Fraunhofer-Gesellschaft

Publica

Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Study of reactive melt processing behavior of externally plasticized cellulose acetate in presence of isocyanate

 
: Erdmann, Rafael; Kabasci, Stephan; Kurek, Joanna; Zepnik, Stefan

:

Materials 7 (2014), No.12, pp.7752-7769
ISSN: 1996-1944
English
Journal Article
Fraunhofer UMSICHT Oberhausen ()
melting; processing; crosslinking; cellulose acetate; rheology; thermal properties

Abstract
Two types of externally plasticized cellulose acetate (CA) were chemically modified using 4,4'-methylene diphenyl diisocyanate (MDI) as crosslinking agent. Crosslinking was performed in the molten state by means of melt mixing in an internal mixer. The viscoelastic properties of the non-crosslinked, externally plasticized CA show typical temperature dependence, similar to conventional thermoplastics. A strong increase in storage modulus is observed with increasing crosslink density indicating that the crosslinked compounds exhibit predominately elastic response. The complex viscosity also increases considerably with increasing crosslink density and does not reach the typical Newtonian plateau at low radial frequencies any more. The viscoelastic properties correlate well with the data recorded online during reactive melt processing in the internal mixer. In comparison to the non-crosslinked CA, the crosslinked compounds show higher glass transition temperature, higher VICAT softening temperatures, improved thermal stability and lower plasticizer evaporation at evaluated temperatures.

: http://publica.fraunhofer.de/documents/N-319465.html