Additives of PPO

Additives of PPO:

1. Flame retardants

2. Glass fibers

Grades of PPO

They are available in the following grades. 

-  Glass reinforced 

-  Foam grade

-  Plating grade

-  High modulus grade

-  Blow moulding grade

-  Injection moulding grade

Processing considerations  of PPO

-  Typical cylinder temperatures are about 280-300°C and mold temperatures 100 – 120°C. 

-  If overheated, the material oxidizes resulting in poor finish and streakiness. Because of this it is advisable to  purge machines before they are cooled down after molding. 

-  The melt of PPO are almost Newtonian  viscosity being almost  independent of shear rate. 

-  Due to their extremely low moisture absorption  PPO resin can be molded without the need of drying. 

-  Surface defect in case of due to the trapped moisture, can be avoided by proper drying.

-  Drying temperature vary with the resin grades. Temperature of  110°C for 2 hours are recommended for drying. 

They can be processed by the following processing techniques.

-  Extrusion

-  Foam moulding

-  Thermoforming 

Surface Finishing of PPO

- Screen printing and hot embossing are common. 

- Alkyd, acrylic and epoxide based lacquers are used for coating. Vacuum metallizing is used for metal finishes.

Machineability of PPO

Joining

 Welding 

Surface temperature of 260 to 2900C are selected for heated tool welding. Friction welding takes place at speeds of 1200 rpm and contact pressure of 20 N mm-2. Ultrasonic and resistance wire welding are also used.

 Bonding

 PPO can be bonded using solvents such as dichloroethylene, toluene, chloroform or 950, dichloroethylene with 5% carbontetrachloride .High tensile and shear strength are achieved with rubber, epoxide, resin, silicon, cyanoacrylate and PU adhesives.

Applications of PPO

Automotive: Instrument panels, steering column, cladding, central consoles, loud speaker housings ventilator grills, nozzles, parcel shelves, radiator tanks, cable connectors, bulb sockets, air inlet and outlet grills and outer mirror housings. 

Electricals/Electronics: Television tuner strips, microwave insulation component, transformer housings. Computer terminals, printers, modems, typewriter bases, video games, copier, capacitor   casings, outlet boxes, coil bobbins, smoke detectors, intrusion alarm, motor covers and switches. 

Miscellaneous:

Water pumps, water meters, sprinkler systems, hot water tank, washing machine parts, welder’s protective visors, tennis racquets, textile components and valves for drink vending machines. 

Blends of PPO:

- Polyphenylene oxide is completely miscible with polystyrene in all proportions. The glass transition temperature of these blends change smoothly with composition. 

- These blends with 25-60% (weight) of PPO, designed for injection or blow moulding, extrusion calendering, thermoforming and reinforced with 0-30 weight percentage glass fiber. 

- They have good processability, toughness, flame retardance, dimensional stability, resistance to hot water, economy, HDT (95-150°C), low density and moisture absorption. 

PPO / Nylons 

- These are blends (compatibilized) with 40-60 weight percentage of nylon. 

- PPO provide excellent heat resistance, toughness and nylon (crystalline) resists oils, gasoline and solvent, PPO / Nylons alloys have a lower density, higher toughness and show less tool/machine wearcompared to machine filled Nylon.

- Polyamide grades are used for automotive body panels which require paint oven temperature upto 175°C.

- PPO/Nylon grades are used in fluid handling applications which require chemical resistance, dimensional stability and  heat resistance.

Polyether Imide (PEI)

POLYETHER IMIDE (PEI): General Electric (US) introduced PEI under the name of Ultem in early 1982. This thermoplastic fills the gap between the polyethersulfones and the considerably more expensive polyamide­ imides and polyfluorocarbons.

PEI is a high performance, amorphous thermoplastic based upon regular repeating ether and imide linkages. The aromatic imide units provide stiffness while the ether linkages allow for good melt-flow characteristics and processability. 

Polyetherimide is an amorphous, amber-to-transparent thermoplastic with characteristics similar to the related plastic PEEK. Relative to PEEK, PEI is cheaper, but is lower in impact strength and usable temperature.

The glass transition temperature of PEI is 217 °C. Its amorphous density at 25 °C is 1.27 g/cm³. It is prone to stress cracking in chlorinated solvents. Polyetherimide is able to resist high temperatures with stable electrical properties over a wide range of frequencies. This high strength material offers excellent chemical resistance and ductile properties suitable for various applications, even those including steam exposure.

