Glossary PP
This glossary contains an overview of the most used terms in the polypropylenes business.
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Alphabetical Search |
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| F |
| FEM |
Film Energy absorption Measurement = a measurement of the impact strength by a drop test.
FEM-method: a weight of 2 kg, provided with a piezo-electric crystal for recording the force, is dropped from a height of 1 m onto a film specimen of 127 mm in circumference held in a clamping frame, to determine the fracture energy/unit of thickness (SABIC-method).
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| Fibrillated Yarn |
Yarn produced from slitted tape, drawn and twisted. Main applications: ropes and twines.
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| Flex cracking resistance |
The ability of a plastic to withstand repeated stretching or flexing without developing cracks.
This is an important property for the packing of liquids e.g. bag in box wine packaging. Two aspects can be shown: Cracking resistance (used for film) and fatigue (used for injeciton moulding articles). Fatigue: Is the process of localised permanent structural change, occurring in a material subjected to fluctuating stresses, which may culminate in cracks or in complete fracture. This can be shown in an S-N-diagram, in which the stress S is plotted against the number of cycles N necessary to break similar specimens in a fatigue test. The stress can be varied; the number of cycles to break iis recorded. Note: Flexural strength is the strength measured in a flexure test, and has nothing to do with flex cracking resistance, which is measured by applying fluctuating stresses. In a flexure test, flexural stress increases at a constant rate and is applied in one direction only.
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| Flow or viscosity curve |
Curve showing the relation between viscosity and shear rate at a certain temperature.
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| Food approval |
The certification from a producer that its products meets the governmental regulations regarding the specific use in food packaging film.
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| Formability |
The ease with which a plastic object can be given its final form. This can happen in the rubbery state (vacuum forming) or in the solid state (cold stretching).
The formability is important for confectioning e.g. for cheese packaging on a thermo form-fill-seal line.
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| Friction |
When handling and storing plastic packages it is important that friction between packages and pallets, shelves etc. or between packages itself is suitable. Coefficient of starting and sliding friction (static and dynamic friction) of film is measured by using a moving sled, force transducer and a static horizontal testing table. Friction can be measured either film against film or film versus metal or other material. It is determined by the material structure and the addivation, especially the addition of slip agents and antiblocking agents.
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