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Polybutylene Terephthalate (PBT)

Polybutylene Terephthalate (PBT). CORPORATE TRAINING AND PLANNING. Polybutylene Terephthalate (PBT). Linear polyesters were studied by Carothers during his classical researches for development of Polyamides.

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Polybutylene Terephthalate (PBT)

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  1. Polybutylene Terephthalate (PBT) CORPORATE TRAINING AND PLANNING

  2. Polybutylene Terephthalate (PBT) • Linear polyesters were studied by Carothers during his classical researches for development of Polyamides. • But it was Whinfield and Dicson who developed PET at Calico Printers Association, England I 1941 (As Fibres, Terylene and Dacron and as Film, Melinex and My lar, with the expiry of the basic ICI patents on PET there was considerable development in terephthalate polymers in the early 1970’s. • More than a dozen companies introduced PBT as an Engineering Plastics during this time. • The fiber in the name of Kodel and Film in the name of Kodar was developed by Kodak. • PBT was introduced commercially in 1969 by Celanese. CORPORATE TRAINING AND PLANNING

  3. Monomer Ingredients for PBT • The ingredients which are used for preparing PBT are 1,4 butanediol and dimethyl terephthelate. • HO – CH2 – CH2- CH2- CH2 – OH • 1,4 - butanediol Dimethyl terephthelate CORPORATE TRAINING AND PLANNING

  4. Chemistry of Preparation of PBT Polybutylene Terephthelate (PBT) also called polytetramethylene terephthalate (PTMT) resin is a semicrystalline polyester resin. It is produced by the catalytic polycondensation of 1,4 butanediol and dimethyl terephthelate. n HO-CH2 -CH2 -CH2 CH2 -OH +n CH3 OOC - O COOCH3 o o -[O-C- 0 -C-O CH2 -CH2 -CH2 -CH2- 0]+ 2n CH3 OH CORPORATE TRAINING AND PLANNING

  5. Manufacturing of PBT • PBT is manufactured using similar principles of PET manufacturing. • At first step PBT is produced by the catalytic polycondensation of 1,4 butanediol and dimethyl terephthalate, Subsequent post condensation raises transerterified product to the desired molecular weight. CORPORATE TRAINING AND PLANNING

  6. Relations of Structure and Properties of PBT • There are various classes of linear polyesters. • The concentration of ester groups has predominant effect on the properties of linear polyesters. • For the aromatic classes of linear polyester, decreasing the concentration of ester groups apparently leads to a reduction in melting point. • However, in such aromatic linear polyester the decrease in concentration of ester group is accompanied by the p-phenylene group concentration. • It is found from aliphatic polyester that the ester group concentration has little effect on the melting point. • In fact a decrease in ester group concentration leads to a slight increase in the melting point. CORPORATE TRAINING AND PLANNING

  7. Relations of Structure and Properties of PBT • It is found that in an ester group the in chain ether link –C-O-C- increase the chain flexibility compared with a polyethylene chain to decrease the heat of fusion. • At the same time there will be some increase in inter chain attraction via the carbonyl group which will decrease the entropy of fusion. • Since these two effects almost cancel each other out there is almost no change in ester group concentration. • With all linear series of polyester as the no. of methylene groups in the repeating unit increases so the polymer becomes more like a linear polyethylene (polymethylene). CORPORATE TRAINING AND PLANNING

  8. Relations of Structure and Properties of PBT • It is also observed that Tm (melting point) of a polymer with an odd no. of methylene groups in the aliphatic portion of the repeat unit is lower than for the polymer with one more but an even no. of methylene groups. • Generally, the highest melting points are obtained where the in-chain aromatic ring is of the p-phenylene type. • The materials have a disadvantage of sensitivity to water and alkaline solution. • These materials are crystalline and only proton donors that are capable of inter action with the ester groups are effective solvents.

  9. Characteristics of PBT ( For Identification) • The PBT is semicrystalline material. • It is having good wear characteristics and good insulating properties. • It is also having good dimensional stability. • It is identified by orange colored sooty flame. • When burns melt drips and gives sweet smell • The melting point is 220-230°C • Short term and long term service temperature are respectively 160 and 100°C CORPORATE TRAINING AND PLANNING

  10. Characteristics of PBT • High strength & rigidity • Excellent dimensional stability • Low co-efficient of friction • Good abrasion resistance • Good resistance to creep at ambient & elevated temperature • Low moisture absorption • Resistance to weak acid, bases, alcohols, ketones, oils, fats and aliphatic hydrocarbons • Good resistance to motor oil, gasoline and brake fluids • High temperature resistance • Excellent flame resistance • Good electrical resistance • High arc resistance & dielectric strength • Low dissipation factor CORPORATE TRAINING AND PLANNING

  11. Properties of PBT PropertiesUnits Values Specific gravity ---- 1.31 Tensile strength MPa 55 Tensile modulus MPa 2551 Flexural modulus Mpa 2275 Elongation at break % 200 Impact strength izod, Notched, J/m 53 Hardness R -72 Deflection temperature under load 0C 205-210 (1.82 Mpa) Coefficient of linear expansion mm/mm/0C 7.4 x 10-5 Water absorption, 24hrs % 0.1 Dielectric strength KV/mm 15.8 Dielectric constant 10-6 Hz 3.24 Power factor 0.019 Volume resistivity Ohm.m 4 x 1017 Melting point 0C 225 Glass transition temperature °C 40 CORPORATE TRAINING AND PLANNING

