Optimum conditions for the synthesis of linear polylactic acid-based urethanes

Borda, J M; Bodnár, Ildikó; Kéki, Sándor; Sípos, László; Zsuga, Miklós

doi:10.1002/1099-0518(20000815)38:16<2925::aid-pola100>3.0.co;2-e

Cited by 28 publications

(30 citation statements)

References 3 publications

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“…For PET, branching was obtained by reaction with pyromellitic dianhydride, [24][25][26], and with various epoxy-based chain-extenders, [27][28][29][30][31]. For PLA, various diisocyanate were investigated for this purpose [32][33][34][35][36][37][38][39]. All these bifunctional molecules have a narrow processing window and can lead to gel formation.…”

Section: Introductionmentioning

confidence: 99%

Rheology and extrusion foaming of chain‐branched poly(lactic acid)

Mihai

Huneault

Favis

2009

Polymer Engineering & Sci

225

204

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Rheology and extrusion foaming of chain-branched poly(lactic acid)Mihai, Mihaela; Huneault, Michel A.; Favis, Basil D.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. In this study, the effect of macromolecular chainbranching on poly(lactic acid) (PLA) rheology, crystallization, and extrusion foaming was investigated. Two PLA grades, an amorphous and a semi-crystalline one, were branched using a multifunctional styrene-acrylicepoxy copolymer. The branching of PLA and its foaming were achieved in one-step extrusion process. Carbon dioxide (CO 2 ), in concentration up to 9%, was used as expansion agent to obtain foams from the two PLA branched using chain-extender contents up to 2%. The foams were investigated with respect to their shear and elongational behavior, crystallinity, morphology, and density. The addition of the chain-extender led to an increase in complex viscosity, elasticity, elongational viscosity, and in the manifestation of the strain-hardening phenomena. Low-density foams were obtained at 5-9% CO 2 for semi-crystalline PLA and only at 9% CO 2 in the case of the amorphous PLA. Differences in foaming behavior were attributed to crystallites formation during the foaming process. The rheological and structural changes associated with PLA chain-extension lowered the achieved crystallinity but slightly improved the foamability at low CO 2 content. POLYM. ENG. SCI.,

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Section: Introductionmentioning

confidence: 99%

Rheology and extrusion foaming of chain‐branched poly(lactic acid)

Mihai

Huneault

Favis

2009

Polymer Engineering & Sci

225

204

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“…Higher molar excess of MDI‐1 (i.e., more than 3 equiv.) resulted, however, in crosslinking . Therefore, instead of the required PCL–MDI‐1 = 1:2 molar ratio, it was set for 1:3 to produce the PU‐prepolymer with active terminal NCO groups (see Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Poly(ε‐caprolactone) and Pluronic Diol‐Containing Segmented Polyurethanes for Shape Memory Performance

Czifrák

Karger‐Kocsis

Daróczi

et al. 2014

Macro Chemistry & Physics

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A series of novel segmented linear and crosslinked polyurethanes (PUs) are synthesized from poly(ε-caprolactone) (PCL) (25 kg mol −1 ), methylene diphenyl diisocyanate (MDI), and various polyether diols (Pluronic (PLU) and polyethylene glycol (PEG)). The basic structures of the highly deformable PUs are PLU/PEG-MDI-PCL-MDI-PLU/PEG and PLU-MDI-PCL-MDI-PLU, respectively. The linear and crosslinked PUs are characterized. Changes in the tensile behavior are attributed to the effects of compositional variables and alterations in the crosslink density. Additional information on the morphology of the segmented PUs is deduced from differential scanning calorimetry, as well as transmission and scanning electron microscopy investigations. Both the linear and the crosslinked PUs exhibit a broad rubbery plateau above the melting temperature of the crystalline PCL phase, which is highly benefi cial for shape memory function. This work highlights that the chemical build-up of soft segments containing high-molecular-weight crystallizable chain units is a proper tool to tailor the morphology and mechanical properties of PUs, and thus also their shape memory properties.

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“…Literature offers a number of research works devoted to modification of PLA by polymerization, copolymerization, blending, and composite processing technologies. The main discussed properties of polylactides and their related samples are structure, molecular weight properties, thermal properties, mechanical properties, and biodegradation behavior . The effect of different modifications of PLA in terms of thermal properties was studied mainly as a change in glass transition temperature, crystallization, and melting behavior.…”

Section: Introductionmentioning

confidence: 99%

Thermal stability of modified end‐capped poly(lactic acid)

Berger

Gregorová

2014

J of Applied Polymer Sci

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The influence of functional end groups on the thermal stability of poly(lactic acid) (PLA) in nitrogen‐ and oxygen‐enriched atmospheres has been investigated in this article using differential scanning calorimetry, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Functional end groups of PLA were modified by succinic anhydride and l‐cysteine by the addition–elimination reaction. PLA was synthesized by azeotropic condensation of l‐lactic acid in xylene and characterized by nuclear magnetic resonance. The values of the activation energies determined by TGA in nitrogen and oxygen atmospheres revealed that the character of functional end groups has remarkable influence on the thermal stability of PLA. Moreover, DMA confirmed the strong influence of functional end groups of PLA on polymer chains motion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41105.

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Optimum conditions for the synthesis of linear polylactic acid-based urethanes

Cited by 28 publications

References 3 publications

Rheology and extrusion foaming of chain‐branched poly(lactic acid)

Rheology and extrusion foaming of chain‐branched poly(lactic acid)

Poly(ε‐caprolactone) and Pluronic Diol‐Containing Segmented Polyurethanes for Shape Memory Performance

Thermal stability of modified end‐capped poly(lactic acid)

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