PLASTIC MATERIALS

PLASTIC MATERIALS

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1.1    Introduction:

The modern plastic industry mainly deals with moldable materials. The term “plastic” is applied to any organic substance of high molecular weight, which can be formed to desired shape by moulding, casting etc. and can be retained its shape, dimension and quality under ordinary conditions of temperature are technically known as “Polymers.

1.2    What is a polymer?
Substance in which molecules form long chains usually several thousands of atoms together starting from a single molecule.
Single molecule is called Monomer. Monomer is the start material

A monomer on polymerization becomes a polymer.  

Polymerization: is the process of combining molecules of start material (monomer) in to a long chain under favorable conditions of heat, pressure and catalyst

(A Macro molecule, a polymer).

Thus,

Ethylene    becomes       Poly ethylene

Propylene    becomes    Poly propylene

Basically, all polymers are formed by the creation of chemical linkages between monomers. The linkages are formed by either one or a combination of two types of reactions namely addition and condensation reactions

The behaviour and structure of the polymers are based both on the chemical nature and the way in which the chains fit together The term “plastic” is derived from the Greek word ‘Plasticos’ means “to form”. Plastics are very large group of synthetic materials whose structures are based on the chemistry of carbon. An important characteristic of plastic is that they can be readily moulded into finished products by the application of heat and pressure.

1.3    Advantages & Disadvantages over Metal

Advantages of plastics over metals

• Low weight. Plastics are many times lighter than metal. The ratio on weight is 1:7 to 1:8. Articles made out of plastics are easier to handle
• Easy time saving and labour saving in processing. Most of the Plastics are more easily be reshaped or moulded under heat and pressure.
• Good corrosion and erosion resistance. Plastics are very resistant to chemicals, moisture and totting.
• Good electrical properties.
• Plastics have a high specific resistance, breakdown strength and good dielectric properties.
• Good insulation properties.
• Good surface properties. Plastics have a smooth even surface and are there fore easy to clean. When required, they can be provided with different surface structure.
• Economical for production. Even the manufactures of complicated articles require only a few steps.
• Plastics are also available in the form of syrup or liquid. Paints are thermosetting plastics.
• Plastics can be casted to shape cold condition. When epoxy resins are mixed with curing agent, it remains solid.
• Some of the plastics are flexible.
• Plastic products are cheaper.
• Most of the Plastics are reusable.
• Plastics have good optical properties. Plastics are available in opaque, transparent and translucent shades in relation to its capability towards light transmittance.
• Plastics can be coloured

Disadvantages of Plastics over Metal

• Low strength. Only few materials when reinforced will get good strength.
• Low heat resistance
• Plastic articles are not dimensionally stable for a long period.
• Resistance to aging is very poor.
• After rework, the original surface finish can not be achieved.
• Plastic articles are difficult or in some case impossible to repair.
• Poor mechanical properties.
• Plastics are expensive
• Plastics have post shrinkage and environmental dimensional changes. They absorb water and moisture and hence change its weight and dimension.
• Destructions of plastic is very difficult. Generally most of the plastic disposable items are insoluble and infusible and it can lead to environmental contaminations.

1.4    Classification of Plastics

Plastics are broadly classified in to three groups

     Natural plastics -Milk of Rubber three, Cellulose (No use as it is)

Semi-Synthetic plastics -processed Milk of rubber tree (rubber sheet)

Synthetic plastics - Lab made products (compared with Rasna-Pinapple essence

Plastics are again divided in to two groups based on Chemical behavior and by the way it reacts with heat

Thermoplastic

Thermoset plastics

Thermoplastic resin consists of long molecules each of which may have side chains or groups that are not attached to other molecules (i.e.  They are not cross linked). Thus they can be repeatedly softened and hardened by heating and cooling.

Usually thermoplastic materials are in granular form. Heat softens the material so that it can   be formed. Subsequent cooling hardens it to the final desired shape. No chemical change takes place during forming.

In thermosetting resins reactive portions of the molecules form cross links during polymerization. Once polymerized or cured the material cannot be softened by heating. Normally they are available in powder form and are cured in the mould at high pressure and temperature.

As technology progresses the line between thermoplastics and thermoplastics has become less distinct. More and bore processes are evolved which make use of the economic processing of thermoplastics and converting the material to a thermoset.

e.g.: Extruded polyethylene wire coating is cross linked after extrusion chemically or by irradiation. The polyethylene is converted to thermoset material which cannot be melted by subsequent heating. On the other hand materials and machinery have become modified to provide the economics of thermoplastic processing to thermosetting materials.

   e.g.: Injection moulding of thermosets.

Some plastic materials are even members of both the, groups

  e.g.: Thermoplastic polyesters and thermoset poly esters.

Difference between thermoplastics & thermoset plastics

Thermoplastics	Thermoset
Can be softened and re-softened and reused	Cannot be re-softened and reused
No chemical changes take place during heating and melting and pressurizing	Chemical changes take place during heating , melting and pressurizing
In granular form generally	Usually in powder form
Needle like structure of molecules	Cross linked chain molecules
Rigid but effected by further heating	Rigid and unaffected by further heating
Hard but not brittle	Hard and brittle

Thermoplastic

Thermoplastic in general use for injection moulding include different materials like

ABS      -Arylonitride Butadiene Styrene              PMMA   - Polymethylmethacrylate

CA        -Cellulose Acetate (Perspex)                 POM   -Polyoxymethylene (Delrin)

HDPE   -High Density Polyethylene                     POLYESTER       -Polyester

LDPE   - Low Density Polyethylene                     PP     - Polypropylene

IONOMER - Ionomer                                           PS      -Polystyrene

PA        -Polyamide (Nylon)                                 PTFE -Teflon (Polytetrafluroethylene)

PC        -Polycarbonate                                        PVC   -Polyvinyl Chloride

PEEK   - Polyetheretherketone                            PUR  - Polyurethane

PET   - Polyethylene Teraphthalite                      SAN   -Styrene Acrylonitrile

The thermoplastic moulding materials are normally produced commercially in granular form. The shape and size of the individual granular differ according to the type of material. The particular form of granulate is dictated primarily by processing requirements, but also during manufacture. For optimum processing the most important requirement is a completely clean free running granulate without any tendency to agglomerate. Size and shape of pellet should be such that optimum melts conditions will be facilitated .A constant bulk density of granulate is   important on machines where volume feeding is employed. The nature of the surface of the pellet should be such that   absorption of moisture will be maintained at tolerable level even during lengthy periods of storage. A high absorption of water leads to the production of steam in the heating cylinder and hence to faulty product. With many materials, optimum quality of product can only be obtained after intensive drying of the granulate before use. Equipment available for drying, range from drying chambers for bulk quantities to hopper with integral drying equipment.

