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Cellulose acetate butyrate (CAB) and poly(L-lactic acid) (PLLA) were successfully blended through solvent blending method followed by solution dropping technique to fabricate composite CAB/PLLA beads with the variation of PLLA content (0, 10, 20, and 30 wt%) and polymer blend concentration in solution (10 wt% and 15 wt%). The obtained composite beads were applied as adsorbent for methylene blue removal from aqueous solution under the condition of various pH. Batch equilibrium adsorption was carried out to observe the effect of various PLLA content, polymer concentration, and pH on the adsorption performance (adsorption capacity and % dye removal), and to study the adsorption kinetics. The adsorption performance of the composite beads showed that the absorption capacity (Q) and dye removal percentage (%R) generally increases with the increasing of PLLA content for both polymer concentration of 10 wt% and 15 wt%. Beads fabricated from higher polymer concentration (15 wt%) possessed higher Q and %R compared to those from polymer concentration of 10 wt% under the same operation condition. Adsorption performance of beads was better in pH neutral than in acid or base condition. The highest Q and %R values were obtained by composite bead of CAB/PLLA (70/30) 15 wt%, which are 2.54 mg/g and 25.35% respectively at the adsorption condition of pH 7, temperature 30 °C, initial dye concentration of 20 mg/L, and beads dose of 2 g/L. The %R increased to 69.85% by increasing the beads dose to 20 g/L. The kinetics data obtained from the experiment fitted well with Largergren’s pseudo-first-order model which is the characteristic of physically adsorption. [ABSTRACT FROM AUTHOR]

This study aimed to isolate lactate-degrading bacteria via treatment with poly(L-lactic acid) (PLLA) in a thermophilic anaerobic digestion reactor to investigate their ecophysiological characteristics. Enrichment cultures were established with a basal medium (pH 7.0) supplemented with lactate and a thermophilic digester sludge as an inoculum, followed by anaerobic culturing at 55°C without shaking. Thereafter, 16S rRNA gene-based cloning analyses revealed that the predominant bacteria in the enrichment culture were of genus Moorella. Roll-tube cultures containing lactate and Moorella-resistant streptomycin were serially diluted to isolate Moorella cells from a series of the diluted enrichment cultures. Fluorescence in situ hybridization analyses using a Morl93 probe revealed that a pure culture of the strain (strain Hama-1) was successfully obtained. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Hama-1 is closely related to Moorella perchloratireducens strain An10T with 99.6% sequence similarity. Strain Hama-1 completely converted lactate to acetate, and was clearly phenotypically different from M. perchloratireducens strain An10T. Characterization of strain Hama-1 would further help the current understanding of lactate degradation to stably operate the thermophilic anaerobic digestion reactor using PLLA. [ABSTRACT FROM AUTHOR]

The enthalpy relaxation of poly(l-lactic acid) (PLLA) crystallized at 95 °C and 135 °C is compared with the behavior of a completely amorphous sample in the same undercooling conditions. The enthalpy loss (Δha) normalized to the mobile amorphous fraction has allowed to distinguish the PLLA samples crystallized at different temperatures. From the Tg values an almost unconstrained mobile amorphous fraction and a slightly constrained mobile amorphous fraction have been identified in PLLA crystallized at 135 °C and 95 °C, respectively. The normalized Δha data of the semi-crystalline samples have been found to deviate from the Δha values of the totally amorphous sample at high undercooling. This behavior has been rationalized by assuming that also the rigid amorphous fraction contributes to the structural relaxation process in the semi-crystalline samples through sub-segmental local motions. The experimental data suggest that the contribution of small-scale local motions to physical ageing becomes recognizable with reducing Ta, likely in parallel with the concomitant decrease in the cooperative segmental motions, which could be prevalent at low undercooling. [ABSTRACT FROM AUTHOR]

