Direct electron microscopic observation of transcrystalline layers in microfibrillar reinforced polymer-polymer composites

• Published in: Journal of materials science 2002-10, Vol.37 (20), p.4299-4305
• Main Authors: FRIEDRICH, K, UEDA, E, KAMO, H, EVSTATIEV, M, KRASTEVA, B, FAKIROV, S
• Format: Article
• Language: English
• Subjects: Analysis and structure; Applied sciences; Exact sciences and technology; Fracture surfaces; Injection molding; Low density polyethylenes; Materials science; Polyethylene terephthalate; Polymer industry, paints, wood; Polymer matrix composites; Polymers; Properties and testing; Technology of polymers; Transcrystalline layers; Transmission electron microscopy
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1020692200486

Microfibrillar reinforced composites (MFC) comprising an isotropic matrix from a lower melting polymer, i.e., low density polyethylene (LDPE), reinforced by microfibrils of a higher melting polymer, recycled from bottles, i.e., poly(ethylene terephthalate) (PET), were processed under industrially relevant conditions via injection molding in a weight ratio of PET/LDPE = 50/50. Dog bone samples with MFC structure were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy. SEM observations on cryogenic fracture surfaces show an isotropic LDPE matrix reinforced by more or less randomly distributed PET microfibrils. By means of TEM on stained ultrathin slices one observes the formation of transcrystalline layers of LDPE matrix on the surface of the PET microfibrils. In these layers the crystalline lamellae are aligned parallel to each other and are placed perpendicularly to the fibril surfaces. This is in contrast to the bulk matrix where the lamellae are quasi-randomly arranged.