General Description

PEl is characterized by the following properties:

- Very high strength (even when unreinforced),

- high stiffness and hardness,

- high heat distortion temperature (> 200 °C),

- high continuous service temperature (170 °C),

- high dielectric strength,

- dielectric properties remain almost constant over a wide range of temperature & frequency

- transparent amber color,

- low coefficient of thermal expansion,

- high resistance to chemicals and hydrolysis,

- high weathering resistance,

- high resistance to g-radiation,

 low flammability (V-0 at 0.76 mm thickness) &

  low smoke emission, 

- good, economic processability.

Processing

1. PEI is easily processed on conventional injection molding/ extrusion/blow molding m/c

2. Resin viscosity vs. shear rate profile comparable to PC or PSF (rather than conventional polyimides), although the processing temperature is much higher.

3. Due to its thermal stability, PEI exhibits a much higher processing window than most other engineering plastics. 

4. PEI absorbs so much water when stored in air that predrying is required. Molding compounds should not contain >0.05% water for processing. 

5. Melt temperature is 375 to 425°C, 

6. Mold temperatures 100 to 150°C. 

7. Shrinkage is between 0.2 to 0.7%

8. Readily converted into film sheet & profiles via melt extrusion because of its high melt strength. 

9. Owing to its melt integrity PEI is easily thermoformed or blow molded using injection or extrusion techniques. 

Structure and Properties

PEI consist of imide groups O=C-N-C=O linked by ether groups and thus they have good mechanical and thermal properties. 

The ether groups are also responsible for a certain flexibility of the polymer chain and hence good processability.

Structure and Properties

1. PEI consist of imide groups O=C-N-C=O linked by ether groups and thus they have good mechanical and thermal properties. 

2. The ether groups are also responsible for a certain flexibility of the polymer chain and hence good processability.

Additives

The main additive is glass fiber reinforcement.

Availability

1. Commercially available granules from General Electric Co. under the trade name of Ultem®. 

2. Standard grade (Ultem 1000) 

3. Grades reinforced with 10 - 40% w/w glass fiber, 

4. Grades reinforced with 15% Carbon fiber 

5. The development range (D 6000) distinguished mainly by increased HDT

6. Special purpose grades for moldings subjected to wear and for manufacturing printed circuit boards.

Machining

1. Laser beams are used when high drilling and cutting speeds are required. 

2. Close tolerances, the absence of swarf, burrs, etc and low internal stresses are the advantages of this technique. 

3. Holes as small as 0.15 mm diameter can be bored in positions inaccessible to conventional drills.

Joining-1

Molded-in threads or self cutting screws can be used for screw connections. 

Inserts are molded in or inserted by vibration. 

Snap joints use the elastic recovery of PEI.

Joining -2

Diffusion bonding (using methylene chloride) is a suitable method for PEI to PEI glued joints. Adhesion bonding can be used to join PEI to PEI or other materials. Adhesion bonding agents are based on silicone, non­amine epoxide resins & hot melt polyamide adhesives.

Typical Applications

1. High voltage circuit breaker housings, connectors, microwave oven components,         flow solder ­resistant terminal strips,

2. Transmission components, pistons and brake cylinder parts, carburetor housings, headlamps, 

Aircraft seat shells, safety belt clips, 

Cables,

Bearings, gears,

Vanes for pumps.

PROPERTIES

1. Very high mechanical properties

2. Resistance to most chemicals

3. Excellent resistance to UV radiations

4. Can be stabilised by ethylene oxide and gamma radiation

5. Excellent flame resistance

6. Exhibits the highest LOI 47%

7. Very good thermal stability and warp resistance at elevated temperature.

Transition Temperatures

The high stiffness and good dimensional stability at elevated temperatures are not surprising in view of the high Tg of the original grades (217 °C) and of the development grades (230 °C).

Density: 1.27 g/cm³

Formula: (C₃₇H₂₄O₆N₂)_n

Classification: Thermoplastic

Appearance: Amber-to-transparent solid

Molar mass: Variable

Molecular weight: 592.61 g/mol.

APPLICATIONS

Industrial

Corrosion resistant fluid and gas handling parts, strong mechanical couplers and threaded fasteners, bearing sleeves.

Medical

Nerve simulators, surgical lamp housings, manifold valves for ventilators, endodontic cases

Electrical/Electronics

Precision fibre optic components PCB and IC chip carriers, bobbins, protective clothing for fire fighters, insulating tapes and wire insulators.

