Saturday 25-06-2022

NIKK Knowledge Base: B

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Barrier properties

A polymer with the ability of reducing or totally preventing the transport of gases or other molecule through itself is called a barrier.

By means of bending of a sample or compound it is deformed in a round shape with a specific radius. The deformation is a result of a force or tension that acts in the middle of the compound. The bending load could be calculated by means of the Euler Bernoulli equation:
This formula describes the characteristic of the tension as a function of the cross section. In the formula means:
M = torsional moment
I = torsional moment of inertia

Bending test
In a bending test a sample is fixed at both ends and it would be loaded in the middle by means of a pressure stamp or a double pressure stamp (tree-point or four-point bending). The bending test was performed normally in a destructive way where the E-modulus, the fracture strength and the yield stress could be measured.

The bending E-modulus is measured in a bending test. By means of the stress-strain-diagram the E-modulus could be calculated.
The bending E-modulus is mostly higher than the E-modulus measured in tension.

Bisphenol A
Bisphenol A is an organic compound produced from Phenol. Bisphenol A is used for the fabrication of polycarbonate, polyester resins and vinylester resins.
By brominating of Bisphenol A chemical compounds are formed suitable for use as flame retardant additives.

A block-copolymer is a polymer that consists of many different monomers. It is constructed out sequences or blocks A, B, C... that have defined positions in the polymer chain. A PP-Block-Copolymer for example has the configuration AAAAABAAAAABAAAAAB.....
By means of co-monomers the properties of homo polymers could be increased in many sectors.
Industrial used block-copolymers are: PP-B, E-CTFE, PVDF-C.

Blow moulding
Blow moulding is a process to produce thermoplastic hollow parts (e.g. bottles, tanks, hoses).
The blow moulding process could be divided into three different types:
- Extrusion blow moulding: typical is the continuous production process for producing e.g. hoses and thin sheets
- Injection blow moulding: during this process molten thermoplastic material is injected into a mould to produce e.g. tanks and bottles.
Stretch forming blow moulding: typical for this process is the fact that a produced part was stretched by means of an inner pressure or a mechanical load.

Break down voltage
The break down voltage of a plastic is the minimum voltage to produce an electrical conductive path through the plastic.

Butylene rubber
Butylene rubber is a synthetic rubber produced from isobutylene and isoprene-rubber. The symbol IIR stands for Isobutylene-Isoprene-Rubber. Butyl rubber has low permeation coefficient for gases and was therefore used as a barrier layer in tires.
Due to the outmost chemical resistance against acids butyl rubber is also used for corrosion protection of steel parts.

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