KeywordsWood-bascd compositcs Particlcboard Hot prcssing Modclling Tcmpcrature Vapour prcssurc Hcat and moisturc transfcr Sitka sprucc Ptcea sitchensis SummaryUsing a thcorctical modcl, thc Variation of tcmpcraturc and vapour prcssurc within a particlcboard mattrcss during thc hot prcssing Operation is prcdictcd. Changc in thcsc variables with timc at a givcn Position in thc mattrcss, or with position in cithcr a vcrtical or a horizontal plane at a givcn timc, can rcadily bc studicd.Thc cffcct of a numbcr of proccssing variables on tcmpcraturc and vapour prcssurc Variation is analyscd, with the prcdictions of thc modcl bcing comparcd with cxpcrimcntal data. Thc prcdictcd data agrce well in trcnd, if not in absolute magnitudc, with thosc obscrvcd cxpcrimcntalty.

Using a thcorctical modcl, thc Variation of moisture contcnt and relative humidity within a particlcboard mattress during thc hot prcssing Operation is prcdictcd. Changc in thcsc variables with timc at a givcn Position in thc mattrcss, or with position in cithcr a vcrtical or a horizontal plane at a givcn timc, can rcadily bc studicd. Thc cffcct of a numbcr of proccssing variables on moisture contcnt Variation is analyscd, with thc prcdictions of thc modcl bcing comparcd with thc limitcd cxpcrimcntal data availablc. Thc prcdictcd data agrce rcasonably well with thosc obscrvcd cxpcrimentally.

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A new method for measuring formaldehyde released from cured urea formaldehyde resins under conditions favouring hydrolysis is described. The technique is devised for both industrial quality control and research and it is relatively fast, permits the independent control of water activity and temperature and guarantees the absence of leaching of resin ingredients. The aim of verifying the suitability of the method was persuaded through studying the effect of F: U molar ratio, type of UF concentrate, manufacturing technology, type and concentration of catalyst, type of formaldehyde-scavenging and acid-neutralising additives, on the hydrolytic stability of cured urea-formaldehyde resins. The fact that qualitatively similar results have been reported by other researchers using the Flask method, or versions of the WKI method confirms the reliability of the new technique.

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