Materials

I. Properties

Basic types of PE: PE is obtained by polymerization of ethylene through various processes, resulting in polyethylenes with different properties (e.g., high and low-pressure processes), such as LDPE, MDPE, HDPE, and LLDPE.

a) Density: - LDPE branched: 0.914 to 0.94 g/cm³

• LLDPE: 0.918 to 0.943 g/cm³

• HDPE: 0.94 to 0.96 g/cm³

b) Structure: non-polar, partially crystalline thermoplastic with varying degrees of branching, affecting crystallinity (from 40 to 55% for LDPE and from 60 to 80% for HDPE). PE hardly absorbs water.

c) Mechanical properties: mechanical and chemical properties depend on crystallinity (density) and polymerization degree (melt flow index, MFI). With increasing density (linearity), PE exhibits higher tensile and flexural strength, stiffness, hardness, temperature resistance, and chemical and solvent resistance, while transparency, stress-corrosion resistance, and product flexibility decrease. Depending on crystallinity, it can be either rigid or soft. LDPE is particularly prone to creep.

d) Color: uncolored PE is milky white, almost transparent in very thin films. It is capable of covering in all colors.

e) Electrical properties: it has excellent electrical insulation properties. Dielectric properties are almost independent of density, melt flow index, temperature, and frequency. High-frequency heating is not possible. It often carries a strong electrostatic charge, leading to dust attraction. Therefore, antistatic agents are added. Conductivity is increased with the addition of 25 to 30% salt.

f) Temperature resistance: the upper temperature limit for LDPE is 60°C, for HDPE 95°C, temporarily even higher. Brittleness occurs at approximately -50°C, even lower with higher molecular weight. The crystalline melting range is from 105 to 115°C for LDPE, and from 125 to 140°C for HDPE. LDPE is more oxidation-resistant than HDPE. PE burns with a bluish flame and drips while burning.

g) Resistance: resistant to diluted acids, bases, salt solutions, water, alcohols, esters, oils, HDPE is also resistant to gasoline. Below 60°C, PE is practically insoluble in almost all organic solvents. It is not resistant to strong oxidizing agents, especially at elevated temperatures. LDPE swells in hydrocarbons. Oxygen and some other gases have greater permeability compared to most plastic materials. It exhibits very low water vapor permeability. Resistance to direct sunlight exposure is improved with the addition of 2 to 2.5% salt.

h) Physiological properties: PE is odorless, tasteless, and physiologically safe. It can generally be used in contact with food.

i) Susceptibility to stress cracking: stress cracking mainly occurs when surface-active substances (emulsifiers, cleaning agents) are used. This phenomenon is less common in PE with lower density and lower melt flow index (longer molecular chain lengths). Crack-resistant types of polyethylene contain polyisobutylene additives.

II. Processing

a) Injection molding: types of PE with good flowability (higher MFI) are used for injection molding. The ratio of amorphous to crystalline composition in the final product is greatly influenced by the cooling of the melt (mold temperature). This ratio affects shrinkage during processing and subsequent shrinkage. Mass temperatures (depending on type and composition) range from 160 to 300°C; tool temperatures range from 20 to 80°C, which is the upper limit for a higher proportion of crystallized particles and better surface gloss. Shrinkage during processing is 1.5 to 3.5% for LDPE and up to 5% for HDPE. Injection pressure is 600 bars for LDPE and up to 1200 bars for HDPE.

b) Extrusion: mainly high molecular weight types with lower melt flow index (0.2-4 MFI) are used for extrusion. The mass temperature depends on the type and ranges from 190 to 250°C, for the production of monofilaments and cables up to 300°C.

c) Extrusion blowing: high molecular weight types are highly suitable. The mass temperature depends on the type and ranges from 140 to 220°C, tool temperature from 5-40°C. High mass temperatures and rapid cooling enable the production of highly transparent profiles with LDPE.

d) Thermoforming: carried out at temperatures ranging from 130 to 180°C, mainly using vacuum forming processes in a mold. Tool temperature ranges from 40-90°C. LDPE sheets are highly dependent on temperature due to their low temperature resistance, so the use of a protective gas is recommended.