Mechanical Properties

1. The structure of PEI results in very high strength and stiffness. 

2. The tensile strength of the unreinforced material is greater than 100 N mm-2.  

3. The flexural modulus is 3300 N mm-2. 

4. Both values are far above the levels of other thermoplastics.

Notch sensitivity

The unreinforced material possesses adequate impact strength although it is notch sensitive. 

Stress concentrations in moldings, on sharp edges, for example, should therefore be avoided.

Wear Properties

The special purpose grade PEI is particularly suitable for applications which require high wear resistance, e.g. bearings and vane pumps.

Thermal Properties

One of the most outstanding properties of PEI is its ability to withstand exposure at elevated temperatures. PEI exhibits a Tg at 419℃.

The HDT (at 1.82 N mm-2) of PEI is 200°C, the same as that of PES while those of PSF and PC are 170 and 135 °C, respectively. This accounts for its excellent retention of physical properties at elevated temperatures. 

Electrical Properties

1. The unmodified and 30% glass-reinforced PEI resin exhibits an excellent balance of electrical properties which remain stable over a wide range of environmental conditions. 

2. The favorable dielectric properties and high volume resistivity of PEIs are constant over a wide range of temperature and are hardly affected by environmental influences.

3. The dissipation factor remains low over a wide range of frequency particularly in the kHz (103 Hz) and GHz (109 Hz) region. 

4. This property is significant for logic components in electronics applications or components for microwave applications where the material should absorb as little electrical energy in the form of heat as possible.

Water Absorption

1. The unreinforced PEIs absorb 0.3% water at 60% atmospheric humidity.

2. The maximum permitted content is, however, 0.05%.

Resistance to Chemicals PEI is very resistant to: 

1. mineral acids

2. salt solutions, 

3. aqueous alkaline solutions (pH < 9), 

4. antifreeze, automotive and aviation lubricants, 

5. fuels and cleaning agents, alcohols, 

6. carbon tetrachloride, ether. 

7. hydrolysis.

It has limited resistance to ketones. 

It is not resistant to ethyl acetate, MEK 

and chlorine containing solvents.

Resistance to Stress Cracking

PEI has only limited resistance to stress cracking. The glass fiber reinforced grades are superior to unreinforced grades.

Weathering Resistance

PEI is resistant to UV radiation without the addition of stabilizers. 

Resistance to High Energy Radiation

The resistance to high energy radiation (g-radiation from a Co60 source) is remarkably high. 

Even a radiation dosage of 5000 kJ kg-l causes a loss of only 6% in the tensile strength.

Flammability

PEI is flame resistant without the incorporation of additives. 

In fire incidents, PEI gives  off only very small amounts of smoke. 

Additives of Polyamide 6

Additives of Polyamide 6

1. Functional Additives                      2. Fillers

3. Reinforcements

Functional Additives

1. Anti oxidants                                  2. Heat stabilizers

3. UV stabilizers                                4. Nucleating agents

Fillers:

1. Silicon dioxide - increase tear strength

2. Mica and  talc improve stiffness, strength, hardness, heat distortion characteristics, dimensional stability and surface finish

3. Metal powders (aluminium, bronze, steel, lead, zinc, copper, nickel) improve heat distortion characteristics and particularly, electrical conductivity

4. MoS2 and graphite are used particularly in glass fiber reinforced polyamides to improve slip and wear characteristics.

Reinforcements:

- The main reinforcement for PA is glass fiber material.

- It is used in proportions of up to 50% w/w in PA 6 and PA 66 and upto 30% w/w in PA 69, 61, 11 and 12. Tensile strength, stiffness, hardness, heat distortion characteristics, tracking resistance, chemical and hydrolysis resistance are all improved.

- Carbon fibers increase the elastic modulus significantly more than glass fiber material and also improve slip properties, thermal and electrical conductivity.

Grades of Polyamide 6

The Polyamide 6 is available in various grades 

- Injection molding grade

- Extrusion grade

- Rotational Molding grade

- Fluidized bed coating grade

Processing considerations for Polyamide 6

- The tendency of the material to absorb water

- The high melting point of the homopolymer

- The low melt viscosity of the homopolymers

- The tendency of the material to oxidise at high temperature where oxygen is present

- The crystallinity of the solid polymer and hence the extensive shrinkage during cooling.

- The material has to be predried at 80°C for 2 - 4 hours.

While molding Polyamide attention on the following points is essential. 

- High Injection speed of the molding machine

- Control of shot or size

- Minimizing drooling by nozzle of reverse tapper type.

