Banded spherulites in poly(L-lactic acid): Effects of the crystallization temperature and molecular weight

2007 ◽  
Vol 105 (6) ◽  
pp. 3500-3504 ◽  
Author(s):  
Yaming Wang ◽  
João F. Mano
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Crystallization Temperature ◽  
Banded Spherulites

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.

Study on the Preparation and Characterization of Carboxyl Terminated Poly(L-Lactic Acid) (PLLA) Prepolymers

2017 ◽  
Vol 872 ◽  
pp. 165-170
Author(s):  
Shi Chao Lu ◽  
Yang Chuan Ke ◽  
Qian Zhou ◽  
Zhao Rui Meng ◽  
Guo Liang Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Average Molecular Weight ◽  
Polymerization Temperature ◽  
Capping Agent ◽  
Molar Amount ◽  
Optimum Reaction ◽  
Catalyst Content ◽  
End Capping

The carboxyl terminated poly (L-lactic acid) (PLLA) prepolymers were prepared via polycondensation of L-lactic acid and 1,6-adipic acid (end capping agent) under the catalyst of stannous octoate. The effects of synthetic condition, such as reaction temperature, amount of catalyst, content of the end capping agent, etc, on the molecular weight of PLLA were discussed. Fourier transform infrared and 1H nuclear magnetic resonance were used to characterize the PLLA prepolymers. The results indicated that the polycondensation was performed under an optimum reaction condition as following: the amount of the catalyst was 500 ppm based on the mass of lactic acid, the amount of the end capping agent was 1% (the molar amount of the lactic acid), and the polymerization temperature was 170 °C. The viscosity-average molecular weight of the product reached 2.826×104 at this polymerization temperature and the yield was 73.34%.

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 Texture Induced by Molecular Weight Dispersity: Polymorphism within Poly(L-lactic acid) Spherulites

2020 ◽  
Vol 38 (12) ◽  
pp. 1365-1373
Author(s):  
Da-Peng Hu ◽  
Min Chen ◽  
Yu-Hui Yang ◽  
Han-Ying Li
Keyword(s):  
Molecular Weight ◽  
Lactic Acid
Sign in / Sign up

Export Citation Format

Share Document