e) Bonding: as PE is non-polar, it has low adhesion properties. Sometimes, surface pretreatment is necessary, such as flaming, soaking in chromic-sulfuric acid, or surface electrification. Adhesive, contact (PUR, synthetic rubber), and two-component adhesives (EP, PUR) are used for bonding.

f) Welding: the best joints are made by hot air welding, using thermal elements and friction. Welding with thermal impulses is suitable for films. Ultrasonic welding is used only in special cases. High-frequency welding is not possible due to dielectric losses.

g) Machining: machining of PE is rare; ultrahigh molecular weight PE semi-finished products can be machined. Special tools for plastic processing are required.

h) Surface treatment: surface treatment by flaming or surface electrification in a vacuum chamber is necessary; followed by appropriate immediate further treatment. Printing: as screen printing or indirect lithographic printing. Coating: using standard procedures with two-component paints. Hot forging: at temperatures from 110 to 130°C. Metallization in a hot vacuum after surface electrification and priming.

i) Powder sintering: involves hot-melt processes at 220°C in a powder sintering oven with LDPE powder. Used for coating steel pipes, refrigerator grids, chairs, and more. Only limited coating thicknesses are possible.

j) Compression: compression with pre-pressure at 200°C and pressures from 20 to 50 bars, followed by slow cooling. Mostly used with high molecular weight PE with a melt flow index of 0.01, which does not crack, has good wear and sliding properties; thus used for gears, seals, filter plates.

k) Rotational molding: suitable for producing large seamless containers or vessels. Special PE powder is used, e.g., LLDPE. Wall thicknesses are limited.

III. Examples of Use

a) Machinery and vehicle components: seals, closure caps, handles, corrosion protection, battery housings, interior linings, textile bobbins

b) Electromechanics: insulation for high-voltage cables, power lines, installation pipes, distributors, motor housings, bobbins.

c) Construction elements: pipes for drinking and wastewater, heating pipes, fittings, cover films, sealing films, tanks for hot oil, artificial grass

d) Transport elements: transport carriers, bottle crates, various containers, packaging films, bottles, tubes, cans, garbage bins, various carrying films, tying films e) Miscellaneous: monofilaments for nets and ropes, textile industry bobbins, toys of all kinds, household containers

IV. Special Types of PE

a) PE in powder form: with defined grain size for rotational processes, powder sintering, and coating. Applications: rotationally formed hollow bodies, electrostatic or powder sintering coating.

b) LLDPE: has higher strength and stiffness at the same density as LDPE. Particularly suitable for thin, about 5mm thick blown and laminated films (for packaging), as well as rotationally formed parts (large hollow bodies, such as containers, sailboards).

c) High molecular weight PE: also ultrahigh molecular weight PE, used for special purposes such as bearings, gears, coatings, abrasion-resistant, requiring high impact and notch toughness, and good wear properties. Processing involves pressing powdered raw materials into semi-finished products, which can only be further processed by machining.

d) Cross-linked PE: HDPE cross-linking occurs by injection molding using peroxide and at tool temperatures of 200-230°C or with energy-rich radiation. Properties: cross-linking increases long-term stability, impact toughness at lower temperatures, and resistance to stress cracking. Short-term usage temperatures are up to 200°C. Only elastic softening of the material occurs at high temperatures due to cross-linking. Applications: automotive and electrical components. PE can also be cross-linked during extrusion (energy-rich radiation). Applications: hot water supply, underfloor heating systems, coatings for high-voltage cables.

e) Ethylene Vinyl Acetate Copolymer (EVA): copolymerization of ethylene with vinyl acetate changes some properties. Increasing VA content makes the mass more flexible and gives it rubber-like properties; toughness at low temperatures, resistance to thermal shocks, flexibility, stress crack resistance, transparency, weather resistance, and adhesion increase; however, hardness, stiffness, melting point, tensile strength, and temperature resistance decrease.

