RHEOLOGICAL BEHAVIORS OF FILLED POLYMER MELTS

The rheological behaviors of polymer solutions and melts filled with discrete particles are defined by viscoelastic properties of a matrix, specificity of interaction between matrix and filler and ability of filler particles to own structures build.

In a composite material the hydrodynamic and structuring effect of filling takes place. The hydrodynamic effect gives in identical change (in basic to magnification) elastic modulus and viscosity of all relaxation modes. At high concentrations of filler the structuring effect of filling is beginning to essential effect on a composite properties. Thus the relaxation spectra is dilated in the leg of major relaxation times. The filler aggregating increase activation energy of relaxation times at the expense of immobilisation of a part of matrix polymer in voids of aggregates and on interfaces of phases. It gives in amplification of concentration dependence of viscosity and elastic modulus at magnification of test temperature.

Nature, dispersity and concentration of filler effect on quantity of elastic deformation of decay of flow structural units, essential defining all complex of rheological behaviour in nonlinear area of deformation.

 

The flow of composite materials at high shear rates can be accompanied by vacuole formation because of losses of contact between a matrix and filler with the relevant drop of density and strength of extrudates.

 

 

 

The processing of filled thermoplastics often may by impacted by instability of their extensional flow.

Stability conditions of the uniform deformation and dynamics of geometric imperfections development in uniaxial stretching of viscoelastic media have been considered by approximating a single valued dependence of stress on the strain and its rate.

Effect of composition factors on the strain-strength characteristics and the flow stability for a number of composite materials was examined by applying a computerised test with noncontact measurement of diameter in a fixed point of the specimen stretched.

 

The uniaxial stretching of polymers with a narrow molecular mass distribution was analysed on the basis of co-rotation and co-deformation models for one-element Maxwell liquids. Polymers wherein a separate group of slow relaxation processes in relaxation time spectra has been registered partially satisfy both models. Herein, a group of rapid relaxators suits the co-rotation model, while a group of slow relaxators satisfies the co-deformation model. In result, a region of strain localisation and a section of flow stabilisation have been obtained for large strains.

 

  • See also:
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    • 1. M.G.Tsiprin, L.A.Faitelson. Peculiarities of melt flow of low density polyethylene filled with calcium meta-silicate. Mechanics of Polymers (in Russian) 1969, No 4

    2. M.G.Tsiprin. The relaxation spectrums of filled polyethylene melts. Transactions of Academy of Science of Latvian SSR (in Russian),1970, No 2

    3. M.G.Tsiprin, L.A.Jirgens, V.A.Lappo. Rheological and technological characteristics of polyethylene melts filled with chalk and ground limestone. Mechanics of Composite Materials (in Russian) 1992, No 6

    4. M.G.Tsiprin, L.A.Jirgens. Stability of longitudinal flow and spinnability of polymer melts. Mechanics of Composite Materials (in Russian) 1992, No 1

    5. M.G.Tsiprin, L.A.Jirgens. Characteristics of stretching of high-impact polystyrene and polycarbonate close to the glass transition temperature. Mechanics of Composite Materials (NY) 1995, No 4

    6. M.G.Tsiprin, L.A.Jirgens. Stability of the longitudinal flow and slow relaxation processes in filled polymers. Ninth Int. Conf. On Mechanics of Composite Materials, Riga, Oct.17...20, 1995. Book of Abstracts. Riga, IPM LAS, 1995, p.229

    7. J.J.Indulevich, L.A.Jirgens, G.M.Kerch, D.E.Pablaks, M.G.Tsiprin. Automated equipment for determination of rheological properties of polymer solutions and melts. Mechanics of Composite Materials (in Russian) 1985, No 1

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