The Potential of an Itaconic Acid Diester as Environmentally Friendly Plasticizer for Injection‐Molded Polylactide Parts

Abstract

This work reports on the use of dibutyl itaconate (DBI) as an environmentally friendly plasticizer for polylactide (PLA) with different proportions of DBI in the 2.5–20 wt% (weight content) range. A co‐rotating twin‐screw extrusion process followed by injection molding is employed for the manufacturing of the samples. The results show that the plasticized PLA formulation with 10 wt% DBI offers the most balanced overall properties, with a noticeable increase in the elongation at break from 4.6% (neat PLA) up to 322%, with a tensile modulus of 1572 MPa, and a tensile strength of 23.8 MPa. In the case of 15 and 20 wt% DBI formulations, PLA reaches the saturation point with no more increase in the elongation at break and a clear decrease in the tensile modulus. DBI also decreases the glass transition temperature (Tg) from 61.3 °C (neat PLA) down to 23.4 °C for plasticized PLA formulation containing 20 wt% DBI, thus showing the high plasticization efficiency of DBI.

Improvement of Poly(lactide) Ductile Properties by Plasticization with Biobased Tartaric Acid Ester

“…In spite of the fact that PLA reached its saturation point related to diethyl L‐tartrate, no phase separation was observed in the FESEM images, which is in accordance with the calculated solubility parameters that showed good miscibility between PLA and DET. A very similar result was observed by Ivorra‐Martinez et al [ 31 ] in plasticized PLA blends with dibutyl itaconate (DBI).…”

“…On the other hand, the melting temperature of PLA is located at 175 °C, and it can be observed how the plasticizer progressively decreases it down to a value of 150 °C for the sample with 50 wt.% of DET. This phenomenon was also observed by Ivorra‐Martinez et al [ 31 ] in PLA plasticized with dibutyl itaconate. The crystallinity degree is also increased from a value of 33% for neat PLA to values of 57% and 67% for the samples with 40 and 50 wt.% of DET, respectively.…”

“…This is ascribed to the plasticization effect of DET, which increases the mobility of the PLA polymeric chains. [ 31 ] Considering that the glass transition is related to the mobility of the amorphous phase of the polymer, this result was predictable, achieving a value of 23 °C for the sample with 50 wt.% of DET. The PLA used in this study is a semicrystalline polymer, as it can be deduced from the cold crystallization temperature peak, which appears at 103.6 °C.…”

“…This behavior is ascribed to the plasticizing effect of DET, which promotes a reduction in the attraction forces between PLA polymer chains, so their movement requires less energy, making it possible to obtain more elongation capacity. [ 31 ] Once 20 wt.% of DET is surpassed, the plasticizing effect is still surprising, with elongation at break values of 463% for 30 wt.% of DET or 399% for 50 wt.% of DET, although it is worse in comparison with 20 wt.% of DET. This could be related to PLA reaching saturation related to the plasticizer, a very similar phenomenon to the one observed by Ivorra–Martinez et al [ 31 ] when plasticizing PLA with dibutyl itaconate (DBI).…”

“…[ 31 ] Once 20 wt.% of DET is surpassed, the plasticizing effect is still surprising, with elongation at break values of 463% for 30 wt.% of DET or 399% for 50 wt.% of DET, although it is worse in comparison with 20 wt.% of DET. This could be related to PLA reaching saturation related to the plasticizer, a very similar phenomenon to the one observed by Ivorra–Martinez et al [ 31 ] when plasticizing PLA with dibutyl itaconate (DBI). Therefore, 20 wt.% DET can be considered the optimal plasticizer concentration in order to achieve the best mechanical properties.…”