The nature of the material should be such that it can be plasticized at temperatures within a practical range to a homogeneous melt to permit even filling of mould cavity. The material must be stable under temperature changes and not be subject to chemical decomposition during processing. Such decomposition will show up in a number of ways, particularly after overheating. If the materials inside the heating cylinder are exposed to high temperatures or at normal temperatures remain too long in the cylinder due to stoppage in the cycle, thermoplastic of low thermal will quickly show signs of decomposition. This is known as burning and the degraded material may run through the product as streaks or even discolours it through out. These affects are more apparent in transparent or light coloured plastics. Thermal instability in the material may separate out the chemical components in the plastics, which are often corrosive and may attack the interior of the heating cylinder and the mould. Poisonous gases which affect the operator may also be formed.

Ingredients are often added to the material to alter its colour consistency or other properties. These substances include dyes, fillers, plasticizers, dispersers (designed to Increase the adhesion of the pigment dye) and materials to aid free flowing   properties. These materials should posses the same thermal stability as the bulk materials and must also be free from constituents which evaporate during processing. For the products to be of uniform size and shape, the materials must exhibit small and even shrinkage on cooling.

Plasticizing the material:

The change in consistency in thermoplastic materials from granulates to a homogeneous plastic   state suitable for injection take place in the machine. The materials pass through three different stages. The change from one to the next stage is not sharply defined owing to the differing length of the molecular chains. From the solid state, the materials pass through the thermo elastic state which begins as the softening temperature is reached. It is marked by break down in the intermolecular binding forces.  Solidifying decreases due to loosening of the molecular structure. As the thermal effect is increased the intermolecular forces are further reduced until at the melting point (where the material is said to be in thermoplastic state) the molecules are completely mobile within the melt.

Melt flow index (MFI)

MFI indicates the flow capacity of different grades of thermoplastics and  is inversely related to the molecular weight. A high MFI grade will flow faster and has a low molecular weight. It is expressed as the amount of material (in grams) extruded in ten minutes through an orifice of standard dimensions under a standard load and at a particular temperature .(MFI of PP is measured at 230 0C  under a load of 21.6 N ).

Spiral flow:

It is another way of expressing the flow of a particular grade inside the mould and is determined on a standard mould having a spiral cavity marked in cm. Spiral flow test using different grades of PP.

Grade	Spiral flow (cm) at 2600C cylinder temperature and 70MPa   injection pressure
m 1730	25.00
m 3030	32.00
m 5630	36.00
m 0030	46.25

                                                                   

Flow length to wall thickness ratio (L/T ratio or flow ratio)

The L/T ratio expresses the flow behaviour of the material inside the mould. It is defined as the ratio of the largest flow paths to the thickness of the moulding under optimum moulding conditions. The higher the flow ratio higher is the temperature required to obtain fast mould filling and consequent freedom from stresses). The maximum obtainable flow ratio varies with different grades of plastic. It depends on MFI.   

Grade	MFI	L/T ratio
M 1730	1.7	150
M 3030	3.0	225
M 5630	5.6	275
M 0030	10	350

Important thermoplastic which are available for injection applications can be broadly divided into two categories - Commodity and engineering plastics 

The commodity plastics are used where in no-load or very low load applications, while the engineering plastics can be designed to carry loads for a long period of time

Commodity plastics can be again classified as polyolefin, styrene, vinyl, others.

Polyolefin family contains polyethylene (PE), polypropylene (PP), polybutylene (PB) etc

Styrene family contains polystyrene (PS), styrene-acryonitrile (SAN),

Styrene-butadiene (SB), acryonitrile- butadiene -styrene- (ABS) etc

Vinyl family consists of polyvinyl chloride (PVC),  chlorinated polyvinyl chloride (CPVC),

Other commodity thermoplastic contains polymethyl-methacrylate (PMMA), cellulose acetate, cellulose nitrate etc

Engineering plastics contains acetals, fluoro-plastics, polyamides (nylons), polyamide-imides, polyarylates, polycarbonates, polyesters, polyketones, polyphenyleneoxide, polyphenylenesulfide and sulfone etc.

Important thermoplastic which are available for injection applications can be broadly divided again into two categories according to their structure

Crystalline and Amorphous

In crystalline materials, molecules are packed closer together and aligned themselves in some orderly pattern. During processing, they tend to develop higher strength in the direction of the molecules. Since commercially perfect crystalline polymers are not produced, they are identified technically as semi- crystalline thermoplastics. A crystalline material is stiffer and stronger. It is difficult to process crystalline materials due to high melt temperature, melt viscosity, shrinkage

Examples are PP, PE, Nylon

Amorphous materials are having molecules going in all different directions and are normally transparent. They will under go small volumetric changes on processing. They are tougher and more flexible. They will often soften gradually as they are heated but they do not flow easily. Therefore it is easy to process amorphous plastic. A crystalline plastic is heated to a particular temperature and sudden quenching give amorphous structure

Examples are ABS, PMMA, PC, PS, PVC

Properties of Crystalline and Amorphous materials

Crystalline	Amorphous
Fibers	Elastomers
Crystalline	Amorphous
Plastics	Plastics
Good mechanical properties	Weak mechanical properties
Tough	Brittle
Opaque	Transparent
Min. shrinkage	Max. shrinkage

1.5  Different thermoplastic materials commonly used:

ABS - Acrylo Nitrile Butadiene Styrene

Density = 1.05 gm./cc

Shrinkage =0.5 %

A general purpose material

Properties

It is a hard tough material with good resistance to heat and impact. It has low water absorption and good electrical insulation properties. The surface is resistant to scuffing and marking. Pre drying is necessary and is done at 80°c for 4 hours. Its flow properties are similar to PS.

Applications

Safety helmets, automotive instrumental panels and other interior components, pipe fittings, hole security devices and housings for small appliance, heavy duty domestic appliance and fittings, cabinet for radio, TV, typewriter, communication equipment, business machines, automobile grills, wheel covers, mirror housings, refrigeration liners, luggage shells, boat hull,  and so on.

