Direct Reactive Extrusion of PLA in the Presence of a Multifunctional Chain Extender

Öz

The environmental impact of non-renewable, fossil fuel-based polymers has led to growing interest in sustainable alternatives such as Poly(lactic acid) (PLA). PLA is biodegradable and suitable for packaging application, however due to limited number of efforts to effectively recycle PLAs, its disposal still contributes to the plastic pollution problem. In general, plastic recycling methods could be categorized into three main groups: (i) incineration for energy generation, (ii) chemical recycling, and (iii) mechanical recycling. Among those strategies, mechanical recycling would be the optimal choice due to its applicability to current plastic production lines. However, limited thermal stability of PLA during melt mixing make its mechanical recycling challenging. This study explores the direct use of ketene-based chain extenders in the melt mixing step without any pre-treatments to enhance PLA's properties during thermal recycling. Those ketene-based chain extenders could increase the molecular weight and hence melt viscosity of PLA by reacting its hydroxyl and carboxylic acid end groups. For this purpose, copolymers of styrene, methyl methacrylate and 2,2,5-trimethyl-5-(4-vinylbenzyl)-1,3-dioxane-4,6-dione (MA) were synthesized and directly melt mixed with PLA in micro compounder at 210 °C for 3 mins. Force values were monitored simultaneously through this mixing step. Final molecular weights and thermal properties of PLAs were also analyzed through GPC and DSC analyses.

Anahtar Kelimeler

• Poly(lactic acid)
• Ketenes
• Meldrum’s acid
• Chain extender
• Direct melt mixing

Kaynakça

1. Aasa J, Granath F, Törnqvist M. 2019. Cancer risk estimation of glycidol based on rodent carcinogenicity studies, a multiplicative risk model and in vivo dosimetry. Food Chem Toxicol, 128: 54–60.
2. Abdel-Rahman MA, Tashiro, Y, Sonomoto K. 2013. Recent advances in lactic acid production by microbial fermentation processes. Biotechnol Adv, 31(6): 877–902.
3. Al-Itry, R, Lamnawar K, Maazouz A. 2012. Improvement of thermal stability, rheological and mechanical properties of PLA, PBAT and their blends by reactive extrusion with functionalized epoxy. Polym Degrad Stab, 97(10): 1898–1914.
4. AlkanGoksu, Y. 2024. Enhancing the Sustainability of Poly(Lactic Acid) (PLA) Through Ketene-Based Chain Extension. J Polym Environ.
5. AlkanGoksu, Y, Kumbaraci V, Yagci, Y. 2019. Modular photoinduced grafting onto approach by ketene chemistry. J Polym Sci A Polym Chem. 57(3): 274–280.
6. Atalay S.E, Bezci B, Özdemir B, Göksu, YA, Ghanbari A, Jalali A, Nofar M. 2021. Thermal and Environmentally Induced Degradation Behaviors of Amorphous and Semicrystalline PLAs Through Rheological Analysis. J Polym Environ, 29(10): 3412–3426.
7. Auras R, Harte B, Selke S. 2004. An Overview of Polylactides as Packaging Materials. Macromol Biosci, 4(9): 835–864.
8. Badia J.D, Ribes-Greus A. 2016. Mechanical recycling of polylactide, upgrading trends and combination of valorization techniques. Eur Polym J, 84: 22–39.

