Glossary
A
ABS (acrylonitrile-butadiene-styrene-copolymer). Amorphous, thermoplastic terpolymer (derived from three monomers), chiefly used for housings of domestic appliances and office equipment.
Amorphous structure. No crystalline structures can be found in a microscopic range. Opposite of a partially crystalline structure.
ASA (Acrylnitrile-styrene-acrylic ester-polymer blend). Acrylic ester is dispersed evenly in a SAN (styrene-acrylnitrile) polymer structure and joined to it by the grafted-on SAN chains. Externally durable, transparent thermoplastic material.
Blowing agent. A substance used to cause expansion in the manufacture of hollow or cellular articles. Blowing agents may be compressed gases, volatile liquids or chemicals which split off a gas during fuming-off or other reaction.
Bonding agent. Substance which allows or improves bonding of the resin matrix to the surface of a reinforcing material. A bonding agent can be applied the surface of the reinforcement and/or mixed with the resin.
BPA (Bisphenol-A). Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several important plastics and plastic additives. With an annual production of 2–3 million metric tonnes, it is an important monomer in the production of polycarbonate (PC).
Suspected of being hazardous to humans since the 1930s, concerns about the use of bisphenol A in consumer products was regularly reported in the news media in 2008 when several governments issued reports questioning its safety, and some retailers removed products made from it off their shelves
Cellulose acetate (CA). Acetic acid ester of cellulose.
Cellulose acetate butyrate (CAB). Mixed acetic acid and butyric acid ester of cellulose.
Cellulose acetate propionate (CAP). Mixed acetic acid and proprionic acid ester of cellulose.
Cellulose propionate (CP). Propionic acid ester of cellulose.
Chemical resistance. During material selection many designers only consider the mechanical properties and only on very few occasions, the chemical resistance of the polymers. Chemical or physical processes, or a combination of the two, are the main causes of aging. Aging and chemical resistance are influencing the performance of polymer components. Hence, in the concept and design phase of plastic products, this point is often not taken into consideration.
Compound (moulding compound) An intimate mixture of a polymer or several polymers with other ingredients such as fillers, plasticisers, pigments and other additives through extrusion (compounding) to improve and change property values. These moulding compounds are processed thermoplastically, e.g. by injection-moulding or extrusion.
Conditioning. A whole series of operations intended to bring a sample or specimen into a reference state with regard to temperature and humidity.
Copolymer. A polymer made of more than one kind of monomer. As a rule the monomer units are distributed statistically in polymer chains.
Deep drawn thermoforming. Thermoforming process in which the sheet being formed under a deep draw ratio can slide inwards during the forming process and takes on the shape of the mould.
Degree of polymerisation (P). The average number of basic units per macromolecule, which are made up of regularly repeated units. The type of average must be given according to the method of determination used: number average, average viscosity or mass average.
Dynamic strength (fatigue strength). Dynamic, long-term stressing can lead to failure of the construction material. Depending on the degree of cyclic mechanical stress, breakage occurs after a certain number of load cycles.
Elastic modulus (modulus of elasticity). Ratio of stress to corresponding strain in a material below the proportional limit - from flexural or tensile tests.
Elastic deformation. Part of total deformation of a stressed plastic which disappears after removal of the load.
Elastomer. A macromolecular material which returns rapidly to its initial dimensions and shape after substantial deformation by a weak stress and release of the stress.
EPDM (Ethylene-propylene-diene copolymer). Elastomeric, thermoplastic terpolymer. The diene is butadiene, where remaining double bonds can be made to form branching and cross-linking. M stands for monomer.
Epoxy resin (EP). Synthetic resin containing epoxy groups which can be cross-linked to form unmeltable thermosets by multi-functional substances (hardeners) e.g. two-component adhesives and floor coverings.
Extruder screw. A shaft with one or more helical ribs, often divided into different zones with differing depths of the channel and sometimes, different pitch, usually having a cylindrical part at one end and a curved or pointed surface at the other to drive the plastic mass along the barrel.
Extrusion. A processing method where heated or unheated plastic is forced through a shaping orifice to form one continuously formed piece.
Extrusion blow moulding: A thick-walled parison is freely extruded vertically downwards in moulding cycles. Very high-viscosity polymers with high melt strength are required so that the wall strengths do not change as the parison is pulled down under its own weight. The parison is blown up in a two-part mould and, through cooling, takes on the shape of the required hollow container. Used in under-bonnet automotive applications (e.g. with PA).