Cellulose polymers (CA)

Density = 1.3 gm./cc

Shrinkage =0.3 – 0.8 %

Cellulose is a starch. It is one of the main structural polymers in plant(specially that of wood or cotton). These natural fibers are treated with acids to produce a resin, a process called esterfication. Cellulose acetate (Perspex), Cellulose acetate butyrate (CAB) and Cellulose acetate propionate (CAP) are three common materials

Properties

CA combines toughness, transparency and a natural surface texture. Some cellulose resins are biodegradable allowing their use for envelops with transparent widows that can be disposed of as if they were paper alone.

Applications

Tool handles, panels for illuminated signs, steering wheels, bathroom fittings, decorative trim for cars and consumer durables, drawing stencils, pens, blister packing, laminating with aluminum foil, spectacle frame, goggles, covers for TV screens, cutlery handles

High Density Polyethylene (HDPE)

Density = 0.95 gm./cc

Shrinkage HDPE= 3.0 – 4.0%

One of the groups in Polyethylene, first synthesized in 1933, looks like the simplest of molecules, but the number of ways in which the PE units can be linked in large. It is the first of the polyolefin, the bulk thermoplastic polymers that account for a dominant fraction of all polymer consumptions.

Properties

Higher density, rigidity, tensile strength and hardness. Higher chemical resistance while comparing LDPE. Extremely resistant to fresh and salt water, food, and most water-based solutions. Very cheap and particularly easy to mould and fabricate. Accepts a wide range of colours, can be transparent, translucent or opaque

Applications

The property of high stiffness combined with high impact strength and low weight makes it popular material for moulding articles like milk  bottle crates, fish boxes, containers used for refrigeration and transport. Pipes from dia 25mm to 800mm for carrying water and chemicals, packing films, woven sacks, monofilament for fishing nets, rope, cane for furniture, coating on paper etc.

Low Density Polyethylene (LDPE)

Density = 0.92 gm./cc

Shrinkage LDPE= 0.8 – 1.5%

One of the groups in Polyethylene, first synthesized in 1933, looks like the simplest of molecules, but the number of ways in which the PE units can be linked in large. It is the first of the polyolefin, the bulk thermoplastic polymers that account for a dominant fraction of all polymer consumptions.

Properties

Crystalline and not available in transparent. Tough and moderate tensile strength. It can be coloured. Oxidation occurs when overheated in barrel. So necessary to add antioxidants

Applications

Shopping baskets, waste paper baskets, artificial flowers and fruits, hair brushes, and blow moulded components, pipes up to 150mm diameter for transporting water, packaging films, coating paper, textiles etc. Linear LDPE is used for overhead water tanks

Ionomer  (I)

Density = gm./cc

Shrinkage =0.2 – 0.8%

Introduced by DuPont in 1964, Ionomers are flexible thermoplastics but they have ionic cross-links, from which they derived their name. Their thermoplastic character allows them to be processed by blow moulding injection moulding rotational moulding and thermoforming. But cooled below 40o C, they acquire the characteristics of thermoset

Properties

High strength, good adhesion and chemical stability. It is highly transparent particularly resistant to

Applications

Food packaging, athletic soles with metal inserts, ski boots, ice skate shells, wrestling mats, thermal pipe insulations, license plate holder, golf ball covers, automotive bumpers, snack food packaging, blister packs, bottles.

Nylon (Polyamide-PA)

Density = 1.1 gm./cc

Shrinkage =0.7-1.5%          

Nylon is a general term for polyamides

Properties

Tough and can withstand repeated impacts. High rigidity whose properties can be increased by glass reinforcement. Excellent abrasion resistance and exceptionally low co-efficient of friction. High chemical resistance and high temperature resistance. It can be machined. Partially crystalline, therefore cloudy or white and not transparent

Applications

Light duty gears, bushings, sprockets and bearings, electrical equipment housings, lenses, containers, tanks, tubing, furniture casters, plumbing connections, bicycle wheel covers, ketchup bottles, chairs, toothbrush bristles, handles, food packaging, hot melt adhesives for book binding, ropes, fishing nets, carpeting, cables, protective clothing, electrical insulations

Polycarbonate (PC)

Density = 1.2gm./cc

Shrinkage =0.5-0.7%                            

PC is one of the engineering thermoplastics, meaning that they have better mechanical properties than the cheaper commodity polymers

Properties

Optical transparency and good toughness and rigidity, even at relatively high temperatures. It is possible to co-polymerize the molecules with other monomers to improve the flame retardency, refractive index and resistance to softening, reinforce the PC with glass fibers to give better mechanical properties at high temperatures. Can be electroplated

Applications

Safety shields and goggles, lenses, glazing panels, business machine housings, instrument casings, lighting fittings, safety helmets, electrical switchgears, laminated sheet foe bullet-proof glazing, twin-walled glazing, kitchenware and tableware, microwave cookware, medical (sterilisable) components.

Polyether ether ketone  (PEEK)

Density = 1.26 to 1.32 gm./cc

Shrinkage = 0.5%

A high performance thermoplastic. The cost is 50 times more expensive than PP and 10 to 20 times more than nylon. This limits it use to applications in which technical performance

Properties

Among thermoplastics it has exceptionally high stiffness, strength and resistance to heat

Applications

Electrical connectors, hot water meters, F1 engine components, valve and bearing components, wire and cable coatings, film and filament for specialized applications, pump wear rings, bearings bushings.

Polyethylene Teraphalate (PET)

Density =1.38 gm./cc

Shrinkage = 1.5%

The name polyester derives from a combination of polymerization and esterification. Saturated polyesters are thermoplastics – examples are PET & PBT

Properties

Good mechanical properties to temperature as high as 175o C. Pet is crystal clear, impervious to water and carbon dioxide, but little oxygen get through. It is tough, strong, easy to shape, join and sterilize – allowing reuse. When its first life comes to an end, it can be recycled to give fibers and fleece materials for clothing and carpet

Applications

Electrical fittings and connectors, blow moulded bottles, packaging films, films, photographic & x-ray films, audio/video tapes, industrial strapping, drawing office transparencies, metallized balloons, photography tapes, videotapes, carbonated drink containers, oven-proof cookware, credit cards

Polymethyl methacrylate (PMMA - Acrylic)

Density = 1.18 gm./cc

Shrinkage =0.2-0.8%          

when you think of PMMA, think transparency. This is a family of acrylic group

Properties

Best transparency and optical properties. Colourless with 92% light transmition. Exceptional resistant to sunlight and outdoor exposure and ultra violet radiation. Unaffected by human tissues

Applications

Lenses of all types, cockpit canopies and aircraft windows, signs, domestic baths, packaging, containers, electrical components, drafting equipments, tool handles, automotive tail lights, chairs, contact lenses, advertising signs, compact discs.

