Influence of the chain extension on the crystallization behavior of polylactide

Abstract

International audienceA semicrystalline poly(lactic acid) (PLA) was modified with the help of an epoxy-based chain extender (CE) during reactive extrusion. Different amounts of CE were used resulting in samples with increased and broadened molar mass distributions as revealed by size exclusion chromatography. Thermal properties were then investigated using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). On one hand, the thermal ramps performed with DSC revealed that the glass transition was not modified by the chain extension process. On the other hand, thecrystallization behavior was found to be highly impacted by this molecular modification. Decreases in the cold crystallization temperatures Tcc and in the melting temperatures Tm occurred when the CE content was raised. Isothermal crystallizations from the melt were performed using both DSC and POM. It revealed that the overall crystallization process was significantly faster for the chain-extended PLAs while crystalline ratios were lowered. An improvement of the nucleation process coupled with a reduced crystal growth was assumed to be responsible for this change

Improvement of microstructures and properties of poly(lactic acid)/poly(ε‐caprolactone) blends compatibilized with polyoxymethylene

“…That is consistent with the optimum T c for the melt crystallization of neat PLA reported by Wei et al . and Corre et al . As we all known that the crystallization process of PLA consists of two steps: nucleation followed by crystalline growth.…”

“…The optimal T c leading to a minimized t 1/2 is 100 8C for all the PLA/PCL samples regardless of POM loadings. That is consistent with the optimum T c for the melt crystallization of neat PLA reported by Wei et al 41 and Corre et al 43 As we all known that the crystallization process of PLA consists of two steps: nucleation followed by crystalline growth. Hence, the overall crystallization rate is dominated by the combination of the nucleation rate and the crystal growth rate.…”

Effect of chemical modification on the thermal and rheological properties of polylactide

“…The crystallinity of the materials was calculated by the use of a heat of fusion of 93.1 J g −1 for 100% crystalline PLA homopolymers .…”

Non-isothermal crystallization behaviors of poly(lactic acid)/cellulose nanofiber composites in the presence of CO2

“…Different strategies have been employed to enhance the crystallization kinetics of PLA including chain branching [12][13][14][15], iso-/non-iso-thermal treatment under plasticizing gas environments at elevated pressures [8,12,16,17], polymer blending [18][19][20][21][22], incorporation of inorganic/organic fillers or nucleating agents [8,21,[23][24][25][26][27][28][29][30], and strain-induced crystallization [31][32][33]. Among these, adding inorganic/organic fillers or nucleating agents has been considered one of the most common and effective approaches.…”