scholarly journals Glycerolysis of Poly(lactic acid) as a Way to Extend the “Life Cycle” of This Material

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1963 ◽  
Author(s):  
Marcin Borowicz ◽  
Joanna Paciorek-Sadowska ◽  
Marek Isbrandt ◽  
Łukasz Grzybowski ◽  
Bogusław Czupryński
Keyword(s):  
Lactic Acid ◽  
Life Cycle ◽  
Raw Materials ◽  
Gel Permeation Chromatography ◽  
Acid Value ◽  
Economic Losses ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Economic Point

The article concerns the use of glycerolysis reaction as an alternative method of processing post-production and post-consumer waste from poly(lactic acid) (PLA). Management of waste is a very important issue from an environmental protection and economic point of view. Extending the “life cycle” of PLA is extremely important because it allows to make the most of this material. It also limits economic losses resulting from its disposal in the biodegradation process at the same time. This paper presents a method of glycerolysis of poly(lactic acid) waste using various amounts of anhydrous glycerol (mass ratio from 0.3 to 0.5 parts by weight of glycerol per 1.0 part by weight of PLA). This process was also carried out for pure, unmodified PLA Ingeo® (from NatureWorks) to compare the obtained results. The six liquid oligomeric polyhydric alcohols were obtained as a result of the synthesis. Then, they were subjected to physicochemical tests such as determination of color, smell, density, viscosity, and pH. In addition, the obtained raw materials were subjected to analytical tests such as determination of the hydroxyl value, acid value, water content, and elemental composition. The average molecular weights and dispersity were also tested by gel permeation chromatography (GPC). The assumed chemical structure of the obtained compounds was confirmed by spectroscopic methods such as FTIR, 1H NMR, 13C NMR. Glycerolysis products were also subjected to differential scanning calorimetry (DSC) to determine thermal parameters. The obtained research results have allowed the precise characterization of newly obtained products and determination of their suitability, e.g., for the synthesis of polyurethane (PUR) materials.

scholarly journals Feasibility of Reprocessing Natural Fiber Filled Poly(lactic acid) Composites: An In-Depth Investigation

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Sujal Bhattacharjee ◽  
Dilpreet S. Bajwa
Keyword(s):  
Lactic Acid ◽  
Natural Fiber ◽  
Environmental Concern ◽  
Wood Flour ◽  
Gel Permeation Chromatography ◽  
Thermomechanical Properties ◽  
Poly Lactic Acid ◽  
Filler Concentration ◽  
Scanning Calorimetry ◽  
Abrupt Decrease

Poly(lactic acid) (PLA) based composites are biodegradable; their disposal after single use may be needless and uneconomical. Prodigal disposal of these composites could also create an environmental concern and additional demand for biobased feedstock. Under these circumstances, recycling could be an effective solution, since it will widen the composite service life and prevent the excessive use of natural resources. This research investigates an in-depth impact of recycling on the mechanical and thermomechanical properties of oak wood flour based PLA composites. Two composite formulations (30 and 50 wt% filler), each with 3 wt% coupling agent (PLA-g-MA), were produced and reprocessed six times by extrusion followed by injection molding. Measurements of fiber length and molecular weight of polymer were, respectively, carried out by gel permeation chromatography (GPC). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) tools were used to study morphological and molecular alterations. With consecutive recycling, PLA composites showed a gradual decrease in strength and stiffness properties and an increase in strain properties. The 50% and 30% filler concentration of fibers in the composite showed an abrupt decrease in strength properties after six and two reprocessing cycles, respectively.