Filler (additive). A relatively inert solid material added to a plastic and evenly mixed with it to improve its strength, stability, processing or other properties or to lower costs.
Film extrusion. Process of making film by extruding an heated thermoplastic through a die (slot-die extrusion).
Flame retardant. A substance that retards markedly the propagation of a flame. Flame retardants can be incorporated in plastics as additives or as chemical groups in the base polymer by use of reactive intermediates in the polymerisation process.
Graft polymer. A polymer, the molecules of which have one or more species of block connected to the main chain as side chains. These side chains have different structural characteristics to the main chain.
Heat sealing. Process of bonding two or more thin layers of materials, at least one of which is a thermoplastic film, by heating areas in contact with each other to the temperature at which fusion of the thermoplastic film(s) occurs. The bonding is usually completed by the application of pressure.
High-frequency welding (HF welding). A pressure welding process in which the surfaces to be united are softened by heat produced in a high-frequency field.
Homopolymer. A polymer based on only one kind of monomer.
Hot stamping (embossing). A process of decorating or marking plastics during which a pigmented or metallised film is pressed against the plastic by a hot die, thereby transferring and firmly bonding the pigment or the metal to the plastic.
Injection blow moulding. A blow moulding process in which a parison is formed over a mandrel by injection moulding and blown to its final form and dimensions in a second mould.
Injection moulding. A process of moulding a material by injection under pressure from a heated cylinder through a sprue (runner, gate) into the cavity of a closed mould where it cools and solidifys.
Insert. A part made of metal or other material which is bedded into the material in the required position during moulding or is inserted into the finished shaped part.
LCP (Liquid Crystal Polymers). High-temperature melting thermoplastic materials with high crystallinity whereby this has a reinforcing effect on the tensile strength in a uniaxial direction. These aromatic polyesters are high performance plastics with high resistance to heat.
Light transmission. Light Transmission is the percentage of light that passes through a sample or test part.
Lubricant. A substance added in small proportions to the formulation of a plastic to facilitate processing or to prevent sticking.
Masterbatch. A well-dispersed mixture of a polymer and high percentages of one or more components (colorants and/or other additives) in known proportions for use in blending in appropriate amounts with the basic polymer in the preparation of a compound.
Moulded part. Part or article produced in a closed mould, e.g. by compression moulding, transfer moulding, injection moulding.
Mould release agent (demoulding agent). A substance put on the inside of a mould or added to a moulding material to facilitate removal of the moulded part from the mould.
Molecular weight, M. Ratio of the average mass per formula unit of a substance to 1/12 of the mass of an atom of nuclide 12C. M is expressed in gram.
Oligomer. A substance composed of molecules containing a few of one or more species of atoms or groups of atoms (constitutional units) repetitively linked together.
PA (polyamide) Polymer molecules which contain the repeated amide group -CO-NH- . Also called nylon. As an engineering plastic, PA is compounded with many kinds of additives to obtain improved properties.
PAR (polyarylate). Amorphous thermoplastic material based on terephthalic and isophthalic acids and bisphenol A in the polymer chains. It is a weather-resistant, semi-aromatic polyester.
PBT (polybutylene terephthalate). A thermoplastic polyester created by polycondensation of butylene glycol with terephthalic acid or dimethyl terephthalate. Use of selected additives results in the engineering plastic PBT.
PC (polycarbonate) A thermoplastic, amorphous polymer where the repeated structural unit in the polymer chain is the carbonate group (-O-COO-). Applications include extremely impact resistant, transparent, protective and viewing windows and protective helmets.
PEBA (Polyetherblockamide) Polyamide high performance elastomers. Polymer chain contains polyamide hard segments and polyether soft segments.
Pellet. A small mass of preformed moulding material, having relatively uniform dimensions in a given lot, used as feedstock in moulding and extrusion operations.
PET (polyethylene terephthalate) A polyester where the repeated structural unit in the polymer chain is the ester group (-COO-) interspersed with the benzene ring (-C6H4-) and ethyl (-CH 2 – CH 2-), made through polycondensation of terephthalic acid and ethylene glycol, it is used for the manufacture of polyester fibres and PET drink bottles.
Plastification. A process of rendering a thermoplastic compound more processible by means of mechanical working and/or application of heat or, e.g. also by the addition of a plasticiser.