Polyoxymethylene  (POM – Acetal)

Density = 1.42gm./cc

Shrinkage =2.5%          

POM was first marketed by DuPont in 1959 as DELDRIN. It is rarely used without modification. Most often filled with glass fiber or blended with PTFE or PU. It is used where requirement for good mouldability, fatigue resistance and stiffness justify its high price relative to PE

Properties

Stiffer and has better fatigue and water resistance. POM/PU blend has good toughness.

Costlier than PE

Applications

Seat-belt components, steering columns, window support brackets, shower heads, faucet cartridge and various fittings, quality toys, garden sprayers, stereo cassette tarts, zippers, telephone components, couplings, pump impellers, conveyor plates, gears, sprockets, springs, cams, bushings, clips, door handles, watch components, mechanical pen and pencil parts, milk pumps, food conveyor, TV tuner arms, automotive under hood components

Polyester

Density = 1.2 gm./cc

Shrinkage =0.8%

It is available in both thermoplastics and thermoset. The thermoplastic polyester have wide popularity and application especially in electronic, audio-video, blown bottles and photographic field. Thermoset and thermoplastic polyester is generally known as unsaturated and saturated polyester respectively.

Properties

Highly crystalline with a melting point near 225oC. Hard and strong and extremely tough. High resistance to abrasion and low coefficient of friction. It can be reinforced with glass fiber. It can be extruded, injection moulded or even blow moulded

Applications

Gears, bearings, housing for pumps and appliance , impellers, pulleys, switch parts, packaging materials, blow moulded bottles, etc

Polypropylene  (PP)

Density = 0.91 gm./cc

Shrinkage =1.0 – 3.0%

First produced commercially in 1958. A very similar molecules with similar price, processing methods and application  as polyethylene. It is produced in large quantities(more than 10 million tones per year I 2000 and 10% increase in every year.

Properties

Flammable and degradable in sunlight. Fire retardants make it slow to burn and stabilizers give it extreme stability, both to UV radiation and to fresh and slat water and most aqueous solutions.

Applications

Ropes, general polymer engineering, automobile air ducting, parcel shelving and air cleaners, garden furniture, washing machine tanks, wet-cell battery cases, pipes and pipe fittings, bear bottle, crates, cable insulations, kitchen kettles, car bumpers, shatter proof glasses, suitcases, thermal underwear.

Polystyrene  (PS)

Density = 1.05 gm./cc

Shrinkage =0.2-0.8%

Properties

It is an optically clear, cheap, easily moulded (formed) polymer. In its simplest form, PS is brittle. It’s mechanical properties are dramatically improved by blending with polybutadiene, but with a loss of optical transparency. High impact PS(10% polybutadiene) is much stronger even at low temperature( as low as –12oC.

Applications

The single largest use of PS is form packaging. Other ruses includes toys, light diffusers, beakers, cutlery, general household appliances, video/audio cassette cases, electronic housings, refrigerator liners.

Polytetrafloroethylene (PTFE)

Density =2.15 gm./cc

Shrinkage =5.0 - 10%

It is called Teflon and a member of the fluroplastic family. As cost is very high, it is used in high-value applications.

Properties

Exceptionally low friction, water repellant and extremely stable. Very much chemical inert and best thermal stability and non-wettability- means nothing sticks to it.

Applications

Wire and cable covers, high quality insulating tapes, corrosion resistant lining for pipes and valves, protective clothing, seas and gaskets, low friction bearings, transparent roofing, non-stick cooking products, water repellent fabrics.

Poly vinyl chloride (PVC)

Density = 1.2gm./cc

Shrinkage Flexi=1.5-3.0%

                Rigid=0.2-0.4%         

One of the cheapest , most versatile and with polyethylene – the most widely used polymer and epitomizes their multi facetted character

Properties

Rigid and not very tough, very low cost , incorporating plasticizers creates flexible PVC a material with leather-like or rubber-like properties and used a substitute for both. Reinforcement with glass fibers gives a material that is sufficiently stiff, strong and light weight structural panels

Applications

Pipes, fittings, road signs, cosmetic packaging, garden hoses, vinyl flooring, windows, vinyl records, dolls, medical tubes, blood storage bags, artificial leather, wire insulation, film, sheet, fabrics, car upholstery.

Polyurethane (PUR)

Density = 1.5gm./cc

Shrinkage =0.8-1.0%         

Properties

Very tough, extremely abrasion resistant. Posses good electrical properties and chemical resistance. It can be made in solid moulding or flexible forms.

Applications

Used for PUR springs. Used for making forms

Styrene Acrylonitrile (SAN)

Density = 1.08gm./cc

Shrinkage =0.2 – 0.6%          

Copolymer of styrene and acrylonitrile exhibits most of the properties of polystyrene

Properties

Excellent resistance to acids, alkalis, salts and dilutes alcohol. Good resistance to many foods and oils, gasoline, cleaning agents, detergents, cosmetic cream and lotion. Higher tensile strength and better stress corrosion resistance and heat resistance.

Applications

Used for cups, tumblers, dishes, trays, picnic wares, cosmetics and other packaging items

1.6    Thermosetting materials

A thermoset are resin that under go chemical change called curing during    processing to form cross-linked structure and become permanently insoluble and infusible. Among plastic materials thermosetting materials generally provide one or more of the following advantages

• High thermal stability
• Resistance to creep
• Resistance to deformation under load
• High dimensional stability
• High rigidity and hardness
• Light weight
• High electrical insulation properties

These advantages are coupled with the light weight and excellent electrical insulation properties. The compression and transfer moulding together with the recent evolution of thermo set injection moulding techniques offer low processing cost.

Thermosetting moulding compounds consist of two major ingredients.

1. a resin system which generally contains such components as curing agents, hardeners, Inhibitors and plasticizers.
2. Filler and or reinforcements which may consist of mineral or organic particles, inorganic or organic fibers and or inorganic or organic chopped cloth or paper.

The resin system usually exerts the dominant effect, determining to a great extent cost, dimensional stability, electrical qualities, heat resistance, chemical resistance decorative possibilities and flammability. Fillers and reinforce affect all these properties to varying degrees, but their most dramatic effects are in strength, toughness and sometimes electrical qualities.