I. Properties

a) Density: from 0.895 to 0.92 g/cm³

b) Structure: semi-crystalline, non-polar thermoplastic with a crystallinity between 60 and 70%, resulting from isotactic arrangement of methyl groups. Copolymers with ethylene have higher impact strength (even at lower temperatures) and better weather resistance.

c) Color: colorless, slightly transparent to crystalline white, with high surface gloss. Capable of full coverage in all colors.

d) Mechanical properties: higher stiffness, hardness, and strength, but lower notched impact toughness than PE. Glass fibers are used to reinforce it for highly demanding structural parts. Other fillers and reinforcing agents include talc, wood flour, glass fibers, glass beads, glass mats for products with large surfaces, and carbon black.

e) Electrical properties: similar to PE. Dielectric properties are frequency-independent, thus not suitable for high-frequency heating. Despite high insulation properties, it tends to build up static electricity, so antistatic agents are added.

f) Temperature properties: Pure PP tends to oxidize at higher temperatures (despite the stabilization of PP types). The upper service temperature in the air is 110°C, higher for highly stabilized and reinforced types. The brittle temperature is at 0°C, lower for modified types. The crystalline melting range is from 158-168°C. Flammability is similar to PE.

g) Chemical resistance: Resistant to aqueous solutions of inorganic salts, weak inorganic acids and bases, alcohols, certain oils, and solutions of common bases up to 100°C. Not resistant to strong oxidizing agents. Swells in aliphatic and aromatic hydrocarbons such as gasoline and benzene, especially at high temperatures. Not resistant to halogenated hydrocarbons and partially not resistant to contact with copper!

h) Physiological properties: Odorless and tasteless, physiologically harmless, does not harm the skin. Widely used in the food and pharmaceutical industries.

i) Susceptibility to stress cracking: Low.

II. Processing

a) Injection molding: Due to lower density than PS, the plasticizing capacity of PP is only 70% of PS capacity. The use of shut-off nozzles is suitable. Material temperatures range from 200 to 300°C, mostly from 270-300°C, with injection pressure up to 1200 bars. Tool temperatures range from 20 to 100°C; higher temperatures yield better surface gloss. Shrinkage ranges from 1.0 to 2.5%.

b) Extrusion: A short-compression screw extruder is suitable. Extrusion temperatures range from 230-270°C. Special additives (nucleating agents) increase the crystallization rate.

c) Extrusion blow molding: Produces hollow products with good temperature resistance. Biaxial stretching increases strength.

d) Thermoforming: Involves forming with stretching, bending, and trimming at temperatures below the crystalline melting range. Forming temperatures range up to 150 to 160°C under pressure and up to 200°C in a vacuum. Tool temperatures range from low to 90°C; lower tool temperatures result in better transparency, higher temperatures in better temperature resistance.

e) Adhesion: Due to high chemical resistance and non-polar structure, PP has poor adhesion capability. Often, adhesive bonding is used, e.g., polychloroprene adhesives.

f) Welding: Joints made by hot gas, friction, and heat elements are durable. High-frequency welding is not possible.

g) Removal: Possible with special tools and processes; cooling is generally unnecessary.

h) Surface treatment: Surface treatment can improve adhesive properties (e.g., flaming or corona). Printing and lacquering are also possible. For electroplating, a nickel layer can be used instead of copper to protect against copper. Hot forging without prior treatment is also possible.

III. Examples of Use

a) Machine and vehicle components: Heating and ventilation pipes, fan blades, gas pedals, pump housings, fans, and other household items: kitchen appliances, cooking foils, internal components of dishwashers, drums for washing machines.

b) In electrical engineering: Transformer station housings, cable coatings, installation parts, antenna parts, battery housings.

c) Building elements: Flow pipes, fittings, underfloor heating pipes, radiators, hot water boilers.

d) Miscellaneous: Suitcases, tool cabinets, packing tapes, bags, monofilaments, gauze, medical devices, ropes, syringes, shoe heels.

