Structure of Materials Descriptions of general non-crystalline features and shoer range order. Use as examples: linear polymers: e.g., polyethylene, PVC, polystyrene elastomer: e.g., natural rubber (polyisoprene), (acrylonitrile butadiene) three dimensional networks thermosetting polymers: e.g. Phenol formaldehyde, epoxides inorganic glasses: e.g., oxide glasses, silica, borosilicate gels: e.g., asphalt and Portland cement Polymers and plastics: description of the basic structural unit 'mer', monomer, polymer. addition and condensation polymerisation, briefly, with examples. distinguish between thermoplastics and thermosets with six examples of each. discuss crystallinity in polymers with examples of crystalline polymers eg, HDPE, nylon, PP, PTFE and amorphous polymers e.g: PVC, polystyrene, PMMA. relate to crystallinity to mechanical properties like rigidity and thermal transitions. additives, to include filters, reinforcements, plasticizers, UV stabilisers, anti-oxidants, lubricants, colourings and flame retardants. Plastics and polymers processing and use: Emphasise the use of additives to vary polymer properties a tailor polymer to appropriate uses. Processing descriptions to include compounding, injection moulding, extrusion, blow moulding, and compression moulding. Describe the use of the major polymers in the above areas highlighting properties of importance in selected applicants by example, eg, polymers used as binders in foundry sands, dielectrical properties for electrical, low cost for agriculture, low permeability of water, oxygen for food packaging and freezer packaging. Ceramic materials: Describe ceramic structures of AX type with various co-ordination numbers (relate to ionic radii) use simple examples only ed, CsCl, NaCl, ZnS, Ax2, and A 2X3 types briefly with examples; two metal compounds briefly eg, BaTiO3. Detailed structure of SiO4, tetrahedra as the basic structural unit and relate the importance to bricks, cement, glass, crockery, technical insulators. Describe silica SiO2 and quartz. Mention refractory nature but problem of cracking under temperature chance due to structural changes. Vitreous or fused silica and properties compared to silica and especially uses with temperature change. Introduce binary (eg, MgO-AlxO3) and ternary diagrams (eg, MgO-AlxO3-SiO2) Manufacture of ceramic articles: raw materials: clays, flints, feldspars, effect of water, shaping by pressure fabrication, hydroplastic forming and slip casting. drying and shrinkage, refer to brick and earthenware product manufacture. describe sintering (fixing) and associated shrinkage. engineering ceramics: eg, silicon nitride, silicon carbide. Glass: describe the vitreous or glassy state and the basic structural unit sio4 tetrahedra. describes glass formers, glass modifiers and intermediates and their role in glass structure. examples of each. properties of glass: viscosity, mechanical, optical. special glass treatments: tempered glass, compare properties with normal annealed glass, effect of compression stresses in surface material. explain devitrification of glass and accompanying changes in properties. glass ceramics: applications. Fibres: fibres and whiskers, metallic and non-metallic carbon fibres, glass, Al2O3, SiC fibres specific modulus and relation to strength to weight ration discuss economic viability of fibres Composite materials: define and give examples, including concrete, wood fibre composites, glass reinforced plastics, foams, reinforced rubbers (tyres). describe the structure of fibre composite and function of fibre composites in actual applications: eg, aerospace, sporting goods. briefly cover concrete, portland cement and raw materials. define hydraulic cement mention the importance of portland cement, compositions and use. factors affecting concrete strength: eg, mixing, measuring, water/cement ration, aggregate/cement ration, aggregate strength and proportions and curing conditions. Adhesives: briefly describe adhesion and adhesives. describe surface properties of liquids and solids especially wetting and non-wetting conditions, include surface tension briefly and relate to choice of adhesive and substrate. |