Structure and properties of poly(lactic acid)/poly(lactic acid)-α-cyclodextrin inclusion compound composites

2017 ◽  
Vol 37 (9) ◽  
pp. 897-909
Author(s):  
Li Zhang ◽  
Weijun Zhen ◽  
Yufang Zhou
Keyword(s):  
Lactic Acid ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Polymerization Temperature ◽  
Scanning Calorimetry ◽  
Synthesis Conditions ◽  
Cyclodextrin Inclusion ◽  
Comprehensive Performance

Abstract Poly(lactic acid) (PLA) was synthesized using a green catalyst, nano-zinc oxide (ZnO). The optimum synthesis conditions of PLA were as follows: a stoichiometric amount of 0.5 wt% of nano-ZnO, polymerization time of 14 h, and polymerization temperature of 170°C. Gel permeation chromatography results showed that the weight-average molecular weight (Mw) of PLA was 13,072 g/mol with a polydispersity index (PDI) of 1.7. Furthermore, PLA-α-cyclodextrin inclusion compounds (PLA-CD-ICs) were prepared by ultrasonic co-precipitation techniques. X-ray diffraction analysis and Fourier transform infrared spectroscopy demonstrated the change in lattice of α-CD from a cage configuration to a tunnel structure and the existence of some physical interactions between α-CD and PLA in the PLA-CD-ICs. To enhance the crystallization properties of PLA, PLA/PLA-CD-IC composites were blended with different contents of PLA-CD-ICs as nucleating agents. The crystallization behavior and comprehensive performance were investigated by differential scanning calorimetry, polarized optical microscopy, tensile testing, dynamic mechanical analysis, and scanning electron microscopy. Compared to PLA, the crystallinities of PLA/PLA-CD-IC composites were increased by 24.0%, 26.3%, 27.3%, and 31.8%. The results of all the analyses proved that PLA-CD-ICs were useful as green organic nucleators and improved the comprehensive performance of PLA materials.

The Influence of Amount of Succinic Anhydride in Chain Extension Reaction on Increasing Molecular Weight of Poly(lactic acid)

2013 ◽  
Vol 747 ◽  
pp. 148-152
Author(s):  
Chaichana Piyamawadee ◽  
Duangdao Aht-Ong
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Succinic Anhydride ◽  
Gel Permeation Chromatography ◽  
Chain Extension ◽  
Proton Nuclear Magnetic Resonance ◽  
Poly Lactic Acid ◽  
Condensation Polymerization ◽  
Scanning Calorimetry ◽  
Molar Ratios

High molecular weight PLA was successfully synthesized by chain extension reaction of hydroxylated prepolymer using succinic anhydride as a chain extender. Hydroxylated prepolymer was prepared by direct condensation polymerization of L-lactic acid in the presence of 1,4-butanediol. Various molar ratios between hydroxylated prepolymer and succinic anhydride (i.e, 1:1, 1:2, 1:3) were investigated. The results showed that succinic anhydride can help increasing molecular weight of hydroxylated prepolymer approximately up to 47% as characterized by gel permeation chromatography (GPC) technique. Proton nuclear magnetic resonance (1H-NMR) was used to investigate structure of chain-extended PLA. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine thermal properties while the crystallinity was investigated by X-ray diffraction (XRD).

scholarly journals High-Toughness Poly(lactic Acid)/Starch Blends Prepared through Reactive Blending Plasticization and Compatibilization

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5951
Author(s):  
Huan Hu ◽  
Ang Xu ◽  
Dianfeng Zhang ◽  
Weiyi Zhou ◽  
Shaoxian Peng ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Performance Test ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Amorphous Region ◽  
Poly Lactic Acid ◽  
Esterification Reaction ◽  
Melt Blending ◽  
Scanning Calorimetry ◽  
Starch Blends

In this study, poly(lactic acid) (PLA)/starch blends were prepared through reactive melt blending by using PLA and starch as raw materials and vegetable oil polyols, polyethylene glycol (PEG), and citric acid (CA) as additives. The effects of CA and PEG on the toughness of PLA/starch blends were analyzed using a mechanical performance test, scanning electron microscope analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, rheological analysis, and hydrophilicity test. Results showed that the elongation at break and impact strength of the PLA/premixed starch (PSt)/PEG/CA blend were 140.51% and 3.56 kJ·m−2, which were 13.4 and 1.8 times higher than those of pure PLA, respectively. The essence of the improvement in the toughness of the PLA/PSt/PEG/CA blend was the esterification reaction among CA, PEG, and starch. During the melt-blending process, the CA with abundant carboxyl groups reacted in the amorphous region of the starch. The shape and crystal form of the starch did not change, but the surface activity of the starch improved and consequently increased the adhesion between starch and PLA. As a plasticizer for PLA and starch, PEG effectively enhanced the mobility of the molecular chains. After PEG was dispersed, it participated in the esterification reaction of CA and starch at the interface and formed a branched/crosslinked copolymer that was embedded in the interface of PLA and starch. This copolymer further improved the compatibility of the PLA/starch blends. PEGs with small molecules and CA were used as compatibilizers to reduce the effect on PLA biodegradability. The esterification reaction on the starch surface improved the compatibilization and toughness of the PLA/starch blend materials and broadens their application prospects in the fields of medicine and high-fill packaging.

