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Titolo:
CURE CHARACTERIZATION OF POLYURETHANES WITH LIGNIN AND CELLULOSE DERIVATIVES
Autore:
TOFFEY A; GLASSER WG;
Indirizzi:
VIRGINIA TECH,CTR BIOBASED MAT BLACKSBURG VA 24061 VIRGINIA TECH,DEPT WOOD SCI & FOREST PROD BLACKSBURG VA 24061
Titolo Testata:
Holzforschung
fascicolo: 1, volume: 51, anno: 1997,
pagine: 71 - 78
SICI:
0018-3830(1997)51:1<71:CCOPWL>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
STRUCTURE PROPERTY RELATIONSHIPS; ENGINEERING PLASTICS; NETWORKS; KINETICS; SYSTEM;
Keywords:
DYNAMIC MECHANICAL THERMAL ANALYSIS; STORAGE MODULUS; LOSS MODULUS; GELATION; VITRIFICATION; GLASS TRANSITION TEMPERATURE; ACTIVATION ENERGY; ORDER OF REACTION; FRACTIONAL CURE; DAMPING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
16
Recensione:
Indirizzi per estratti:
Citazione:
A. Toffey e W.G. Glasser, "CURE CHARACTERIZATION OF POLYURETHANES WITH LIGNIN AND CELLULOSE DERIVATIVES", Holzforschung, 51(1), 1997, pp. 71-78

Abstract

The cure kinetics of hydroxypropyl cellulose (HPC) and hydroxypropyl lignin (HPL)- based polyurethanes were studied by dynamic mechanical thermal analysis (DMTA) using the model proposed by Provder (1989). Thebiobased polymers were crosslinked with polymeric methylene diisocyanate (pMDI). The crosslinking reaction followed n(th) order kinetics with an order of reaction of 1.8 and an apparent activation energy of 13.40-14.7 kcal/mol. HPC lends itself less readily to crosslinking with I?MDI as compared to HPL. The optimum safe storage temperature was determined as -16 degrees C for both resins. Vitrification and damping behavior of HPL-based polyurethanes were also studied as a function of resin stoichiometry (NCO:OH). The glass transition temperature (T-g) measured at the tan delta-peak maximum and its corresponding activation energy showed a positive linear increase with increasing NCO:OH. Increasing NCO:OH was observed to cause a broadening of the tan delta peak and a decline of the tan delta peak height. Using the vitrification model proposed by Wisarankkit and Gillham (1990) it was possible to construct a partial TTT-cure diagram of HPL-based polyurethanes. This followed the S-shaped pattern typical of thermosets.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 21:05:02