ENGINEERING PLASTICS:
1. Engineering Plastics are the family of Plastics that are capable of withstanding high loading for a period of time at elevated temperature and in adverse environment conditions.
2. Engineering Plastics exhibit a good balance of high tensile strength, Shear Strength, toughness to use as replacement of metals in many applications.
ADVANTAGES OF ENGINEERING PLASTICS:
1. Rigidity with high impact strength
2. High temperature resistance with good dimensional stability.
3. Outstanding resistance to corrosion
4. Superior wear, fatigue, creep & other load bearing properties.
5. Intricate and multi functional part design.
6. Easy assembly of moulded parts
7. Elimination of finishing operations such as self threading, etc.
8. Ease of property modifications by using fillers.
9. Light weight and low cost.
Properties of Modified Plastics
By using bulk fillers, reinforced fillers, additives and blends.
BULK FILLERS: Mica, talc, calcium carbonate, asbestos, metallic powders, graphite, molybdenum disulphide
REINFORCING FILLERS: Glass fibres, carbon fibres, aramid fibres, boron fibres and synthetic fibres.
1. Better dimensional stability reduction in warping shrinkage and creep
2. Low co-efficient of thermal expansion
3. Re-tension of mechanical properties over a much wider temperature range
4. Low co-efficient of friction and therefore improvement in wear resistant property
5. Higher stiffness and rigidity
6. Higher impact strength at higher & lower temperatures
7. Improvement in flexural strength and modulus
8. Higher heat distortion temperature
9. Imparting electrical and thermal conductivity
FIVE MAJOR GROUPS OF ENGINEERING PLASTICS
Crystalline materials
1. Polyamides
2. Acetals
3. Polyesters
Amorphous materials
1. Polycarbonates
2. Modified Phenylene
POLYAMIDES
1. The Polyamides (nylons) were the first materials to be recognized as engineering thermoplastics.
2. Polyamides are polymers characterized by the amide group (CONH) as a part of the main polymer chain.
3. Chemically the polyamides are divided into two types:
Based on diamines and dibasic acids
Based on amino acids or lactams.
4. Aliphatic polyamides such as nylons 66, 6, 10 and 11 are linear polymers and thus thermoplastic.
5. The Nylon 6,6 is prepared from hexamethylene diamine and adipic acid. The polyamide 6 prepared from caprolactam.
STRUCTURE OF POLYAMIDES
Polyamide 6 -[ HN (CH2)6 CO ]-n
Polyamide 6,6 -[ HN (CH2)6 NH-CO (CH2)4 CO]-n
Polyamide6,10 -[HN(CH2)6NH-CO (CH2)8 CO]-n
Polyamide 11 -[ HN (CH2)10 CO ]-n
Polyamide 12 -[ HN (CH2)11 CO ]-n
PROPERTIES
1. Good combination of mechanical properties like Fatigue creep strength, stiffness, toughness and resilience
2. Good abrasion resistance
3. Self lubricating characteristics
4. Suitable for prolonged, service temperature from - 400C to 1200C
5. Good electrical insulator, but the electrical properties are influenced by moisture content
6. Resistance to fuels, oils, fats, most solvents and chemicals
7. Low permeability to gas and vapours
Non-toxic
8. Easy processable by conventional processing techniques like injection, extrusion, blow and rotational moulding.
APPLICATIONS OF POLYAMIDES
Automobile Industry
1. Radiator fan
2. Radiator grill
3. Instrument housings
4. Speedometer gears
5. Fuel, oil filter housing
6. Electrical junction box
7. Head/Tail lamp housing
8. Front fork bush
9. Steering column bush
Textile Industry
1. Drafting spacer
2. Tension grades
3. Magnetic holder
4. Drive pulley
5. Ring tubes
6. Gears, Bushes
7. Bobbins
8. Yarn separators
9. Shutters
Electrical, Electronics Industry
1. Circuit breaker housing
2. Power capacitor Housing
3. PCB frame
4. Cable sheathing
5. Switch/Switch parts
6. Terminal block
7. Battery casing
8. Potentiometer spindle
9. Insulator housings
10. Ventilator fan
Engineering Industry
1. Gears/Bushes
2. Channels and profiles
3. Rollers
4. Fasteners
5. Ropeway tyres
6. Coupling components
7. Impellers/fans
8. Bearings
9. Water meter housings
10. Nuts and washers
Miscellaneous
1. Door handles
2. Latched/Hinges
3. Safety helmets
4. Shoe soles/studs
5. Moulded zips
BLENDS OF POLYAMIDES
PA/ABS BLENDS
1. Impact and abrasion resistance
2. Chemical and heat resistance
3. Low moisture absorption
4. Good processability and surface finish
APPLICATION
Automotive, chemical, electrical, consumer and
sport industries.
PA/ELASTOMER (EPDM/EPR) BLENDS
1. Low temperature impact strength
2. Good processability
3. The moulded articles can suppress vibration even at subzero temperature
APPLICATION
1. Automotive, home appliances, sport, business equipments and consumer products.
PA/PP BLENDS
1. Shows good processability
2. Reduced water absorption
3. Low density (i.e.. Low cost per volume
4. Improvement in printability
APPLICATIONS
1. Automotive, building, furniture & industrial
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