Patent ID: 11879026
Assignee: SABIC GLOBAL TECHNOLOGIES B.V.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  F | IPC C  F

Claim 11:
12. The polypropylene composition according to claim 1, wherein the polypropylene composition has <Gp>/Y of at least 7.0, wherein <Gp> is strain hardening modulus and Y is yield stress and <Gp>/Y is determined by:
a) providing a specimen of the polypropylene composition by compression molding a sheet from the polypropylene composition according to ISO 1873-2 to a thickness of 0.3 mm±0.025 mm and punching a specimen having a geometry of a test specimen described in ISO/DIS 18488 from the sheet, wherein the sheet is annealed after the compression molding and before the punching at a temperature of 100° C. for 1 hour and cooled down to room temperature,
b) elongating the specimen at a constant traverse speed of 20 mm/min at 100° C.,
c) measuring a load sustained by the specimen during the elongating to obtain a stress-strain curve and measuring a yield stress Y,
d) calculating true stress-true strain curve from the stress strain curve obtained by step c) and calculating a tensile strain hardening modulus <Gp> from the true stress-strain curve, according to the method as described in ISO/DIS 18488 and
e) calculating a quotient of the tensile strain hardening modulus <Gp> divided by the yield stress Y.