Polylactide stereochemistry: effect on enzymic degradability

Reeve, Michael S.; McCarthy, Stephen P.; Downey, Milton J.; Gross, Richard A.

doi:10.1021/ma00081a030

Cited by 420 publications

(347 citation statements)

References 7 publications

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“…Considerable efforts have been made to control and accelerate the hydrolytic degradation rate. Despite the considerable number of reports concerning the enzymatic degradation of PLA [6][7][8] and various PLA blends [9], the compost degradability of PLA and its blend with conventional petrochemical-based polymers are still very little known. Very limited researches on degradation behavior of PLA/PE exist in the literatures [10][11][12] till date.…”

mentioning

confidence: 99%

Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

As’habi¹,

Jafari

Khonakdar³

et al. 2013

Express Polym. Lett.

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Abstract. Polylactic acid (PLA)/linear low density polyethylene (LLDPE) blend nanocomposites based on two different commercial-grade nanoclays, Cloisite ® 30B and Cloisite ® 15A, were produced via different melt mixing procedures in a counter-rotating twin screw extruder. The effects of mixing sequence and clay type on morphological and rheological behaviors as well as degradation properties of the blends were investigated. The X-ray diffraction (XRD) results showed that generally the level of exfoliation in 30B based nanocomposites was better than 15A based nanocomposites. In addition, due to difference in hydrophilicity and kind of modifiers in these two clays, the effect of 30B on refinement of dispersed phase and enhancement of biodegradability of PLA/LLDPE blend was much more remarkable than that of 15A nanoclay. Unlike the one step mixing process, preparation of nanocomposites via a two steps mixing process improved the morphology. Based on the XRD and TEM (transmission electron microscopic) results, it is found that the mixing sequence has a remarkable influence on dispersion and localization of the major part of 30B nanoclay in the PLA matrix. Owing to the induced selective localization of nanoclays in PLA phase, the nanocomposites prepared through a two steps mixing sequence exhibited extraordinary biodegradability, refiner morphology and better melt elasticity.

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mentioning

confidence: 99%

Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

As’habi¹,

Jafari

Khonakdar³

et al. 2013

Express Polym. Lett.

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“…Naturally occurring amino acids as constituents of protein are L-isomers. As reported by Reeve et al (1994) proteinase K was not able to cleave D-stereoisomer of PLA. It seems reasonable to conclude that PLA-degrading enzyme is protease-type enzyme which recognizes the repeated L-lactic acid unit of PLA as L-alanine unit of silk fibroin (protein).…”

Section: Pla-degrading Enzyme Purification and Characterizationmentioning

confidence: 47%

New Insight into Biodegradation of Poly (L-Lactide), Enzyme Production and Characterization

Sukkhum¹,

Kitpreechavanich²

2011

Progress in Molecular and Environmental Bioengineering - From Analysis and Modeling to Technology Applications

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“…Hydrolytic and enzymatic degradability of semicrystalline polylactides and their stereocopolymers have been extensively studied. [1][2][3] Degradation rate is controlled by the degree of crystallinity and lamellar organization, and the introduction of a second stereoisomer into the polymer chain influences not only the morphology but also selectivity in enzymatic degradation. 2,3 To improve control over degradability and other properties of crystalline polylactides, the effect of comonomer type and content on crystalline order and morphology needs to be established.…”

Section: Introductionmentioning

confidence: 99%

Solid-State Microstructure of Poly(l-lactide) and l-Lactide/meso-Lactide Random Copolymers by Atomic Force Microscopy (AFM)

2003

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Tapping mode atomic force microscopy was used to investigate the lamellar morphology of poly(L-lactide) and two poly(L-lactide-co-meso-lactide) random copolymers containing 3% and 6% meso-lactide. Samples were isothermally crystallized at selected temperatures, and qualitative and quantitative analyses of lamellar structure were performed using height and phase images. This is the first study of the morphology of polylactide stereocopolymers using a real-space probe, and the important effects of scanning parameters on the acquired images are described. More open spherulites with an abundance of screw dislocations between edge-on lamellar stacks were observed in samples crystallized at higher temperatures. Mean lamellar thicknesses are lower for the random copolymers compared to PLLA, particularly at lower ∆T, in agreement with the results of our previous small-angle X-ray scattering (SAXS) experiments. Mean lamellar thicknesses derived from the current real-space examination are in good agreement with those determined previously from SAXS. Internal surfaces-from microtomed specimens-were also studied to investigate the bulk crystal morphology. Although quantitative analysis was not feasible (for reasons discussed in the text), lamellar organization similar to that seen in the surface experiments is observed at high magnifications.

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Polylactide stereochemistry: effect on enzymic degradability

Cited by 420 publications

References 7 publications

Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

New Insight into Biodegradation of Poly (L-Lactide), Enzyme Production and Characterization

Solid-State Microstructure of Poly(l-lactide) and l-Lactide/meso-Lactide Random Copolymers by Atomic Force Microscopy (AFM)

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