Papers by Keyword: NTC Effect

Abstract: The paper deals with the temperature sensitivity of a new type strain sensor named carbon fiber smart layer (CFSL) made of epoxy-matrix composites with short carbon fiber mats. The experiment result indicated that the epoxy matrix CFSL is sensitive to temperature variation. It exhibits NTC effect in -5°C~25°C and exhibits PTC effect in 25°C~50°C. The NTC effect is relatively gentle and the PTC effect is relatively dramatic. The mechanism of both NTC effect and PTC effect is discussed based on the temperature sensitivities of carbon fiber itself and the fiber to fiber interface. Further experiment demonstrated its temperature sensing properties in the temperature scale in which the NTC effect or PTC effect exhibits individually.

Abstract: Carbon fiber (~5mm long)-reinforced mortar is found to be an effective thermal sensor. In this paper, relations between temperature change and resistivity of carbon fiber- reinforced mortar (CFRM for short) with different carbon fiber contents (0.4%~1.2% by mass of cement) are studied. The results show that during the initial period, the resistivity decreases when the temperature increases (Negative Temperature Coefficient effect). After the temperature reaches a certain value, the resistivity increases when the temperature increases (Positive Temperature Coefficient effect). Besides, with the change of carbon fiber content, the transit temperature of NTC/ PTC effect also changes. Based on the experimental results, the CFRM shows a potential use as a thermal sensor. The mechanisms of temperature- sensitive properties and NTC/ PTC transition are also discussed.