Processing properties and pyrolysis behavior of novolak-hexamethylenetetramine mixtures

Abstract

This work investigates the influence of the hexamethylenetetramine (hexa) content on the rheological features, pyrolysis reactions, mass-loss kinetics and char yield for two phenolic resins, each with different novolak-hexa mixtures from 0 wt.-% to 15 wt.-%. Curing and viscosity of resins was studied using a rheometer. Pyrolysis, evolved gases and char yield were investigated with TG-FTIR-GC/MS. The obtained results show that the curing of resins shifts to lower temperatures whereas the viscosity and the residual carbon amount both increase with increasing hexa-contents. The presented data suggests a hexa-induced microgel formation for phenolic resins. Models for viscosity and char yield were developed and present a valuable tool to tailor the resin-hardener mixture for the desired application, enable a more efficient processing technology and contribute to a deeper understanding of the pyrolysis of novolak resins.

Graphical Abstract

Keywords:

• Phenol
• novolak
• hexa
• viscosity
• char yield
• pyrolysis
• processing
• evolved gas analysis

Acknowledgment

Special thanks goes to Bakelite Synthetics (Germany) for providing the phenolic resins and hexamethylenetetramine.

Disclosure statement

No potential competing interest was reported by the authors.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

Additional information

Funding

The work was financed by the German Research Foundation (DFG) grant number KR-2005/12-1.