Comparison between cure kinetics by means of dynamic rheology and DSC of formaldehyde-based wood adhesives

ABSTRACT

Comparative analysis of the chemical and rheological curing kinetics of formaldehyde-based wood adhesives is crucial for assessing their respective performance. Differential scanning calorimetry (DSC) and rheometry are the conventional techniques used for monitoring the curing processes leading to crosslinking polymerization of the adhesives. However, the direct comparison of these techniques is inappropriate due to the intrinsic differences in their underlying procedures. To address this challenge, the two adhesive samples were sequentially cured, firstly with rheometry and followed by DSC. The observed higher curing degree in the subsequent DSC procedure underpins the incomplete curing of the samples during initial rheometry. Furthermore, the comparative assessment of the activation energies, molar ratios, and active groups of the two adhesives highlights the importance of the pre-exponential factor in addition to the activation energies, as it attributes to the probability of active groups coinciding at the appropriate spatial arrangement.

KEYWORDS:

• Curing kinetics
• degree of cure
• conversion
• pre-exponential factor
• rheology
• DSC

Acknowledgments

This work was carried out in the frame of research projects supported by the Austrian Research Promotion Agency (FFG) within the COMET program (project Nr: 844608). The authors would like to thank Metadynea GmbH, Krems, Austria and FRITZ EGGER GmbH & CO. OG, Unterradlberg, Austria for providing the materials and their helpful and valuable scientific input.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the FFG [844608].