D

DD varnish is a topcoat applied to boats. It can also be applied as an anti-slip paint, by adding 5-10% anti-slip powder to the paint before use. A boat is finished above the waterline with three coats of DD varnish. Today these are sold under the trade name URKI VOC or PUR 2K lacquer. for info, see; https://www.v-sure.eu/nl/producten/polyurethaan/polyurethaan-vernis/

The dielectric constant is the quantity that determines the electrical capacity of a capacitor and is expressed as the value for vacuum as a unit. No major differences occur between the dielectric constants of the various polymers. These constants are generally between 2 and 5; higher values are also reached in the presence of fillers (7 to 9).

The dielectric loss triangle is a measure of the leakage current through the material that occurs at AC voltage. In this, there are significant differences between various polymers.

Dimensional stability means that a material will no longer expand or contract in certain directions. Putting the cell wall in a permanently swollen state creates a dimensionally stable material that will attract little or no more water.

DMA (dimethylaniline) is the most commonly used amine accelerator. An amine accelerator speeds up the curing process of polyester and vinylester with BPO. The possible disadvantages of amine accelerators are that they give limited potlife, give a yellow to brown colour after curing and are sensitive to UV light at cured stage.

DMPT (dimethylparatoluidine)is an amine accelerator that gives very short gel times. An amine accelerator accelerates the curing process of polyester and vinyl ester with BPO. The possible disadvantages of amine accelerators are that they give limited potlife, give a yellow to brown colour after curing and are sensitive to UV light at cured stage. In some cases, dimethyl paratoluidine serves as a promoter. A promoter gives a shorter gel time and faster curing, which is desirable in production with short cycle times such as: injection, pressing and polyester concrete. A promoter should also be used when working with thin layer thicknesses.

Dosing pumps are a convenient and user-friendly dispensing system for measuring the mekp of hardener. They prevent hardener spillage and ensure that no hardener comes into contact with the skin during measuring.

Dry polishing means smoothing a surface by sanding it.

Thermoplastics are plastics, which once cured cannot be deformed by heating. Thus, unlike thermoplastics, duroplastics cannot be softened by heating.

Dyneema is a fibre used as an alternative to aramid fibres and liquid crystal polymers. The main material for the strong dyneema fibre is polyethylene. The main properties of dyneema fibre are its enormous strength relative to its density and its ability to absorb a lot of energy at low deformation. Another important property of Dyneema is its ability to absorb vibrations. Dyneema fibres are often used for cables and fabrics because of their strength. Dyneema is also used in sports equipment (skis, tennis rackets, etc.) because of its vibration damping capacity.