Biopolymers & Biocomposites Workshop - August 14, 2012

Ultrasonic Welding of PLA Films

David Grewell, Julius Vogel, and Kyle Haubrich
Iowa State University

In this work the weldability of PLA (Polylactic acid), a biodegradable polymer derived from corn starch, was examined. Samples of biaxial oriented PLA films of various thicknesses were ultrasonically welded at various processing parameters with an overlap of 2 mm and a weld width of 10 mm. The results showed that relatively high weld strengths could be achieved over a relatively wide range of parameters. This process can be used with relatively short cycle times (0.15 s - 0.25 s); however it was seen that weld strength consistency was an issue with some settings. For example, with a thickness of 254 µm the average strength was 160 N and had a standard deviation of 60 N. It was also seen that sample thickness affected the optimized welding parameters as well as ultimate strength. Samples with a thickness of 305 µm had a strength of 80 N at a weld time of 0.15 s, while the strength was 25-30 N with sample thicknesses of 200 and 254 µm respectively.