Infrared thermography to evaluate thermoplastic composites under bending load

Infrared thermography (IRT) is a non-contact, non-intrusive technique which detects thermal energy radiated from objects in the infrared band of the electromagnetic spectrum. Such energy is transformed into a temperature map, which can be exploited for many purposes in many different application fields. In particular, an infrared imaging device can be used to monitor the entire existence of a product, from its manufacturing process to completion as well as in-service life. In this work, IRT is used to investigate composite materials which are based on a polypropylene matrix, which may be neat, or modified by addition of a relatively low amount of a specific compatibilizing agent, and reinforced with glass or jute fibres. IRT is used with a twofold function: - for nondestructive evaluation of materials before and after cyclic bending; - to monitor thermal effects developing when the material is under load, either cyclic bending, or quasi-static bending. The obtained results show that: o The presence of a compatibilizing agent in the matrix amplifies the material thermal response to cyclic bending. o It is possible to follow the failure under quasi-static bending from the formation of the initial crack, to its enlargement and final material collapse. In particular, the comprehension of thermal effects may be useful to get information about the laden material behaviour in view of assessing the material performance.