New intercalated layer silicate nanocomposites based on synthesized starch-g-PCL prepared via solution intercalation and in situ polymerization methods: As a comparative study

Advanced Nano-biocomposites Based on Starch

“…They also found that the glycerol (the plasticizer) intercalation was minimized in the oxidized starch film where the intercalation of the oxidized starch chains was preferred (Wilhelm et al 2003a). On the other hand, by replacing some hydroxyl groups of starch with less hydrophilic functional groups such as acetate groups, the polarity matching between the starch and a specific phyllosilicate can differ Hassan Nejad et al 2011;Namazi et al 2009;Nejad et al 2010). For instance, Nejad et al (2011Nejad et al ( , 2010 reported that OMMT (Dellite 67G or Dellite 43B), compared with MMT-Na + (Dellite LVF), matched better with hydrophobic starch derivatives (starch acetate, starch propionate, and starch propionate acetate laurate) as the matrices.…”

“…As a result, very good dispersion and partially exfoliated structures were achieved. Namazi et al (2009) compared solution intercalation and in situ polymerization methods for preparing starch-g-PCL nano-biocomposites reinforced by Cloisite 15A. Their result showed that, even though the d 001 could be varied by the clay addition level and swelling/process time, the diffusion and intercalation of copolymer into the interlayer spaces were generally better by solution intercalation than by in situ intercalative method (Namazi et al 2009).…”

“…To seek better performance, various chemically modified starches have also been experimented to develop nano-biocomposites Hassan Nejad et al 2011;Kvien et al 2007;Namazi et al 2009;Nejad et al 2010;Qiao et al 2005;Wilhelm et al 2003a;Xu et al 2005). Chemical modification can result in starch derivatives with varied properties such as the molecular chain length and hydrophilicity, which could affect the interactions with a phyllosilicate.…”

“…-Oxygen barrier property: a higher oxygen barrier can be ascribed to the silicate layers inducing a higher tortuosity and longer diffusion pathways for oxygen molecules (Lilichenko et al 2008;Maksimov et al 2009;Zeppa et al 2009). -Thermal stability: improvement in the thermal stability can be due to several concomitant phenomena such as (a) the higher thermal stability of the inorganic phase (phyllosilicate) compared to the organic one (starch), (b) the phyllosilicate acting as a heat barrier which enhances the overall stability (Cyras et al 2008;Ibrahim 2011), (c) the increase in the tortuosity of the diffusion pathways for oxygen and the combustion (pyrolysis) gas (Alexandre and Dubois 2000;Chiou et al 2007;Chivrac et al 2010d;Cyras et al 2008;Namazi et al 2009;Xu et al 2005), and (d) the reorganization of the starch structure with less exposed hydroxyl groups and thus less susceptibility to degradation (Pandey and Singh 2005;Wang et al 2010b;Wilhelm et al 2003b). …”

“…In this case, a phyllosilicate is swollen in a monomer solution, and then the monomer polymerization takes place, leading to a d 001 increase, till in some cases a fully exfoliated morphology . Since starch molecular chains are synthesized during plant growth and then extracted from the vegetal, in situ polymerization is limited to nano-biocomposites with chemically modified starch such as starch graft copolymer, which is synthesized in situ with a phyllosilicate Luo et al 2005;Namazi et al 2009;Wu et al 2000;Zhou et al 2011).…”