- Shrinkage of the part

- Annealing at 130° to 149°C for 10 - 20 hrs.

Polyamide 6 – By casting Technique

Cast Polyamide 6: This is made by activated anionic polymerization of monomeric caprolactam in molds. Properties are similar to PA 6. Cast Polyamide 6 is normally of very high molecular weight. Depending on the polymerization condition, its properties can be varied between tough and elastic to tough and hard.

- Thick walled mouldings, high weight mouldings (upto 1000 Kg), embedding of components (Roller cores)

Large mouldings of all kinds eg. heating oil tanks upto 10000 liters capacity

Surface finishing of Polyamide 6:

- Moldings may be painted or printed without pretreatment 

- The high resistance of PA to solvent facilitates coating and even recoating with stoving requires bond on UF or MF resins

- Mouldings can be colored by immersing in aqueous or alcoholic solution of dye stuffs, particularly azo dyes

- Hot embossing with suitable foils pose no problem

- Metal finishes are applied by vacuum metallization

- In Recent years there has been growing interest in electroplated PA moldings

- These require extremely high quality surfaces

- Products containing fillers are used for reflective electroplated parts

- Special purpose glass fibre reinforced grades are suitable for moldings with extruded surfaces

- Applications include wheel trims, door handles, window winder and water fittings

Machineability of Polyamide 6:

Cutting: Casted products/ molded products are workable with most of the tools and machining which are designed for working with wood and metal. 

- However higher efficiency is obtainable with equipment specially designed for plastics

Joining: PA components are frequently joined with ordinary or self-lapping screws and rivets as well as snap connectors

Welding of Polyamide 6 

- All processes developed for welding thermoplastics are suitable for polyamides. 

- The preferred methods are ultrasonic friction and heated tool welding (heating by contact or radiation). 

- High frequency and heat impulse welding are used mainly for joining films. 

- The ultrasonic method enables welding of standard injection molded parts to be integrated in automated production.

Bonding of Polyamide 6

- Polyamides can be bounded with numerous adhesives based on solvents or lacquers. 

- An adhesive can be quickly prepared by shaking a rerorcinol/ Ethanol solvent mixture for 15 minutes. 

- Concentrated formic acid, dimethyl formamide and aqueous phenol (12% water) are also suitable.

- A polyamide containing calcium carbide/ ethonal solvent adhesive can be used for food applications or in water supplies. 

- It is resistant, non-toxic and odour-free, solid adhesives with or without chemical cross linking can be used for example for bonding bearing bushes into metal assemblies

Applications of Polyamide 6(Areas of Applications)

1. Appliances                               2. Automotive

3. Business equipment              4. Consumer products

5. Electrical                                  6. Hardware

7. Machinery                                8. Packaging

Applications of Polyamide 6

- Laundry equipment          - Dishwashers and disposers

- Cooking equipment          - Housecleaning equipment

- Consumer electronics      - Small kitchen appliances

- Sewing machine               - Personal care and grooming

- Cooling equipment

Automotive

- Chassis parts                            - Power plant

- Decorative body parts              - Functional body parts

- Electrical parts                          - Fuel system

- Instrumentation                        - Heating, ventilating

- Air-conditioning                        - Accessories

Business equipment

- Business machines                  - Vending machines

- Office equipment

Consumer products 

- Kitchen utensils                         - Toys

- Sporting goods                          - Apparel fitments

- Personal accessories               - Photographic equipment

- Musical instruments.                - Brush bristles

- Packaging                                  - Film for cooking 

- Fishing line

Electrical  

- Industrial controls                 - Wiring and associated devices

- Industrial connectors.           - Batteries

- Telephone parts.                   - Switches

Hardware 

- Furniture fittings Door and window fittings.        - Tools

- Lawn and garden implements                            - Boat fittings

Machinery  

- Agricultural Mining and oil drilling         - Food processing

- Printing.                               - Textile processing

- Engine parts                         - Pumps, valves, meters, filters

- Air blowers                           - Material handling equipment

- Standard components.                            - Gears

- Cams             - Sprockets.           - Bearings

- Gaskets.        - Pulleys.               - Brushes

Packaging

- Film and coated substrates

Blends of Polyamide 6/PE

- In compatible hydrocarbon polymers such as PE can be melt with Polyamides to yield compositions that have improved higher permeability and are processable film and filaments and bottles. 

- Improvement in moisture absorption,  impact strength, flexibility, moulding characteristics  and structure uniformity are claimed  for blends made from Polyamide and ethylene / alkyl acrylate ester copolymers.

