scholarly journals Improving Recycled Poly(lactic Acid) Biopolymer Properties by Chain Extension Using Block Copolymers Synthesized by Nitroxide-Mediated Polymerization (NMP)

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2791
Author(s):  
Juan José Benvenuta-Tapia ◽  
Pascale Champagne ◽  
José Alfredo Tenorio-López ◽  
Eduardo Vivaldo-Lima ◽  
Ramiro Guerrero-Santos
Keyword(s):  
Lactic Acid ◽  
Block Copolymers ◽  
Molar Mass ◽  
Average Molecular Weight ◽  
Melt Processing ◽  
Cold Crystallization ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Chain Extenders ◽  
Nitroxide Mediated Polymerization

The aim of this contribution is to assess the use poly(styrene-co-glycidyl methacrylate-b-styrene) copolymers synthesized by nitroxide mediated polymerization (NMP) as chain extenders in the recycling of poly(lactic acid) biopolyester. Concisely, the addition of such block copolymers during the melt processing of recycled poly(lactic acid) (rPLA) leads to important increases in the viscosity average molecular weight of modified polymeric materials. Molar masses increase from 31,000 g/mol for rPLA to 48,000 g mol−1 for the resulting rPLA/copolymer blends (bPLA). Fortuitously, this last value is nearly the same as the one for pristine PLA, which constitutes a first piece of evidence of the molar mass increase of the recycled biopolymer. Thermograms of chain extended rPLA show significant decreases in cold crystallization temperature and higher crystallinity degrees due to the chain extension process using NMP-synthesized copolymers. It was found that increasing epoxide content in the NMP-synthesized copolymers leads to increased degrees of crystallinity and lower cold crystallization temperatures. The rheological appraisal has shown that the addition of NMP synthesized copolymers markedly increases complex viscosity and elastic modulus of rPLA. Our results indicate that P(S-co-GMA)-b-S) copolymers act as efficient chain extenders of rPLA, likely due to the reaction between the epoxy groups present in P(S-co-GMA)-b-PS and the carboxyl acid groups present in rPLA. This reaction positively affects viscometric molar mass of PLA and its performance.

scholarly journals Preparation of Higher Molecular Weight Poly (L-lactic Acid) by Chain Extension

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Chenguang Liu ◽  
Yuliang Jia ◽  
Aihua He
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Average Molecular Weight ◽  
Hexamethylene Diisocyanate ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Weight Changes ◽  
H Nmr ◽  
Left Handed ◽  
Ft Ir

High molecular weight poly (lactic acid) (PLA) was obtained by chain extending with hexamethylene diisocyanate (HDI). The influences of the amount of chain extender, reaction time, and molecular weight changes of prepolymers on the poly(lactic acid) were investigated. PLA prepolymer with a viscosity, average molecular weight (Mη) of 2 × 104 g/mol was synthesized froml-lactide using stannous octoate as the catalyst. After 20 min of chain extension at 175°C, the resulting polymer hadMwof 20.3 × 104 g/mol andMnof 10.5 × 104 g/mol. Both FT-IR and1H-NMR verified that the structure of PLA did not change either before chain extending or after. The optically active characterized that the chain extending-product was left handed. DSC and XRD results showed that both theTgand the crystallinity of PLA were lowered by chain-extension reaction. The crystalline transformation happened in PLA after chain extending, crystallineα′form toαform.

scholarly journals Influence of melt processing conditions on poly(lactic acid) degradation: Molar mass distribution and crystallization

2014 ◽  
Vol 110 ◽  
pp. 353-363 ◽  
Author(s):  
Pierre Erwan Le Marec ◽  
Laurent Ferry ◽  
Jean-Christophe Quantin ◽  
Jean-Charles Bénézet ◽  
Frédéric Bonfils ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Mass Distribution ◽  
Molar Mass ◽  
Melt Processing ◽  
Molar Mass Distribution ◽  
Poly Lactic Acid ◽  
Processing Conditions ◽  
Acid Degradation

scholarly journals Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties—From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1822
Author(s):  
Evangelia Balla ◽  
Vasileios Daniilidis ◽  
Georgia Karlioti ◽  
Theocharis Kalamas ◽  
Myrika Stefanidou ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Plastic Pollution ◽  
Practical Applications ◽  
Decomposition Reactions ◽  
Melt Polycondensation ◽  
Polymerization Conditions ◽  
Molecular Weight Increase

Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000–50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review.

