Effect of Glucose on the Crystallization and Thermal Properties of Poly(L-Lactic Acid) Prepared Through Mixed Solution Method

Abstract

Abstract. The blends of PLLA (PLLA) and glucose(Glu) were prepared by mixing PLLA solution and glucose solution with various ratios when PLLA and glucose were respectively dissolved in N,N-dimethyl acetamide to prepare solutions. The structure, thermal properties and crystallinity of PLLA, glucose and PLLA-Glu blends were investigated by Fourier transform infrared spectrometry, differential scanning calorimetry, thermal gravity analysis, X-ray diffraction and polarized optical microscopy. PLLA and glucose in blends are partially compatible due to their interaction through hydrogen bonding. Glucose performs an important effect on the crystallisation, thermal properties and morphology of PLLA in PLLA-Glu blends. The crystallization degree of PLLA-Glu blends increased with the increase of glucose. The addition of glucose can promote thermal degradation of PLLA due to the defect of PLLA crystal caused by glucose impurity or trans-esterification between PLLA and glucose.

Preparation and Properties of Stereocomplex of Poly(lactic acid) and Its Amphiphilic Copolymers Containing Glucose Groups

“…On account of the comprehensive effects of the above factors, the T max of sc-PLAG-0.5% was about 262 • C, then the T max of sc-PLAG samples increased steadily with the increase of glucose content in feeding until the glucose content in feeding was 5%. Compared to PLLA-glucose blends [26] and PLA with different processing methods [41], the T b , T max , and T f of all sc-PLAG were lower than those of PLLA-glucose blends and the PLA materials, which indicated that the copolymerization of poly(lactic acid) and glucose and stereocomplex of PLA was more able to promote thermal degradation of PLLA.…”

“…Compared to PLLA-glucose blends [26] and PLA with different processing methods [41], the Tb, Tmax, and Tf of all sc-PLAG were lower than those of PLLA-glucose blends and the PLA materials, which indicated that the copolymerization of poly(lactic acid) and glucose and stereocomplex of PLA was more able to promote thermal degradation of PLLA.…”

“…Figure 5 shows the TGA curves of PLLA and sc-PLAG samples. The beginning degradation temperature T b (at 5 wt% mass loss), the maximum degradation temperature T max (at 50 wt% mass loss), the final degradation temperature T f (at 95 wt% mass loss) [41], and the carbon residue ratio W r at 600 • C [26] of each sample were obtained from the analysis of Figure 5, and the results are listed in Table 3.…”

“…Glucose, as the most common monosaccharide in nature, is well-known for its extensive sources, low price, nontoxicity, and high hydrophilicity, etc. Glucose possessing five hydroxyl groups is easily modified with PLA by blending [14,26] or copolymerization [27]. Because of its advantages, such as low cost, simple technology, and convenient operation, the direct polycondensation may be used to prepare PLA and its copolymers, and the obtained PLA usually has low molecular weights [28].…”