Injection molding and characterization of polylactide stereocomplex

Srithep, Yottha; Pholharn, Dutchanee; Turng, Lih‐Sheng; Veang-in, Onpreeya

doi:10.1016/j.polymdegradstab.2015.07.017

Cited by 44 publications

(27 citation statements)

References 32 publications

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“…However, the degradation behavior of the stereocomplex and silane blending lms is complex due to the intermolecular and intramolecular trans-esterication and racemization. 48…”

Section: Conrmation Of Stereocomplex Formation Via Thermal Analysismentioning

confidence: 99%

In situ formation of PLA-grafted alkoxysilanes for toughening a biodegradable PLA stereocomplex thin film

et al. 2019

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Poly(lactide) (PLA) has received tremendous attention recently from researchers and industrialists due to its ability to solve environmental problems related to plastic pollution. However, PLA's brittleness, poor thermal stability, low elongation at break, and poor melt processing prevent its use in a broader spectrum of applications. Herein, we produced a very tough and thermally more stable PLA stereocomplex by simply mixing PLA with organoalkoxysilane. The stereocomplex PLA/silane (sc-PLA-silane) composite was prepared by simple mixing of three types of organoalkoxysilanes in sc-PLA followed by in situ formation of a silane-based rubbery core with a cross-linked PLA shell. Mechanical and thermal properties were improved by stereocomplexation of PLA with a small amount (1-5 wt%) of PLA-grafted silanes. The addition of organoalkoxysilane with different functional groups resulted in a plasticizer of rubbery silica-PLA core-shell gel through in situ condensation and grafting of long PLA chains at the interface between the stereocomplex and silane particles. The results revealed that the toughness of sc-PLA was improved dramatically with only a small addition (only 2.5%) of 3-(triethoxysilyl)propyl isocyanate (ICPTES). The morphology and mechanical and thermal properties of the toughened stereocomplex films were characterized. The results revealed that elongation at break was increased from 16% to 120%, while other mechanical properties such as tensile strength and modulus were retained. Surface analysis confirmed that this toughness was achieved by formation of a silica-PLA core-shell gel. The mechanical properties of PLA were improved without any significant reduction in modulus and tensile strength using this simple methodology. environmental pollution. 5,6 Nevertheless, the brittleness of PLA is a main hindrance, along with thermal limitations. 7-10 PLA is an optically isomeric polymer, having D(+) and L(À) stereoisomers. The polymers made from L and D forms considerably differ in thermal properties. Thermal properties, such as thermal stability and glass, crystallization, and melt transitions, can be modied using stereoselective polymerization and by blending D and L in different proportions. 11 The mechanical properties of PLA can also be improved by stereocomplexation. 12-14 Stereocomplexed PLA is a suitable polymeric material for certain applications such as drug carriers, wound dressing, biomedical implants, and scaffolds for tissue engineering. 15,16 PLLA and PDLA have optical activity due to their chiral structures. The melting temperatures (T m ) of PLLA and PDLA do not exceed 180 C. However, T m drops quickly, and the crystallization capacity decreases sharply with a decrease in optical purity. 12,17 The low thermal stability limits thermal processes like injection molding and extrusion. 18 However, the melting temperature can be increased from 180 C to about 230 C through stereocomplexation of PLLA and PDLA. 18,19 PLA is an inherently brittle polymer, which has 4-7% elongation at break;Preparation of...

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“…However, the degradation behavior of the stereocomplex and silane blending lms is complex due to the intermolecular and intramolecular trans-esterication and racemization. 48…”

Section: Conrmation Of Stereocomplex Formation Via Thermal Analysismentioning

confidence: 99%

In situ formation of PLA-grafted alkoxysilanes for toughening a biodegradable PLA stereocomplex thin film

et al. 2019

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“…However, fabrication of scPLA films by melt processing is interesting, because of its possible use in industrial-scale applications. Specimens of scPLA have been prepared by injection [18] and extrusion [19,20]. For these purposes, PLLA and PDLA were melt blended within a screw barrel.…”

Section: Introductionmentioning

confidence: 99%

Influence of Chain-Extension Reaction on Stereocomplexation, Mechanical Properties and Heat Resistance of Compressed Stereocomplex-Polylactide Bioplastic Films

Baimark

Kittipoom

2018

Polymers

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Stereocomplex polylactide (scPLA) films were prepared by melt blending of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) with and without an epoxy-based chain extender before compression molding. The obtained scPLA films were characterized through differential scanning calorimetry, X-ray diffractometry (XRD), tensile testing and dimensional stability to heat. XRD patterns revealed that all the scPLA films had only stereocomplex crystallites. The obtained results showed that the chain-extension reaction improved mechanical properties of the scPLA films, however, it suppressed stereocomplexation and heat resistance.

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“…It is known that PLA is very sensitive to high temperature and has low heat tolerance and stability. At over 200°C, obvious thermal degradation occurs but it has been reported that stereocomplexes between enantiomeric PLA have enhanced thermal tolerance . Improved thermal stability of PLA or St‐PLA will allow it to be become part of more durable industrial products.…”

Section: Resultsmentioning

confidence: 99%

Melt compounding and characterization of poly(lactide) stereocomplex/natural rubber composites

Pholharn

Srithep

Morris

2017

Polymer Engineering & Sci

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Poly(lactide) (PLA) is an interesting biodegradable polymer but has limited application because of its brittleness and low thermal stability. We found that both drawbacks of PLA were solved by forming stereocomplexes augmented with natural rubber (NR). Equal amounts of poly(l‐lactide) (PLLA) and poly(d‐lactide) (PDLA) stereoisomers were blended to form a stereocomplex (St‐PLA). Varying amounts of NR (5–30% by weight) were added simultaneously to equal amounts of the stereo isomers by melt blending. FTIR and XRD spectra demonstrated that, despite the added NR, the stereocomplex structures were still generated and complete. Stereocomplex crystallinity decreased with increasing NR content, verified by DSC and XRD, as well as polarizing optical micrographs which showed fewer spherulites at higher NR content. Measured glass transition temperatures (Tg) of St‐PLA/NR blends were significantly lower than for neat St‐PLA, exhibiting shifts to as low as 46°C at 30%wt NR content, because of rubber dispersed in St‐PLA segments expanding the free volume and enhancing chain mobility. Thermal stability of the blends, estimated by TGA, showed desired results, for example, at the 50% weight loss point, the temperature of all St‐PLA/NR blends moved to higher temperatures than neat St‐PLA. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

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Injection molding and characterization of polylactide stereocomplex

Cited by 44 publications

References 32 publications

In situ formation of PLA-grafted alkoxysilanes for toughening a biodegradable PLA stereocomplex thin film

In situ formation of PLA-grafted alkoxysilanes for toughening a biodegradable PLA stereocomplex thin film

Influence of Chain-Extension Reaction on Stereocomplexation, Mechanical Properties and Heat Resistance of Compressed Stereocomplex-Polylactide Bioplastic Films

Melt compounding and characterization of poly(lactide) stereocomplex/natural rubber composites

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