Twice recycled polymer powder composition for additive manufacturing including PEKK, siloxane and carbon fiber

A method of preparing a powder composition suitable for use in laser sintering for printing a three-dimensional object, the method including the steps of:

• providing a first fraction comprising a polyetherketoneketone (PEKK) powder having a plurality of PEKK particles;
• providing a third faction comprising carbon fiber;
• mixing the first fraction and the third fraction to form a mixture;
• preparing recycled PEKK from the mixture by the following steps:
• heating the mixture in a first SLS build having a bed temperature between an upper melting point of the PEKK before the first SLS build (TM1) and 20° C. less than TM1;
• heating the mixture in a second SLS build having a bed temperature between an upper melting point of the PEKK after the first SLS build and before the second SLS build (TM2) and 20° C. less than TM2;
• providing a second fraction comprising a siloxane powder having a plurality of siloxane particles, the plurality of siloxane particles having a mean diameter between 30 μm to 90 μm;
• mixing the recycled PEKK powder with the siloxane powder to obtain a powder composition suitable for use in selective laser sintering;
• wherein the third fraction is between 5% and 25% of the composition by weight;
• wherein the second fraction is between 0.5% and 1.5% of the composition by weight.