9. Bagheri A.R, Laforsch C, Greiner A, Agarwal, S. 2017. Fate of So‐Called Biodegradable Polymers in Seawater and Freshwater. Global Chall. 1(4): 1700048.
10. Beltrán F.R, Lorenzo V, Acosta J, Orden M.U, Martínez-Urreaga J. 2018. Effect of simulated mechanical recycling processes on the structure and properties of poly(lactic acid). J Environ Manage. 216: 25–31.
11. Berg D, Schaefer K, Moeller M. 2019. Impact of the chain extension of poly(ethylene terephthalate) with 1,3‐phenylene‐bis‐oxazoline and N , N ′‐carbonylbiscaprolactam by reactive extrusion on its properties. Polym Eng Sci. 59(2): 284–294.
12. Cisneros-López EO, Pal AK, Rodriguez AU, Wu F, Misra M, Mielewski DF, Kiziltas A, Mohanty AK. 2020. Recycled poly(lactic acid)–based 3D printed sustainable biocomposites: a comparative study with injection molding. Mater Today Sustainability. 7: 100027.
13. Corre YM, Duchet J, Reignier J, Maazouz A. 2011. Melt strengthening of poly (lactic acid) through reactive extrusion with epoxy-functionalized chains. Rheol Acta, 50(7–8): 613–629.
14. Elkholy HM, Abdelwahab MA, Naveed M, Abdelaziz K, Rabnawaz M. 2024. Food-safe glycidyl-free chain extenders for polylactides. Green Chem. 26(7): 3968-3978.
15. Grigora ME, Terzopoulou Z, Tsongas K, Klonos P, Kalafatakis N, Bikiaris DN, Kyritsis A, Tzetzis D. 2021. Influence of Reactive Chain Extension on the Properties of 3D Printed Poly(Lactic Acid) Constructs. Polymers, 13(9): 1381.
16. Guclu, M, AlkanGöksu Y, Özdemir B, Ghanbari A, Nofar M. 2022. Thermal Stabilization of Recycled PET Through Chain Extension and Blending with PBT. J Polym Environ. 30(2): 719–727.
17. Haider TP, Völker C, Kramm J, Landfester K, Wurm FR. 2019. Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on Society. Angew Chem Int Ed Engl. 58(1): 50–62.
18. Huysman S, DeSchaepmeester J, Ragaert K, Dewulf J, DeMeester S. 2017. Performance indicators for a circular economy: A case study on post-industrial plastic waste. Resour Conserv Recycl. 120: 46-54.
19. Jaszkiewicz A, Bledzki AK, van der Meer R, Franciszczak P, Meljon A. 2014. How does a chain-extended polylactide behave? a comprehensive analysis of the material, structural and mechanical properties. Polymer Bull. 71(7): 1675–1690.
20. Kahraman Y, Özdemir B, Gümüş BE, Nofar M. 2023. Morphological, rheological, and mechanical properties of PLA/TPU/nanoclay blends compatibilized with epoxy‐based Joncryl chain extender. Colloid Polym Sci. 301(1): 51–62.
21. Karayannidis GP, Psalida EA. 2000. Chain extension of recycled poly (ethylene terephthalate) with 2, 2′‐(1, 4‐phenylene) bis (2‐oxazoline). J Appl Polym Sci, 77(10): 2206–2211.
22. Kawashima N, Usugi S, Ogawa R. 2023. Diisocyanate‐based chain extension via Mg(II) catalyzed amide formation to high‐molecular‐weight poly(lactic acid). J Polym Sci. 61(20): 2506–2513.
23. Kylmä J, Tuominen J, Helminen A, Seppälä J. 2001. Chain extending of lactic acid oligomers. Effect of 2,2′-bis(2-oxazoline) on 1,6-hexamethylene diisocyanate linking reaction. Polymer, 42(8): 3333–3343.
24. Leibfarth FA, Hawker C. 2013. The emerging utility of ketenes in polymer chemistry. J Polym Sci A Polym Chem. 51(18): 3769–3782.
25. Leibfarth FA, Kang M, Ham M, Kim J, Campos L, Gupta N, Moon, B, Hawker, C. 2010. A facile route to ketene-functionalized polymers for general materials applications. Nat Chem. 2(3): 207–212.
26. Liu X, Khor S, Petinakis E, Yu L, Simon G, Dean K, Bateman S. 2010. Effects of hydrophilic fillers on the thermal degradation of poly(lactic acid). Thermochim acta, 509(1–2): 147–151.
27. Meng Q, Heuzey M, Carreau P. 2012. Control of thermal degradation of polylactide/clay nanocomposites during melt processing by chain extension reaction. Polym Degrad Stab. 97(10): 2010–2020.
28. Mihai M, Huneault M, Favis B. 2010. Rheology and extrusion foaming of chain-branched poly(lactic acid). Polym Eng Sci. 50(3): 629–642.
29. Najafi N, Heuzey M, Carreau, P, Wood-Adams P. 2012. Control of thermal degradation of polylactide (PLA)-clay nanocomposites using chain extenders. Polym Degrad Stab. 97(4): 554–565.
30. Piyamawadee C, Aht-Ong D. 2013. The Influence of Amount of Succinic Anhydride in Chain Extension Reaction on Increasing Molecular Weight of Poly(lactic acid). Adv Mat Res. 747: 148–152.
31. Raffa P, Coltelli M, Savi S, Bianchi S, Castelvetro V. 2012. Chain extension and branching of poly(ethylene terephthalate) (PET) with di- and multifunctional epoxy or isocyanate additives: An experimental and modelling study. React Funct Polym. 72(1): 50–60.
32. Ramos‐Hernández T, Robledo‐Ortíz J, González‐López, M, delCampo A, González‐Núñez R, Rodrigue D, Pérez-Fonseca A. A. 2023. Mechanical recycling of PLA : Effect of weathering, extrusion cycles, and chain extender. J Appl Polym Sci. 140(16): e53759
33. Rocca-Smith J, Whyte O, Brachais C, Champion D, Piasente F, Marcuzzo E, Sensidoni A, Debeaufort F, Karbowiak T. 2017. Beyond Biodegradability of Poly(lactic acid): Physical and Chemical Stability in Humid Environments. ACS Sustain Chem Eng. 5(3): 2751–2762.
34. Rudnik E, Briassoulis D. 2011. Degradation behaviour of poly(lactic acid) films and fibres in soil under Mediterranean field conditions and laboratory simulations testing. Ind Crops Prod. 33(3): 648–658.
35. Standau T, Nofar M, Dörr D, Ruckdäschel H, Altstädt V. 2022. A Review on Multifunctional Epoxy-Based Joncryl® ADR Chain Extended Thermoplastics. Polym Rev. 62(2): 296–350.
36. Tavares A, Silva D, Lima P, Andrade, D, Silva, S, Canedo, E. 2016. Chain extension of virgin and recycled polyethylene terephthalate. Polymer Test. 50: 26–32.
37. Tuna B, Ozkoc G. 2017. Effects of Diisocyanate and Polymeric Epoxidized Chain Extenders on the Properties of Recycled Poly(Lactic Acid). J Polym Environ. 25(4): 983–993.
38. Wang S, Pang S, Xu N, Pan L, Lin Q. 2016. In-situ compatibilization of polylactide/thermoplastic polyester elastomer blends using a multifunctional epoxide compound as a processing agent. J Appl Polym Sci. 133(20): 43424
39. Yahyaee N, Javadi A, Garmabi H, Khaki A. 2020. Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid). Macromol Mater Eng. 305(2): 1900423
40. Zhao G, Thompson M, Zhu Z. 2019. Effect of poly(2‐ethyl‐2‐oxazoline) and UV irradiation on the melt rheology and mechanical properties of poly(lactic acid). J Appl Polym Sci. 136(40): 48023.