POLYMERS AND COMPOSITES
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- Versione italiana
- Academic year
- 2015/2016
- Teacher
- FRANCESCO MOLLICA
- Credits
- 12
- Curriculum
- MATERIALI
- Didactic period
- Annualità Singola
- SSD
- ING-IND/22
Training objectives
- The course concerns basic aspects about the mechanics, design and manufacturing of parts made of polymeric or composite materials
Prerequisites
- Basic chemistry, mechanics of materials, heat transfer and fluid dynamics
Course programme
- General properties of plastics: advantages and disadvantages.
Chemical bonds. Morphology. Configuration and conformation. Molecular weight. Classification. Thermoplastics and thermosets. Transition temperatures: glass transition, melting, crystallization. Measurement.
Properties of solid plastics: rubber elasticity. Viscoelasticity, linear viscoelasticity. Creep and relaxation curves, Isocrones. Creep compliance and relaxation modulus. Constitutive equations: Maxwell fluid, Voigt, Zener model. Dynamic mechanical analysis, time temperature superposition. Pseudoelastic method: exercises. Ribs. Assembly. Welding. Snap fits.
Properties of molten plastics. Non Newtonian fluids, viscosity, rheology, rheometry. Capillary viscometer, rotational rheometers, Melt Flow Index. Polymer processing: Extrusion, injection molding, blow molding, thermoforming, rotomolding, film blowing. Freeze time estimation. In mold contraction, cooling time. Additives. Plasticds materials: polyolefins, styrenics, PVC. Polyamides, polyesters, polyacetal, polycarbonate, acrylics. High performance Polymers. Elastomers and expanded polymers, polyuretanes. Failure. Case studies.
Composites
Stiffness for anisotropic materials. Orthotropic materials, Transverse isotropy. Unidirectional lamina, plane stress. Laminates, classical lamination theory.
Stiffness matrix for laminates.
Particular laminates:
symnmetric, balanced, skewsymmetric, quasi-isotropic, angle ply, cross ply.
Exercises.
Failure. First Ply Failure, Ultimate Laminate Failure, Delamination.
Processing: manual lay up, prepreg lay up and autoclave curing, filament winding, Resin Transfer Molding, pultrusion. Didactic methods
- Lectures, computer simulations with dedicated software and lab classes
Learning assessment procedures
- Oral exam constituted by:
- 1 general question about polymeric materials among the topics seen in class
- 1 design project of a plastic part, of which the candidate must specify material, dimensions, static analysis and injection molding simulation using the Moldflow injection molding simulation software
- 1 discussion about a plastic part, given the day of the exam, of which the candidate must recognize the plastic material, the forming technique and possible manufacturing problems
- 1 general question about composites concerning topics seen in class
- 1 exercise about the mechanics of composite laminates
- 1 lab project concerning design and manual impregnation of carbon fiber with epoxy resin for realizing a part to be loaded in 3 point bending Reference texts
- H. Belofsky - Plastics: Product design and process engineering - Hanser Gardner
D.H. Morton Jones - Polymer processing - Chapman and Hall
J.A. Brydson - Plastics Materials - Butterworth Heineman
R.F. Gibson - Principles of composite materials mechanics - McGraw Hill
I. Crivelli Visconti - Materiali compositi - Hoepli