Plastic raw material (virgin material). Plastic material in granule, pellet or powder form which is prepared for further processing.
Plasiciser. A substance of low or negligible volatility incorporated in a plastic to lower its softening range and to increase its workability, flexibility or extensibility.
PMMA (polymethyl methacrylate, acrylic glazing material, Perspex) A transparent thermoplastic material with crystal clarity and brilliance. Due to its hardness and weatherability it is widely used in automotive construction. Brittleness is prevented by mixing with elastomers (with acrylonitrile as monomer). The chemical structure of PMMA the linear CH 2 chain has a methyl (CH3-)- and a methylester group (-COO-CH3 ) on every second position.
Polyacrylate (PAK). Polymer of an acrylic acid ester, a homologous or a substituted derivative of acrylic acids. A moulding material made up mainly of polyacrylates.
Polyamide 6 (polycaprolactam, PA 6, Nylon 6) A polyamide with 6 C-atoms in the monomer unit, manufactured from the ring-shaped caprolactam (7-link chain with an amide group) through ring-opening polymerisation to form polymer chains. With the addition of additives, PA 6 is a tough engineering plastic. It is used in barrier films and chemical fibres.
Polyamide 66 (PA 66, Nylon 66) PA 66 is manufactured through polycondensation of hexamethylene diamine (6 C-atoms) and adipic acid (6 C-atoms) with splitting-off of water. With the addition of additives, a tough engineering plastic is created which is used in automotive and electrical parts. PA 66 is also well known as a chemical fibre.
Polyamide 12 (PA 12 ) A thermoplastic polymer with 12 C-atoms in the monomer unit. It is manufactured through ring-opening polymerisation of laurolactam (13-link chain with an amide group) to form polymer chains and has the lowest water absorption capacity of all types of polyamides and thus the least change in properties due to environmental effects.
Polyblends (alloys) These are mixtures, often also called alloys, of different thermoplastic materials to create new plastic materials with previously unknown property profiles.
Polyester A thermoplastic material manufactured through the esterification of polyvalent alcohols and acids. They are used among other things as fibres, resins and paints (thermoplastic or thermosetting alkyd resin).
Polyether. A polymer which has the repeated structural unit in the chain is of the ether type (-0-).
Polyethylene (PE) A family of soft, semi-crystalline, thermoplastic materials manufactured from ethylene (CH2 =CH2 ), with different structures: Branched macromolecules: PE-LD (low density) = high-pressure PE. Linear macromolecules: PE-HD (high density) = low pressure PE with higher cristalline content. A new metallocene catalysed PE is characterised by improved properties due to higher linearity. PE is a widely used bulk plastic material.
Polyisobutylene (PIB). A polymer of isobutylene (2-methylpropene).
Polyolefine. A polymer of one or more olefines. Plastics based on these polymers and copolymers of such monomers with other monomers, the olefine monomer (or monomers) being in the greatest amount by mass, e.g. PE and PP.
POM (polyoxymethylene, polyacetal). Semi-crystalline engineering plastic with the repeated structural unit ( – CH2 – O-) in the chain. It is manufactured from formaldehyde (CH2 O) or its cyclic timer (trioxan). POM is characterised by hardness, stiffness and good anti-friction properties.
Polyvinyl alkohol (PVOH). Polymer of the hypothetical vinyl alcohol; in practice it is prepared by the hydrolysis of polyvinyl acetate.
PP (polypropylene) A thermoplastic, crystalline bulk plastic manufactured through the polymerisation of propylene. PP is widely used, inexpensive and has the greatest potential for growth. Copolymers and block-copolymers exist. The newly introduced isotactic and syndiotactic PP with regular molecular arrangement exhibit greatly improved properties and is produced in part with new metallocen catalysts.
PPA (polyphthalamide HT-PA) A group of high-temperature polyamides made from the aromatic monomers therephthalic acid and isophthalic acid (HOOC-C6H4 – COOH) and hexamethylene diamine (6 C-atoms), e.g. PA 6T/6I with the highest temperature resistance of polyamides. These are new products for automotive and electrical components.
PPE (polyphenylene ether or – oxide = PPO) An aromatic polyether with the ether group (-O-) between the methyl-substituted benzene rings. As polycondensate it is not resistant above 100O C and is, therefore, only commercially available as polyblend with polystyrol or polyamide.
