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Research Programmes

 

Advanced Polymers and Composites

Prof. RNDr. Josef Jančář, CSc.
Research Group Leader

THEMATIC RESEARCH FOCUS

RESEARCH AREAS

  • Synthesis of specialty organic and organic-inorganic polymers and copolymers
  • Multi-scale structure-property relationships in polymers and polymer composites
  • Development of advanced functional materials based on nanostructured hierarchical polymers
  • Syntheses of controlled life-span polymers, resorption of biomedical polymers, service life-time period predictions for commodity plastics
  • Physics of heterogeneous polymer systems, deformation and fracture phenomena in polymers, reptation dynamics, nanocomposite viscoelasticity, self assembly
  • Synthesis of biopolymeric materials for tissue engineering and drug delivery

MAIN OBJECTIVES

Biomaterials

The development of novel composite biomaterials that can induce the growth of connective tissue on the surface of implants and therefore accelerate healing and improve the strength and biological stability of the implanttissue connection (materials for replacement of soft and hard tissues).

Materials for energetics and ecology

The development of novel composite materials with a functionally graded structure for the improvement of the effi ciency and lifetime of components and devices for energetics, communication and control technologies (conductive polymer materials for electrodes, biopolymers and precursors from plants and plant residues).

Structural materials

The development of novel polymeric composites with excellent mechanical and thermal properties for structural applications (polymer multifunctional composites for high-tech engineering applications).

CONTENT OF RESEARCH

Advanced polymers and composites

The main activity of the research group is to investigate advanced methods of preparing multifunctional homogeneous and heterogeneous polymeric materials (biomaterials, electromaterials and structural materials) to characterise their structure on various dimensional scales, to quantify structure-property-function relationships on the various structural levels and to develop procedures for engineering the properties of this class of materials in the process of their preparation.

The specifi c research activities include:

Preparation of advanced multifunctional polymeric and biopolymeric materials

Research of the preparation of novel, advanced multilevel and multifunctional homogeneous and heterogeneous polymeric materials employing advanced syntheses of multifunctional macromonomers and polymers, ultrathin nanostructured polymeric layers and including function specifi c chemical modifi cations of biopolymers, syntheses of monomers and polymers from renewable resources and the utilisation of genetically modifi ed micro-organisms to produce biopolymers of the prescribed molecular structure.

Quantification of structure-property-function relationships in bulk materials

The characterisation of the structural parameters, specifi c functions and properties of the synthesised materials on various dimensional scales from nanoscale through microscale to macroscale and research on the routes to control the properties and functions in the various steps of material preparation from the molecular level,

through supermolecular level and morphology to the phase structure and spatial arrangement of the heterogeneities, in addition to the physico-chemical and mechanical properties, the biotoxicity and ecotoxicity of the new materials will also be investigated.

Mechanisms of polymer degradation

Research on the mechanisms and kinetics of degradation of the synthesised materials via hydrolysis and bacterial action, migration of the degradation products to biotic and abiotic components of the environment including investigations of the retention of these species in the environment and in living organisms on the molecular, cell, tissue and metabolic levels; the use of blood derivatives as bioindicators will also be investigated. Later, the research of degradation mechanisms of commodity plastics and compounds. The investigation of phenomena taking place in the polymer matrix under application conditions; the development of new, more stable materials and ways of making reliable predictions of their service life.

Electrical properties and life-time prediction by means of accelerated ageing

To achieve the overall goal, which is monitoring and evaluating the electrical properties of (polymeric) materials, two measuring workplaces must be established – a workplace for the material degradation tests and a high voltage workplace.

Degradation tests will be carried out in climatic and thermal shock chambers with the possibility of setting up and maintaining the working factors applied to the test samples of materials for the duration of the test. Specifi cally, this means accelerated life tests accelerated thermal ageing, electrical stress and multistress ageing, cyclical thermal stress (variations in temperature), thermal shock testing, higher relative humidity impact and the eff ects of visible and UV radiation.

The electrical properties of materials exposed to accelerated degradation tests will be analysed by high level voltage diagnostic methods. The impact of the intensity of the electric fi eld on the pre-breakdown and breakdown states of dielectric materials in a high intensity AC electric fi eld will be investigated. The electrical material properties will be observed as functions of temperature, frequency and voltage and the material properties changes during the course of diff erent degradation mechanisms (temperature ageing, electrical and multistress ageing) will be monitored. AC bridge methods bring possibilities for measuring the electrical properties (parts of complex permittivity, dissipation factor and breakdown voltage) in voltage and temperature dependence and monitoring the partial discharge in insulation materials in the domain of industrial frequency.