The characteristics and properties of eight generic families of thermoset moulding compounds are given below.

Alkyds:

They are primarily electrical materials. They cast less and posses good insulating properties. Their mould ability is excellent; cure time short and pressure are low. They are stable upto a temperature of’ 120 to 150o C.

General purpose grades are normally mineral filled, Compound filled with glass or synthetic fibers improve mechanical strength. Short fiber and mineral fillers give lower cost and good mould ability, longer fibers give optimum strength.

Typical uses for alkyds include circuit breaker insulation, capacitor and resistor encapsulation, cases, housing and switch gear components.

Allelic:

Diallyl phthalate (DAP) is r commonly used moulding material in the allylic family. They are relatively costlier. They posses excellent dimensional stability and a high insulation resistance. They can withstand temperatures of 150 to 175oC. They are normally reinforced with glass, asbestos, acrylic and polyester fibers.

Epoxies:

These materials offer excellent electrical properties and dimensional stability coupled with high strength and moisture absorption. It is used in combination with glass fibers (epoxy glass reinforced plastics) in aircraft components, filament wound  rocket motors, casing for missiles, pipes, tank pressure vessels and jigs and fixtures. They are also used In the encapsulation or casting of various electrical and electronic components.

Urea (urea formaldehyde):

Excellent colourabililty, moderately good strength and low cost are the primary attributes of these materials. Dimensional stability and impact strength are poor.

The material is used for producing lighting fixtures, wiring devices, buttons etc.

Phenolics (phenol formaldehyde) :

They are lower in cost, possess good electrical properties, excellent heat resistance and good mechanical properties coupled with excellent mouldability. They are generally limited in colour (usually black or dark brown) and colour stability.

They are generally filled with saw dust or flock. They are suitable for use at temperature upto 150°C. heat resistant grades, usually mineral or glass filled can withstand temperatures in the range of 200 to 260oC They are used for moulding wiring devices, switch gear, relay system, connectors etc.

Melamine:

They posses extreme hardness, excellent and permanent colourability and are resistance and non cracking characteristics, They re self extinguishing. Dishes and other house ware articles and electrical items are manufactured from this plastic.

Polyesters:

Polyester resins can be formulated to be brittle and hard tough and resilient or soft and flexible. When reinforced with glass fibers they. exhibit excellent mechanical properties, high strength to weight ratio and chemical resistance. They are used as liquid resin for

casting furniture part. Polyester glass is used for such parts as automobile body parts, boat hulls, building panels etc.

1.7    Fillers and Additives

Plastics are material that are composed not only of large polymeric molecules, but also usually include some additional small molecule materials that have been added to give the plastic some particular characteristics. The characteristics of colour, flexibility, and rigidity, flame resistance, weathering behaviour and process ability can be significantly altered by the use of additives and fillers.

Plastic additives may be grouped into two main categories.

The first comprises of those additives which modify the base polymer’s characteristics by physical means. Additives of this type perform s plasticizer, lubricants, impact modifiers, fillers and pigments.

The second group of additives achieves their effect by chemical reactions. This type includes flame retards, stabilizers, ultraviolet absorbers and antioxidants.

Fillers :

Fillers are classified as inorganic, organic, mineral, natural and synthetic. They are more commonly used with the thermosetting materials such as phenolics, urea and melamine. They fill some thermoplastics as well. Large amounts of fillers are referred as extenders because they increase the bulkiness and decrease the cost of a plastic. Since the properties of an extended plastics often suffer, the use of fillers is often limited to less critical application.

Fillers normally endow plastics with specific mechanical, physical and electrical properties. Filler usually comprises between 10 and 50% of the mass of the mix.

One of the most widely used fillers for the thermoplastic is wood flour. It consists of finely ground powder of hard woods or nut shells. They are cheap, light weight, strong (due to their fibrous nature) and easy to compound. But they have low thermal resistance, low dimensional stability and poor electrical properties.

Mineral fillers used are the purer form of silica, mica, quartz, inorganic pigment, refined metal oxides, sulfates etc. Large amounts of inorganic and mineral fillers increase the brittleness. Asbestos (mineral fiber) combines the advantages of. an inorganic filler with those of fiber. (recently asbestos has

come under stringent safety regulations).

The factors for choosing filler are:

1. Cost. Availability and uniformity

2. Compatibility or meltability  with the resin

3. Moisture absorption

4. Physical properties

5. Thermal. stability and mould temperatures

6. Resistance to chemicals

7. Abrasiveness

8. Effect on plastic flow characteristics.

The following chart shows the different fillers used for the different purposes

Purpose	Bulk	Reinforce- ment	Hardness	Thermal insulation	Chemical  resistance	Appearance
Fillers	*Wood flour *Sawdust *Wood pulp *Sisal Jute *Purified cellulose *Mica rock	*Glass fiber *Asbestos fiber *Cellulose fiber *Cotton fiber *Paper *Synthetic    fiber	*Inorganic pigment *Mineral pigment *Mineral powder *Metallic oxides *Powdered metal *Graphite	*Asbestos *Ceramic oxides *Silica	*Glass fiber *Fabric fiber *Synthetic fiber *Graphite *Metallic oxides	*Colour pigment *Carbon block *Powdered metal *Woven fabrics

Plasticizers :

Plastics may need to be plasticized to enhance flexibility, resiliency and resiliency flow. Without the addition of a plasticizer, it would not be possible to make plastics sheeting, tubing, film and other flexible forms of plastics. The plasticizers enable the molecular chains of Polymers to move freely with respect to one another, with minimum entanglement or internal friction. A plasticizer thus acts as an internal lubricant. It is not chemically linked to the plastic.

Nearly 80 % of all plasticizers are used in PVC, but they are used in cellulous, nylon. ABS.

Most plasticizers are liquids; a few are solids that melt at compounding temperature. All must exhibit good compatibility with the resin they modify. They are usually colourless, odourless and posses good thermal stability. But they decrease the strength characteristics, heat resistance, dimensional stability and solvent resistance of resins.

The popular general purpose plasticizers are the phthalates, eporcies, phosphates, adipate diesters, sebacates etc. Plasticizers compose upto 50 to 60% of a final PVC product.