IV. Special Types of PP

a) PP - elastomeric blends: Mixing EPM and EPDM rubber with PP yields a plastic mass with increased impact toughness, better weather resistance, and good processing properties. Such masses are particularly suitable for vehicle components (spoilers, bumpers, covers, etc.).

b) PP with narrow molecular weight distribution: Controlled rolling properties, used for parts with very thin walls, especially in the packaging industry (cups).

I. Properties

a) Density: 1.05 g/cm³
b) Structure: Amorphous thermoplastic with low water absorption capability.
c) Color: Clear with high surface gloss; transparent and capable of full coverage in all colors.
d) Mechanical properties: Hard, rigid, brittle, and very impact and notch sensitive. Exhibits low tendency to creep. Glass fibers are sometimes used for reinforcement.
e) Electrical properties: Good electrical resistance properties nearly independent of moisture content; surface moisture affects electrical properties. Excellent dielectric properties independent of frequency. Prone to static electricity buildup, hence antistatics are added.
f) Optical properties: Used for indoor optical purposes. Surface gloss decreases and yellowing occurs with outdoor use.
g) Temperature properties: Usable up to 70°C, thermally resistant types up to 80°C. Highly flammable, with a strong sooty flame.
h) Chemical resistance: Resistant to concentrated and diluted mineral acids (except oxidizing acids), bases, alcohols (except higher alcohols), water; highly resistant to aging. Not resistant to organic solvents such as gasoline, ketones (acetone), aromatics (benzene), and chlorinated hydrocarbons, essential oils. Sensitive to UV radiation, hence UV stabilizers are sometimes added.
i) Physiological properties: Physiologically non-hazardous.
j) Susceptibility to stress cracking: Strong tendency to stress cracking, especially in the open air.

II. Processing

a) Injection molding: Most commonly used processing method. Material temperatures range from 180 to 250°C, tool temperatures from 30 to 60°C. Shrinkage during processing ranges from 0.4 to 0.7%, with practically no subsequent shrinkage. For achieving high surface gloss and transparency, pre-drying of granules (1-2 hours at 70 to 80°C) is recommended.
b) Extrusion: Possible to extrude products with higher Vicat softening temperature. Extrusion temperatures range from 180 to 220°C, PS packaging films are biaxially stretched.
c) Thermoforming: Rarely used due to the formation of stresses during shaping, leading to more frequent material cracking. Thermoforming temperatures range from 130 to 150°C, with vacuum forming with pneumatic or mechanical pre-stretching.
d) Adhesion: Most commonly used bonding method. Solvent-based adhesives (e.g., toluene, dichloromethane, butyl acetate) are mainly used, in which up to 20% of polystyrene can be dissolved. Bonding to other materials is done with two-component or adhesive adhesives.
e) Welding: Welding is done with heat elements, heat impulses, and ultrasonically. High-frequency welding is not possible due to low dielectric losses.
f) Removal: Possible; cooling of cut locations with water or air is recommended.
g) Special processing methods: Blow molding of smaller products for packaging, and decorative processes for final products, such as printing, vacuum metallization, and hot stamping.

III. Examples of Use

a) Packaging: Products for packaging with high surface gloss and transparency; e.g., for cosmetics, disposable items, pens, small food packaging.
b) Lighting: Lights of all kinds with a crystal glass effect, for indoor use only.
c) Precision engineering and electrical engineering: Instrument covers, magnetic and film reels, insulation foils, relay parts, reels.
d) Miscellaneous: Household boxes, workshop and hobby boxes, cases, disposable syringes, simple toys, disposable tableware and utensils, fashion accessories, toothbrushes, household items, containers, cake covers, egg containers.
e) Special PS types: Represent alloys of polystyrene and polyolefins, mainly used in the packaging industry. Despite having impact-resistant polystyrene, these plastic masses have lower rigidity and poorer color-covering ability. However, despite the polyolefins, they can be processed in the same way as polystyrene (on the same extruders and thermoforming machines). They have lower water vapor permeability than pure PS, with improved resistance to stress cracking and temperature resistance.