Additives of PPS

Additives of PPS:

- Among the high temperature resistant additives, the most important are glass fiber, carbon fiber & mineral fillers such as chalk, iron oxide and others

- Carbon fiber reduces surface resistance & in special cases achieves a desired electrical conductivity

- Mineral fillers improve processability, reduce shrinkage (particularly anisotropic shrinkage) and improve surface gloss

- Graphite increases the stiffness of molded material

- PTFE improves the friction and wear characteristics. 

Availability

Four basic grades of PPS compounds are:

1. glass-reinforced     

2. glass- & mineral filled 

3. pigmented glass- & mineral filled

4. carbon fiber-reinforced. 

40% glass-reinforced material has lower density and higher mechanical strength than glass- and mineral filled compounds which  offer a good balance of properties at a lower cost & the pigmented glass- & mineral filled grade offers competitive properties & attractive colour at an intermediate cost. 

Thermal Properties:

1. No appreciable weight loss in filled PPS below 500oC in N2 or air.

2. Coefficient of linear expansion is comparable to that of aluminium. 

3. Water absorption of PPS is low. After immersion in water for 31 days at 100 °C, the increase in weight was only 1.01 %.

4. Good Heat ageing resistance  - UL long-term temperature indices of 170 °C for 40% w/w glass reinforced PPS & 200 °C for 40% w/w  glass- and mineral filled PPS 

Resistance to Chemicals:

1. Excellent chemical resistance, better than other advanced engineering plastics

2. No known solvents below 200°C

3. Inert to steam, strong bases, fuels and acids

4. Minimal moisture absorption

5. Very low coefficient of linear thermal expansion

6. Stress-relieving manufacturing

7. PPS ideally suited for precise tolerance machined components 

At room temperature PPS is resistant to

1. dilute mineral acids,

2. alkaline solutions, 

3. aliphatic and aromatic hydrocarbons, 

4. ketones, 

5. alcohols 

6. chlorinated hydrocarbons, 

7. oils, 

8. fats, 

9. water and hydrolysis

Flammability

- PPS exhibits excellent fire retardancy (LOI = 53)

- When exposed to a flame, molded PPS extinguishes only after removal of the ignition source & then chars forming shiny black crust there is slight expansion

- It burns with a yellowish-orange flame giving off grey smoke with black traces and a smell of rotten eggs

- It does not drip.

Processing

- PPS is injection and compression molded. 

- Non-stick coatings are applied to metal parts by fluidized bed dipping or electrostatic spraying.

- Mold cavities should be well ventilated as air inclusions lead to weak flow lines.

Pre-drying

- The glass fiber reinforced grades require  drying only when stored in poor conditions.

- It is recommended that the mineral-filled grades are dried for 6 hours at 160°C.

- Regrind must be pre-dried. The excellent thermal stability of the material enables the proportion of regrind to be as high as 35%.

- Melt temperature is 340 to 370°C 

- Mold temperature 25 to 200°C. At 120°C, molding surfaces become smooth and shiny. The toughest moldings are obtained at 40°C

- Molding shrinkage is 1 % for unreinforced & 0.2% for glass fiber reinforced material

- Metal inserts cause stress cracking which can be avoided by selecting special purpose grades

Joining

1. Moldings can be joined by screws. Vibration welding provides higher strength joins than ultrasonic welding.

2. PPS can be bonded to itself and most other materials including metals with epoxide resin adhesives, cyanoacrylate and reactive monomeric acrylate systems.

Typical Applications

1. PPS is also used in the coatings industry. 

2. Slurry coatings can be applied by a spraying and baking operation. 

3. Release coatings are formulated from PPS along with small amounts of PTFE and appropriate pigments and applied by slurry techniques.

Pump Parts:

Housings, impellers, bushings, ball valves, pump vanes, end plates, oil well valves , oil well sucker rod guides and heat shields 

Electrical components: 

High voltage enclosures and sockets, coil bobbins, yokes and connectors, printed circuits for digital watches, relay housings, guides and switch relays, encapsulating of contacts and connectors.

New applications:

1. High pressure liquid chromatography components, 

2. Wafer retaining rings for CMP polishing, 

3. Hydrocarbon pump, valve & compressor parts 

4. Oil field parts, 

5. Aerospace components

6. Medical and diagnostic device parts

7. Electronic device encapsulation,

8. Microwave cookware, 

9. Thick-walled mechanical parts, 

10.High arc resistance, 

11. High modulus anti-friction devices.