  12. Properties of PBT Mechanical Properties The material has very good strength, stiffness, hardness and maintain toughness at low temperature. Thermal Properties The melting temperature of PBT is 225°C. It has excellent dimensional stability at variable temperature range. Electrical Properties PBT is a good electrical insulator and this is little affected by water absorption. Electrolytic corrosion or contact-impairing deposits are unlikely. The dielectric strength is also independent of temperature. CORPORATE TRAINING AND PLANNING

  13. Properties of PBT • Water Absorption • The low moisture absorption ensure consistent mechanical performance and dimensional stabiltiy. • Permeability to Water vapour and Gases • Permeability resembles that of PET films, i.e. it is good compared to other polymers. • Chemical Properties • PBT is resistant to water, aqueous solutions (at room temperature), weak acids, many organic solvents, oils, fats, brake fluid, carbon tetrachloride. • It is not resistant to strong acids, alkaline solutions, phenol, ethyl acetate, acetone. Extended contact with water at 60°C leads to hydrolytic decomposition. • PBT is not susceptible to stress cracking. CORPORATE TRAINING AND PLANNING

  14. Properties of PBT • Resistance to Weathering and High Energy Radiation • The properties are same as discussed for PET. • Flammability • Unreinforced PBT burns slowly with an orange, sooty flame. The melt drips. Glass fiber reinforced material burns more rapidly because there is less tendency to drip. • Toxicity • PBT is suitable for applications involving contact with food stuffs. It is physiologically inert. CORPORATE TRAINING AND PLANNING

  15. Additives of PBT 1. Functional additives 2. Fillers 3. Reinforcements CORPORATE TRAINING AND PLANNING

  16. Functional Additives 1. Anti-oxidants 2. UV absorbers 3. Flame retardants CORPORATE TRAINING AND PLANNING

  17. Fillers and Reinforcements 1. Mica - Fillers 2. Thermoplastics glass fiber - Reinforcements CORPORATE TRAINING AND PLANNING

  18. Grades of PBT • The PBT is available in the following grades. • Injection moulding grade • Extrusion grade CORPORATE TRAINING AND PLANNING

  19. Processing of PBT • PBT can be processed by the following techniques • Injection Moulding • Extrusion • Blow Moulding CORPORATE TRAINING AND PLANNING

  20. Processing considerations of PBT • This resin must be dried to a moisture of 0.02% or less before processing to ensure desired quality performance. The drying condition should be 120°C for 2-4 hours. The injection moulding machine should be cleaned thoroughly with polyolefin or polystyrene to remove any residual material in the cylinder. The cylinder temperature should be maintained at 230-260°C. The recommended mould temperature should be 60-120°C. The maximum recommended regrind / reclaimed material which can be mixed without adverse affect on resin properties is 25%. CORPORATE TRAINING AND PLANNING

  21. Surface Finishing of PBT • The high chemical resistance of the polyalkylene terephthalates necessitates the use of special purpose lacquers to ensure good adhesion. • The same applies to hot embossing (temperature range of the die 140 - 200°C). • PBT can be polished easily. Metallization can be only be carried out by high vacuum deposition. • Where high gloss surfaces are required on filled and reinforced product, an intermediate lacquer must be used. CORPORATE TRAINING AND PLANNING

  22. Machineability of PBT • Cutting • Cutting can be possible in PBT with suitable equipments in a specified speed. • Joining • Welding • Moldings and semi-finished products can be welded and bonded. Unreinforced moldings can be joined by hot gas and heated tool welding. With increasing glass fiber and the flame retardant content, the welded joints decrease in strength. Friction and ultrasonic welding are efficient joining methods. • The conditions for heated tool welding are • Heated tool temperature - 260°C • Contact pressure at start of heating - 0.5 bar • Contact pressure at start of welding - 0.5 bar • Heating up time (according to wall thickness) - 10 to 30 s CORPORATE TRAINING AND PLANNING

  23. Applications of PBT • Electrical and electronic applications • Automobile applications • Others CORPORATE TRAINING AND PLANNING

  24. Applications of PBT Electrical and electronic applications: Connector, IC Sockets, Terminal blocks, bobbins, push-buttons of telephone set, micro switch, TV parts, hair dryer parts, micro motor housing, glue gums etc. Automotive plug connector CORPORATE TRAINING AND PLANNING

  25. Applications of PBT • Automobile applications: • Wiper gear case, outer handle, distributor, coupler, Ignition system parts, bumper, valve of exhaust, gas treating system etc. Application of PBT in various areas CORPORATE TRAINING AND PLANNING

  26. Applications of PBT Air bag cover Optical connector Fuse holder Car seat frame CORPORATE TRAINING AND PLANNING

  27. Applications of PBT Iron box Inhaler Overhandle Blood filter CORPORATE TRAINING AND PLANNING

  28. Blends of PBT • PBT/PET • The injection molding of glass fiber reinforced PBT leads to long directional orientation and anisotropy in the molded part. • And additional deficiencies is the poor surface quality of the molded parts. • But when blended with PET warpage of the part is clearly diminished and surface quality improved. • The blends also show improvements in heat deflection temperature and impact strength. CORPORATE TRAINING AND PLANNING

  29. Blends of PBT • PBT/Elastomers • The blends developed for molding show good heat deflection temperature processability, electrical properties stiffness, strength, dimensional stability impact strength, solvent and chemical resistance • PBT/ABS (contain upto 30% glass fiber) • The blend shows excellent processability, high gloss, stiffness at high temperature and mechanical strength, heat deflection temperature, low shrinkage, good dimensional stability, impact strength as well as solvent and chemical resistance. CORPORATE TRAINING AND PLANNING

  30. List of Manufacturers/Suppliers of PBT CORPORATE TRAINING AND PLANNING CORPORATE TRAINING AND PLANNING

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