Thermal Effects on Ultrasonic Joining of Thin Plastic Films Using Torsional Vibrations

Abstract

Heat generation caused by high-amplitude ultrasonic vibrations at the interface has long been believed to be the most dominant factor for the mechanism of ultrasonic plastic joining. However, the authors have not found any conspicuous thermal effects in experiments of ultrasonic joining of thin very low density polyethylene (VLDPE) films using torsional vibrations. In the process of joining, the temperature at the interface of two VLDPE films of 0.1 mm thickness has increased up to 73 C only and no trace of melting of the material has been observed at this interface under a polarizing microscope. Investigation using a differential scanning calorimeter (DSC) has revealed that the ''melting point'' of VLDPE is about 110 C, and an ultrasonically joined specimen, unlike a heat-sealed specimen, shows no significant difference in thermal characteristics compared with an intact VLDPE film. The VLDPE films cannot be been joined, even after being pressed together for a period of 30 min or longer at a temperature approximately 80 C.

Experimental Investigation on Thermal Effects in Ultrasonic Joining of Thin Poly(ethylene terephthalate) Films Using Torsional Vibrations

“…In this field of engineering, it has long been believed that heat generation caused by highamplitude ultrasonic vibration ''melts'' plastic parts and joins them at their interface. However, the authors determined in a previous study 2) that thermal effects are not a dominant factor in the ultrasonic joining of very low density polyethylene (VLDPE) 3,4) films of 0.1 mm thickness using torsional vibration. In fact, no trace of ''melting'' at the interface between the joined VLDPE films was observed.…”

“…For many years, Adachi and coworkers have been attempting to elucidate the mechanism of ultrasonic plastic joining, 1,2) which has been used since the mid 1960s and is still one of the most sophisticated fabrication techniques in production engineering. In this field of engineering, it has long been believed that heat generation caused by highamplitude ultrasonic vibration ''melts'' plastic parts and joins them at their interface.…”

In Situ Fluorescent Illumination of Microplastics in Water Utilizing a Combination of Dye/Surfactant and Quenching Techniques

“…Staining conditions: dye/surfactant = 1 g/L; dye/MP = 2.5 wt%; MP/aqueous solution = 1 g/L; staining time = 60 min; staining temperature = 80 °C. References [ 2 , 5 , 18 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 36 , 48 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ] are cited in the Supplementary Materials.…”

Ultrasonic Heating of Poly(ethylene terephthalate), Polypropylene, High-Density Polyethylene, and Low-Density Polyethylene Films

“…hen polymer films are joined using an ultrasonic joining machine, the interface temperature between the films increases. [1][2][3][4][5][6][7][8] The heat production by the direct friction using the joining machine was previously interpreted as a major origin of the interface temperature increase. Watanabe et al studied the heat production mechanism theoretically and concluded that the heat production by the friction at the interfaces was more dominant than that by the viscosity.…”