Thermal conductivity coefficient of slices and fillers of nylon 6 base stock;
Dispersity and bonding degree of fillers in nylon 6 matrix;
Shape and content of fillers;
The interface bonding characteristics of fillers and nylon 6.
1. The use of slices and fillers of nylon 6 base stock with a relatively higher thermal conductivity coefficient.
The thermal conductivity of pure nylon 6 slice is generally from 0.244 to 0.337W/M.K, and its value is closely related to the relative viscosity of polymer, the distribution of molecular weight and the orientation of the polar molecule.
Fillers used for the modification of non-insulator thermal conductive nylon 6 include aluminum, copper, magnesium and other metal powder as well as graphite and carbon fiber, etc. The higher the thermal conductivity coefficient of the metal powder is, the better the thermal conductivity is. However, considering the quality, cost and processing performance of different materials comprehensively, aluminum powder is much more preferable.
Fillers used for the modification of insulator thermal conductive nylon 6 include alumina and magnesium oxide. Alumina is cheap, high-quality, and easy to process, which is accepted by more customers.
2. Improve the shape of the filler
For the filler used in the thermal conductive nylon 6 material, the thermal conductivity of the filler is better if it is more beneficial to the formation of the thermal conduction path. The relative order is the Whisker > Fibrous > Flake > Granular. The smaller the particle size of the filler, the better the dispersity in the nylon 6 matrix, the better the thermal conductivity.
3. The use of fillers with content near the critical value
If the content of thermally conductive plastics fillers in the nylon 6 is too small, the thermal conductivity effect is not obvious, and the mass fraction exceeds 40% in many cases. However, if the content is too high, its mechanics properties will decrease greatly. In most cases, there is a critical value for the content of the filler in the nylon 6 matrix, and under this value, the fillers will interact with each other, so as to form a mesh or chain-like heat conduction network chain in the nylon 6 matrix and thus increase the thermal conductivity.
4. Improve the interface bonding characteristics between filler and nylon 6 matrix
The higher the degree of combination between the filler and the nylon 6 matrix, the better the thermal conductivity. The surface treatment on the filler with an appropriate similar maleic anhydride graft compatilizer and coupling agent can improve the interface characteristics between the nylon 6 and the filler, and the thermal conductivity coefficient of the thermal conductive nylon 6 material can be increased by 10% to 20%.