Crystallization behaviour and morphological features of LARC-CPI

Muellerleile, Joan T.; Risch, Brian G.; Rodrigues, D. E.; Wilkes, Garth L.; Jones, Dina M.

doi:10.1016/0032-3861(93)90365-h

Cited by 51 publications

(26 citation statements)

References 36 publications

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“…This has been reported previously for other semicrystalline PIs. 10,12,17 Obviously, a narrow window of 5-10°C is insufficient for practical operations such as melt impregnation of fibers; hence, the use of pure PI for composite materials is not feasible if crystallinity is to be retained.…”

Section: Processing Conditionsmentioning

confidence: 99%

Semicrystalline polyimide matrices for composites: Crystallization and properties

Yudin

Светличный

Gubanova

et al. 2002

J of Applied Polymer Sci

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New semicrystalline polyimide/oligoimide blends, designated for matrices in carbon fiber-reinforced composites, were developed. A specific advantage of the proposed polyimides is their ability to crystallize from the melt, therein retaining their crystallinity throughout the manufacturing process. The generation of crystallinity after melting, referred to as recrystallization, was investigated here as affected by blending the polyimides with oligoimides of a similar chemical structure. Based on thermal analysis and enthalpy measurements, comparative X-ray diffraction analyses, and polarized light microscopy of hot-stage-controlled crystallization, the recrystallization ability was determined for five different oligoimides. In some cases, the addition of oligoimides, both amorphous and crystalline, resulted in complete recrystallization. The main contribution of the oligoimides is suggested to be through plasticization, allowing segmental chain mobility during crystallization, and not via nucleation. A similar effect was obtained by lowering the molecular weight of the polyimide; this, however, generates mechanical property reduction, rendering the polyimide irrelevant to composite materials. Finally, it was shown that crystallization was also enhanced by carbon fibers, serving as a nucleating agent and generating transcrystallization.

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Section: Processing Conditionsmentioning

confidence: 99%

Semicrystalline polyimide matrices for composites: Crystallization and properties

Yudin

Светличный

Gubanova

et al. 2002

J of Applied Polymer Sci

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“…Nonlinearity of the Avrami plots is usually accounted for by secondary crystallization, onset of impingement of growing crystallites, and/or change in crystal perfection. 8,9 Fractional values of the Avrami exponent are quite often encountered in polymer systems. They are generally associated with noncompliance with some of the assumptions adopted in deriving the Avrami equation.…”

Section: Introductionmentioning

confidence: 99%

Crystallization behavior of poly(N‐methyldodecano‐12‐lactam). III. Kinetics of isothermal crystallization

Kratochvíl

Sikora

2004

J of Applied Polymer Sci

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Differential scanning calorimetry, combined with Avrami theory, was used to investigate the kinetics of three steps of the complex crystallization process of poly(Nmethyldodecano-12-lactam) (MPA): (1) primary melt crystallization at respective crystallization temperature (T c ), (2) additional crystallization at 30°C, and (3) recrystallization at 54°C. Kinetics of the three steps was discussed with respect to T c . The Avrami exponent n of primary melt crystallization decreased between 2.5 and 1.9 in the range of T c values of Ϫ10 to 20°C, which suggests heterogeneous nucleation, followed by two-dimensional growth, with a larger involvement of homogeneous thermal nucleation at greater supercoolings. The crystallization rate constant k decreased with increasing T c . The value of n ϭ 1.5 for additional crystallization implies a two-dimensional diffusion-controlled crystal growth with a suppressed nucleation phase. For T c values ranging from Ϫ10 to 0°C and 0 to 20°C, k showed weak and quite strong decreasing dependencies on T c , respectively. The recrystallization mechanism involved partial melting of primary crystallites and two-dimensional rearrangement of chains into a more perfect structure. The rate of this process was almost independent of T c . The values of activation energies were derived for the three steps of MPA crystallization using the Arrhenius equation.

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“…Originally, thermoplastic PIs have been developed as amorphous or mesomorphic polymers, the reluctance of which to crystallize derives from the high viscosity of their melt. [1][2][3] Concurrently, another class of thermoplastic PIs has also been developed, which can crystallize from the melt, including LARC-CPI (Langley research center crystalline polyimide), [4,5] LARC CPI-2 (Langley research center crystalline polyimide -second generation), [6] PI-2 (3,3,4,4 0 -benzophenonetetracarboxylic dianhydride and 2,2-dimethyl-1,3-(4-aminophenoxy)-propane), [7] TPI (thermoplastic polyimide), [8][9][10] TPEQ-ODPA (1,4-bis(4-aminophenoxy)benzene and 4,4 0 -oxydiphthalic anhydride), [11] and TPER-BPDA (1,3-bis-(4-aminophenoxy)benzene and 3,3 0 ,4,4 0 -biphenyltetracarboxylic dianhydride). [12] A specific feature of these PIs is their ability to crystallize from the melt to form crystalline matrices for composite materials.…”

Section: Introductionmentioning

confidence: 99%

The Nucleating Effect of Carbon Nanotubes on Crystallinity in R‐BAPB‐Type Thermoplastic Polyimide

Yudin

Svetlichnyi

Shumakov

et al. 2005

Macromol. Rapid Commun.

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Summary: The relatively high degree of crystallinity of a new thermoplastic polyimide (PI) makes it a favorable matrix candidate for fiber reinforced composites. This advantage is the result of the ability of the matrix to recrystallize during the composite manufacturing process. In this study we examine the potential nucleating effect of carbon nanotubes on a thermoplastic PI. In addition to their inherent mechanical contribution, the carbon nanotubes help recover a significant proportion of the original crystallinity.Scanning electron micrograph of the spherulitic structure of a recrystallized carbon nanotube/polyimide film.magnified imageScanning electron micrograph of the spherulitic structure of a recrystallized carbon nanotube/polyimide film.

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Crystallization behaviour and morphological features of LARC-CPI

Cited by 51 publications

References 36 publications

Semicrystalline polyimide matrices for composites: Crystallization and properties

Semicrystalline polyimide matrices for composites: Crystallization and properties

Crystallization behavior of poly(N‐methyldodecano‐12‐lactam). III. Kinetics of isothermal crystallization

The Nucleating Effect of Carbon Nanotubes on Crystallinity in R‐BAPB‐Type Thermoplastic Polyimide

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