Abstract:
A multiply polymer pipe has a polyamide-based outer ply, an inner ply made of polyvinylidene fluoride or its copolymers, as well as an adhesive intermediate ply that adhesively interconnects the inner and outer plies.
Abstract:
The invention concerns hydrolytically polymerized polycaprolactam produced using a novel method of chain control, the polymerization of the caprolactam (I) being carried out with 0.1-0.7 % by wt. of an aromatic dicarboxylic acid (II), 0-0.7 % by wt. of an aliphatic or cycloaliphatic diamine (III) which includes a primary or tertiary amino group, and/or 0.01-0.7 % by wt. of 4-amino-2,2,6,6-tetraalkylpiperidine (IV), the amounts of components I to IV adding up to 100 % by wt. and the sum of components III and IV amounting to 0.05-0.7 % by wt.
Abstract:
The invention concerns a process for direct chemical modification of (co)polyesters in which at least one monomer compound of general formula (I) or (II) where G = a chemical group containing at least one polyester-foreign heteroatom selected from the group P, N and S; and R = reactive bond of the type lactone in a 4-, 7-, or 8-ring or cyclic anhydride or epoxide, is mixed in an application-determined quantity of up to 10 mol % with respect to the repeating polyester units, with (co)polyester or (co)polyester melt, optionally together with additional compounds, and mixed at 260 DEG C in a closed system which is blocked off against gas exchange and at a pressure greater than the steam pressure of the compounds used, with the (co)polyester melt which is produced by melting or is already existing. The group is built into the (co)polyester or bound to it through a reaction, and after a total reaction and residence time of less than 30 minutes, the chemically modified (co)polyester melt is processed further or withdrawn from the furnace, granulated and then further processed.
Abstract:
The invention concerns a recondensed paper-machine felt consisting of a polyamid base fabric with a needled-in polyamide face layer, the felt having a relative viscosity in sulphuric-acid solution of at least 5 when determined in accordance with DIN 53 727. The invention also concerns a method of increasing the molecular weight of paper-machine felt, the felt being impregnated with a solution of recondensation catalysts, dried and subsequently thermally condensed in the solid phase in the absence of oxygen at a temperature below the melting point of the polyamide.