Data/hora: 26/09/2024 09:49:27

Biblioteca(s): 	Embrapa Florestas.	
Data corrente: 	18/10/2019	
Data da última atualização: 	17/11/2020	
Autoria: 	LOURENÇON, T. V.; ALAKURTII, S.; VIRTANEN, T.; JÄÄSKELÄINEN, A.-S.; LIITIÄ, T.; HUGHES, M.; MAGALHAES, W. L. E.; BOLZON DE MUNIZ, G. I.; TAMMINEN, T.	
Afiliação: 	Tainise V. Lourençon, Aalto UniversitY; Sami Alakurtti, VTT Technical Research Centre of Finland; Tommi Virtanen, VTT Technical Research Centre of Finland; Anna-Stiina Jääskeläinen, VTT Technical Research Centre of Finland; Tiina Liitiä, VTT Technical Research Centre of Finland; Mark Hughes, Aalto University; WASHINGTON LUIZ ESTEVES MAGALHAES, CNPF; Graciela I. Bolzon de Muniz, UFPR; Tarja Tamminen, VTT Technical Research Centre of Finland.	
Título: 	Phenol-formaldehyde resins with suitable bonding strength synthesized from "less-reactive" hardwood lignin fractions.	
Ano de publicação: 	2020	
Fonte/Imprenta: 	Holzforschung, v. 74, n. 2, p. 175-183, Feb. 2020.	
DOI: 	10.1515/hf-2018-0203	
Idioma: 	Inglês	
Conteúdo: 	The substitution of phenol by lignin in phenol-formaldehyde (PF) resins is one of the most promising end uses of lignin valorization. Lignin from grasses and softwood has been the focus of the studies in this field as they present a higher number of theoretical reactive sites for resin synthesis. Herein we examined the composition and chemical reactivity of ?less-reactive? hardwood lignin fractions and their performance in PF resins, synthesized by substituting 50 wt% of the phenol with lignin. Before resin synthesis, the samples were hydroxymethylated and the maximum formaldehyde consumption was recorded. By doing so, we observed that hardwood fractions consumed formaldehyde close to the theoretical calculation, whereas the reference softwood lignin consumed only about ¼ of the theoretical value. In the resin synthesis, we added formaldehyde to the formulation according to the measured maximum formaldehyde consumption. Thus, low values of free formaldehyde in lignin-PF (LPF) resins were achieved (<0.23%). Moreover, the resin bonding strength displayed similar performance irrespective of whether the LPF resins were made with softwood or hardwood lignin (range of 3.4?4.8 N mm?2 at 150°C and 45?480 s of press time). Furthermore, we concluded that hardwood kraft lignins present no disadvantage compared to softwood lignins in PF resin applications, which have significant practical implications.	
Palavras-Chave: 	Formaldehyde consumption; Formaldeído; Kraft; Phenolic resins; Reactive sites; Resina fenólica; Technical lignin.	
Categoria do assunto: 	X Pesquisa, Tecnologia e Engenharia	
Registro original: 	Embrapa Florestas (CNPF)	
Exemplares: 	CNPF - (56984-1) - UPC - AP - DD -  -  -  - DIS