Fracture mechanisms in biopolymer films using coupling of mechanical analysis and high speed visualization technique

• Published in: European polymer journal Vol. 46; no. 12; pp. 2300 - 2309
• Main Authors: Paes, Sabrina S., Yakimets, Iryna, Wellner, Nikolaus, Hill, Sandra E., Wilson, Reginald H., Mitchell, John R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-12-2010; Elsevier
• Subjects: Applied sciences; Biopolymers; Cassava; Cassava starch; Cellulose and derivatives; Crack propagation; Exact sciences and technology; Fracture mechanics; Fracturing; Gelatin; High speed; High speed imaging; Homogeneity; Hydroxypropyl cellulose; Image analysis; Mechanical analysis; Natural polymers; Physicochemistry of polymers; Proteins; Starch and polysaccharides; Visualization; Cassava starch; Hydroxypropyl cellulose; Image analysis; Gelatin; High speed imaging; Crack propagation; Fourier transformation; Fracture mechanics; Film; In situ; Mechanism; Stress cracking; Investigation method; High speed; Cellulose(hydroxypropyl); Cellulose ether; Starch; Coupled method; Experimental study; Imagery; Protein; Infrared spectrometry; Tensile stress; Oside polymer; Fracture mode
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2010.10.003

The aim of this study was to provide a detailed description of the fracture mechanisms in three different biopolymer thin materials: gelatin, hydroxypropyl cellulose (HPC) and cassava starch films. That was achieved by using a combination of fracture mechanics methodology and
in situ visualization with high speed imaging technique. By analyzing the unstable and stable crack propagation that occurs in these materials, the brittle to ductile transition induced by water plasticization was assessed and discussed. Each biopolymer material exhibited a distinctive brittle and ductile fracture mode, which were described in this work. In order to evaluate the occurrence of permanent deformation in the proximity of the crack propagation front, FTIR maps with polarized light microscopy were employed, which enabled the visualization of structural homogeneity and cohesivity. The differences in fracture behaviour were interpreted taking into account the structural organization within these materials during stretching. The coupling of mechanical data and advanced visualization techniques was a particularly effective method to describe and interpret the complex fracture mechanisms in biopolymer materials which is strongly affected by their interaction with water molecules.