PLA degradation pathway obtained from direct polycondensation of 2-hydroxypropanoic acid using different chain extenders

Ramírez-Herrera, Claudia Angélica; Flores‐Vela, A.; Torres‐Huerta, A.M.; Domínguez‐Crespo, M.A.; Palma‐Ramírez, D.

doi:10.1007/s10853-018-2380-7

Cited by 13 publications

(18 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The branching reaction occurs when more than two PLA chains react with one TMA molecule. Accordingly, Ramırez‐Herrera et al also reported a complex branching reaction that generated a crosslinked structure or gel when 1 wt% PMDA was incorporated into PLA. In this sense, the TMA molecule acts as a bifunctional chain extender since it behaves like a bridge between two PLA chains or fragments and induces an increase in the PLA viscosity, as it is shown in the scheme of Fig.…”

Section: Resultssupporting

confidence: 56%

“…b. This mechanism identical to that proposed by Xanthos et al , Awaja et al , and Ramırez‐Herrera et al for PMDA concerns the reaction of one TMA moiety with two PLA chains, thus causing the increase in the molecular weight. Concomitantly, the involvement of a third PLA chain results in chain branching and in the change of the molecular weight distribution.…”

Section: Resultsmentioning

confidence: 68%

“…Figure a displays the potential chemical reactions responsible for PLA upgrading by using CAP. Due to the great structural similarities between CAP and CBC, the mechanism of the chain extension of PLA with CAP can be the same proposed as by Ramırez‐Herrera et al and Buccella et al for CBC. The mechanism involves the nucleophilic attack of the terminal hydroxyl group (OH) either at the central carbonyl group or at the carbonyl of the rings of the caprolactam, and intermediate reactions occur forming carbonates, urethane, and urea .…”

Section: Resultsmentioning

confidence: 94%

“…Due to the great structural similarities between CAP and CBC, the mechanism of the chain extension of PLA with CAP can be the same proposed as by Ramırez‐Herrera et al and Buccella et al for CBC. The mechanism involves the nucleophilic attack of the terminal hydroxyl group (OH) either at the central carbonyl group or at the carbonyl of the rings of the caprolactam, and intermediate reactions occur forming carbonates, urethane, and urea . Also, Buccella et al reported that the nucleophilic substitution is possible at low temperatures, while at higher temperatures the caprolactam ring opening is more likely to occur.…”

Section: Resultsmentioning

confidence: 99%

“…Besides, Najafi et al found that the epoxy chain extender and the processing conditions contributed to attaining a good dispersion of nanoclay platelets in PLA nanocomposites and in increasing significantly their modulus and toughness. Ramırez‐Herrera et al studied the structural, thermal, and mechanical properties of PLA modified with three different chain extenders (1,3‐phenylene‐bis‐2‐oxazoline [PBO], pyromellitic dianhydride [PMDA], and 1,10‐carbonyl bis caprolactam [CBC]). PBO, PMDA, and CBC chain extenders were added at three concentrations during the three stages of PLA processing, that is, monomer dehydration, oligomer polycondensation, and melt polycondensation.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Mayouf

Guessoum

Fuensanta

et al. 2020

Polymer Engineering & Sci

View full text Add to dashboard Cite

The potential of ε-caprolactam (CAP) and trimellitic anhydride (TMA) compounds as novel chain extenders for poly(lactic acid) (PLA) has been assessed; the amounts of 0.01, 0.025, and 0.05 wt% each additive have been added. The chain extension was evidenced by the increase in PLA/CAP and PLA/TMA viscosities in mixing torque measurements and by infrared spectroscopy. PLA reaction with CAP and TMA has also been confirmed from contact angle and surface free energy studies, which have shown that the increase in TMA amount decreased the hydrophilicity of PLA due to the decreased concentration of terminal surface hydroxyl groups. However, the addition of CAP accentuated the PLA hydrophilicity as indicated by the increase in the polar component of the surface energy. On the other hand, the glass transition temperature of PLA/TMA and PLA/CAP decreased as a result of a local plasticizing effect, which favored the chain mobility and the crystallization of PLA due to the concomitant nucleating effect of the chain extenders moieties too. Furthermore, the higher molecular weight of PLA/CAP and PLA/TMA was responsible for their increased thermal stability and higher impact strength with respect to PLA. POLYM. ENG. SCI., 60:944-955, 2020.

show abstract

Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Mayouf

Guessoum

Fuensanta

et al. 2020

Polymer Engineering & Sci

View full text Add to dashboard Cite

show abstract

Surface Modification of Li_1.144Ni_0.136Co_0.136Mn_0.544O₂ by Hybrid Protection Layer with Enhanced Rate Capability