scholarly journals Properties and Degradation Performances of Biodegradable Poly(lactic acid)/Poly(3-hydroxybutyrate) Blends and Keratin Composites

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2693
Author(s):  
Martin Danko ◽  
Katarína Mosnáčková ◽  
Anna Vykydalová ◽  
Angela Kleinová ◽  
Andrea Puškárová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microbial Growth ◽  
Hydrolytic Degradation ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Environmental Aspects ◽  
Scanning Calorimetry ◽  
Biodegradable Poly ◽  
Basic Hydrolysis

From environmental aspects, the recovery of keratin waste is one of the important needs and therefore also one of the current topics of many research groups. Here, the keratin hydrolysate after basic hydrolysis was used as a filler in plasticized polylactic acid/poly(3-hydroxybutyrate) blend under loading in the range of 1–20 wt%. The composites were characterized by infrared spectroscopy, and the effect of keratin on changes in molar masses of matrices during processing was investigated using gel permeation chromatography (GPC). Thermal properties of the composites were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of keratin loading on the mechanical properties of composite was investigated by tensile test and dynamic mechanical thermal analysis. Hydrolytic degradation of matrices and composites was investigated by the determination of extractable product amounts, GPC, DSC and NMR. Finally, microbial growth and degradation were investigated. It was found that incorporation of keratin in plasticized PLA/PHB blend provides material with good thermal and mechanical properties and improved degradation under common environmental conditions, indicating its possible application in agriculture and/or packaging.

scholarly journals Preparation, Mechanical, and Thermal Properties of Biodegradable Polyesters/Poly(Lactic Acid) Blends

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Zhao ◽  
Wanqiang Liu ◽  
Qingsheng Wu ◽  
Jie Ren
Keyword(s):  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Biodegradable Polyesters ◽  
H Nmr ◽  
Melt Polycondensation ◽  
Twin Screw

Series of biodegradable polyesters poly(butylene adipate) (PBA), poly(butylene succinate) (PBS), and poly(butylene adipate-co-butylene terephthalate) (PBAT) were synthesized successfully by melt polycondensation. The polyesters were characterized by Fourier transform infrared spectroscopy (FTIR),1H-NMR, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively. The blends of poly(lactic acid) (PLA) and biodegradable polyester were prepared using a twin screw extruder. PBAT, PBS, or PBA can be homogenously dispersed in PLA matrix at a low content (5–20 wt%), yielding the blends with much higher elongation at break than homo-PLA. DSC analysis shows that the isothermal and nonisothermal crystallizabilities of PLA component are promoted in the presence of a small amount of PBAT.

Processing and characterization of poly(lactic acid) blended with polycarbonate and chain extender

2014 ◽  
Vol 34 (7) ◽  
pp. 665-672 ◽  
Author(s):  
Yottha Srithep ◽  
Wuttipong Rungseesantivanon ◽  
Bongkot Hararak ◽  
Krisda Suchiva
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Chain Extender ◽  
Chain Extension ◽  
Morphological Properties ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Commercial Applications ◽  
A Chain

Abstract Currently, use of poly(lactic acid) (PLA) is limited for commercial applications because it has a low heat resistance. In this research, an increase of over 40°C heat distortion temperature (HDT) of PLA alloy was obtained by blending PLA with polycarbonate (PC) and a chain extender (CE). Molecular weight, thermal, mechanical and morphological properties of PLA and PC blend with different CE contents were investigated. Gel permeation chromatography (GPC) results showed that some PLA-PC copolymers were produced and the compatibility of the PLA phase and in the PC phase was improved via the chain extension reaction. In addition, the reaction induced by CE also affected the crystallization behaviors of PLA, as observed from differential scanning calorimetry (DSC) results and the enthalpy of melting of PLA decreased with increasing CE content. The combined effects of the CE increasing molecular weight, improving compatibility and limiting the crystallization behavior of PLA/PC alloy greatly improved the HDT.