I. Characteristics

a) Density: 1.20 to 1.24 g/cm³

b) Structure: It is an amorphous, non-crystalline thermoplastic, characterized by low water absorption, slight tendency to crystallization, after conditioning in water it contains 0.5% moisture.

c) Color: Transparent, transparent in all colors and capable of coverage. It has a high surface gloss.

d) Optical properties: It has a high refractive index (1.584), light transmittance in the visible range is up to 89%.

e) Mechanical properties: It exhibits high strength, hardness, and toughness, very good dimensional stability and low temperature dependency up to 130°C, high impact toughness, but homopolymers are very notch sensitive. Favorable time stability, even at higher temperatures. Under low loads, wear properties are mainly satisfactory. It absorbs a lot of energy upon impact. Strength, time stability, and stiffness are increased with the addition of glass and especially carbon fibers, but toughness is reduced. Surface coating improves scratch resistance.

f) Electrical properties: It has good electrical insulation properties, almost independent of moisture content and ambient temperature. When used in a high-frequency field, care must be taken to ensure that the loss factor at frequencies above 10^3 Hz does not exceed the tenth power. The addition of antistatic agents can prevent electrostatic charging for a certain period. Types reinforced with carbon fibers are antistatic.

g) Temperature properties: It exhibits high temperature resistance up to 130°C; for types reinforced with glass fibers up to 145°C. It becomes brittle only at -150°C. It has a lower coefficient of thermal expansion, especially when reinforced with glass fibers. It burns with a bright, sooty flame, forming bubbles, is self-extinguishing, further improvement with the addition of flame retardants.

h) Durability: Resistant to diluted mineral acids, saturated aliphatic hydrocarbons, gasoline, fats, oils, water (below 60°C), alcohols (except methyl alcohol). Not resistant to bases, acetone, ammonia, aromatic hydrocarbons, benzene, amines, ozone. Generally, it is weather-resistant. Intensive UV radiation requires the use of UV-stabilized types or treatment with soot or subsequent surface treatment. Chemical degradation occurs in water above 60°C or in water vapor. The solvent is dichloromethane.

i) Physiological properties: Tasteless and odorless, non-irritating. Special types are approved for use in contact with food.

j) Susceptibility to rheological cracks: Contact with certain chemicals (e.g., tetrachloroethylene) often leads to the formation of stress cracks, especially in molded products. Tempering releases internal stresses and improves resistance to stress crack formation.

II. Processing

a) Pre-processing: Drying of moist granules for at least 4 hours at a temperature of 120 to 130°C; the bed height is less than 2cm. The use of hoppers with heated covers is beneficial for processing machines. Pre-processing is not necessary with the use of vented cylinders.

b) Injection molding: Injection molding machines with screw plasticization are used. The use of vented cylinders and shut-off nozzles is beneficial. Injection pressure is at least 800 bars. The mass temperature is from 280 to 320°C; mold temperature is from 85 to 120°C. Release agents are almost not necessary. For better surface properties, high injection speeds and high mold temperatures are used (especially for types reinforced with glass fibers). Shrinkage during processing in all directions is from 0.7 to 0.8%, for types reinforced with glass fibers from 0.2 to 0.5%. When work is interrupted, cylinder temperatures should be reduced to 160 to 180°C.

c) Extrusion: High-viscosity types are used. Drying is more intensive than in injection molding. The temperature drops from 290 to 240°C from the hopper to the die. Mass temperatures at the outlet from the dies are from 230 to 260°C.

d) Thermoforming: Only completely dry sheets and foils are thermoformed, otherwise bubbles (blowholes) are formed. Pre-drying at a temperature of 150°C. Forming temperatures are from 180 to 220°C; the use of metal tools with temperatures from 130 to 150°C is suitable.

e) Machining: Possible without lubrication. Cooling is done with air or water (not with oil emulsions). High gloss is achieved by polishing with alkaline polishing pastes.

