Dielectric analysis as a cure monitoring system for UF particle boards

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• 作者：Uwe Mü ; ller^a ; ; Claudia Pretschuh^a ; Roland Mitter^b ; Stephan Knappe^c
• 关键词：Wood adhesives ; Wood and wood composites ; Dielectric spectroscopy ; Non-destructive testing ; Curing/hardening
• 刊名：International Journal of Adhesion and Adhesives
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：73
• 期：Complete
• 页码：45-50
• 全文大小：903 K
• 卷排序：73

文摘

To achieve good quality wood composites, the degree of curing of the adhesive – often an aminoplastic thermosetting resin – is an important factor. Dielectric analysis (DEA) is an established method for characterizing the curing behaviour of coatings. This method is also promising for the online-monitoring of the curing of aminoplastic thermoset resins.By DEA, changes in the curing behaviour as a result of processing conditions (of the composite) can be immediately observed during the production; furthermore DEA enables control and optimisation of the production time.In the present work, DEA cure monitoring was tested in pilot plant scale production of urea-formaldehyde (UF) based particle boards. The measurements were performed during hot-pressing; the pressing times and binder types were varied. The degree of curing was calculated from logarithmic ion viscosity values. Sufficient cross-linking resulted in a significant increase of the ion viscosity. The logarithmic ion viscosity values which are measured at the end of the pressing process were correlated with the transverse tensile strength of the obtained particle boards.