Thermal degradation kinetics of Opuntia Ficus Indica flour and talc-filled poly (lactic acid) hybrid biocomposites by TGA analysis

2021 ◽  
pp. 002199832110082
Author(s):  
Azzeddine Gharsallah ◽  
Abdelheq Layachi ◽  
Ali Louaer ◽  
Hamid Satha
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Melt Processing ◽  
Thermal Degradation Kinetics ◽  
Poly Lactic Acid ◽  
Opuntia Ficus Indica ◽  
Model Free

This paper reports the effect of lignocellulosic flour and talc powder on the thermal degradation behavior of poly (lactic acid) (PLA) by thermogravimetric analysis (TGA). Lignocellulosic flour was obtained by grinding Opuntia Ficus Indica cladodes. PLA/talc/ Opuntia Ficus Indica flour (OFI-F) biocomposites were prepared by melt processing and characterized using Wide-angle X-ray scattering (WAXS) and Scanning Electron Microscope (SEM). The thermal degradation of neat PLA and its biocomposites can be identified quantitatively by solid-state kinetics models. Thermal degradation results on biocomposites compared to neat PLA show that talc particles at 10 wt % into the PLA matrix have a minor impact on the thermal stability of biocomposites. Loading OFI-F and Talc/OFI-F mixture into the PLA matrix results in a decrease in the maximum degradation temperature, which means that the biocomposites have lower thermal stability. The activation energies (Ea) calculated by the Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) model-free approaches and by model-fitting (Kissinger method and Coats-Redfern method) are in good agreement with one another. In addition, in this work, the degradation mechanism of biocomposites is proposed using Coats-Redfern and Criado methods.

Microcellular foaming of poly(lactic acid) branched with food‐grade chain extenders

2021 ◽  
Vol 138 (29) ◽  
pp. 50686
Author(s):  
Krishnaa B. Venkatesan ◽  
Sonal S. Karkhanis ◽  
Laurent M. Matuana
Keyword(s):  
Lactic Acid ◽  
Poly Lactic Acid ◽  
Food Grade ◽  
Microcellular Foaming ◽  
Chain Extenders

Incorporation of an antibiotic in poly(lactic acid) and polypropylene by melt processing

2016 ◽  
Vol 14 (3) ◽  
pp. 0-0 ◽  
Author(s):  
Roberto Scaffaro ◽  
Luigi Botta ◽  
Andrea Maio ◽  
Giuseppe Gallo
Keyword(s):  
Lactic Acid ◽  
Melt Processing ◽  
Poly Lactic Acid

scholarly journals Synthesis of polylactic acid-diol (PLA-diol) from lactic acid and 1,4-butanediol

2016 ◽  
Vol 19 (4) ◽  
pp. 58-65
Author(s):  
Ha Thi Thai La
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Polyethylene Glycol ◽  
1H Nmr ◽  
Biodegradable Polymer ◽  
Average Molecular Weight ◽  
Chain Extension ◽  
Structure And Properties ◽  
Chain Reaction ◽  
A Chain

In this research, the PLA-diol were synthesized from lactic acid (LA) and 1.4 butanediols (BD) with a tin octoate Sn(Oct)2 catalyst at a temperature of 180 °C and the pressure 5 mmHg. The structure and properties of PLA-diol are analyzed by the following methods: GPC, 1H-NMR and DSC. As a result, with the change in the content of Sn (Oct)2 from 0.1 to 1.0%, the molecular weight Mn of PLA - diol increased gradually from 4.119,2 to 7.359,6 g / mol . In addition, the BD content increased from 2.0% to 5.0%, the average molecular weight of the product decreased gradually from 7.536,9 g / mol to 4.735 g / mol, respectively. This change will affect the ability to use PLA-diol in the next denaturation research to apply in the field of biodegradable polymer such as copolymer with polyurethane, copolymer with polyethylene glycol diacid, or chain extension with other polymer in a chain reaction,...

scholarly journals Crystallization, Structure and Significantly Improved Mechanical Properties of PLA/PPC Blends Compatibilized with PLA-PPC Copolymers Produced by Reactions Initiated with TBT or TDI

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3245
Author(s):  
Lixin Song ◽  
Yongchao Li ◽  
Xiangyu Meng ◽  
Ting Wang ◽  
Ying Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Average Molecular Weight ◽  
Toluene Diisocyanate ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Cooling Process ◽  
Material Degradation ◽  
Elongation At Break ◽  
Poly Propylene

Poly (lactic acid) (PLA)-Poly (propylene carbonate) (PPC) block copolymer compatibilizers are produced in incompatible 70wt%PLA/PPC blend by initiating transesterification with addition of 1% of tetra butyl titanate (TBT) or by chain extension with addition of 2% of 2,4-toluene diisocyanate (TDI). The above blends can have much better mechanical properties than the blend without TBT and TDI. The elongation at break is dramatically larger (114% with 2% of TDI and 60% with 1% of TBT) than the blend without TDI and TBT, with a slightly lower mechanical strength. A small fraction of the copolymer is likely formed in the PLA/PPC blend with addition of TBT, and a significant amount of the copolymer can be made with addition of TDI. The copolymer produced with TDI has PPC as a major content (~70 wt%) and forms a miscible interphase with its own Tg. The crystallinity of the blend with TDI is significantly lower than the blend without TDI, as the PLA blocks of the copolymer in the interphase is hardly to crystallize. The average molecular weight increases significantly with addition of TDI, likely compensating the lower mechanical strength due to lower crystallinity. Material degradation can occur with addition of TBT, but it is very limited with 1% of TBT. However, compared with the blends without TBT, the PLA crystallinity of the blend with 1%TBT increases sharply during the cooling process, which likely compensates the loss of mechanical strength due to the slightly material degradation. The added TDI does not have any significant impact on PLA lamellar packing, but the addition of TBT can make PLA lamellar packing much less ordered, presumably resulted from much smaller PPC domains formed in the blend due to better compatibility.

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