The dissolution-precipitation method has been identified as a potentially viable solution to plastic waste recycling in the Philippines. In this study, the effect of solvent temperature and composition on the dissolution kinetics of low-density polyethylene (LDPE) in D-limonene/xylene were determined. Dissolution temperature was varied within 100°-120°C with solvent composition of 0-100 wt% D-limonene for both 2-layer and 3-layer laminates of LDPE and polyethylene terephthalate (PET). The data were fitted to the Korsmeyer-Peppas model and the kinetic parameters were determined. Based on the experimental data, it was observed that there is no definitive relation between the dissolution rate and temperature for all solvent composition except at pure xylene, where the behavior at 110°C and 120°C appeared to be identical. It was also observed that introducing even a small amount of D-limonene to the solvent solution significantly increases the rate of dissolution, with a 1:3 limonene-to-xylene ratio having a K value that is 0.075 higher than that of pure xylene. Dissolution in D-limonene was observed to best fit the Fickian model, while that in xylene generally followed the non-Fickian model. Lastly, the 2-layer laminates showed to follow anomalous transport, wherein solvent diffusion and disentanglement of chains have comparable rates.

• plastic laminates ,
• dissolution-kinetics ,
• chemical recycling ,

[1] Global Alliance for Incinerator Alternatives. PLASTICS EXPOSED: How Waste Assessments and Brand Audits are Helping Philippine Cities Fight Plastic Pollution. Quezon City, PH: Global Alliance for Incinerator Alternatives. 2019

[2] Senate Economic Planning Office. Philippine Solid Wastes: At a Glance. Senate of the Philippines. 2017

[3] Geyer, R., Jambeck, J. R., & Law, K. L.. Production, use, and fate of all plastics ever made. Science advances, 3(7), e1700782. 2017

[4] Hopewell, J., Dvorak, R., & Kosior, E. Plastics recycling: challenges and opportunities. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1526), 2115-2126. doi:10.1098/rstb.2008.0311. 2009

[5] Siddique, R., Khatib, J., & Kaur, I. Use of recycled plastic in concrete: A review. Waste management, 28(10), 1835-1852. 2008

[6] The Philippine Clean Air Act of 1999. (PHI.).

[7] Kannan, P., Lakshmanan, G., Shoaibi, A. A., & Srinivasakannan, C. Polymer Recovery through Selective Dissolution of Co-mingled Post-Consumer Waste Plastics. Progress in Rubber Plastics and Recycling Technology, 33(2), 75–84. doi:10.1177/147776061703300202. 2017

[8] K. V. Escasa, R. I. I. Alindayu, R. G. Mae, M. J. Mopon, and T. Tumolva, “Performance of D-Limonene/Ethanol in the Selective Recovery of PE from LDPE/VMPET/PET Laminates ESCASA Karl Vincent H.,” Key Eng. Mater., vol. 833, pp. 134–138. 2020

[9] Bruschi, M.L. Mathematical models of drug release.. Strategies to Modify the Drug Release from Pharmaceutical Systems, 63–86. doi:10.1016/b978-0-08-100092-2.00005-9. 2015