Development of three-dimensional printing filaments based on poly(lactic acid)/hydroxyapatite composites with potential for tissue engineering

2021 ◽  
pp. 002199832098856
Author(s):  
Marcela Piassi Bernardo ◽  
Bruna Cristina Rodrigues da Silva ◽  
Luiz Henrique Capparelli Mattoso
Keyword(s):  
Tissue Engineering ◽  
Lactic Acid ◽  
Fused Deposition Modeling ◽  
Three Dimensional ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Three Dimensional Printing ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
3D Printed

Injured bone tissues can be healed with scaffolds, which could be manufactured using the fused deposition modeling (FDM) strategy. Poly(lactic acid) (PLA) is one of the most biocompatible polymers suitable for FDM, while hydroxyapatite (HA) could improve the bioactivity of scaffold due to its chemical composition. Therefore, the combination of PLA/HA can create composite filaments adequate for FDM and with high osteoconductive and osteointegration potentials. In this work, we proposed a different approache to improve the potential bioactivity of 3D printed scaffolds for bone tissue engineering by increasing the HA loading (20-30%) in the PLA composite filaments. Two routes were investigated regarding the use of solvents in the filament production. To assess the suitability of the FDM-3D printing process, and the influence of the HA content on the polymer matrix, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were performed. The HA phase content of the composite filaments agreed with the initial composite proportions. The wettability of the 3D printed scaffolds was also increased. It was shown a greener route for obtaining composite filaments that generate scaffolds with properties similar to those obtained by the solvent casting, with high HA content and great potential to be used as a bone graft.

Properties of poly(lactic acid)/montmorillonite/carbon nanotubes nanocomposites: determination of percolation threshold

2021 ◽  
Author(s):  
Olawale Monsur Sanusi ◽  
Abdelkibir Benelfellah ◽  
Lazaros Papadopoulos ◽  
Zoe Terzopoulou ◽  
Dimitrios N. Bikiaris ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Lactic Acid ◽  
Percolation Threshold ◽  
Poly Lactic Acid

scholarly journals Preparations of Poly(lactic acid) Dispersions in Water for Coating Applications

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2767
Author(s):  
Giada Belletti ◽  
Sara Buoso ◽  
Lucia Ricci ◽  
Alejandro Guillem-Ortiz ◽  
Alejandro Aragón-Gutiérrez ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Sem Analysis ◽  
Water Phase ◽  
Poly Lactic Acid ◽  
Water Emulsion ◽  
Preparation Conditions ◽  
Ft Ir ◽  
Homogenization Methods ◽  
Oil In Water Emulsion

A green, effective methodology for the preparation of water-based dispersions of poly(lactic acid) (PLA) for coating purposes is herein presented. The procedure consists of two steps: in the first one, an oil-in-water emulsion is obtained by mixing a solution of PLA in ethyl acetate with a water phase containing surfactant and stabilizer. Different homogenization methods as well as oil/water phase ratio, surfactant and stabilizer combinations were screened. In the second step, the quantitative evaporation of the organic provides water dispersions of PLA that are stable, at least, over several weeks at room temperature or at 4 °C. Particle size was in the 200–500 nm range, depending on the preparation conditions, as confirmed by scanning electron microscope (SEM) analysis. PLA was found not to suffer significant molecular weight degradation by gel permeation chromatography (GPC) analysis. Furthermore, two selected formulations with glass transition temperature (Tg) of 51 °C and 34 °C were tested for the preparation of PLA films by drying in PTFE capsules. In both cases, continuous films that are homogeneous by Fourier-transform infrared spectroscopy (FT-IR) and SEM observation were obtained only when drying was performed above 60 °C. The formulation with lower Tg results in films which are more flexible and transparent.

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