Effect of the chain length of geraniol esters on the plasticization efficiency with poly(lactide)

[EN] This work reports on the development of environmentally friendly PLA formulations utilizing different esters derived from geraniol as plasticizers. Geranyl formate, acetate, propionate, butyrate, isovalerate and caproate at 10 wt% were combined with PLA in formulations that were produced through extrusion and injection moulding processes. Theoretical solubility parameter studies predicted good miscibility between PLA and all the plasticizers. This was confirmed by tensile test, which showed elongation at break values between 200 and 300 %, totally in contrast with the 8 % value of neat PLA. Geranyl acetate and geranyl formate exhibited the highest elongation at break behavior. These values of elongation at break were supported by FESEM images, which showed clear signs of plasticization. The plasticization effect was further corroborated by DSC and DMTA analysis, where a clear decrease in the glass transition temperature was observed from a typical value of 60 °C for neat PLA down to 40¿50 °C for the plasticized blends. This was related to an enhanced chain mobility of the amorphous regions of PLA. Moreover, the plasticizers slightly increased the water absorption capabilities of PLA, as demonstrated by an increase in the water contact angle and water uptake for 11 weeks. This research is a part of the grant PID2020-116496RB-C22, funded by MCIN/AEI/10.13039/501100011033 and the grant TED2021- 131762A-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European Union "NextGenerationEU"/PRTR. Authors also thank Generalitat Valenciana-GVA for funding this research through the grant numbers AICO/2021/025 and CIGE/2021/094. Funded with Aid for First Research Projects (PAID-06-22), Vice -rectorate for Research of the Universitat Politecnica de Valencia (UPV) . R.T.-O. wishes to thank UPV for the grant received though the PAID-01-20 program. J. I.-M. wants to thank FPU19/01759 grant funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future. J. G.-C. wants to thank FPU20/01732 grant funded by MCIN/AEI/10.13039/501100011033 and by ESF Investing in your future. V. M. thanks Ge eralitat Valenciana-GVA for funding a postdoc position through the APOSTD program co -funded by ESF Investing in your future, grant number CIAPOS/2021/67. Microscopy Services at UPV are also acknowledged by their help in collecting and analyzing images. Gómez-Caturla, J.; Ivorra-Martinez, J.; Tejada-Oliveros, R.; Moreno-García, V.; Garcia-Garcia, D.; Balart, R. (202