Improvement of Properties of Poly(L-lactic acid) through Solution Blending of Biodegradable Polymers

This study concerns the improvement and enhancement of the properties of poly(l-lactic acid) (PLLA) through simple solution blending of pure PLLA with different kinds of biodegradable polymers. Synthesized PLLA was blended with synthesized poly(d,l-lactic acid) (PDLLA) or poly(ethylene glycol) (PEG) at various composition ratios in a solvent mixture of dichloromethane/ethanol at room temperature to produce dipolymer. The polymer-blend properties were analyzed using FTIR, DSC, UTM data and an enzymatic degradation test was conducted. It was found that PLLA blend films were obtained with limitation of the second polymer content up to 20% (w) through solvent casting. From the DSC data, two different melting temperature peaks showed that stereocomplex formation occurred during polymer precipitation for all PLLA/PDLLA blends, while only one single melting temperature peak appeared in the PLLA/PEG blend. Regarding the mechanical properties, the PLLA/PEG blend showed better performance with an improvement of the mechanical strength by around 11.18% and an improvement of the elongation at break by around 89% compared to pure PLLA. Furthermore, after the 48-hour enzymatic biodegradability test, the PLLA/PEG blends showed improvement of biodegradability with 21.88% of sample weight-loss compared to 2.53% for pure PLLA

Molecular Weight and Structural Properties of Biodegradable PLA Synthesized with Different Catalysts by Direct Melt Polycondensation

Production of biodegradable polylactic acid (PLA) from biomassbased lactic acid is widely studied for substituting petro-based plastics or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst, γ-aluminium(III) oxide (γ-Al2O3) or zinc oxide (ZnO), in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol) than that from γ-Al2O3 (81,400 g/mol). The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods – polycondensation and ring opening polymerization –showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as –OH vibration peak and at 1,750 cm-1 as –C=O carbonyl vibrational peak

Structure-property relationships of iron-hydroxyapatite ceramic matrix nanocomposite fabricated using mechanosynthesis method

Hydroxyapatite (HAp) is an attractive bioceramics due to its similar composition to bone mineral and its ability to promote bone-implant interaction. However, its low strength has limited its application as load bearing implants. This paper presented a work focusing on the improvement of HAp mechanical property by synthesizing iron (Fe)-reinforced bovine HAp nanocomposite powders via mechanosynthesis method. The synthesis process was performed using high energy milling at varied milling time (3, 6, 9, and 12 h). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM). Its mechanical properties were investigated by micro-Vicker's hardness and compression tests. Results showed that milling time directly influenced the characteristics of the nanocomposite powders. Amorphous BHAp was formed after 9 and 12 h milling in the presence of HPO4 2 - ions. Continuous milling has improved the crystallinity of Fe without changing the HAp lattice structure. The nanocomposite powders were found in spherical shape, agglomerated and dense after longer milling time. The hardness and Young's modulus of the nanocomposites were also increased at 69% and 66%, respectively, as the milling time was prolonged from 3 to 12 h. Therefore, the improvement of the mechanical properties of nanocomposite was attributed to high Fe crystallinity and homogenous, dense structure produced by mechanosynthesi

Lipoprotein (a) and Arterial Stiffness in Patients with Diabetes Mellitus

Background: Type 2 Diabetes Mellitus (T2DM) increases morbidity and mortality of cardiovascular disease including atherosclerotic complications. The pathogenesis of atherosclerosis in T2DM is primarily due to changes in lipid profiles and lipoproteins. High levels of lipoprotein (a)/Lp (a) are known to be a risk factor for atherosclerosis. However, the correlation between Lp (a) levels and arterial stiffness has not been widely known. Objectives: To determine the correlation between Lp (a) and arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV) in patients with T2DM in Endocrine Metabolic and Diabetes Unit of RSUD Dr. Soetomo Teaching Surabaya. Methods: The cross-sectional observational analytical research was conducted on T2DM patients aged ≥45 in Endocrine Metabolic and Diabetes Unit of Dr. Soetomo Teaching Hospital from June 2015 to August 2015. T2DM was determined based on the American Diabetes Association (ADA) 2014 criteria. Lp (a) was measured using Latex agglutination testand arterial stiffness was measured by baPWV. Results: Among 39 T2DM patients, 25.6% had Lp (a) ≥30 mg/dL with mean of Lp (a) levels of 21.66±18.67 mg/dL and 94.9% of patients had the mean of baPWV of 16.61±2.57 cm/s. The correlation result of Lp (a) and baPWV showed p = 0.88 and r = 0.026. Conclusion: There was no correlation between Lp (a) and arterial stiffness (using baPWV measurement) in patients with T2D

Synthesis of bovine hydroxyapatite-iron composite via dry mechanochemical process for biodegradable bone scaffolds

Hydroxyapatite (HAp) is widely used in orthopedic and dental surgeries [1]. This study aims to synthesize a Fe-reinforced natural HAp composite via dry mechanochemical process without chemical addition. An improvement to the mechanical strength and cytocompatibility is expected with the presence of Fe ions in the HAp structure

Improvement of Properties of Poly(L-lactic acid) through Solution Blending of Biodegradable Polymers

This study concerns the improvement and enhancement of the properties of poly(l-lactic acid) (PLLA) through simple solution blending of pure PLLA with different kinds of biodegradable polymers. Synthesized PLLA was blended with synthesized poly(d,l-lactic acid) (PDLLA) or poly(ethylene glycol) (PEG) at various composition ratios in a solvent mixture of dichloromethane/ethanol at room temperature to produce dipolymer. The polymer-blend properties were analyzed using FTIR, DSC, UTM data and an enzymatic degradation test was conducted. It was found that PLLA blend films were obtained with limitation of the second polymer content up to 20% (w) through solvent casting. From the DSC data, two different melting temperature peaks showed that stereocomplex formation occurred during polymer precipitation for all PLLA/PDLLA blends, while only one single melting temperature peak appeared in the PLLA/PEG blend. Regarding the mechanical properties, the PLLA/PEG blend showed better performance with an improvement of the mechanical strength by around 11.18% and an improvement of the elongation at break by around 89% compared to pure PLLA. Furthermore, after the 48-hour enzymatic biodegradability test, the PLLA/PEG blends showed improvement of biodegradability with 21.88% of sample weight-loss compared to 2.53% for pure PLLA

Improvement of Properties of Poly(L-lactic acid) through Solution Blending of Biodegradable Polymers

This study concerns the improvement and enhancement of the properties of poly(l-lactic acid) (PLLA) through simple solution blending of pure PLLA with different kinds of biodegradable polymers. Synthesized PLLA was blended with synthesized poly(d,l-lactic acid) (PDLLA) or poly(ethylene glycol) (PEG) at various composition ratios in a solvent mixture of dichloromethane/ethanol at room temperature to produce dipolymer. The polymer-blend properties were analyzed using FTIR, DSC, UTM data and an enzymatic degradation test was conducted. It was found that PLLA blend films were obtained with limitation of the second polymer content up to 20% (w) through solvent casting. From the DSC data, two different melting temperature peaks showed that stereocomplex formation occurred during polymer precipitation for all PLLA/PDLLA blends, while only one single melting temperature peak appeared in the PLLA/PEG blend. Regarding the mechanical properties, the PLLA/PEG blend showed better performance with an improvement of the mechanical strength by around 11.18% and an improvement of the elongation at break by around 89% compared to pure PLLA. Furthermore, after the 48-hour enzymatic biodegradability test, the PLLA/PEG blends showed improvement of biodegradability with 21.88% of sample weight-loss compared to 2.53% for pure PLLA