f) Adhesion: Before bonding, the surface must be cleaned with petroleum ether or gasoline. Bonding is done with reactive adhesives (EP, PUR), adhesive varnishes, or solvents-based adhesives (e.g., ethylene chloride or dichloromethane). Care must be taken to prevent stress crack formation. Finally, temper at 90°C for 6 hours.

g) Welding: Pre-drying of parts is recommended. After welding with hot air, tempering is necessary. Ultrasonic welding and welding with heat elements and friction are also favorable.

h) Tempering: mainly injection molded parts and semi-finished products; 30 minutes at 120°C in oil or air. Tempering relieves internal stresses.

i) Surface treatment: For better scratch resistance, special varnishes that do not attack the material and do not cause stress cracks are used. Printing and hot stamping are done by conventional methods. Metallization by high vacuum vapor deposition, followed by varnishing, is recommended.

III. Special Types

a) PC copolymers: There are special types with increased flame resistance, which are no longer transparent, special types with increased temperature resistance, e.g., aromatic polyester carbonates. These materials also have higher notch impact toughness at lower temperatures. With increasing ester content, temperature resistance increases, but toughness and flowability decrease.

b) PC alloys: They have high temperature resistance and cold impact toughness; PC/ABS alloys, high stiffness and better resistance to chemicals and fuels; PC/PBT, mainly used for parts in the automotive industry. PC/ASA; mainly improved weather resistance.

IV. Applications

a) In electronics: bobbins, contact strips, pipe joints, protective switches, distributors, battery covers, light housings, and fuse cabinets, computer housings, casings, compact discs.

b) In optics: microscope parts, binocular housings, cameras, slide projectors, slide trays, light-conductive and light-storage elements.

c) In precision mechanics, appliances: pneumatic parts, water pumps, appliance windows, valves, fans, sewing machine parts, air mail tubes, filter housings, medical devices.

d) In households: utensils, baby bottles, lighters, parts of small household appliances, coffee filters, shaver housings, vacuum cleaners, hair dryers, coffee machines, microwave oven containers.

e) Others: protective covers, visors, helmets, safety glasses, safety glazing, fishing equipment, pencil cases, rulers, templates, light housings and windows, shields.

f) Films: for scales, printed plates on appliances, dashboard panels, chocolate molds.

I. Characteristics

a) Density:

• PA6: 1.2-1.4 g/cm³

• PA46: 1.18 g/cm³

• PA66: 1.2-1.4 g/cm³

• PA610: 1.13-1.14 g/cm³

• PA612: 1.06-1.08 g/cm³

• PA11: 1.04 g/cm³

• PA12: 1.01 g/cm³

b) Structure: They are partially crystalline thermoplastics (up to 60% crystallinity); crystallization is improved with nucleating agents (fine spherulitic structure). They absorb water strongly (especially PA6 and PA66), more in the amorphous than in the crystalline region. Polyamides sometimes contain plasticizers (PA11).

c) Color: Uncolored ones are crystal white, capable of covering in all colors. Amorphous polyamides are almost transparent.

d) Mechanical properties: Depend on the type of polyamide, crystallinity, and water content. With higher crystallinity, they are rigid and hard, becoming very tough after water absorption. Higher strength is achieved with stretching (monofilaments, ropes, tapes). They have high fatigue resistance, good impact and notch impact toughness, abrasion resistance, good sliding properties, which can be improved with additives such as MoS2, PTFE, and graphite. Strength and modulus of elasticity are increased with the addition of glass and carbon fibers, while shrinkage is reduced and temperature resistance is increased. Modified polyamides have very high impact and notch impact toughness. Fillers and reinforcement additives: glass fibers, carbon fibers, glass beads, mineral substances, chalk, smoothing agents like MoS2 and graphite.

e) Electrical properties: Depend on the water content. Good surface resistance partially prevents static charging. They have high dielectric losses due to polarity, so they are not suitable for insulation in the high-frequency range, but can be used as additives in the low-frequency range. They have good resistance to tracking current.

