Wednesday 15-06-2022

NIKK Knowledge Base: C

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Calcium carbonate
Calcium carbonate (CaCO3) is often used as an additive in PVC-U to increase the impact resistance. It increases also the processing properties of thermoplastics.

Foils or thin sheets are mainly produced by means of calendering where melted thermoplastic material was pressed through the gap of two or more rolls.


Carbon is a chemical element and ingredient of every organic molecule.

Carbon black
Carbon black is an additive consisting of very small carbon particles with a carbon content of more than 96%. Carbon black is produced as agglomerated nanoparticles and used in rubber materials as a reinforcing additive or in other plastics for colouring or in higher amount for increasing the electrical conductivity. Carbon black increases also the UV resistance of plastics.

Carbon dioxide
Carbon dioxide (CO2) is a colourless and odourless gas. Carbon dioxide is also used to foam polymers.

Carbon fibres are produced out PAN or pitch by means of a carbonation process. Carbon fibres are used in plastics for reinforcing – as a result of carbon reinforcing very strong and lightweight components could be produced. Carbon fibre reinforced plastics (CRP) are used in the aircraft and aerospace industry as well in the race industry and for racing cycles.

Chemical resistance of plastics --> see also Corrosion of plastics 
The chemical resistance of plastics could not be predicted theoretically out of the chemical structure. Every polymer is characterized by a special chemical structure and reacts in a special way in contact with chemicals. Polyolefines (PE and PP) were affected by means of oxidizing agents. Chlorinated or fluorinated polymers have a higher chemical resistance also against oxidizing agents. Plastics could also absorb small molecules and as a result of this it swells and the properties would be changed.
Plastics that are dramatically affected by chemicals are not suitable for this application.
NIKK could help you in choosing the right material and could give you estimation on the lifecycle of the chosen polymer.

Chlorine gas
Chlorine gas also well-known as di-chlorine (Cl2) is a yellow-green toxic gas with characteristic odour. Polymers are modified with chlorine to get special properties of the polymers. By means of the high bond strength of chlorine to carbon in the polymer chlorinated polymers have a very high chemical resistance. E.g. PVC, PVDF, E-CTFE.

Chloroprene is a synthetic monomer to produce poly chloroprene or better known as Neoprene.
Neoprene is often used for corrosion protection of steel parts, safety gloves, as raw material for adhesives, for diving-suits, etc.

Chromic acid test
To test the residual stresses in PP the chromic acid test would be applied.
CIE colour system
The CIE colour system is based on the addition of three fundamental colours red 700 nm, green 541.6 nm and blue 435.8 nm. By the addition of the two colours every other colour could be mixed.

Coextrusion is called a continuous extrusion process where two or more different raw materials could be processed together to produce components with two or more different layers. By means of coextrusion compounds could be produced having for example low permeation properties for fuel, oxygen or other gases.

Plastics without any halogens are normally combustible according to DIN 4102 (normal flammable).
PVC, PVDF and other chlorinated or fluorinated plastics are flame resistant or self-extinguishing in case of removing the ignition source.

Combustibility of plastics
Plastics are normally combustible. But every plastic could become flame resistant by means of special additives or due to the chemical structure itself. Chlorinated or bromated additives, as well as antimony trioxide or antimony pentoxide, aluminium hydroxide or phosphates are such additives.

Corrosion protection of metals
Metals are not resistant against acids and oxidizing substances. Corrosion protection is therefore indispensible. The corrosion protection could consist of rubber lining, coatings or thermoplastic liners.
NIKK has a lot of practical experience in the field of corrosion protection of steel. NIKK could assist you in choosing the right material and in the application of the lining or coating.

Corrosion resistance of polymers
The meaning of corrosion of polymers is the change of properties due to the influence of temperature and chemicals. The chemical resistance of polymers could be not predicted theoretically but have to be measured be means of laboratory tests or tested in practical experiences.
Based on more than 20 years experience in the field of chemical industry and other applications with corrosive environments for plastics could NIKK give advice for choosing the appropriate polymer for the special application. Or NIKK could test the polymer to determine the suitability for the chosen application.

Polymer materials react in case of mechanical load in a visco-elastic manner. That means that plastics will avoid a mechanical load due to plastic flow that is called creep.

Creep modulus
The long term E-Modulus was also called creep modulus. Plastics have a plastic flow also at room temperature under mechanical stress. For stress calculations this creep modulus has to take into account.

Polyester or vinylester cure with help of curing agents (peroxides). During curing heat is produced due to the chemical reaction.

Cyclo-hexanone-peroxide is a curing agent for polyester resins.

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