Colourants:

The use of colourants makes it possible to produce a variety of materials in colours varying from pastels to deep hues. This types of colourants are used, dyes and pigments of organic and inorganic nature. Dyes are fairly soluble in plastics while the pigments are not. The choice depends on resin compatibility or the need for solubility. The colourants should be stable. Dyes have lower thermal stability and will be discoloured on overheating. Colour concentrates are also supplied with the plastics by the manufacturer.

Heat stabilizers:

Stabilizers are used to prevent the degradation of resins during processing, when melts are subjected to high temperatures. They are also used to extend the life of the end parts. PVC is vulnerable to degradation during processing and is the prime consumer of heat stabilizers. The commercial stabilizers are based on solid barium, cadmium, lead etc.

Antioxidants:

Antioxidants are used to protect materials from deterioration through oxidation brought on by heat, light or chemically induced mechanism. Oxidation causes, brittleness, melt flow instability, loss of tensile properties and discolouration.

Ultra violet light absorbers:

Virtually every plastic degrades in sunlight. They lose their colour and physical properties. PS, PVC, ABS, polyesters are affected much. The choice of ultra violet absorber depends on the application, the. basic resin, the ultimate effect and the required durability of the end product. (Ultra violet absorbers are used up in time).

Flame retardants :

Flame retardants are used to affect combustion in plastics.

Flame retardants work on four basic principles. When

1. they insulate or
2. create an endothermic cooling reaction or
3. coat the product and exclude oxygen or
4. actually influence combustion through reaction.

The most common flame retardants are antimony, boron, halogens, nitrogen and phosphorus The most common in PVC are phosphate esters.

Antistatic agents:

Antistatic agents also called destatisisers are used to reduce the build up of electrostatic charges an the surface of plastics materials by increasing surface conductivity

Plastics susceptible to electrostatic charges are PE, PP, PS, PA, polyesters, urethanes, cellulosies acrylics and acrylonitriles.

The most common antistatic for plastics are amines, ammonia, compounds, phosphate esters, and polyethylene glycol esters.

Antistatic agents are selected on the basis of application, durability, necessary concentration, and  effectiveness at low humidity.

Lubricants:

Lubricants are additives used to help in the processing of plastics. Internal lubricants act within the plastic to reduce the forces acting between molecules. External lubricants reduce the adhesion of the plastic to the metal surface of the process machinery and mould

Lubricants fall into five categories, metallic stearates, fatty acid amides and esters, fatty acids, hydro carbon waxes and low molecular weight polyethylene.

Reinforced plastics:

Reinforced plastic are composite material consisting of a thermoplastic or thermoset matrix combined with another stronger and stiffer material, usually in fiber form which acts as the reinforcement The purpose of the fiber is to carry as much of the load applied to the composite as possible The plastic matrix exists primarily to transfer the load-form point of application into the load-bearing fibers.

The effectiveness of such fibrous reinforcement is dependent on a number of factors. The degree of adhesion between plastic and fiber is fundamental. Other factors of importance are the relative volumes of reinforcement and plastic matrix, the length of’ fiber used and the physical chemical and temperature properties of fiber and plastic.

Reinforcements:

Glass filaments are a low cost readily available reinforcement Glass fibers with perfect surface have very high ultimate tensile strength.

Glass fibers are manufactured by extruding molten glass through a die then drawing the glass down to a fine diameter strand (0.01)

Ceramic fibers:

To achieve the highest possible strength, stiffness and temperature capabilities of reinforced plastic, ceramic fiber reinforcements may be used. Carbon and boron fibers are presently used.

Fiber to plastic bonding:

The effectiveness of fiber reinforcement depends on the bond between matrix and fiber. Glass fibers are generally coated with substances which act as coupling agents to encourage good bounding.

Mould release agents:

In moulding any of the reinforcement materials, regardless of the type of reinforcement or the rein used, the tendency of part to stick to the mould surface is a common characteristic. To facilitate the removal of such parts from the mould a release agent ( also called parting agent or mould release ) is used. The release agent forms a barrier film between the mould surface and the part .There are two types of release agent commonly used.

1. External release agent which are applied to the mould surface.

     E.g. regenerated cellulose, polyvinyl alcohol (PVA), PVA and nylon solution, pure carnauba wax etc.

2. Internal release agent which are combined with the resin.

    E.g. Zinc and calcium stearates, silicone oils, high melting point waxed etc.

Selection of plastic material based on application

Field	Properties required	Application	Preferred material
Packaging	1) Corrosion resistance 2) Chemical resistant 3) Non toxic 4) Light weight 5) elastic	Food package, oil    containers, milk bottles	*Polyethylene (PE) *Polypropylene(PP)
		Carry bags, liquid package, electronic equipment package	*Polyethylene(PE)
		Soft drink containers	*Polyethylene terephthalate (PET)
		Disposable cups	*Polystyrene(PS)
		Film package	*Cellulose Acetate          (CA - Perspex)
		Water bottle	*Polycarbonate(PC)
Home Appliances	1) Impact resistance 2) Resilience 3) Good colour stability 4) Chemical resistance 5) tough	Computer, TV cabinet, telephone, mixer, vacuum cleaner, cassette holder	*Acrylonitrile Butadiene Styrene(ABS)
		Hinged applications	*Polypropylene(PP)
		Coffee maker, toaster	*Polypropylene(PP) *Acrylonitrile Butadiene Styrene(ABS)
		Printer cover	*Polycarbonate(PC)
		Cassette cover	*Styrene Acrylonitrile (SAN)
		Video cassette parts (bobbin)	*Polyoxymethyle (POM) *Polyacetal (Delrin)
Optics	1) Transparent 2) Wear resistance 3) Tough	Air craft canopies, safety spectacles, lightings	*Polymethyle Methacrylate (PMMA) *Polycarbonate(PC)
		Light housings	*Polycarbonate(PC)
		lenses	*Polymethyle Methacrylate (PMMA) *Nylon (PA)
		Eye glass frame, optical frame, display package	*Cellulose Acetate (CA)
		Optical lenses, sun wear lenses, CD, DVD, VCD	*Polycarbonate(PC)(Lexan)
Environment exposed	1) UV resistance                  2) weather resistance	Road signs	*Polyvinyl chloride(PVC) *Polymethyle Methacrylate (PMMA)
		Advertisement display	*Polyvinyl chloride(PVC)
		Letter box	*Polyvinyl chloride(PVC)
		Translucent roofing	*Polytetrafluoroethylene (PTFE – Teflon) *Polycarbonate(PC)