Computer modelling and simulations

The development of novel simulation procedures and methods for computer modelling of structure-property-function relationships in heterogeneous polymeric materials and failure in anizotropic polymeric systems to support computer aided material design, non-fi ckean diff usion in degrading solids to predict the lifespan of the polymeric waste.

KEY RESEARCH EQUIPMENT

PLANNED RESEARCH INFRASTRUCTURE

Technology Units

  • Molecular structure and morphology
  • Mechanical and rheological testing
  • Polymer synthesis
  • Polymer degradation and stability
  • Specialty polymers and biopolymers
  • Reactive compounding and processing

CURRENT RESEARCH INFRASTRUCTURE

  • Brabender Kneader 50 ml (2x), Plasticorder Lab Station Brabender + Twin-Screw extruder Brabender 25 DSE (d=25 mm; l=180mm; l/d=34), Lab Plate Press Fontijne LBP 300, Lab Press Scientifi c, Labtech Engineering 80t – used for polymeric materials homogenisation, compounding and test specimens preparation.
  • Mechanical properties and behaviour of polymers in the solid phase is determined using Stress-strain tester Zwick/Roell Z010 + thermo-chamber, Instrumented impact tester Ceast Resil Impact Junior, Impact tester Zwick/Roell, Instrumented impact tester Ceast Fractovis, Dynamic-mechanical thermal analysis TA Instruments 2980 + Gas Cooling Accessory, Rheometer AR-G2 TA Instruments, DMA RSA-G2 TA Instruments.
  • Heat absorption behaviour is determined using Thermogravimetric analysis Perkin Elmer TGA6, Diff erencial scanning photocalorimetry TA Instruments 2920.
  • Optical properties are assessed by means of Transmition optical microscope Olympus BX50, Confocal laser scanning microscope Olympus – Lext OLS 3000.
  • Other instruments for polymer fl ow properties determination such as Melt Flow Tester (MFI) Ceast, Gel permeation chromatograph – HP pump HPP5001, column PLgel10, RI detector Ruby05, Gas chromatograph – Chrom 5, UV curing – Targis, Vectris (Ivoclar) are used.

MAIN PROJECTS

  • Effect of thermal history on morphology and fracture behaviour of polypropylene impact-copolymers (GA104/07/1631), Czech Science Foundation, 2007-2009, J. Jančař, Brno University of Technology.
  • The effect of nanoparticles on chain mobility and kinetics of polyolefi n nanocomposites crystallization (GAP205/10/2259), Czech Science Foundation, 2010-2012, J. Jančař, Brno University of Technology.
  • The use of newly synthetised bio materials (2B06130), Ministry of Education, Youth and Sports, 2006-2011, A. Nečas, University of Veterinary and Pharmaceutical Sciences Brno, J. Motlik, the Institute of Animal Physiology and Genetics AS CR, E. Sykova, Institute of Experimental Medicine AS CR, P. Gal, Masaryk University, J. Jančař, Brno University of Technology.
  • Multifunctional heterogeneous materials based on synthetic polymers and biopolymers (MSM0021630501), Ministry of Education, Youth and Sports, 2005-2011, J. Jančař, Brno University of Technology.

SELECTED PUBLICATIONS

  • TOCHACEK, J., JANCAR, J., KALFUS, J., HERMANOVA, S. Processing stability of polypropylene impact-copolymer during multiple extrusion – Effect of polymerization technology. Polymer Degradation and Stability. 2011, 96(4), p. 491-498.
  • HERMANOVA, S., TOCHACEK, J., JANCAR, J., KALFUS, J. Eff ect of Multiple Extrusion on Molecular Structure of Polypropylene Impact – Copolymer. Polymer Degradation and Stability. 2009, 94(10), p.1722-1727.
  • TOCHACEK, J., JANCAR, J., KALFUS, J., ZBORILOVA, P., BURAN, Z. Degradation of Polypropylene Impact-Copolymer During Processing. Polymer Degradation and Stability. 2008, 93(3), p. 770-776.
  • ZIDEK, J., JANCAR, J. Simulation of Inelastic Stress Strain Response of nanocomposites by a Network Model. Key Engineering Materials. 2006, 334-335(2), p. 857-860.
  • JANCAR, J. Eff ect of interfacial shear strength on the mechanical response of polycarbonate and PP reinforced with basalt fi bers. Composite Interfaces. 2006, 13(8-9), p. 853-864.
 

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