of PCL scaffold with nanoclay promotes in vitro biomineralization when subjected to simulated body fluid (SBF), indicating bioactive characteristics of the hybrid scaffolds. The degradation rate of PCL increases due to the addition of nanoclay. In addition, a significant increase in crystallization temperature of PCL is also observed due to enhanced surface interactions between PCL and nanoclay. The effect of nanoclay on the mechanical properties of electrospun fibers is also evaluated. The feasibility of using nanoclay-enriched PCL scaffolds for tissue engineering applications is investigated in vitro using hMSCs. The nanoclay-enriched electrospun PCL scaffolds support hMSCs adhesion and proliferation. The addition of nanoclay significantly enhances osteogenic differentiation of hMSCs on the electrospun scaffolds as evident by an increase in alkaline phosphates activity of hMSCs and higher deposition of mineralized extracellular matrix compared to PCL scaffolds. Given its unique bioactive characteristics, nanoclayenriched PCL fibrous scaffold may be used for musculoskeletal tissue engineering.

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“…[18][19][20][21][22] The T g -composition relationship observed in our blends (Table 1 and Figure 3) has been described in the left half of the diagram by an empirical equation of Kwei [35] T blend…”

Section: Thermal Properties Of Cured Er þ Peo Blendsmentioning

confidence: 99%

Thermophysical Properties and Molecular Relaxations in Cured Epoxy Resin + PEO Blends: Observations on Factors Controlling Miscibility

Kalogeras

Vassilikou‐Dova

Christakis

et al. 2006

Macro Chemistry & Physics

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Summary: Thermophysical properties and molecular relaxations in aromatic amine‐cured diglycidyl ether of bisphenol‐A (DGEBA) epoxy oligomer and poly(ethylene oxide) (PEO) mixtures were determined by DSC and dielectric techniques (TSC, DRS). The binary blends were judged to be fully miscible in the amorphous state (wPEO < 40 wt.‐%), as evidenced by the single composition‐dependent glass transition temperatures Tgs. In the amorphous blends, negative deviations of dielectric/thermal Tg‐estimates from the linear mixing rule or the behavior predicted by the Fox equation reveal weaker intermolecular interactions, compared to strong self‐association of hydroxyls in the cured thermoset. Morphological changes in PEO‐rich blends (wPEO ≥ 40 wt.‐%) are in accordance with their complicated interface structure, previously reported to consist of amorphous PEO regions, branched epoxy resin chains and an imperfect epoxy resin network located between PEO lamellae. In these blends, PEO crystallites exert steric hindrances in the amorphous regions, causing strong Tg upshifts. Changes in the relaxation dynamics of glyceryl segments (e.g., in the activation energy barrier and relaxation strength) are in accordance with the idea that the close matching between the molecular polarities of PEO, epoxy resin and the cure agent significantly contributes to the observed miscibility.

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Miscibility, crystallization kinetics and real-time small-angle X-ray scattering investigation of the semicrystalline morphology in thermosetting polymer blends of epoxy resin and poly(ethylene oxide)

Cited by 110 publications

References 37 publications

Nanoscale Confinement Effects on the Relaxation Dynamics in Networks of Diglycidyl Ether of Bisphenol-A and Low-Molecular-Weight Poly(ethylene oxide)

Nanoscale Confinement Effects on the Relaxation Dynamics in Networks of Diglycidyl Ether of Bisphenol-A and Low-Molecular-Weight Poly(ethylene oxide)

Nanoclay-Enriched Poly(ɛ-caprolactone) Electrospun Scaffolds for Osteogenic Differentiation of Human Mesenchymal Stem Cells

Thermophysical Properties and Molecular Relaxations in Cured Epoxy Resin + PEO Blends: Observations on Factors Controlling Miscibility

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