In this work we investigate the thermal transitions in nylon polymers by studying the steady-state fluorescence anisotropy of the fluorescent probe, pyrene, embedded in the polymer matrix. Nylon-6, Nylon-66 and three different blends of both of these are used in the study. A comparative study using DSC shows that the anisotropy values of pyrene efficiently follow the thermal relaxations in the polymer. © 2002 Elsevier Science Ltd. All rights reserved.

Ashok Kumar Mishra

Department Of Chemistry

Tiju L. Thomas

Anisotropy

Differential scanning calorimetry

Fluorescence

Relaxation processes

THERMAL RELAXATION

Nylon polymers

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Fluorescence anisotropy of pyrene incorporated in nylon as a tool to monitor thermal relaxations in nylon

Polymer Testing

The photophysical properties of two new tetra substituted derivatives of pyrene: 1,3,6,8-tetraethynylpyrene (TEP) and 1,3,6,8-tetrakis(trimethylsilylethynyl)pyrene (TEP-TMS) have been studied. Studies were done with respect to mirror image symmetry in the absorption and emission spectra and permissive or forbidden nature of S0-S1 transition, solvent sensitivity of the first and third vibronic bands and fluorescence anisotropy. Both the derivatives exhibited a strongly allowed S0-S1 transition, high fluorescence quantum yield, shorter fluorescence lifetime compared to pyrene and invariance of the vibronic band intensity ratio to solvent polarity. The behavior of the two pyrene derivatives validates the hypothesis "solvent polarity mediates vibronic coupling and therefore the emission band intensities, for forbidden S0-S1 transitions". The trimethylsilyl derivative (TEP-TMS) was characterized by a strong fluorescence in solid state. The tetraethynyl derivative (TEP) showed high fluorescence anisotropy comparable to the well-known anisotropy probe DPH in glycerol at 0 °C. The fluorescence intensities of TEP and TEP-TMS did not show any significant change in the temperature ranger 0-40 °C for a low viscous solvent like ethanol and in the range 0-60 °C in glycerol. Unlike pyrene, no excimer emission was observed even up to 10-3 M for TEP and TEP-TMS. © 2006 Elsevier B.V. All rights reserved.

Chemical Physics

1,3,6,8-Tetraethynylpyrene and 1,3,6,8-tetrakis (trimethylsilylethynyl) pyrene: Photophysical properties in homogeneous media

Journal of Polymer Science Part C: Polymer Symposia

Fluorescence methods in polymer science

The Wiley Database of Polymer Properties

Progress in Polymer Science

Luminescent probe studies of the microstructure and mobility of solid polymers

Journal of Applied Polymer Science

A study on blends of nylon-6 and nylon-66

Journal of Polymer Science: Polymer Physics Edition

The effect of crystallinity and crosslinking on the depression of the glass transition temperature in nylon 6 by water

Journal	Polymer Testing
ISSN	01429418
Open Access	No