Effect of crystallization on barrier properties of formulated polylactide

Abstract

Science Arts & Métiers (SAM)is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Polylactide (PLA), a biodegradable polymer obtained from biomass, was formulated with a nucleating agent, talc, and a plasticizer, acetyl tributyl citrate, and cold crystallized in α and α form. The barrier properties of crystallized PLA were investigated as a function of the formulation and the crystalline form, thanks to three molecules with increasing polymer interactions, i.e. helium, oxygen and ethyl acetate (EA). Contrary to expectation, the oxygen diffusion coefficient in neat and formulated PLA did not decrease with crystallization. Even an increase of the diffusion coefficient was noticed for the most interacting probe, EA, in formulated PLA. Conditioning of neat and formulated PLA in an atmosphere containing EA vapour caused a modification of the material structure by plasticization and induced crystallization even at small EA activities. The plasticizing effect caused the glass transition temperature T g to shift to below ambient temperature. In the case of neat PLA induced crystallization in solely the α form was obtained, and in the case of formulated PLA a blend of α and α forms was observed.

Potential of Lignins as Antioxidant Additive in Active Biodegradable Packaging Materials

“…Neat PLA oxygen barrier properties are in accordance with published data [54,[60][61][62][63][64][65]. Interestingly, the inclusion of at least 10 wt% of lignin yielded a decrease in oxygen permeability of around 20 %.…”

“…The elongation at break decreased slightly for the PLA/lignin SARKANDA formulation with the increase of lignin content. However, as PLA on itself is already a brittle material [54][55][56][57][58], further decrease was difficult to detect. The measured strain at break values of neat PLA data were in agreement with the data given by the provider in the PLA 2002D datasheet and with literature results [56,59].…”

Characterisation of low-odour emissive polylactide/cellulose fibre biocomposites for car interior

“…However, these two samples exhibit different melting behaviour: the ndPLA-C pellets resulted from compounding and granulation present a melting peak at 167.8°C with a shoulder (160.9°C), whereas after injection moulding, the PLA-CI materials shows an exotherm at 150.4°C, before the melting endotherm peak at 166.6°C. As explained by Pan and Inoue [55], and also observed by Courgneau et al [53], this exotherm prior to the Figure 5. a) DSC thermograms of dPLA pellets, PLA-C pellets and PLA-CI bars, b) DSC thermograms of dPLA pellets, PLA10F-C pellets and PLA10F-CI bars.…”

“…Contrary to the rigid amorphous phase fraction (RAF), which cannot contribute to the glass transition due to the partial trapping of the molecules in the crystalline lamellae, the MAF, sensitive to the constrains in the matrix, relaxes at the glass transition temperature. This phenomenon is observed in the present case for compounded PLA pellets (ndPLA-C) submitted to drying at 80°C for 72 h. The second drying step acted as an isothermal cold crystallisation cycle [53], and the amorphous ndPLA-C pellets crystallised up to 37%. The implicit confinement of the MAF results in a large broadening and shift of the T g , from about 54°C (for amorphous ndPLA-C pellets) to about 62°C (for semi crystalline dPLA-C pellets).…”

Blending of Polyhydroxybutyrate-co-valerate with Polylactic Acid for Packaging Applications – Reflections on Miscibility and Effects on the Mechanical and Barrier Properties

“…The results reveal the high strength of pure PLA with a YM of 3169 N mm -2 , s of 72 N mm -2 , and a e of 3.6 %, which is in accordance with other literature. 45,75 In contrast, PHBV shows lower strength (s 28 N mm -2 ) and elongation at break (e 1.2 %). The brittle behaviour and low mechanical flexibility of PHBV has already been reported in literature.…”