Abstract: The invention relates to a process for the preparation of semi-crystalline semi-aromatic polyamide by direct solid-state polymerization of a diamine-dicarboxylic acid salt, comprising steps of (a) providing at least two salts of terephthalic acid and diamine, wherein each of these diamine/terephthalic acid salts is in solid state and has a melting temperature of at least Tx, wherein Tx is at least 260° C.; (b) preparing a mixture of the diamine/terephthalic acid salts, while retaining the salts in solid state; and (c) heating the mixture obtained from step (b) in the solid state to a temperature (T-c) in the range from 200° C. to 260° C., under a pressure below the saturation vapor pressure of water at said temperature, thereby condensing and polymerizing the salts and forming a semi-crystalline semi-aromatic polyamide in solid form.

Abstract: The invention relates to a process for the preparation of semi-crystalline semi-aromatic polyamide by direct solid-state polymerization of a diamine-dicarboxylic acid salt, comprising steps of (a) providing at least two salts of terephthalic acid and diamine, wherein each of these diamine/terephthalic acid salts is in solid state and has a melting temperature of at least Tx, wherein Tx is at least 260° C.; (b) preparing a mixture of the diamine/terephthalic acid salts, while retaining the salts in solid state; and (c) heating the mixture obtained from step (b) in the solid state to a temperature (T-c) in the range from 200° C. to 260° C., under a pressure below the saturation vapour pressure of water at said temperature, thereby condensing and polymerizing the salts and forming a semi-crystalline semi-aromatic polyamide in solid form.

Abstract: The invention relates to flame retardant compositions that contain mixtures of melamine polyphosphates with layered silicates added to the polymer substrates, particularly polyamides.

Abstract: The invention relates to flame retardant compositions that contain mixtures of melamine polyphosphates with layered silicates added to the polymer substrates, particularly polyamides.

Abstract: The invention relates to the preparation of polyamides in the presence of a phosphonate, which is already added at the beginning of the polycondensation or polyaddition process. The resulting prepolymer exhibits a high molecular weight and is almost colorless. A further aspect of the invention is the use of a phosphonate for increasing the molecular weight and modification of polyamides during polycondensation.

Abstract: A mixing apparatus suitable for mixing and conveying solid, particulate, polymeric materials, comprising a barrel that can be heated and cooled, at least two co-rotatable, self-wiping extruder screws located within the bore of the barrel, the screws being connected through a laterally flexible coupling to a drive means which can reverse the direction of rotation of the screws upon the occurrence of a predetermined event. The apparatus also comprises a closeable feed port and a closeable discharge port, both of which can be made gas-tight, the shafts of the screws being provided with seals capable of withstanding elevated gas pressures inside the barrel.

Abstract: The invention provides a process for directly manufacturing a diamine/dicarboxylic acid salt with a low water content. The process includes reacting a diamine with a dicarboxylic acid to form a diamine/dicarboxylic acid salt. The reaction of the diamine and the dicarboxylic acid is carried out in the presence of about 0.5% to about 25% by weight water, based on the weight of the reaction mixture, while providing conditions in the reaction mixture such that the reaction mixture is in substantially solid particulate form.