Two types of cellulose materials were utilized as filler in biodegradable polymer poly(L-lactic acid) (PLLA) to obtain new biocomposite materials with better properties. The physical properties of those biocomposite materials which include transparency, mechanical property, and thermal stability were investigated by using visual observation, dynamic mechanical analysis (DMA), and thermo-gravimetric analysis (TGA), respectively. In this study, two different particle sizes and crystallinity of cellulose were used to show the effect of particle size and crystallinity of cellulose filler on the properties of PLLA. The cellulose materials used in this research include the following: microcrystalline cellulose (MCC) from Avicel and cellulose fiber from rice straw biomass (CF-RS). The filler content in PLLA matrix was adjusted to be varied: 0 wt%, 2.5 wt%, 5 wt%, 7.5 wt%, and 10 wt%. The crystallinity of MCC and CF-RS measured by x-ray diffraction (XRD) shows the value of 70.25% and 34.9%, respectively. The transparency of PLLA/MCC and PLLA/CFRS biocomposite films decrease with the increase in cellulose filler content. However, the transparency of PLLA/MCC biocomposite films is better than that of PLLA/CF-RS biocomposite films because the particle size of MCC filler is smaller than that of CF-RS filler so that the dispersion of the MCC filler in PLLA matrix is also better. The mechanical property in term of tensile strength of two types of biocomposite films decrease with the increasing of cellulose content. The decrease in tensile strength after the addition of cellulose filler is due to the agglomeration of the filler since the adhesion between filler and polymer matrix is weaker than that between each of the filler. Because the dispersion of filler MCC in the PLLA matrix is better than that of filler CF-RS in PLLA matrix, the decrease in tensile strength value of PLLA/MCC films is not significant compare to that of PLLA/CF-RS films. Moreover, the high crystallinity of MCC also has contribution to the strength of biocomposite films. The thermal stability of PLLA enhance after the addition of cellulose filler. The films with CF-RS component show moderate thermal stability compare to the films with MCC component. For highest filler content, the percent weight residue at 400 °C of PLLA/MCC (90/10) and PLLA/CF-RS (90/10) films are 4.35 % and 10.47 %, respectively. [ABSTRACT FROM AUTHOR]

Microfibrillar composites (MFCs) from petrochemical-derived polymers have been investigated for several years and the technique can result in significant improvements in mechanical properties when compared with the neat matrix material of the respective composite. The current work applies the technique to biodegradable, biocompatible polymers for potential applications in bioabsorbable medical devices. MFCs were prepared from melt blended poly(L-lactic acid) (PLLA) and poly(glycolic acid) (PGA) via cold drawing then compression molding of extruded yarn. These MFCs were shown to have higher Young's moduli than that of neat PLLA but for load-bearing applications the creep characteristics are of interest. The MFC sheets resulting from compression molding were subjected to tensile relaxation tests at 37°C in the fiber orientation direction. Specimens were also tested via dynamic mechanical thermal analysis (DMTA). Neat PLLA specimens were subjected to the same tests for comparison. Results indicate that at 37°C PLLA/PGA MFCs exhibit lower creep resistance than that of neat PLLA due to the more rapid relaxation of stress observed. DMTA results elucidate the loss modulus changes in PLLA/PGA MFCs which occur as the material approaches the glass transition temperature of PGA (~45°C). [ABSTRACT FROM AUTHOR]

We designed a new polymer film transducer that can generate a surface acoustic wave. The transducer is fabricated by rolling a piezoelectric poly(l-lactic acid) (PLLA) film into a long thin roll (PLLA film roll transducer). The PLLA film roll transducer induced the rotation of an object placed its the upper end face via the torque caused by the generated surface acoustic wave. Moreover, a noteworthy experimental result is that the clockwise and counterclockwise rotation of the object can be freely controlled by changing the frequency of the ac voltage applied to the PLLA film roll transducer. We emphasize that no special complex mechanical parts were used in this study. [ABSTRACT FROM PUBLISHER]