Field	Properties required	Application	Preferred material
Engineering	1) Fatigue resistance 2) Impact resistance 3) Resilience 4) Wear resistance 5) Dimensional stability	Gears	*Nylon (PA) *Phenol Formaldehyde (PF) *Polyoxymethylene      (POM-delrin)
		Gaskets	*Nylon (PA) *Silicon moulding compound (SMC) *Polytetrafluoroethylene (PTFE-Teflon)
		Bushing, bearings	*Nylon (PA) *Polyether ether keton (PEEK)
		Transmission belt	*Polyurethane (PU)
		Conveyor	*Polyoxymethylene      (POM-delrin)
		Adhesive, O-rings	*Silicon moulding compound (SMC)
		Machine parts under stress	*Ultra high molecular weight high density polyethylene (UHMHDPE)
		Valve stem	*Polyamide imide (PAI)
Electrical applications	1) Heat resistance 2) Flame retardant 3) Stiffness	Wire insulation	*Polyethylene (PE) *Polytetrafluoroethylene (PTFE-Teflon) *Polyvinyl chloride(PVC) *Silicon moulding compound (SMC)
		Switch, handles	*Phenol Formaldehyde(PF)
		Cover for electrical instruments	*Polycarbonate(PC)
		Electrical connectors, housings	*Polyether ether keton (PEEK) *Polybutylene Terephthalate (PBT)
		Insulation tape	*Polytetrafluoroethylene (PTFE-Teflon)
		Encapsulation of electrical coils	*Epoxy
		Arc resistant electrical parts	*Melamine formaldehyde  (MF)
Safety Equipment	1) Tough 2) Wear resistance	Helmet visor	*Polycarbonate(PC)
		Safety glasses	*Cellulose Acetate (CA)
		Suitcases	*High density polyethylene (HDPE) *Acrylonitrile Butadiene Styrene(ABS)
Field	Properties required	Application	Preferred material
Automotive	1) Tough 2) Impact resistance 3) Fatigue resistance 4) Wear resistance 5) Weather resistance 6) Heat resistance	Bumper	*Polypropylene(PP) *Polyurethane (PU) *Polybutylene Terephthalate (PBT) *Polycarbonate(PC)
		Automotive body, train interiors	*Unsaturated Polyester resins
		Fender	*Nylon (PA)
		Radiator	*Nylon (PA)
		Rear view mirror housings	*Acrylonitrile Butadiene Styrene(ABS) (Geloy – AST)
		Battery casings	*Acrylonitrile Butadiene Styrene(ABS)
		Air duct	*Polypropylene(PP)
		Dash board	*Polypropylene(PP-talc filled) *Polycarbonate(PC) *Acrylonitrile Butadiene Styrene(ABS)
		Fuel tank	*High density polyethylene (HDPE)
		Carburetor	*Polyoxymethylene      (POM-delrin)
		Door handles	*Polyoxymethylene      (POM-delrin) *Nylon(PA)
		Head lamp shield	*Polycarbonate(PC)
		Instrumental panels	*Polymethyle Methacrylate (PMMA) *Styrene Acrylonitrile (SAN) *Polypropylene(PP-talc filled) *Polyurethane (PU)
		Tail lamp, windows	*Polymethyle Methacrylate (PMMA)
		seats	*Polyurethane (PU)
		Spark plug cover	*Polyvinyl chloride(PVC)
Plumbing parts	1) Heat resistance 2) Flexibility 3) Tough 4) chemical resistance	Pipes	*Polyvinyl chloride(PVC) *High density polyethylene (HDPE) *Polypropylene(PP) *Nylon(PA) *Polyoxymethylene      (POM-delrin)
		Corrosion resistant pipes & valves	*Polytetrafluoroethylene (PTFE-Teflon)
		Pump wear rings	*Polyether ether keton (PEEK)
Field	Properties required	Application	Preferred material
Thermal applications	1) Heat resistant 2) Flame resistant	Kitchen utensil handles	*Phenol Formaldehyde     (PF – Bakelite)
		Thermal pipe insulation	*Ionomer(I)
		Hot water meters, thermal insulation for refrigerators	*Polyether ether keton (PEEK)
		Spoon, tray	*Melamine Formaldehyde (MF)
Toys	1) Light weight 2) Non toxic 3) Attractive colours	Toys	*Polyethylene (PE) *Polystyrene (PS) *Cellulose Acetate          (CA-Perspex)
		Lego	*Acrylonitrile Butadiene Styrene(ABS)
		Ping pong ball	Cellulose Nitrate(CN)
Furniture	1) Elastic 2) Impact resistance 3) Wear resistant 4) Resilient 5) Damping	Seat	*Polyurethane (PU)
		Chair	*Polypropylene(PP)
		Chair wheels	*Nylon(PA)
		Chair net, handles	*High density polyethylene (HDPE)
Hardware Equipments	1) Tough 2) Wear resistant 3) Good appearance	Tool handles	*Polyoxymethylene      (POM-delrin) *Acrylic
		knife handles	*Phenol Formaldehyde     (PF – Bakelite)
		Power tool housing	*Cellulose Acetate          (CA-Perspex) – may break *Nylon(PA) *Polycarbonate(PC) costly
		Electrical screw drivers	*Cellulose Acetate          (CA-Perspex)
Sports	1) Tough 2) Wear resistant 3) Good appearance	Ski board, skate shell, wrestling mats, golf ball, athletes shoe sole with stud	*Ionomer (I)
		Tennis racket	*Nylon(PA)
		Surfing board	*Acrylonitrile Butadiene Styrene(ABS)
		Shoe soles	*Polyurethane (PU)
		Swimming caps, goggle seal	*Silicon moulding compound (SMC)

