The effect of storage conditions on extraction efficiency and identification of extractives in wood-containing paper

TMP-based newsprint paper was submitted to accelerated ageing at 60 degrees C for up to 7 days. The papers were submitted to storage in an oven either by hanging freely, in closed vials in ambient air, or in closed vials flushed with nitrogen. The amount and composition of accessible extractives decreases significantly during ageing of samples hanging freely, as analysed by gas chromatography and size-exclusion chromatography. Samples in closed vials in ambient air and in nitrogen showed only a small decrease of analysed extractives during the time of ageing. After alkaline hydrolysis of the extracts, dioic acids were present in all samples, but for the samples treated in open air in largest amounts. Oxidation is an important but not an exclusive mechanism of alteration of the extractives. To significantly slow down oxidation and other alteration processes, simple enclosure of the paper samples in glass vials is enough.