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Objectives
Students should learn basic skills in the field of elastomeric composites and should achieve the ability to correlate composites structure and properties, with reference to their most important applications, such as the one for tyre compounds.
Program
Lesson – 3 hours
Concepts of organic chemistry. The polymeric nature of solids. Introduction to polymers. Sources. Nomenclature. Chemical composition. Structure. Dimension. Average molecular mass. Synthesis of polymers: stoichiometry, thermodynamics, kinetics.. Intermolecular and intramolecular bonds in polymers. Stereochemistry..
Organization of polymers at the solid state: amorphous and crystalline polymers. Thermodynamic origin of melting point. Main types of polymers Transitions of polymers and thermodynamics. Thermal transitions in polymers.
Exercise 3 hours
Structure of polymers. Thermal transitions in polymers
Lesson 3 hours
Elastomers and rubbers. Definitions. Worldwide production. Trends.
Entropic elasticity: classical and statistical thermodynamics.
Design of an elastomer: from molecular structure to entropic elasticity.
Main types of rubbers. Poly-isoprene rubber: natural and synthetic. Butadiene and styrene-butadiene, butyl and halo-butyl rubber. Polyolefin elastomers. Special elastomers: poly(chloroprene), nitrile, fluorinated, silicon elastomers.
Exercise 2 hours
Elastomers and elasticity
Lesson 3 hours
Tensile and dynamic-mechanical properties of polymers.
Viscosity and viscoelasticity. Mechanical compliance. Relaxation modulus. Dynamic-mechanical properties. Dynamic-mechanical measurements and transitions of polymers. Boltzmann superposition principle. Time Temperature superposition principle. The master curve. Viscoelastic models.
Exercise – 1 hour
Viscosity and viscoelasticity
Lesson 6 hours
Reinforcing fillers for elastomeric composites: carbon black and silica. Main features: surface area, structure, aggregates and agglomerates.
Reinforcement of elastomers. Reinforcing fillers. Contributions to the modulus. Einstein-Guth-Gold equation. The behaviour at low, medium and large strain. The filler network and the non linearity of modulus: the Payne Effect. Theories to explain the Payne effect. The Mullins effect. The paradox of elastomers.
The behaviour of elastomeric composite materials containing (i) carbon black (ii) silica.
Exercise 3 hours
Reinforcement of an elastomer.
Lesson 6 hours
Rheological behaviours of polymers. Dependence of viscosity on deformation rate, temperature, pressure. Power law. Viscosity and WLF equation. Measurements of viscosity: Mooney viscosity and capillary rheometry. Bagley and Rabinowitch corrections. Elongational viscosity.
Processing of a composite elastomeric material. Distributive and dispersive mixing. Mixing technologies: roll mill, internal mixer: Banbury® type, with tangential and intermeshing rotors. Mixing cycles.
Twin screw extruder: co-rotating and counter-rotating.
Exercise 2 hours
Rheology and processing of elastomeric composites
Lesson 3 hours
Crosslinking of an elastomer. Monitoring the crosslinking of an elastomer: rheometry and calorimetry. Effects of crosslinking on elastomer properties. Chemistry of crosslinking. Crosslinking systems: with peroxides, phenolic resins, sylanes. Vulcanization: crosslinking with sulphur based systems. Mechanism of vulcanization.
Exercise 1 hour
Crosslinking of elastomeric composites
Lesson 3 hours
Polymer blends: few concepts of thermodynamics.
Ingredients for an elastomeric composite.
A tyre: definition and structure. Fundamental parts of a tyre. Tyre compounds and materials. Examples from patent literature. A tyre compound as a multi-transition material. Green tyres. Chemistry of a silica based elastomeric compound for a low dissipation of energy. Coupling agent. The chemistry and the effect of sylanization reaction.
Exercise 3 hour
Polymer blends, tyre compounds, tyres
Examples of tyre compounds: formulations, structure, behaviour
Lesson 2 hours
Rubber nanocomposites.
Lesson 3 Hours
Tyre compounds. Examples: from materials science to performances
Visit to a major tyre company
During the course, visit will be done to a major tyre company.
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Inglese