Abstract: A composition including from: a) 35% to 100% by weight of at least one semicrystalline aliphatic polyamide and/or one polyamide of formula MXDZ wherein MXD is meta-xylylenediamine and Z is a C6 to C12 aliphatic dicarboxylic acid, the semicrystalline aliphatic polyamide and/or the polyamide of formula MXDZ having a total acidity between from 70 to 180 ?eq/g and a total basicity of less than 100 ?eq/g; b) 0 to 25% by weight of polyolefins; c) 0 to 60% by weight, of glass fibers; d) 0 to 2% by weight of at least one additive; e) 0 to 30% by weight of at least one flame retardant; the sum a)+b)+c)+d)+e) being equal to 100%, the semicrystalline aliphatic polyamide and/or the polyamide of formula MXDZ having a melt flow index (MFI) between from 4 to 50 g/10 min.

Abstract: The process comprises creating a screen of non-reactive or inert gas at least at one of the two ends of the heat treating zone or cooling zone of a furnace, the screen being substantially homogeneous and laminar throughout its height. The use of this process permits, on the one hand, a reduction in the flows of gas necessary for the heat treating and, on the other hand, the division of the heat treating furnace into precise zones. The invention is particularly applicable to heat treating furnaces.