Effect of biaxial‐simultaneous stretching conditions on OTR and CO2 permeation of CO2 laser perforated poly(lactic acid) film. Issue 8 (21st June 2018)

• Record Type: Journal Article
• Authors: Winotapun, Charinee; Kerddonfag, Noppadon; Daud, Witchuda; Chinsirikul, Wannee; Takarada, Wataru; Kikutani, Takeshi
• Is Part Of: Packaging technology and science. Volume 31:Issue 8(2018)
• Page Start: 545
• Page End: 556
• Publication Date: 2018-06-21
• Subjects: biaxially oriented films -- laser perforation -- modified atmosphere packaging -- poly(lactic acid); Packaging -- Periodicals; 688.8
• DOI: 10.1002/pts.2381
• Languages: English
• ISSNs: 0894-3214

Abstract

Abstract : The biaxially oriented poly(lactic acid) films prepared using simultaneous biaxial stretching were perforated by CO2 laser with the power of 60 W. The focal spot diameter was fixed at 103 μm. Pulse durations were varied from 1 to 30 μs, which corresponds to the fluence from 1.4 to 42.6 J/cm 2 . The perforated microhole size increased with increasing laser energy. The shape of microholes was circular for the films of equi‐biaxial stretching, whereas elliptical microholes were formed with its long and short axes corresponding to the directions of higher and lower stretch ratios, respectively. Comparing the laser perforation behavior of the as‐drawn films and annealed films, the opening of a microhole in the annealed films started at higher laser fluence, and at the same fluence the size of microhole was smaller. Gas transmission rates of the biaxially oriented poly(lactic acid) films with different thicknesses were examined. The oxygen transmission rates (OTR) of film improved with increased microhole diameter. The OTR of films containing 1 microhole/103 cm 2 (hole diameter of ~110 μm) was 184, 150, and 98 cm 3 /d in comparison with the OTR for the original films without microhole of only 16, 10, and 8 cm 3 /d, respectively. Packaging films with OTR higher than 100 cm 3 /d (equivalent to the 9700 cm 3 /m 2 /d) are required to create a modified atmosphere inside the package of fresh produce for shelf‐life extension. Measured OTR and CO2 TR values of the 3 different shapes of microhole were compared and discussed. Abstract : The biaxially oriented poly(lactic acid) films prepared using simultaneous biaxial stretching were perforated by CO2 laser. The formation of circular or elliptical microhole was found to depend on the difference of stretch ratio of film in machine and transverse directions. Measuring the OTR and CO2 TR values of the different hole shapes on film, hole area is the key important parameter affecting gas transmission through the microhole. Gas transmission rates of films with different thicknesses were also examined.