Impact of Nanoclay on Isothermal Cold Crystallization Kinetics and Polymorphism of Poly(l-Lactic Acid) Nanocomposites

Abstract

Poly(L-lactic acid) (PLLA) intercalated nanocomposite films containing 1, 2, 5, and 10% organically modified montmorillonite (OMMT) have been synthesized by the solvent casting approach. The thermal characteristics, isothermal cold crystallization kinetics, and structural changes of neat PLLA and its nanocomposites during annealing were studied by using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. DSC observation showed that melting temperature and final crystallinity were not affected significantly with OMMT loading. PLLA films with increasing OMMT content exhibited higher crystallization rates than neat PLLA during annealing and suggested that the silicate platelets act as a nucleation agent during annealing. The effect of OMMT content on the isothermal crystallization kinetics of PLLA was analyzed using the Avrami equation. An Avrami constant of 1-2 was observed, suggesting that crystallization proceeds through one-dimensional growth with heterogeneous nucleation. FTIR investigation showed a band at 922 cm(-1) at all T(a), and no band at 908 cm(-1) suggested that all samples form α crystal regardless of OMMT content or T(a).

Lignin-coated cellulose nanocrystals as promising nucleating agent for poly(lactic acid)

“…The value of n was found to be close to 1 for neat PLA, suggesting formation of lamellae, whereas n value close to 2 was obtained for PLA/L-CNC nanocomposites suggesting a two-dimensional crystal growth. The n value obtained in the present study is similar to those reported for the neat PLA and PLA/clay nanocomposites [21,48]. Crystallization half time, t 1/2 , is another important crystallization kinetics parameter; it is defined as the time needed to complete half of the isothermal crystallization and calculated as follows:…”

Influence of graphene on thermal degradation and crystallization kinetics behaviour of poly(lactic acid)

“…where, T 0 and T ∞ denotes the onset and final cold crystallization temperature respectively [27,28]. The crystallization time (t) and the respective temperature (T) are related by the following expression…”

“…where, ϕ is the heating rate [27][28][29]. The values of relative crystallinity are plotted as a function of crystallization time for both neat PLA as well as PLA-GR nanocomposites and the same is portrayed in Fig.…”

Control-release of antimicrobial sophorolipid employing different biopolymer matrices

“…The integrated area under the peak was taken as the heat of fusion (ΔH f ) of the sample. The %-crystallinity (χ c ) of the sample was calculated by using the following equation as described previously (Fischer et al, 1973;Vasanthan et al, 2011).…”