Recovery as a measure of oriented crystalline structure in poly(l-lactide) used as shape memory polymer

Wong, Y.S.; Venkatraman, Subbu S.

doi:10.1016/j.actamat.2009.08.075

Cited by 55 publications

(40 citation statements)

References 31 publications

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“…Previous experimental work revealed complicated dependency of the SM performance on thermo-temporal conditions in an SM cycle. For example, the recovery of SMPs programmed under the same conditions strongly depends on the recovery temperature and heating rate in the recovery step 43,[46][47][48][49][50][51][52] ; in addition, the programming temperature has been shown to affect significantly the free recovery behaviour for SMPs under the same thermo-temporal recovery conditions 31,[53][54][55][56][57] . To date, because the recovery behaviour of an SMP depends on the aforementioned multiple thermo-temporal input parameters, there is no clear understanding how these input parameters can affect the SM performance individually or collectively.…”

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confidence: 99%

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

2014

Nat Commun

235

179

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Shape memory polymers are at the forefront of recent materials research. Although the basic concept has been known for decades, recent advances in the research of shape memory polymers demand a unified approach to predict the shape memory performance under different thermo-temporal conditions. Here we report such an approach to predict the shape fixity and free recovery of thermo-rheologically simple shape memory polymers. The results show that the influence of programming conditions to free recovery can be unified by a reduced programming time that uniquely determines shape fixity, which consequently uniquely determines the shape recovery with a reduced recovery time. Furthermore, using the time-temperature superposition principle, shape recoveries under different thermo-temporal conditions can be extracted from the shape recovery under the reduced recovery time. Finally, a shape memory performance map is constructed based on a few simple standard polymer rheology tests to characterize the shape memory performance of the polymer.

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confidence: 99%

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

2014

Nat Commun

235

179

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“…On the basis of poly(lactide-co-glycolide-co-trimethylene carbonate) 13 C-NMR spectra (Figures 8 and 9), changes in the chain microstructure were observed.…”

Section: The Influence Of Processing and Incorporation Of The Drug Momentioning

confidence: 94%

“…The T trans can be either a glass transition temperature (T g ) or a melting temperature (T m ) of the polymer. 13 Medical devices with shape-memory effect could be implanted with the minimal shape and recovery to its original shape when in the body.…”

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confidence: 99%

Shape‐memory bioresorbable terpolymer composite with antirestenotic drug

Jaworska

Jelonek

Sobota

et al. 2015

J of Applied Polymer Sci

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Shape-memory polymers (SMPs) that combine shape-memory, biodegradability, and controlled drug release properties are very promising for medical and pharmaceutical application. Moreover, incorporation of antirestenotic drug into SMP biodegradable stent seems to be an interesting solution because of possibility to combine the mechanical support that provides stent and also drug elution. The aim of our study was to analyze the effect of incorporation of sirolimus into poly(L-lactide-co-glycolide-co-trimethylene carbonate) on physicochemical and mechanical properties, degradation, and shape-memory effect of the terpolymer. For this purpose, sirolimus was incorporated into the terpolymer by injection molding method. It has been demonstrated that drug-free terpolymer after injection molding characterized insignificant changes in terpolymer composition. Degradation of materials during processing was not observed. Incorporation of drug molecules did not change shape-memory properties of terpolymer.1 H-and 13 C-NMR spectra of poly(lactide-co-glycolide-co-trimethylene carbonate) confirmed that changes during degradation were similar for terpolymer and terpolymer with sirolimus. Sustained and regular release of sirolimus was observed. The developed material presents potential for biomedical and pharmaceutical applications.

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“…They found that increasing the draw ratio increases polymer orientation. Moreover, comprehensive studies have been made to understand the mechanism responsible for the shape recovery of poly (lactic acid), over a range of stretch ratio and several temperatures of deformation [15].…”

Section: Introductionmentioning

confidence: 99%

Crystallization behavior and spherulitic morphology of poly(lactic acid) films induced by casting process

Houichi

Maazouz

Elleuch³

2014

Polym Eng Sci

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A novel way using a polarized optical microscopy and statistical image analysis techniques for direct investigation of the crystallization kinetics and spherulitic morphology of poly (lactic acid) induced by casting process has been proposed. DSC analyses were carried out to explore the effect of drawing in thermal properties of PLA. We found that the rate of cold crystallization was sharply increased with draw ratio. Isothermal calorimetric results reveal that thin films crystallize slowly compared to sheets. Moreover, thin films don't fit the Avrami model demonstrating that more stretching may modify the crystallization kinetics of films. A comparison was made between pure PLA and stretched materials using Hoffman theory and giving a compiled view on the details of crystallization behavior with relation to stretch effect. At draw ratio 167, the growth rate reach its maximum and the crystallization rate go up exponentially. POM experiments showed the existence of two different spherulitic populations in thin films and two nucleation mechanisms was identified. Accordingly, the growth rate was found to be not linear with time.

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Recovery as a measure of oriented crystalline structure in poly(l-lactide) used as shape memory polymer

Cited by 55 publications

References 31 publications

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

Shape‐memory bioresorbable terpolymer composite with antirestenotic drug

Crystallization behavior and spherulitic morphology of poly(lactic acid) films induced by casting process

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