Poly(L‐lactide)/C₆₀ nanocomposites: Effects of C₆₀ on crystallization of poly(L‐lactide)

Abstract

The effects of solvent type and concentration of C 60 on the crystallization of poly(L-lactide) (PLLA) during solvent evaporation, heating from room temperature, and cooling from the melt were investigated by polarized optical microscopy and differential scanning calorimetry. The addition of C 60 enhanced the PLLA crystallization during solvent evaporation, during heating of the melt-quenched films, and during cooling from the melt of As-cast films, except for heating and cooling of the PLLA film with 1 wt % of C 60 prepared with dichloromethane. In the case of solvent evaporation, the difference in crystallinity between the PLLA films with and without C 60 became higher for the solvent with a lower boiling point. In the case of heating of melt-quenched films, the addition of C 60 had a small effect on the crystallinity of PLLA, whereas significantly lowered the peak top and ending temperatures of cold crystallization, except for melt-quenched PLLA film with 1 wt % of C 60 prepared with dichloromethane. The crystallinity of PLLA was determined by the solvent type, rather than by the C 60 concentration. In the case of cooling from the melt of As-cast films, the addition of C 60 elevated the crystallinity and cold crystallization temperature values of PLLA films, except for PLLA films prepared with dichloromethane.

Stereoselective Interaction between Isotactic and Optically Active Poly(lactic acid) and Phenyl‐Substituted Poly(lactic acid)

“…[19] Also, it is probable that the crystallization period in the crystallizable temperature range becomes longer with an increase in starting crystallization temperature (not T cc in the present study). [20] The highest starting crystallization temperature in the blend with Ph-PDLA (133 8C) should have allowed PDLA(H) to stay within the crystallizable temperature range for the longest period, resulting in the highest normalized (ÀDH cc ) value among the specimens.…”

Relatively Short Poly(D‐lactide) Segments as Intra‐Crystallization‐Accelerating Moieties in Stereo Diblock Poly(lactide)s

“…Considering the WAXD result that D4-119 was amorphous before heating of the quenched samples, the presence of melting peak of SC crystallites exhibits that SC crystallites were formed during DSC heating. The onset, peak, and endset cold crystallization temperatures [T cc (O), T cc (P), and T cc (E), respectively], were estimated from DSC thermograms in Figure 2a [14,40,41] and are plotted in The T cc (O), T cc (P), and T cc (E) values dramatically decreased with increasing D-lactyl unit content or M n of PDLA segments and leveled off for D-lactyl unit content above 2.3%, indicating that the sufficiently long PDLA segments accelerate crystallization. It should be stressed that the T cc (E) values of SDB-PLAs with D-lactyl unit contents ¼ 2.3 and 5.8% were much lower by 40 8C than that of L126 (Dlactyl unit content ¼ 0%).…”

“…The onset, peak, and endset crystallization temperatures [T c (O), T c (P), and T c (E), respectively], were estimated from the DSC thermograms in Figure 3a [14,40,41] and are plotted in Figure 3b as a function of D-lactyl unit content, together with X c (S), X c (H), and X c (tot) ¼ X c (S) þ X c (H) evaluated from the WAXD profiles in Figure 1b (Figure 3c). The T c (O) values were constant around 115 8C for D-lactyl unit contents of 0-2.3%, but that for D-lactyl unit content ¼ 5.8% was much higher than those for D-lactyl unit contents of 0-2.3%.…”

Tailoring the crystallization behavior of poly(L-lactide) with self-assembly-type oxalamide compounds as nucleators: 1. Effect of terminal configuration of the nucleators

“…Inorganic fillers are reported in literature for nucleation of PLLA such as talcum, clay, carbon-nano tubes, graphene and C 60 [7][8][9][10][11][12]. Impressively, PLLA crystallization was accelerated by the presence of C 60 assemblies having different shapes depending on the type of solvent [12].…”

“…Impressively, PLLA crystallization was accelerated by the presence of C 60 assemblies having different shapes depending on the type of solvent [12]. Among these nucleating agents, talc has been applied in industrial application as an effective physical nucleating agent of PLA.…”