PPS (polyphenylene sulfide) A linear, high-crystalline thermoplast with S-bridges between the benzene rings in the chain. With branched types, a thermoset structure can be obtained through thermal post-treatement. When reinforced with glass fibres, PPS is heat resistant under long-term exposure to temperatures up to 240O C and is used in applications in the electrical and automotive industries.
PS (polystyrene) A linear bulk thermoplastic material of amorphous character with atactically arranged benzene rings as side-additions to every second C-atom of the CH 2 – polymer chain. PS is transparent and relatively brittle. Many copolymers are derived from it, most well-known being PS foam. New, regularly formed PS structures form syndiotactic PS (=SPS) with higher crystallinity and a melt-temperature of 270OC.
PSU (polysulphone) One of the most heat resistant, amorphous thermoplastic materials; contains sulphone (-SO 2-) and ether (-O-) groups between the semi-aromatic stuctures of the polymer chain. It has good heat resistance and hydrolysis stability and can be sterilised in hot air and steam.
PTFE (polytetrafluorethylene, Teflon). A linearly constructed macromolecule with the monomer unit – CF2–CF2-, high crystallinity and a melt temperature of 327OC. It is the best known fluor polymer with excellent chemical resistance. Its processing is difficult: coatings and impregnation with dispersion, sinter pressing at 380OC, powder-ram or paste extrusion (for hoses).
PUR (polyurethane). Thermoplastische PUR elastomers (T-PUR) are re-meltable polymer structures with hard and soft segments between the urethane structures (-NH-COO-) which connect them in the molecule; made of dioles (-OH) and diisocyanates (-NCO). Multi-functional polyoles and tri-isocyanate or polyisocyanates are used as reactions partner for thermosetting PUR grades with high rubber elasticity. The soft segments may be polyether (-O-) for polyurethane or polyester (-COOO-) for polyester urethane. End products are ski boots, sport track coverings and soft and hard integral foams.
PVC (polyvinyl chloride). This thermoplastic bulk plastic has the monomer structural unit –CH2–CHCl in the polymer molecule and has exceptionally good long-term resistance as PVC-U (hard PVC) used as supply pipes. With the addition of plasticiser, PVC-P (earlier PVC-W) is relative soft and easy to process. Questions have been posed regarding possible environmental damage due to hydrochloric acid (HCl) formed when PVC is burnt.
Reinforced plastic. Plastic with high-strength fibres embedded in the composition, resulting in strength properties greatly superior to those of the basic resin or thermoplastic material.
Relative viscosity. Ratio of the viscosity of a defined solution to the viscosity of the solvent under determined conditions.
Resistance to stress cracking. Stress Cracking is the premature initiation of cracking and embrittlement of a plastic due to the simultaneous action of stress and strain and contact with specific chemical environments.
S
Silicone plastic, SI plastic. A plastic based on polymers in which the main polymer chain consists of alternating silicon and oxygen atoms.
Stabiliser. A substance used in the formulation of some plastics to asisst in maintaining the properties of the material at or near their initial values during processing and working life.
Tensile E-Modulus vs. Temperature. The modulus is an important design parameter and describes the working temperature range of plastic materials. The structure of the plastic remains stiff and solid until the glass transition temperature (Tg) is reached. At temperatures above the glass transition temperature the material becomes softer and less resilient.
Tensile strength. Maximum strength sustained by a material before failure in tension. When the maximum stress occurs at the yield point it is designated tensile strength at yield. When the maximum stress occurs at break, it is designated tensile strength at break.
Tensile strength after weathering. Exposure to UV radiation causes changes in the chemical and physical properties of all plastics including polyamides. This can lead to a reduction of the working life of a construction material.
Thermoforming. A process of shaping heated thermoplastic sheets or films under a high stretch ratio in a mould.
Thermoplastic elastomers. These have specific areas in the macromolecules with physical wide-mesh cross-linking points (strong secondary valency forces or cristallites), which lead to the elastic behaviour but can be neutralised by heat.
Thermoplastic properties. Property of a plastic to be repeatedly softened by heating and hardened by cooling through a temperature range characteristic of the plastic and, in the softened state to be capable of being shaped repeatedly through flow into extruded, moulded or shaped articles or objects.
Ultrasonic welding. A pressure welding process in which the surfaces to be joined are softened by heat produced by intramolecular vibration at ultrasonic frequencies.
Vacuum thermoforming. Thermoforming process in which suction (vacuum) is used to draw a heated sheet of plastic against the moulding surface.
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