Liquefaction of Wood in the Presence of Polyol Using NaOH as a Catalyst and its Application to Polyurethane Foams
Titel:
Liquefaction of Wood in the Presence of Polyol Using NaOH as a Catalyst and its Application to Polyurethane Foams
Auteur:
Maldas, D. Shiraishi, N.
Verschenen in:
International journal of polymeric materials
Paginering:
Jaargang 33 (1996) nr. 1-2 pagina's 61-71
Jaar:
1996-04-01
Inhoud:
The influences of various reaction parameters (e.g. temperature, time, type and concentration of polyol, and swelling agent) on the extent of liquefaction of the wood meal in polyol, and the properties of the liquefied wood-polyol mixtures have been evaluated. The residue % decreases significantly with the increase of reaction temperature. Similarly, residue % decreases with the increase in reaction time up to 1 h, and also with the increase in NaOH concentration from 0% to 2.5%. Moreover, a polyol:wood weight ratio of 4:6 offers lowest residue. The effects of various formulations for the preparation of polyurethane foams from the concentrated liquefied wood-polyol mixtures on the density, compressive strength and modulus of the resulting foams have also been evaluated. Both molecular weight and concentration of the polyols have profound influence on the residue %, acid and hydroxy values, and molecular weight of the liquefied wood-polyol mixtures as well as ultimate properties of the urethane foams. Once again, with the increase in concentration of blowing agent, e.g. water, both density and modulus of the foams increase, while compressive strength decreases. On the other hand, with the increase in isocyanate index both density and modulus decrease, but compressive strength increases.
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