f) Temperature properties: Depend on the type; the upper temperature limit ranges from 80 to 120°C, short-term up to 140°C, higher for glass-reinforced types and PA 46 (up to 130°C). They are generally unaffected by boiling and can also be sterilized. They have a narrow softening range. Lower service temperatures range from -40 to sometimes -70°C. Crystalline melting ranges: PA46: 295°C, PA6: 215 to 225°C, PA66: 250 to 265°C, PA610: 210 to 225°C; PA11: 180 to 190°C, PA12: 175 to 185°C. Polyamides burn with a bluish flame with a yellow edge, dripping with crackling and thread pulling, partially self-extinguishing, improved with flame retardant additives. Improved temperature resistance with heat stabilizers.

g) Durability: In aliphatic and aromatic hydrocarbons, gasoline, oil, fats, some alcohols, esters, ketones, ethers, in most chlorinated hydrocarbons, in weak bases. Stabilized types are more resistant to aging and weathering, which is particularly important for products with thicker walls. Not resistant to mineral acids, strong bases, glycols, chloroform, soluble oxidizing agents, formic acid, phenols, cresols. Amorphous PA is not resistant to ethyl alcohol, acetone, and dichloromethane.

h) Physiological properties: Prolonged exposure to heat poses a risk when in contact with water-containing foods (not for PA11 and PA12). Types containing plasticizers are also not suitable for contact with food.

i) Susceptibility to stress crack formation: Due to excellent toughness, susceptibility to stress crack formation is generally low. It is sensitive to zinc chloride solutions.

j) Water absorption: Under normal conditions, it proceeds very slowly. After four months of exposure under normal conditions (23/50), PA6 flat bars reach a moisture content of 2.3% (not yet saturated). In dry molded products, the moisture content in the usable state is achieved only through conditioning, e.g., conditioning in water, measuring the weight difference between dry and moist states.

I. Characteristics

a) Density: 1.03 g/cm³ to 1.07 g/cm³

b) Structure: It is an amorphous thermoplastic.

c) Color: Due to rubber products, they are not transparent but yellowish-white cloudy; they have covering ability in all colors.

d) Mechanical properties: It is rigid, tough, even at lower temperatures down to -45°C. Typical features include high hardness and good scratch resistance, high impact and notch impact toughness, good mechanical damping, and sound damping. Due to its high resistance, it is used as a cushion for metal parts. Glass fiber and glass bead additives can increase the modulus of elasticity, but at the same time, decrease toughness.

e) Electrical properties: It has high surface resistance and mass resistance, low electrostatic charge, and higher losses than standard PS.

f) Temperature properties: It is well-temperature resistant, usable from approximately -45 to 85°C, sometimes up to 100°C, and even higher for some types. It burns with a sooty flame, does not drip, and there are also self-extinguishing types.

g) Durability: Similar to SAN, depends on the content of styrene, acrylonitrile, and butadiene components. It is resistant to water, aqueous salt solutions, diluted acids and bases, saturated hydrocarbons (gasoline), mineral oils, animal and vegetable fats. Aging resistance is higher in types with carbon black content. Not resistant to concentrated mineral acids, aromatics (benzene), and chlorinated hydrocarbons, esters, ethers, and ketones.

h) Physiological properties: It is physiologically safe.

i) Susceptibility to stress crack formation: It is low in open air.

II. Processing

a) Pre-drying: Recommended before injection molding and extrusion, dry the granules for 2 hours at 80 to 90°C in a circulating air oven.

b) Injection molding: Very good at melt temperatures from 200 to 240°C, up to 280°C for temperature-resistant types; discolors at 240°C due to chain degradation. Tool temperatures range from 40 to 85°C, injection pressure from 800 to 1800 bars. Shrinkage during processing is from 0.4 to 0.8%.

c) Extrusion: Possible, including extrusion blow molding. Extrusion temperatures range from 180 to 230°C. Nitrogen is used as the carrier medium in pipe extrusion.

d) Thermoforming: Very useful; for sheets thicker than 2.5 mm, heat both sides. Temperatures range from 140 to 200°C. The material surface must be dry, or bubbles will form. Store sheets at 20°C and 30% relative humidity, otherwise, they must be dried for 2 to 4 hours at 85 to 90°C, depending on thickness.