Household Articles		Novelties, chopping board, soap cases, comb, disposable trays	*Polystyrene (PS)
		Kitchen kettles,	*Polypropylene(PP)
		Picnic box, razor handles	*Acrylonitrile Butadiene Styrene(ABS)
		Tooth brush bristles	*Nylon(PA)
		Credit cards	*Polyethylene terephthalate (PET)
		Pen box, containers,	*Low density Polyethylene (LDPE)
		Shirt buttons	*Low density Polyethylene (LDPE) *Urea Formaldehyde(UF)
		Buckets	*High density polyethylene (HDPE)
		Overhead water tank	*Linear Low density Polyethylene (LLDPE) *Fiber reinforced plastics (FRP)
		Artificial flowers & fruits	*Low density Polyethylene (LDPE)
		Zip	*Nylon(PA) *Polyoxymethylene      (POM-delrin)
		Hair decorators	*Cellulose Acetate          (CA-Perspex)
		Non-stick coatings, seals, Gaskets	*Polytetrafluoroethylene (PTFE-Teflon)
		Vegetable trays	*Polypropylene(PP) *Acrylics
		Decorative lights	*Acrylics
Medical		Syringe	*Polypropylene(PP)
		Injection fluid bottles	*High density polyethylene (HDPE)
		Medical tubes, blood storage bag, glucose bag	*Polyvinyl chloride(PVC)
		Scanner body	*Acrylonitrile Butadiene Styrene(ABS) *Poly Phenylene oxide (PPO – Noryl)
Agriculture		Irrigation pipes	*Low density Polyethylene (LDPE)
		Garden pipes	*Polyvinyl chloride(PVC)
		Green house	*High density polyethylene (HDPE)

Perspex - cellulose Acetate - CA

Delrin     - Polyoxymethylene – POM – Poly Acetal

Teflon    - Polytetrafluoroethylene - PTFE

Bakelite - Phenol formaldehyde - PF

1.9    IDENTIFICATION OF THERMOPLASTIC MATERIALS

Behaviour of material	Melt blackens	Melts bubble, little carbonization	Softens, bubbles blackens	Softens, bubble blackens	Melts & froth	Softens, bubbles carbonize	Melts & drips	Melts and drips
Burning smell	Very sharp formaldehyde smell	Fruity	Flowery	Faint pleasant	Burnt hair	Pleasant (faint phenolics)	Sharp like vinegar	Rancid cheese or butter
Flame character	Pure blue, no carbon	Blue with yellow top, alight smoke	Yellow smoky	Yellow smoky	Blue with yellow top	Yellow smoky	Yellow flame, moderate black smoke	Dark yellow blue edge, moderate smoke
Whether self extinguishing	No	No	No	No	Mostly yes	Yes	No	No
Ease of Ignition	Moderate	Really burns	Moderate	Readily burns	Moderate	Difficult	Readily burns	Readily burns
Relative density	1.42	1.18	1.02	1.07	1.04 – 1.14	1.2	1.28	1.19
Abbr.	POM	PAA	ABS	MABS	PA	PC	CA	CAB
Material	Acetal	Acrylic	Acrylinitrile butadiene styrene	Meth acryle butadiene styrene	Polyamide (Nylon)	Polycarbonate	Cellulose Acetate	Cellulose Acetate Butyrate
No	1	2	3	4	5	6	7	8

Behaviour of material	Melt blackens	Melts bubble, little carbonization	Softens, bubbles blackens	Softens, bubble blackens	Melts & froth	Softens, bubbles carbonize	Melts & drips	Melts and drips
Behaviour of material	Burns violently	Melts and drips	Chars & cracks, melts  bubbles	melts	Melts & bubbles	Melts & bubbles	Softens and blackens	Melts and drips
Burning smell	Camphor	Paraffin wax	fruity	Paraffin wax	Oppressive flowery	flowery	acidic	acidic
Flame character	Bright yellow	Blue with yellow top	Blue with yellow top, alight carbon	Blue with yellow top	dense black smoke, mooty	Yellow smoky	yellow	yellow
Whether self extinguishing	No	No	No	No	No	No	Yes	Yes
Ease of Ignition	Highly inflammable	Really burns	Really burns	Readily burns	Really burns	Really burns	moderate	moderate
Relative density	*	0.92	1.19	0.9	1.05	1.09	1.4	1.3
Abbr.	CN	PE	PMMA	PP	PS	SAN	PVC	PVC
Material	Cellulose Nitrate	Polyethylene	Polymethyle metha Acrylate	Polypropylene	Polystyrene	Styrene Acrylo Nitrile	Polyvinyl Chloride	Polyvinyl chloride plasticized
No	9	10	11	12	13	14	15	16

Abb	Name		Abb	Name
ABS	Acrylonitryle Butadiene styrene		AMC	Alkyd Moulding Compound
BMC	Bulk Moulding Compound		CA	Cellulose Acetate
CAB	Cellulose Acetate Butyrate		CAP	Cellulose Acetate Propionate
CMC	Carboxymethyl Cellulose		CN	Cellulose nitrate
CP	Cellulose Propionate		CPE	Chlorinated polyethylene
CPVC	Chlorinated Polyvinyl Chloride		CS	Casein
DAP	Diallyphthalate		DMC	Dough Moulding Compound
EP	Epoxy		EC	Ethyl cellulose
EVA	Ethylene vinyl acetate		FEB	Fluoro ethylene Propylene
HDPE	High Density poly Ethylene		HIPS	High impact Polystyrene
LDPE	Low Density Poly Ethylene		LLDPE	Linear Low density polyethylene
MF	Melamine Formaldehyde		NR	Natural Rubber
PA	Polyamide (Nylon)		PBT	Polybutylene  Teraphthalate
PC	Polycarbonate		PCA	Polycarbonate Acrylate
PE	Polyethylene		PEI	Polyetherimide
PEK	Poly ether keton		PEEK	Poly ether ether keton
PET	Polyethylene Teraphthalate		PF	Phenol Formaldehyde
PMMA	Polymethyl Methacrylate		POM	Polyoxymethylene (Polyacetal)
PP	polypropylene		PPCP	Polypropylene Copolymer
PPO	Polyphenylene Oxide		PS	Polystyrene
PTFE	Polytetrafluoro Ethylene		PU(PUR)	Polyurethane
PVA	Polyvinyl acetate		PVC	Polyvinyl chloride
PVCC	PVC Compound		SAN	Styrene Acrylonitrile
SBR	Styrene Butadiene Rubber		SBS	Styrene Butadiene Styrene
SI	Silicone		SMC	Silicon Moulding Compound
SP	Saturated Polyester		UF	Urea Formaldehyde
UHMW HDPE	Ultra High molecular Weight HDPE		UP	Unsaturated Polyester
Reinforced Plastics
BRP	Boron fiber Reinforced Plastic
CRP	Carbon Fiber Reinforced Plastic
FRP	Fiber reinforced Plastic
GRP	Glass Fiber reinforced Plastic
CRTP	Carbon Fiber reinforced thermoplastic
GRTP	Glass Fiber reinforced Thermoplastic
FRTP	Fiber Reinforced Thermoplastic