Even if specialized magazines and articles mention many different additives and ingredients used in ski bases of competition skis, finally we will find out, if we look in much more detail, that there are only two main components which influence the most important features of each ski base type, especially now after fluor ban.
First is the UHMWPE itself which defines the features of the matrix. The matrix itself can get touch in contact with snow surface, that’s the reason why PE is used, because currently there is no other polymer with such a low coefficient of friction and so high hydrophobicity available. With respect to other components the matrix is responsible for the wear resistance and fixation of additives.
For wear resistance the most important figure is the length of molecular chains, the higher the length of molecular chains, the better the wear resistance. Reaching the value of 10.000.000 the polymer can be hardly processed.
Additive fixation in UHMWPE is problematic. The most additives do not form strong chemical bonds with the base matrix. Additives are bound in the matrix either by very weak chemical bonds or by mechanical retention. Especial close to the surface where the contact snow and ski base surface take place especially the mechanical retention decides.
The most important additive used in modern ski base types is soot or carbon black. The importance is given by the amount used in the competition ski base types which reaches up to 20 % of weight fraction in Nordic skis and up to 40 % of weight fraction in Alpine skis and by the way how carbon black is fixed in the PE matrix.
Some carbon black is incorporated directly in the PE matrix, but most of carbon black is filling the free space or cavities between the PE corns which are sintered together using heat and pressure. Especially the second type of soot fixation is responsible for high values of E-modulus which decides how ski base changes elastically under load.
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