Pedrazzoli D, Dorigato A, Pegoretti A
University of Trento, Department of Materials Engineering and Industrial Technologies and INSTM Research Unit, Via Mesiano 77, 38123 Trento, Italy.
J Nanosci Nanotechnol. 2012 May;12(5):4093-102. doi: 10.1166/jnn.2012.6219.
Various amounts of carbon black (CB) and carbon nanofibres (CNF) were dispersed in an epoxy resin to prepare nanocomposites whose mechanical behaviour, under ramp and creep conditions, was monitored by electrical measurements. The electrical resistivity of the epoxy resin was dramatically reduced by both nanofillers after the percolation threshold (1 wt% for CB and 0.5 wt% for CNF), reaching values in the range of 10(3)-10(4) omega . cm for filler loadings higher than 2 wt%. Due to the synergistic effects between the nanofillers, an epoxy system containing a total nanofiller amount of 2 wt%, with a relative CB/CNF ratio of 90/10 was selected for the specific applications. A direct correlation between the tensile strain and the increase of the electrical resistance was observed over the whole experimental range, and also the final failure of the samples was clearly detected. Creep tests confirmed the possibility to monitor the various deformational stages under constant loads, with a strong dependency from the temperature and the applied stress. The obtained results are encouraging for a possible application of nanomodified epoxy resin as a matrix for the preparation of structural composites with sensing (i.e., damage-monitoring) capabilities.
将不同量的炭黑（CB）和碳纳米纤维（CNF）分散在环氧树脂中，以制备纳米复合材料。通过电学测量监测其在斜坡加载和蠕变条件下的力学行为。在逾渗阈值（CB为1 wt%，CNF为0.5 wt%）之后，两种纳米填料均使环氧树脂的电阻率显著降低，对于高于2 wt%的填料负载量，电阻率达到10(3)-10(4)Ω·cm的范围。由于纳米填料之间的协同效应，对于特定应用，选择了一种总纳米填料量为2 wt%、相对CB/CNF比例为90/10的环氧体系。在整个实验范围内观察到拉伸应变与电阻增加之间存在直接相关性，并且还能清晰检测到样品的最终破坏。蠕变试验证实了在恒定载荷下监测不同变形阶段的可能性，这强烈依赖于温度和施加的应力。所得结果对于纳米改性环氧树脂作为制备具有传感（即损伤监测）能力的结构复合材料的基体的可能应用而言是令人鼓舞的。
