Non‐destructive characterisation of polymers during injection moulding with ultrasonic attenuation measurement

Abstract

A non‐destructive ultrasonic attenuation measurement is adopted to characterise the state of polymers in the cavity during injection moulding. According to the relationship between ultrasonic attenuation behaviours and polymer viscosity, elasticity transition as well as crystallisation, the evolution of ultrasonic attenuations for an amorphous polymer (general purpose polystyrene) and a crystalline polymer (polypropylene) were discussed. Experimental results show that the ultrasonic attenuation measurement can not only provide information of the amorphous polymer on filling start, filling stop, elasticity transition and detachment from the mould, but can also extract information of crystallisation for the crystalline polymer throughout the injection moulding process. The ultrasonic attenuation measurement is a potential candidate technology to characterise the state of polymers in the cavity and thereby optimise the injection moulding process for perfect products.

Keywords:

• Injection moulding
• Non‐destructive characterisation
• Ultrasonic attenuation
• Polymers state

The authors would like to acknowledge the financial support from the National Natural Science Foundation Council of China (grant nos. 50875095 and 50905162) and the National 863 Program of China (grant no. 2009AA03Z104).