Effects of molecular weight and catalyst on stereoblock formation via solid state polycondensation of poly(lactic acid)

Kanno, Tomonari; Oyama, Hideko T.; Usugi, Shin‐ichi

doi:10.1016/j.eurpolymj.2014.02.006

Cited by 8 publications

(11 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…and therefore has been regarded as the most promising biodegradable polymer materials with environmentally benign features. PLA has broad applications, e.g., in preparation of biodegradable fibers and plastic parts, drug sustained‐release material, surgical suture, scaffolds, and ophthalmic materials, etc . In the biomedical area, PLA indeed shows some important application prospects.…”

Section: Introductionmentioning

confidence: 99%

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

Liu

Chen

Ding

2016

J of Applied Polymer Sci

View full text Add to dashboard Cite

The novel inorganic SiO 2 -MgO-CaO whiskers (SMCWs) were incorporated into nano hydroxyapatite (HA) contained polylactic acid (PLA) system to prepare the reinforced PLA/HA/SMCWs nanocomposite. Maleic anhydride grafted PLA (PLA-g-MAH) was then used to modify the interface between filler and matrix. The morphology, rheological behavior, crystallization, and mechanical property of the prepared nanocomposites were systematically investigated using scanning electronic microscope, dynamic rheometer, differential scanning calorimeter, polarized light microscope, and mechanical test, respectively. The results showed that the introduced PLA-g-MAH obviously improves the filler dispersion and the filler-matrix interfacial compatibility. Interestingly, the incorporated whiskers obviously decrease the complex viscosity and hence could significantly improve the processability of system. However, the introduction of PLA-g-MAH increases the complex viscosity to a greater extent. In addition, the added whiskers were found to have complicated influences on the PLA crystallization. On one hand, the incorporated whiskers can enhance the melt crystallization capability of PLA macromolecular chains; on the other hand, the introduced whiskers also show the inhibitive effect on the nucleation of PLA polymer chains and the inhibition degree is related to the loading of whiskers. The combination of whiskers and PLA-g-MAH could remarkably improve the mechanical performance of PLA/HA nanocomposite. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43381.

show abstract

Section: Introductionmentioning

confidence: 99%

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

Liu

Chen

Ding

2016

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…A high degree of stereocomplexation between two PLA enantiomers is much more promising and effective to enhance the thermal stability of PLA, because the melting temperature ( T m ) of the resultant sc crystallites is ca. 50 °C higher than that of the homochiral (hc) crystallites. − However, sc crystallization is significantly hindered in a melt mixture of stoichiometric amounts of PLA enantiomers when the molecular weight ( M w ) exceeds 6000 g/mol, whereas the threshold M w in the solution casting method increases to 40 000–400 000 . Although blending of stoichiometric amounts of PLA enantiomers with lower molecular weights is favorable for exclusive formation of sc crystallites without any formation of hc crystallites, such stereocomplex type PLA (scPLA) would exhibit poor mechanical properties due to insufficient molecular entanglements.…”

Section: Introductionmentioning

confidence: 99%

“…Although blending of stoichiometric amounts of PLA enantiomers with lower molecular weights is favorable for exclusive formation of sc crystallites without any formation of hc crystallites, such stereocomplex type PLA (scPLA) would exhibit poor mechanical properties due to insufficient molecular entanglements. Preparation of scPLA with high molecular weight by direct melt blending is difficult, so instead, solid-state polymerization (SSP) of melt blended PLA enantiomers with low molecular weight has been attempted. , However, the reaction time required for the SSP is too long for practical use. Purnama et al reported utilization of supercritical CO 2 in the presence of solvent to obtain scPLA, which was found to be superior to the solution casting method to obtain scPLA with high degrees of stereocomplex formation …”

Section: Introductionmentioning

confidence: 99%

Stereocomplex Poly(lactic acid) Alloys with Superb Heat Resistance and Toughness

Oyama

Abe

2015

ACS Sustainable Chem. Eng.

Self Cite

View full text Add to dashboard Cite

Biobased, biocompatible, and biodegradable poly(lactic acid), PLA, possesses unique properties that give it high potential for a wide range of applications. However, its low thermal stability and brittleness are major obstacles for its use. In this study, both the thermal stability and toughness of PLA were simultaneously improved via stereocomplexation and reactive blending, by generating alloys composed of two PLA enantiomers, PLLA and PDLA, together with poly(ethylene-ran-methylacrylate–ran-glycidyl methacrylate), EMA-GMA. It was found that reactive blending at 200 °C was very effective in generating alloys with high degrees of stereocomplex (sc) crystallinity and that the interfacial reaction between PLA and EMA-GMA contributed to a significant improvement in toughness. Most importantly, a (40/40/20)PLLA/PDLA/EMA-GMA film with high sc crystallinity exhibited both much higher tensile impact strength and thermal stability than neat PLLA, retaining high storage modulus up to 210 °C. The scPLA alloys also exhibited superior chemical resistance to neat PLA. Thus, it was demonstrated that simultaneous complexation and the interfacial reaction transform PLA to the level of high performance materials.

show abstract

“…In the last years, medical applications of polylactic acid (PLA) have gained enormous interest due to the totally body absorbable nature of PLA. PLA can be synthesized by the melt condensation of lactic acid . Removal of water, formed by condensation reaction, from the bulk material is necessary either by evaporation under reduced pressure or by driving it away by a carrier gas (e.g., nitrogen).…”

Section: Introductionmentioning

confidence: 99%

“…Generally, maximum number average molecular weights (MWs) have been reached after 30–90 h at 180–200°C depending on the catalyst ( M n ∼ 2,300–90,000 g mol −1 ) . The use of Sn(II) catalysts activated by sulfonic acids can increase the MW of PLA . 1,3‐propanedisulfonic acid and 1,5‐naphthalene disulfonic acid have been found to successfully synthesize high MW PLA .…”

Section: Introductionmentioning

confidence: 99%

Direct condensation of lactic acid in the presence or absence of supported zirconium sulfate

Raase

Reichert

Schomäcker

2015

J of Applied Polymer Sci

View full text Add to dashboard Cite

Direct condensation of L-lactic acid was studied, aiming at highly crystalline and enantiopure high molecular weight (MW) products. Catalyst-free polylactic acid (PLA) with weight average MW of 80,000 g mol 21 , based on PLA standards, and a crystallinity of 75% is synthesized at 1408C in a fixed-bed reactor under vacuum or nitrogen purging. Supported zirconium sulfate is found to be an efficient and enantioselective catalyst for the melt and solid-state post-condensation of short-chain prepolymers. Small-molecule monohydroxy alcohols, aldehydes, di-and monocarboxylic acids (e.g., acrylic acid [1,700 ppm], propionic acid [1,800 ppm]) are detected in the lactic acid and prepolymers by high performance liquid chromatography, electron spray ionization, and electron impact mass spectroscopy. Thermal degradation of polymer chains, the crystallinity of the prepolymer, and the presence of monofunctional impurities are crucial parameters for the limitation of the MW of the resulting product.

show abstract

Effects of molecular weight and catalyst on stereoblock formation via solid state polycondensation of poly(lactic acid)

Cited by 8 publications

References 21 publications

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

Preparation, dynamic rheological behavior, crystallization, and mechanical properties of inorganic whiskers reinforced polylactic acid/hydroxyapatite nanocomposites

Stereocomplex Poly(lactic acid) Alloys with Superb Heat Resistance and Toughness

Direct condensation of lactic acid in the presence or absence of supported zirconium sulfate

Contact Info

Product

Resources

About