Using isoconversional kinetic analysis of liquid melamine–formaldehyde resin curing to predict laminate surface properties

Abstract

ABSTRACT:The curing kinetics of a liquid melamineformaldehyde impregnation resin were analyzed with differential scanning calorimetry, and the conversion-dependent activation energy for melamine-formaldehyde curing was estimated with the isoconversional model-free kinetic approach developed by Vyazovkin. The conversion-dependent activation energy was used to extend the predictive power of a response surface model describing the influence of some processing factors (press time and resin composition) in the manufacturing of particleboards coated with melamine-formaldehyde-impregnated papers. By substituting the factor ''press time'' in an RSM established for a press temperature of 170 C by the factor ''conversion'' which is accessible from thermo-chemical analysis, additional information on temperature was incorporated into the model. Model applicability for additional temperatures was evaluated with 12 validation experiments. Although chemical resistance was difficult to model, cleanability was sufficiently well described by only one factor (conversion). Surface gloss depended on both the conversion and catalyst amount and was predicted by a two-factor interaction model (R 2 ¼ 0.95). This study demonstrates that parameters derived from the isoconversional kinetic analysis of liquid resins not only are theoretical descriptors but also have direct practical relevance in the modeling of product properties derived from these liquid resins when used to supplement technological databases.

IR spectroscopy: Suitable method for determination of curing degree and crosslinking type in melamine–formaldehyde resins

“…For industrial applications, acidic catalysts (acids or compounds releasing acids at certain conditions) are used in order to increase the reaction rate of the condensation . Although the basic reactions involved in crosslinking are known since long and have already been intensively studied, the reaction mechanism as well as the chemical composition of the resin are rather complex and still remain under investigation . Analytical methods allowing the determination of the various chemical species present and providing an enhanced understanding of network formation are decisive as the hydrolytic stability of the cured resin is influenced by its chemical structure …”

Processing

“…Theoretical curing isotherms can be calculated from various mathematical approaches for model-free data analysis and the results from kinetic analysis are typically validated by comparison to independent experimental data ( Figure 18.10). Such profiles may well be correlated with rheological measurements and may also be suited for correlation analysis with final technological response factors such as hardness or chemical resistance [117,115]. Model-free kinetic analysis is not limited to DSC but can be applied to other thermal methods as well.…”

“…Most importantly, thermal analysis can be used with advantage to derive kinetic models that allow a better understanding of the curing process. In the past decade, a number of studies describing the application of model-free kinetic analysis approaches have been published for analyzing the dynamics of cross-linking of resins (such as epoxy [109À111], lignin-based [112,113], aminoplastic [114,115], and phenolic resins [112,113,116]) using thermochemical data obtained from DSC. In model-free kinetic data analysis the isoconversional approach is important.…”

Drying and curing behaviour of melamine formaldehyde resin impregnated papers

“…Due to the outstanding chemical and physical resistance of the cured polymer, MF fulfils the performance requirements for both low pressure laminates (LPLs) and high pressure laminates (HPLs) . The MF‐based surfaces vary from high gloss to matt appearances, as well as from wood‐like decorative patterns to arbitrary decors developed by designers according to modern market trends.…”

“…For instance, optical spectroscopic methods have been used to characterize aminoplast synthesis as well as the impregnation and drying process . Among the thermal methods, mainly differential scanning calorimetry (DSC) has been used to model the laminates manufacturing …”