Simulation of the free energy of mixing for blend components in a new family of flexible polycyanurates

Hamerton, Ian; Howlin, Brendan J.; Pratt, C. Robert

doi:10.1016/j.polymer.2010.09.068

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…In contrast, tricyanate esters such as Primaset PT-30 offer better high-temperature mechanical and chemical stability, but often require high temperatures to achieve near complete conversion and the attendant requisite levels of long-term hydrolytic stability. Dicyanates have found a variety of applications ranging from repair of aerospace structures to low-dielectric electronics packaging, while tricyanates have been investigated for more demanding environments such as nuclear fusion reactors, nanoscale sesnors, and turbine engines. , Although the past few years have witnessed the development of many new dicyanate − and tricyanate − monomers with improved properties, the use of cocured networks formed by blending various monomer types can also provide useful new combinations of properties. ,,,,− In fact, previous work has shown that, despite the apparent homogeneity of cocured polycyanurate networks, synergistic interactions (herein defined as significant departures from linear rules of mixing for conetwork properties, which can be caused by small differences in the formation of network structures resulting from, for example, mixing of impurities, or to nonlinear physical interactions among mixed network chain segments) among the components frequently occur, leading in many cases to improvements in performance . Figure illustrates two of many known general mechanisms (percolation and staggering) that can lead to nonlinear rules of mixing and, thus, synergistic behavior, in homogeneous multicomponent mixtures.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Physical Properties of Cocured Networks Formed from Di- and Tricyanate Esters

Guenthner

Reams²,

Lamison³

et al. 2013

ACS Appl. Mater. Interfaces

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The co-cyclotrimerization of two tricyanate ester monomers, Primaset PT-30 and 1,2,3-tris(4-cyanato)propane (FlexCy) in equal parts by weight with Primaset LECy, a liquid dicyanate ester, was investigated for the purpose of exploring synergistic performance benefits. The monomer mixtures formed stable, homogeneous blends that remained in the supercooled liquid state for long periods at room temperature, thereby providing many of the processing advantages of LECy in combination with significantly higher glass transition temperatures (315-360 °C at full cure) due to the presence of the tricyanate-derived segments in the conetwork. Interestingly, the glass transition temperatures of the conetworks after cure at 210 °C, at full cure, and after immersion in 85 °C water for 96 h were all higher than predicted by the Flory-Fox equation, most significantly for the samples immersed in hot water. Conetworks comprising equal parts by weight of PT-30 and LECy retained a "wet" glass transition temperature near 270 °C. The onset of thermochemical degradation for conetworks was dominated by that of the thermally less stable component, while char yields after the initial degradation step were close to values predicted by a linear rule of mixtures. Values for moisture uptake and density in the conetworks also showed behavior that was not clearly different from a linear rule of mixtures. An analysis of the flexural properties of catalyzed versions of these conetworks revealed that, when cured under the same conditions, conetworks containing 50 wt % PT-30 and 50 wt % LECy exhibited higher modulus than networks containing only LECy while conetworks containing 50 wt % FlexCy and 50 wt % LECy exhibited a lower modulus but significantly higher flexural strength and strain to failure. Thus, in the case of "FlexCy", LECy was copolymerized with a tricyanate that provided both improved toughness and a higher glass transition temperature.

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Section: Introductionmentioning

confidence: 99%

Synergistic Physical Properties of Cocured Networks Formed from Di- and Tricyanate Esters

Guenthner

Reams²,

Lamison³

et al. 2013

ACS Appl. Mater. Interfaces

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“…The calculation of solubility parameters is a fast approach for evaluating the miscibility of different polymers 32 . The Gibbs free energy of mixing (

Δ G_{normalm}

) is defined below 33 :

Δ G_{normalm} = Δ H_{normalm} - T Δ S_{normalm},

where T refers to the absolute temperature, and

Δ H_{normalm}

and

Δ S_{normalm}

are the enthalpy and entropy of mixing, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…The calculation of solubility parameters is a fast approach for evaluating the miscibility of different polymers. 32 The Gibbs free energy of mixing (ΔG m ) is defined below 33 :…”

Section: Solubility Parameter Calculationmentioning

confidence: 99%

Structure and properties of bio‐based poly(trimethylene terephthalate)/polyamide 56 blends prepared by melt mixing

Wang,

Zhou,

et al. 2023

J of Applied Polymer Sci

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The extensive use of conventional petroleum‐based polymers consumes large amounts of energy and emits a lot of carbon dioxide. Therefore, the development and popularization of bio‐based polymer materials are highly significant for ecological reasons. Herein, a series of poly(trimethylene terephthalate)/polyamide 56 (PTT/PA56) blends with different weight ratios were prepared by melt blending of two bio‐based polymers, PTT and PA56. The phase structure, miscibility, crystallization and melting behaviors, crystal structure, and mechanical and water absorption properties of PTT/PA56 blend systems were investigated. The results showed that PTT and PA56 were immiscible in the whole range of compositions. The immiscibility of the blend system intensified with the increase of dispersed phase content. As PA56 content increased, tensile strength and elongation at break of samples assumed an increasing trend, whereas impact strength initially remained almost unchanged and then gradually decreased. In contrast, increasing PA56 content gradually increased water absorption of samples. Comprehensive analysis indicated that the best combination of different properties was obtained for the PTT/PA56 blends including 60–80 wt% PA56.

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“…From this series, a representative sample of 2200 Da (n = 5, derived from bisphenol A and 4,4′-dichlorobenzophenone, in the molar ratio 3∶2) was selected, whose balance of properties (high degree of conversion coupled with impressive T g ) looked particularly interesting as a model to study (Figure 2b). The simulation approach has been used by our group with some success with other high performance polymers such as epoxy resins [13] and cyanate esters [14] and both commercial and novel polybenzoxazines [15]. However, this has not previously been reported for telechelic species as the length of backbone confers an additional level of complexity to both the structure and the calculations.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Selected Physical and Mechanical Properties of a Telechelic Polybenzoxazine by Molecular Simulation

Hassan¹,

Hamerton²,

Howlin

2013

PLoS ONE

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Molecular simulation is becoming an important tool for both understanding polymeric structures and predicting their physical and mechanical properties. In this study, temperature ramped molecular dynamics simulations are used to predict two physical properties (i.e., glass transition temperature and thermal degradation temperature) of a previously synthesised and published telechelic benzoxazine. Plots of simulated density versus temperature show decreases in density within the same temperature range as experimental values for the thermal degradation. The predicted value for the thermal degradation temperature for the cured polybenzoxazine based on the telechelic polyetherketone (PEK) monomer was ca. 400°C, in line with the experimental thermal degradation temperature range of 450°C to 500°C. Mechanical Properties of both the unmodified PEK and the telechelic benzoxazines are simulated and compared to experimental values (where available). The introduction of the benoxazine moieties are predicted to increase the elastic moduli in line with the increase of crosslinking in the system.

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Simulation of the free energy of mixing for blend components in a new family of flexible polycyanurates

Cited by 5 publications

References 17 publications

Synergistic Physical Properties of Cocured Networks Formed from Di- and Tricyanate Esters

Synergistic Physical Properties of Cocured Networks Formed from Di- and Tricyanate Esters

Structure and properties of bio‐based poly(trimethylene terephthalate)/polyamide 56 blends prepared by melt mixing

Prediction of Selected Physical and Mechanical Properties of a Telechelic Polybenzoxazine by Molecular Simulation

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