Sustainable Bio-Based Phenol-Formaldehyde Resoles Using Hydrolytically Depolymerized Kraft Lignin

Homaira Siddiqui; Nubla Mahmood; Zhongshun Yuan; Ferdinando Crapulli; Luana Dessbesell; Amin Rizkalla; Ajay Ray; Chunbao Charles Xu

doi:10.3390/molecules22111850

Sustainable Bio-Based Phenol-Formaldehyde Resoles Using Hydrolytically Depolymerized Kraft Lignin

Molecules. 2017 Oct 28;22(11):1850. doi: 10.3390/molecules22111850.

Authors

Homaira Siddiqui¹, Nubla Mahmood², Zhongshun Yuan³, Ferdinando Crapulli⁴, Luana Dessbesell⁵, Amin Rizkalla⁶, Ajay Ray⁷, Chunbao Charles Xu⁸

Affiliations

¹ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. hsiddiq5@gmail.com.
² Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. nublamahmood@gmail.com.
³ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. zyuan25@uwo.ca.
⁴ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. fcrapulli@uwo.ca.
⁵ Faculty of Natural Resources Management, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada. arizkalla@eng.uwo.ca.
⁶ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. ldessbes@lakeheadu.ca.
⁷ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. aray6@uwo.ca.
⁸ Department of Chemical and Biochemical Engineering, Faculty of Engineering, Western University, London, Ontario N6A 5B9, Canada. cxu6@uwo.ca.

Abstract

In this study bio-based bio-phenol-formaldehyde (BPF) resoles were prepared using hydrolytically depolymerized Kraft lignin (DKL) as bio-phenol to partially substitute phenol. The effects of phenol substitution ratio, weight-average molecular weight (M_w) of DKL and formaldehyde-to-phenol (F/P) ratio were also investigated to find the optimum curing temperature for BPF resoles. The results indicated that DKL with M_w ~ 1200 g/mol provides a curing temperature of less than 180 °C for any substitution level, provided that F/P ratios are controlled. Incorporation of lignin reduced the curing temperature of the resin, however, higher M_w DKL negatively affected the curing process. For any level of lignin M_w, the curing temperature was found to increase with lower F/P ratios at lower phenol substitution levels. At 25% and 50% phenol substitution, increasing the F/P ratio allows for synthesis of resoles with lower curing temperatures. Increasing the phenol substitution from 50% to 75% allows for a broader range of lignin M_w to attain low curing temperatures.

Keywords: Kraft lignin; curing temperature; depolymerized Kraft lignin; optimization; phenol-formaldehyde resoles.

MeSH terms

Formaldehyde / chemistry*
Hydrolysis
Lignin / chemistry*
Phenol / chemistry*
Temperature

Substances

Formaldehyde
Phenol
Kraft lignin
Lignin