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

Abstract

Abstract. 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-Al 2 O 3 ) 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-Al 2 O 3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol) than that from γ-Al 2 O 3 (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 polymerizationshowed 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.

Cu(II) Ions Adsorption Using Activated Carbon Prepared from Pithecellobium Jiringa (Jengkol) Shells With Ultrasonic Assistance: Isotherm, Kinetic and Thermodynamic Studies

“…As can be seen in Figure 1, the raw PJS had 8 functional groups. Two bands at a wavenumber of approximately 3635-3765 cm -1 with peaks at 3732 and 3645 cm -1 were assigned to O-H stretching of hydroxyl groups [17,26,34,35]. These bands had the highest transmittance compared to the other groups, i.e.…”

Active Nanointerfaces Based on Enzyme Carbonic Anhydrase and Metal–Organic Framework for Carbon Dioxide Reduction

“…The hypothesis is supported by previous studies demonstrating that metal oxides can be used as metal sources for ZIF-8 formation [ 71 ], while ZrO 2 can be used for UiO-66 [ 72 ] synthesis, as well as other reports [ 67 , 73 ] that showed the ability of porous Al 2 O 3 filters to be modified with organic chemicals such as dopamine through a hydroxide-induced covalent reaction [ 67 ]. Furthermore, previous studies showed that a filter’s well-developed porosity and relatively high surface area, large pore volume, and abundant weak Lewis acid sites are essential to promote direct attachment of active molecules [ 74 , 75 ] (here, the FDCA). Such active molecules were further able to incorporate and disperse well into the individual filters’ channels to thus serve as active catalytic species [ 76 ]; such species are all needed for the MIL-160 formation.…”

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

“…The solution within the polymerization reactor was continuously stirred at a speed of 100 rpm and at temperature of 180 °C for 5 hours. A similar experimental set up and operating conditions were reported in our previous research paper [10].…”