INVESTIGADORES
ESTENOZ Diana Alejandra
congresos y reuniones científicas
Título:
Experimental and Theoretical Study of High-Impact Polystyrene (HIPS) Devolatilization
Autor/es:
EMILIO BERKENWALD; NATALIA CASÍS; DIANA ESTENOZ
Lugar:
San Francisco
Reunión:
Conferencia; 2013 Annual Meeting American Institute of Chemical Engineers (AIChE); 2013
Institución organizadora:
AIChE
Resumen:
In
the high-impact polystyrene (HIPS) process, a devolatilization stage is carried
out in order to remove the unreacted monomer and other volatile species
(solvent, oligomers). High temperature reactions take place in the
devolatilizer (DV), affecting the molecular structure and quality variables of
the final product. In this work, an experimental and theoretical study of HIPS
batch devolatilization is developed. The experimental work consisted on a series
of HIPS devolatilizations carried out in a laboratory DV equipment. Monomer and
oligomer content as well as molecular weights were determined from experimental
measurements taken at different times of the process. After devolatilization,
the Swelling Index (SI) of the obtained product was experimentally determined.
The proposed mathematical model is based on the complex reactions kinetics for
HIPS polymerization and the interfacial mass transfer phenomena. Inputs for
this model are HIPS composition, molecular weight distributions of the
different species (free polystyrene, residual polybutadiene and graft
copolymer), crosslinking degree, and DV operating conditions and geometry.
Outputs to the module are the monomer and oligomer content, molecular weight distributions
and rubber molecular weight between crosslinking points. The SI is
theoretically calculated by a modified Flory-Rehner equation (Karam and Tien,
J. Appl. Pol. Sci., 30, 1969, 1985), considering: thermodynamic equilibrium
between the swollen gel and the solvent, equivalent spherical gel, simplified
strain energy function and negligible contributions from interfacial tension
forces to the overall free energy. Osmotic pressure is considered in order to
include the effect of polystyrene occlusions in the rubber particles. A good agreement between measurements and
estimations is observed.