Liao

Deng

et al. 2020

Energy Tech

View full text Add to dashboard Cite

Overlithiated oxide (OLO) materials have received great attention because of their higher recharge capacity (>250 mA h g−1) than that of commercial Li‐ion cathode materials. However, they still have some problems such as poor cyclic stability and rate capability. In this study, La(PO3)3 is coated on Li1.144Ni0.136Co0.136Mn0.544O2 by the dry coating method. The results indicate that 1.0 wt% La(PO3)3–coated Li1.144Ni0.136Co0.136Mn0.544O2 delivers a remarkably high rate capability, with a discharge capacity of 163 mA h g−1 even at 5 C, and an excellent cycling performance of 193 mA h g−1 after cycling 100 times at 1 C. The enhanced electrochemical performance comes from the formation of a hybrid protection layer mainly containing Li, La, P, and O (LLPO), which uses residual alkali compounds, LiOH and Li2CO3, as the lithium source and reacts with La(PO3)3. LLPO can not only protect the Li‐rich cathodes from contacting the electrolyte directly, but also reduce the charge transfer resistance. More importantly, it can serve as a Li+ conductor, which is beneficial for elevation of the rate capability.

show abstract

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Yahyaee

Javadi

Garmabi

et al. 2019

Macro Materials & Eng

View full text Add to dashboard Cite

polymer in processes involving melt stretching (film extrusion, blow molding, foaming, and the like) have been limited due to disadvantages such as intrinsic brittleness, slow crystallization rate, low melt strength, narrow processing window, and low thermal stability. [7][8][9][10][11][12][13] The low melt strength of PLA is due to the inherent degradation behavior of polyesters. PLA degrades at temperatures above its melting point, similar to other polyesters. The degradation reactions include hydrolysis, inter-chain transesterification, and depolymerization by back-biting (intramolecular transesterification). Depending on the process conditions, one of these undesirable reactions overcomes the others. For example, the chain scission, at temperatures above the melting point, is responsible for the degradation of the polymer that leads to a decrease in molecular weight and rheological properties. [1,14,15] To obtain a wider processing window for PLA and thus make the range of its applications broader, improved melt strength is postulated. [16,17] For increasing the melt strength, the modification of PLA is an effective method to achieve a branched high molecular weight structure. Several ways exist for the branching of PLA, including solution polymerization, using the free radical initiator, and functional groups reaction. Due to environmental problems, high costs, low effectiveness, and issues associated with process convenience, solution reactions are not the best choices. Furthermore, as the free radical reaction is a random one, it is more difficult to control the molecular weight when utilizing this method. On the contrary, compared to the free radical branching, reactions of functional groups tend to give rise to long chain branching (LCB) more readily, leading to controlled structures. [18] Chainextension reactions are exploited to increase the melt strength of linear polymers. The advantage of using the chain extenders with functional groups includes re-bonding the degraded chains together and as a result, increasing the molecular weight and the melt strength. For polyesters such as PET and PLA, chain-extension occurs by increasing the molecular weight due to bridging the hydroxyl or carboxyl reactive-end groups using bi-or multi-functional molecules. [1,9] Some researchers have investigated the effect of different chain extenders with different functional groups such as diand multi-functional epoxides, [19][20][21][22][23][24][25][26][27] diisocyanate, [28][29][30] dianhydride, [31][32][33] and so forth. Among these, chain extenders constituted of multi-functional epoxy groups such as Joncryl are highly This research considers a two-step chain extension reaction in the presence of two chain extenders, Joncryl and Pyromellitic dianhydride (PMDA), as a solution for poor melt properties of poly (lactic acid) (PLA). The aim of adding PMDA is to increase the carboxyl groups via the anhydride ring-opening reaction so that the reaction between PLA and Joncryl could be facilitated since the reactivity between t...

show abstract

PLA degradation pathway obtained from direct polycondensation of 2-hydroxypropanoic acid using different chain extenders

Cited by 13 publications

References 57 publications

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Surface Modification of Li_1.144Ni_0.136Co_0.136Mn_0.544O₂ by Hybrid Protection Layer with Enhanced Rate Capability

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Contact Info

Product

Resources

About

PLA degradation pathway obtained from direct polycondensation of 2-hydroxypropanoic acid using different chain extenders

Cited by 13 publications

References 57 publications

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Appraisal of ε‐Caprolactam and Trimellitic Anhydride Potential as Novel Chain Extenders for Poly(lactic acid)

Surface Modification of Li1.144Ni0.136Co0.136Mn0.544O2 by Hybrid Protection Layer with Enhanced Rate Capability

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Contact Info

Product

Resources

About

Surface Modification of Li_1.144Ni_0.136Co_0.136Mn_0.544O₂ by Hybrid Protection Layer with Enhanced Rate Capability