Abstract
Strips of Ca-I [polylactic acid (PLA) monolayer plastic films from Cargill Dow Polymers LLC, Minnetonka, MN] cut in the machine and nonmachine directions were irradiated with an electron beam using a CIRCLE III Linear Accelerator (MeV Industries S.A., Jouy-en-Josas, Cedex, France). The effects of 33-kGy irradiation on the physical properties of the Ca-I strips were studied. In addition, the effects of ultraviolet (UV) light (365-nm) illumination on the degradation of three PLA plastic films, Ch-I (PLA monolayer plastic films from Chronopol, Golden, CO), GII (PLA trilayer plastic films from Cargill Dow Polymers LLC), MN), and Ca-I (PLA monolayer plastic films from Cargill Dow Polymers LLC) were analyzed by a modified ASTM D5208-91 method. Results showed that irradiation had decreased the weight-average molecular weight (M w), stress at break, percentage of elongation, and strain energy of Ca-I by 35.5, 26.7, 32.3, and 44.8%, respectively (P < 0.01). The shelf life of the irradiated Ca-I strips at 5°C and <20 ± 5% RH was about 6 months. The degradation rate of Ch-I, GII, and Ca-I with no UV light treatment at 55°C and 10% RH was 2512, 5618, and 3785 M w/week, respectively. Under the UV light illumination (365 nm), the degradation rate of Ch-I, GII, and Ca-I, was 2982, 8722, and 7467 M w/week, respectively. Hence, the degradation rate of GII and Ca-I was increased 55 and 97% by UV light (P < 0.008), respectively. This trend was not observed in Ch-I because its starting M w (78,000 g/mol) was close to the tensile strength lost range (50,000 to 75,000 g/mol) of PLA films. To our knowledge, this is the first study to demonstrate that UV light does further enhance the degradation of PLA films.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
REFERENCES
ASTM D638–95 (1996) in 1996 Annual Book of ASTM Standards, American Society for Testing and Materials, Villanova, PA, pp. 45–56.
ASTM D5208–91 (1996) in 1996 Annual Book of ASTM Standards, American Society for Testing and Materials, Villanova, PA, pp. 375–377.
C. Birkinshaw, M. Buggy, G. C. Henn, and E. Jones (1992) Polym. Degrad. Stab. 38, 249–253.
J. H. Collett, L. Y. Lim, and P. L. Gould (1989) Polym. Prepr. (Am. Chem. Soc. Div. Polym. Chem.) 30, 468–469.
R. Datta, S. P. Tsai, P. Bonsignore, S. H. Moon, and J. R. Frank (1995) FEMS Microbiol. Rev. 16, 221–231.
K.-L. G. Ho and A. L. Pometto III (1999) J. Environ. Polym. Degrad. 7, in press.
K.-L. G. Ho, A. L. Pometto III, and P. N. Hinz (1999) J. Environ. Polym. Degrad. 7, in press.
E. Ikada, Y. Takeuchi, and M. Ashida (1992) Kobunshi Ronbun 49, 527–533.
J. M. Jay (1996) in Modern Food Microbiology, 5th ed., Chapman & Hall, International Thomson, Boston, London, Paris, Singapore, Tokyo, Toronto, pp. 304–323.
K. E. Johnson, A. L. Pometto III, and Z. L. Nikolov (1993) Appl. Environ. Microbiol. 59, 1155–1161.
D. L. Kaplan, J. M. Mayer, D. Ball, J. McCassie, A. L. Allen, and P. Stenhouse (1993) in C. Ching, D. L. Kaplan, and E. Thomas (Eds.), Biodegradable Polymers and Packaging, Technomic, pp. 1–42.
G. B. Kharas, F. Sanchez-Riera, and D. K. Severson (1994) in D. P. Mobley (Ed.), Plastics from Microbes: Microbial Synthesis of Polymers and Polymer Precursors, Hanser Gardner, OH, pp. 91–137.
M. Kim and A. L. Pometto III (1994) J. Food Protect. 57, 1007–1012.
R. Limpert and J. Balderson (1989) in Waters 150-C ALC/GPC Service Manual, Millipore Corp., Waters Chromatography Division, Milford, MA, pp. 31–32.
SAS Institute, Inc. (1997) SAS Computer Program, Version 6.12, SAS Institute, Cary, NC.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ho, KL.G., Pometto III, A.L. Effects of Electron-Beam Irradiation and Ultraviolet Light (365 nm) on Polylactic Acid Plastic Films. Journal of Polymers and the Environment 7, 93–100 (1999). https://doi.org/10.1023/A:1021860301487
Issue Date:
DOI: https://doi.org/10.1023/A:1021860301487