Expert knowledge from A-Z


Plastic bags and packaging that can be easily opened or that enable the opening of the packaging without tearing or cutting, an extension of the idea of providing convenience for users.

In terms of sunlight, only radiation in the form of visible light, UV-A and UV-B reaches the Earth's surface. Approximately 6% of the solar radiation that reaches the earth is UV rays. Normal window glass is impermeable to a large percentage of ultraviolet rays. This is particularly true of UV rays with short wavelengths (UV-B and UV-C); window glass does, however, allow UV-A through. Even glasses and optical components obstruct high-intensity short-wave ultraviolet rays. Intense UV radiation is capable of splitting organic bonds and does damage organic bonds in instances of extreme exposure (turbidity, embrittlement, decay). This is also called a "photo-oxidising reaction" The time before this takes effect can, according to scientific studies by D.J. Carlsson and D. M. Wiles, (Division of Chemistry, National Research Council of Canada "The Photo-oxidative Degradation of Polypropylene"), range from a few months to several years, depending on the geographic region, sun intensity, and the length of exposure each day for the product on display.

Materials that can be stretched to at least double their original length at room temperature and return to approximately their original length immediately after the end of the stress.

If materials without an electric charge but with different dielectric constants come into contact (such as from rubbing), electrons drift from one material to the other. The charge transfer that this causes remains in place if the two materials are quickly separated and can lead to high levels of electrostatic potential. Various options exist for eliminating this: earthing, using conductive metal fibres, ionising the ambient air or using antistatic agents. A helpful hint for the build-up of static charges on the top layers of adhesive tape when pulling it off: Use double-sided adhesive tape on a wooden slatted frame.

The increase in length, e.g. of a film under stress, expressed as a percentage of the original length. The elongation at break indicates how far the plastic can be extended before it ruptures under controlled conditions. The higher the value, the greater the increase in material length.

Mechanical film property, corresponds to the elongation experienced by a test strip upon breaking; differs lengthwise and crosswise. Stretch films have high values.

Machine for processing thermoplastic plastics in more or less continuous lengths such as rods, bars, films, straight or bent pipes, hoses or profiles. Plastic granulate is continuously melted and fed to the extruder outlet. The melt is then conveyed via a tool that gives the films their shape. An extruder consists primarily of one or more tools known as screws that rotate in a barrel. Screws such as barrier screws or 3-zone screws are used for film extrusion.

Manufacturing films in which melted plastic granulate is blown (blown film extrusion) or poured (cast film extrusion) into a flat film.

Combination of two film webs directly during extrusion; the melt of a thermoplastic plastic is applied to a film and results in a composite film without adhesive.

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