Tensile and fracture behavior of polymer foams

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2006-08, Vol.429 (1), p.225-235
• Main Authors: Kabir, Md. E., Saha, M.C., Jeelani, S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cellular; Dynamic fracture; Exact sciences and technology; Foam density; Forms of application and semi-finished materials; Fracture toughness; Mechanical properties; Physical properties; Polymer foam; Polymer industry, paints, wood; Properties and testing; Technology of polymers; Tensile strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.05.133

Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise- and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness ( K d) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials.