Issue 30

T. Voiconi et alii, Frattura ed Integrità Strutturale, 30(2014) 101-108; DOI: 10.3221/IGF-ESIS.30.14 102 M ATERIALS olyurethane (PUR) materials of four different densities (100, 145, 300 and 708 kg/m 3 ) manufactured by Necumer GmbH, Germany under commercial designation Necuron (100, 160, 301 and 651) were investigated. At low densities 100 and 145 kg/m 3 the materials have a closed cellular structure, while the PUR materials of higher densities show a porous solid structure. The microstructures of the investigated materials (at 1000x magnification) were obtained using QUANTA TM FEG 250 SEM and are presented in Fig. 1. The results of statistic analysis of microstructures are shown in Table 1 together with the experimentally determined values of the densities according with ASTM D 1622- 08 [13]. Necuron 100 160 301 651 Cell diameter, [  m] 104.5±9.4* 83.8±9.6* 68.5±33.9* 49.1±30.2* Cell wall thickness, [  m] 2.9-5.8 5.1-13.1 3.8-21.8 4.7-37.6 Density (determined), [kg/m 3 ] 100.35±0.25* 145.53±0.22* 300.28±1.38* 708.8±3.45 Table 1 : Characteristics of the microstructure and determined densities. (* standard deviation values) a) Necuron 100 b) Necuron 160 c) Necuron 301 d) Necuron 651 Figure 1 : Microstructures of the investigated materials. P