Nanostructure evolution of oriented high-pressure injection-molded poly(ethylene) during heating

• Published in: Polymer (Guilford) Vol. 43; no. 13; pp. 3779 - 3784
• Main Authors: STRIBECK, Norbert, BAYER, Rüdiger, VON KROSIGK, Gebhardt, GEHRKE, Rainer
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.06.2002
• Subjects: Analysis and structure; Applied sciences; Exact sciences and technology; Polymer industry, paints, wood; Properties and testing; Technology of polymers; Melt crystallization; Polyethylene; Melting; Oriented polymer; Supramolecular structure; Injection molding; Structure modification; Nanostructure; Pressure molding; Experimental study; Molded piece; High pressure
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(02)00171-4

High pressure injection moulded polyethylene (PE) rods are studied by ultra small-angle X-ray scattering from a synchrotron during the heating of the polymer. Injection of a cool melt into a cold mould yields highly oriented PE rods with a core-shell structure. Samples from both the core and the shell material are studied. The two-dimensional scattering patterns are evaluated utilizing the multi-dimensional chord distribution function (CDF) analysis. From the obvious evolution of the nanostructure during successive crystalline melting, the sequence of processes occurring during crystallization is elucidated. First, nuclei form one-dimensional lattices with short-range order along the fibre axis. From this row structure, lamellae grow with wide lateral extension. An indication of an intermediate block structure is observed. Finally two steps of insertion crystallization result in two long period halvings. Increase of the mould pressure increases the lateral extension of the inserted lamellae in the shell material. (Original abstract - amended)