Mechanical, Optical and Barrier Properties of PLA-layered Silicate Nanocomposites Coated with Organic Plasma Polymer Thin Films

Abstract

In the frame of the efforts that are nowadays provided to develop new environmentally-friendly products as biosourced alternative to petrochemical polymers, we investigated in this work new PLA-based materials for packaging applications obtained by combining bulk and surface modifications of PLA substrates. Four PLA-based nanocomposites were prepared by adding organo-modified layered silicates (either Cloisite® 30B or Cloisite® 20A) and a nucleating agent, i.e. N,N'-ethylenebisstearamide (EBS). The combination of EBS with CL30B led to very good nanofiller dispersion into PLA-clay nanocomposite while allowing, unlike neat PLA, to preserve the structural and thermal properties of PLA under plasma treatment. Based on this study, PLA/CL30B/EBS nanocomposites have been selected to investigate their surface modification that consisted in depositing on this substrate an organic barrier coating, i.e. an ethyl lactate plasma polymer film (ELPPF) synthesized by plasma polymerization of ethyl lactate. The PLA/CL30B/EBS-ELPPF system allowed increasing the tensile modulus from 3800 MPa (uncoated film) to 5200 MPa at high power plasma while preserving the ultimate mechanical properties. In addition, optical properties study showed that PLA/CL30B/EBS-ELPPF is also the best UV-B protective material while keeping a good transparency. Finally, the oxygen transmission rate was reduced by 53% with respect to neat PLA. All properties of final material are discussed as a function of the characteristics of PLA-clay nanocomposite substrate, of the ethyl lactate plasma polymer film (ELPPF) and of the substrate/plasma film interface.

Supramolecular Approach for Efficient Processing of Polylactide/Starch Nanocomposites

“…These PLLA/clay nanocomposites prepared by conventional melt extrusion exhibited remarkable oxygen permeability values, twice lower for hybrid systems with loadings up to 10 wt % of nanofillers compared to neat PLLA. 9 Recently, a PLLA/CL30B (3 wt %) nanocomposite substrate obtained by melt-mixing and coated with a thin plasma polymer film of ethyl lactate has demonstrated enhanced mechanical and optical properties as well as barrier properties with an oxygen transmission rate reduced by 53% with respect to neat PLLA, as reported by Ligot et al 10 Even though these improvements are not sufficient for packaging applications, the use of nanoclays may find interest in the multilayer concept or can afford a control over the biodegradation of the material. 11,12 However, the toxicity effect of CL30B for food contact applications has been recently highlighted through in vitro experiments.…”

SIFAT TRANSPARANSI DAN PERMEABILITAS FILM BIONANOKOMPOSIT POLYLACTIC ACID DAN POLYCAPROLACTONE DENGAN PENAMBAHAN NANOCRYSTALLINE CELLULOSE SEBAGAI PENGISI [Transparency and permeability properties of Bionanocomposite Film of Polylactic Acid and Polycaprolactone, and Nanocrystalline Cellulose as a Filler]

“…Pengujian transparansi film menggunakan cahaya UV-Vis dilakukan untuk mengetahui nilai transmitan yang dilewatkan melalui film bionanokomposit PLA/PCL dengan penambahan NCC 3%. Berdasarkan standar (ASTM-D1746-03, 2003, transparansi film plastik didefinisikan sebagai transmisi cahaya tampak dalam jarak pendek 540-560 nm (Ligot et al, 2015). Pengujian film bionanokomposit PLA/PCL (Gambar 2) menunjukkan nilai transmitan tertinggi diperoleh pada Film PLA/PCL dengan ratio 1:0 pada setiap panjang gelombang (300-700 nm).…”