Investigation of interdiffusion between compatible polymers under static and co-extrusion processing conditions
Sprache des Titels:
When two compatible polymer melts are brought into contact, a diffuse interphase
is formed that governs the adhesion between them. The degree of interdiffusion is
defined mainly by the processing conditions and the physico-chemical properties
of the materials. Despite the great industrial relevance of co-extrusion in
manufacturing multilayer structures, little research has dealt with interdiffusion
under these processing conditions, where polymer-polymer interfaces are subject
to shear load. In this work, procedures for investigating interdiffusion both under
static and real co-extrusion flow conditions were developed. Using various grades
of poly(methyl methacrylate) and styrene-co-acrylonitrile copolymer, we studied
both theoretically and experimentally the effects of interfacial contact time, temperature,
material compatibility, and interfacial shear stress on interdiffusion. Spectroscopic
analysis of the interfaces using confocal Raman microscopy showed that
the general relationships between interdiffusion, time (Fick's law) and temperature
(Arrhenius relationship) are identical under both static and co-extrusion conditions.
However, the interdiffusion rate is significantly higher under shear influence.
Since the prediction of the interdiffusion process supports material selection and
process design in multilayer manufacturing, a simple analytical model was developed
to quantify the effects of aforementioned material properties and processing
conditions on the apparent mutual interdiffusion coefficient.
confocal Raman microscopy, modeling and simulation, polymer processing