e) Adhesion: Possible with solvents, e.g., methyl ethyl ketone, dichloroethylene, where up to 20% ABS can be dissolved. Two-component adhesives are used for better adhesion and bonding to other materials.

f) Welding: Possible with hot gases, heat elements, friction, ultrasonic welding; ABS types with higher dielectric losses can also be welded with high-frequency. Parts to be welded must be dry (bubble formation). ABS can be welded to PMMA.

g) Screwing: Possible with self-tapping screws.

h) Removal: Possible using standard tools for plastic processing.

i) Special processing procedures: Cold forming is possible with sheets or films. Decorative processing is similar to standard PS. A new process is laser marking of keys. Special types are galvanized after pre-treatment with greater bond strength.

III. Applications

a) In precision mechanics and electrical engineering: housings and handling parts, TVs, radios, film, video, and cameras, telephones, office machines, clocks, lamps, handheld power tools.

b) In vehicles: body parts, dashboards, chrome decorative strips, first aid boxes, steering mechanism covers, drawers, armrests, masks, spoilers.

c) In the furniture industry: chairs, chair shells, children's chairs, cabinet components, fittings.

d) In households: housings for vacuum cleaners, household appliances, small household appliances.

e) Others: technical toys, suitcases, boat parts, sanitary installations (pipes and fittings), protective helmets, transportation crates.

I. Characteristics:

a) Density: 1.08 g/cm³

b) Structure: It is an amorphous thermoplastic with increased water absorption compared to PS.

c) Color: It is transparent, with high surface gloss; transparent in all colors and capable of covering.

d) Mechanical properties: It is rigid, with higher impact toughness than PS but lower than SB. It has the highest elastic modulus of all styrene polymers. Resistant to scratches, it has high surface hardness. It is well-time resistant. Strength and elastic modulus can be increased with glass fiber reinforcements.

e) Electrical properties: It has very good electrical properties and slightly higher dielectric losses than PS, but less dependent on frequency and temperature.

f) Optical properties: Same as standard PS.

g) Temperature resistance: Usable up to 95°C and resistant to temperature changes. Burns with a strong sooty flame and does not drip when burning.

h) Durability: More durable than standard PS, especially in non-polar solvents such as gasoline, oils, and aromatic substances. Durability increases with increasing acrylonitrile content. Not resistant in similar circumstances to standard PS; sensitive to UV radiation.

i) Physiological properties: Physiologically non-hazardous.

j) Susceptibility to stress crack formation: Lower than standard PS.

II. Processing:

a) Injection molding: Pre-drying at 70 to 80°C is recommended. Injection molding works best at melt temperatures from 200 to 260°C and mold temperatures from 40 to 80°C. Shrinkage during processing is from 0.4 to 0.6%, smaller in types reinforced with glass fibers.

b) Extrusion: Mostly extrusion of films. Extrusion blow molding is also possible. Extrusion temperatures range from 180 to 230°C. Biaxial stretching gives better mechanical properties, especially for blown films.

c) Thermoforming: Possible at a temperature of 130°C.

d) Adhesion: It is the most favorable joining process. It exhibits higher solvent resistance but slightly more difficult bonding than standard PS. Solvent-based adhesives or toluene and dichloromethane are commonly used.

e) Welding: Welding can be done with hot gases, heat elements, heat impulses, friction, and ultrasonic welding. High-frequency welding is only possible with SAN with a high acrylonitrile content.

f) Removal and other processing procedures: Similar to standard PS.

III. Applications:

a) High-quality technical products requiring high rigidity and dimensional stability, especially if transparency is required.

b) In precision mechanics and electronics: housing parts for photo-video cameras, office machines, keys, instrument windows, battery housings, tape and film reels, telephones, counters.

c) In households: housings for household appliances, keys, instrument windows, containers.

d) Miscellaneous: packaging for food, cosmetics, bathroom sets, headlight housings, safety triangles, rulers, drawing tools.