engleski

Optical stability of deteriorated deinked paper

This study observes optical stability of newspaper laboratory handsheets after exposing to accelerated ageing. By chemical deinking flotation method under different experimental conditions, Croatian daily newspaper was recycled. Accelerated ageing of prepared handsheets were done in an oven at 60°C and were submitted to accelerate ageing provided by Solarbox 1500e, while exposure time was varied (24, 48 and 72 hours). Optical stability of all handsheets were analysed through changes in reflectance spectrum and compared to those made with frequently used deinking method INGEDE 11. Regardless the process conditions during the flotation deinking, it is a notable increase of the reflection values in the visible part of the spectrum after thermaly handsheets ageing and the highest increase of reflectance values is obtained on handsheet which was prepared from newspaper suspension disintegrated at room temperature during recycling process. The results have shown that the reflectance of samples is almost equalled to reflectance of non aged paper for wavelength higher than 600 nm and that consequential reduction of the reflective spectra for wavelength lower than 600 nm of accelerated aged handsheets treated with Xenon lamp and indoor filter was caused by blue part of visible light.

accelerated ageing, deinking method, newspaper, reflectance spectrum

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