What are Polymers?
Large molecules composed of repeating structural units connected by covalent chemical bonds.
Name the Polymeric materials
• Natural polymers: e.g. shellac, amber, and natural rubber. • Modified natural polymers: e.g. vulcanized rubber from natural rubber • Biopolymers: e.g. proteins and nucleic acids. • Synthetic polymers: e.g. synthetic rubber, Bakelite, neoprene, nylon, PVC, silicone, etc)
Name the Synthetic Polymer Classes
Plastics: • Thermoplastic • Thermosetting Elastomers: A polymer with the property of elasticity. • Thermoplastic elastomer • Thermoset elastomer (most) Polymer foams: Two phase system of gas dispersed in a solid polymer. • Thermoplastic foams – rigid and flexible • Thermosetting foams – rigid and flexible Fibers: Made out of different plastics and elastomers
Define Thermoplastic and Thermosetting
• Thermoplastic: Polymer that turns to a liquid when heated and freezes to a glassy state. It can be remelted and remolded • Thermosetting: Polymer that irreversibly cures
How are polymers produced?
They are produced by combining a large number of small molecular units (monomers) by the chemical process known as polymerization to form longchain molecules (polymer chains.)
Types of polimerization
- Step-growth by poliycondensation of the same or different monomers
- Chain-growth by polymerization or polyaddition
Examples of polymerization processes
Polymer additives. Definition and examples.
Materials used to make and modify polymers:
• Diluents to make the polymers more flexible
• Solvent to make the polymers more flowing
• Colorant to make the polymers more colored
• Static inhibitor to prevent static charging
• Stabilizer to make the polymers more stable
• Fire retardant to make the polymers more durable for fire
• Propellant to make the polymers more porous
Temperature-dependent resistance and force-deflection behavior of amorphus thermoplastic, semi-crystalline thermoplastic, thermosetting plastic and elastomer
Mechanical properties of different plastics (Tensile test) (graph)
Stress-strain curve of elastic and viscoelastic materials at two values of time
Temperature influence in stress and strain
Name Thermoplastics, thermosettings and elastomeres in construction industry
Thermoplastics
- Polytetrafluoroethylene (PTFE): pot bearing for a bridge
- Poyvinychloride (PVC): pipes
- Polyethylene (PE): Plastic coating for PC-strands
- Polyvinylchloride (PVC): cladding
- Polypropylene (PP): Geotextile
- Polymethylmethacrylate (PMMA): acrylic dome
- Polyurethane (PUR): fire stopping mastics
Thermosetting
- Epoxy (EP): Paints and coatings flooring
- Epoxy (EP): Adhesive
- Polyurethane (PUR): Insulation foams
- Melamine resin (UF/MF): Laminate flooring
Elastomeres
- Neoprene: pads for vibration reduction
- Ethylene Propylene Diene Monomer rubber (EPDM rubber) : Gasket
- Silicone rubber: Gaskets
- Silicone rubber: channels and profiles
Effect of chemicals on polymers
Effect of UV-rays on polymers
Behaviour on fire
- Emit toxic gases: Melting of sheet glazing may vent the fire, increasing rate of spread
- Often contribute to the development of fires May emit dense smoke
