Curing mechanism of urea-formaldehyde under ambient temperature

CHEN Yuzhu, FAN Dongbin, QIN Tefu,CHU Fuxiang

JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2015, Vol. 39 ›› Issue (06) : 169-172.

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南京林业大学学报（自然科学版）
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JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2015, Vol. 39 ›› Issue (06) : 169-172. DOI: 10.3969/j.issn.1000-2006.2015.06.029

Curing mechanism of urea-formaldehyde under ambient temperature

  • CHEN Yuzhu, FAN Dongbin, QIN Tefu,CHU Fuxiang*
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Abstract

This article investigates the change of viscosity, gel time and molecular weight distribution of urea-formaldehyde(UF)resin with curing agent ammonium chloride(NH4Cl)under ambient temperature by measuring gel time and gel permeation chromatography(GPC)analysis. It was found that the viscosity of UF resin with 2.0% NH4Cl changed slightly at the beginning, but sharply increased from 99 mPa·s to 10 020 mPa·s after 8 hours. The resin thickened and clustered at this stage. After 10 hours, UF resin took shape and became hard and its gel time decreased to 40 s from 137 s for the un-cured resin. Number average molecular weight and weight average molecular weight increased significantly, and small molecular disappeared gradually while molecular of medium and high weight accounted for higher proportion. The molecular uniformity of UF was improved degree of dispersion dropped from 1.11 to 1.08. The degree of gelation increases and the activity of applicable UF resin decreases with longer elapsed time.

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CHEN Yuzhu, FAN Dongbin, QIN Tefu,CHU Fuxiang. Curing mechanism of urea-formaldehyde under ambient temperature[J]. JOURNAL OF NANJING FORESTRY UNIVERSITY. 2015, 39(06): 169-172 https://doi.org/10.3969/j.issn.1000-2006.2015.06.029

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