Shear rheology of polylactide (PLA)–cellulose nanocrystal (CNC) nanocomposites

Bagheriasl, Davood; Carreau, Pierre J.; Riedl, Bernard; Dubois, Charles; Hamad, Wadood Y.

doi:10.1007/s10570-016-0914-1

Cited by 118 publications

(94 citation statements)

References 39 publications

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“…From these data, it can be deduced that percolation can be induced in CNC suspensions at a concentration around 0.3 g/g. This percolation value is surprisingly lower than what Bagherisal et al reported (between 0.5 and 1 %) for the same CNCs in a molten polylactide (PLA). Such a discrepancy could be due to lower dispersion state in the PLA or the re‐aggregation of particles during the solvent evaporation.…”

Section: Resultssupporting

confidence: 84%

Gelation of crystalline nanocellulose in the presence of hydroxyethyl cellulose

et al. 2017

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In this work, hydroxyethyl cellulose (HEC) was used to induce gelation of electrosterically stabilized cellulose nanocrystal (ECNC) and common cellulose nanocrystal (CNC) suspensions. The main goals were to shift the gelation point to low concentrations of nanoparticles and clarify the role of interactions between ECNCs in contrast to CNCs. The rheological properties of CNC suspensions were investigated in the presence of HEC with or without CaCl2 while ECNC suspensions would be only mixed with HEC since the addition of salt would not alter the viscoelastic properties of the whole system. The structure build‐up kinetics as well as the viscoelastic properties of the suspensions were compared. CaCl2 was used to induce gelation of CNC suspensions at a solid content as low as 0.2 g/g in the presence of HEC. ECNC suspensions were less sensitive to HEC since the best result obtained for inducing gelation was achieved at a concentration of 4 g/g. All the results presented are explained by the adsorption of HEC on the nanoparticles, which was determined by viscometry. High adsorption level of HEC chains imparted CNCs better colloidal stability in the presence of CaCl2 as compared to pristine CNCs, whereas it did not affect the ECNC colloidal stability.

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Section: Resultssupporting

confidence: 84%

Gelation of crystalline nanocellulose in the presence of hydroxyethyl cellulose

et al. 2017

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“…The non-Newtonian behaviour of nanocomposites at the lowest frequencies can be explained considering a solid-like behaviour of the material induced by three-dimensional structures typical of nanofilled systems [37]. The formation of this three-dimensional percolated network is due to the polymer-filler interactions that offer a resistance to the flow [37][38][39]. When the shear rate is higher, this structures are disrupted and the nanocomposites behave as a suspension of nanoparticles in a melt matrix [40].…”

Section: Resultsmentioning

confidence: 99%

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

Scaffaro¹,

Sutera²,

Mistretta³

et al. 2017

Express Polym. Lett.

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Abstract. In this work the effect of multiple reprocessing was studied on molecular structure, morphology and properties of poly(lactic acid)/hydrotalcites (PLA/HT) nanocomposites compared to neat PLA. In addition, the influence of two different kinds of HT -organically modified (OM-HT) and unmodified (U-HT) -was evaluated. Thermo-mechanical degradation was induced by means of five subsequent extrusion cycles. The performance of the recycled materials was investigated by mechanical and rheological tests, differential scanning calorimetry (DSC), intrinsic viscosity measurements and SEM observation. The results indicated that the best morphology was achieved in the systems incorporating OM-HT. On increasing the extrusion reprocessing cycles, the properties showed behavior due to two opposite effects: i) chain scission due to thermo-mechanical degradation and ii) filler dispersion effect resulting from multiple processing. In particular, at low reprocessing cycles, both tensile and rheological properties seem to be mainly affected by HT dispersion, especially when OM-HT was added. After five reprocessing cycles, on the contrary, chain scission, i.e. thermo-mechanical degradation, dominated. As regards the effect of the presence of organic modifier in HT, the results indicated that this variable apparently did not affect the macroscopic performance of the nanocomposites, especially at high reprocessing cycles.

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“…a sample resting for 14 days prior to the commencement of the test) can be observed to reach the maximum shear stress (overshoot stress, s max ) before it achieves the equilibrium value. The overshoot stress was noted in a large number of systems, for example entangled polymer melts and solutions (Ravindranath and Wang 2008;Hernadez et al 2013;Lu et al 2014), nanocrystalline cellulose suspensions, hydrogels (Yin et al 2008;Mahi and Rodrigue 2012;Bagheriasl et al 2016;Chen et al 2017), organoclay nanocomposites (Letwimolnun et al 2007;Chen et al 2017). The initial monotonic increase in the shear stresses is proof for the occurrence of elastic deformation of polymer chains (Ravindranath and Wang 2008;Wang and Wang 2009).…”

Section: Dynamic Rheological Propertiesmentioning

confidence: 98%

Effect of the degree of substitution on the rheology of sodium carboxymethylcellulose solutions in propylene glycol/water mixtures

2017

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The linear dynamic viscoelastic properties and non-linear transient rheology of sodium carboxymethylcellulose solutions (Na-CMC) in propylene glycol/water mixtures were investigated. Measurements were carried out for the solutions of Na-CMC with three different degrees of substitution (DS), namely 0.62, 0.79, 1.04, and the similar average molecular weight (M w & 250,000 g/mol). The strong synergism between the molecules of Na-CMC with DS of 0.62 and 0.79, and propylene glycol has been observed. The occurrence of the overshoot shear stress and the low loss tangent values indicate the physical cross-linking of the polymer chains. The increase of propylene glycol concentration over 80 wt% and sodium carboxymethylcellulose (DS = 0.7) over 1.6 wt% leads to the formation of a physical cross-link network. The absence of overshoot shear stress and terminal behaviour in SAOS flow of the Na-CMC 1.04 solutions in the PG/water mixture shows that no intermolecular cross-linking of polymer chains occurred in them.

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Shear rheology of polylactide (PLA)–cellulose nanocrystal (CNC) nanocomposites

Cited by 118 publications

References 39 publications

Gelation of crystalline nanocellulose in the presence of hydroxyethyl cellulose

Gelation of crystalline nanocellulose in the presence of hydroxyethyl cellulose

Structure-properties relationships in melt reprocessed PLA/hydrotalcites nanocomposites

Effect of the degree of substitution on the rheology of sodium carboxymethylcellulose solutions in propylene glycol/water mixtures

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