Enhancement of stereocomplex formation in poly(l-lactide)/poly(d-lactide) mixture by shear

Song, Yan; Zhang, Xiuqin; Yin, Yongai; Vos, Sicco de; Wang, Ruyin; Joziasse, Cornelis A.P.; Liu, Guoming; Wang, Dujin

doi:10.1016/j.polymer.2015.07.023

Cited by 62 publications

(30 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to explain the results from the viewpoint of the nucleation ability under different pressure and shear conditions, the critical nucleation Gibbs free energy (Δ G* ) following Flory's idea was as eq. shows

Δ G^{*} = 32 \frac{σ^{2} σ_{e}}{Δ F^{2}},

where σ is the side surface free energy, σ e is the end surface energy per unit area, and Δ F stands for the change in bulk free energy per unit volume assuming an infinitely large crystal. σ can be calculated using eq.…”

Section: Resultsmentioning

confidence: 99%

“…According to reports, shear flow can affect SC nucleation and crystal growth process . The effect of shear rate on SC crystallization behavior was investigated by Song et al . Their results show that the nucleation density, crystallization rate, and degree of orientation for SC increased when shear flow was applied, suggesting that the structure formation is closely related to shear‐induced nucleation, phase mixing, and chain mobility.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Flow‐induced crystallization of polylactide stereocomplex under pressure

Song

Zhao

Yang

et al. 2018

J of Applied Polymer Sci

View full text Add to dashboard Cite

Although shear and pressure fields always coexist in practical polymer processing, their combined influence on the crystallization behavior of polylactide stereocomplex (SC) is ambiguous due to the limit of experiment device. In that case, a homemade device was employed to prepare samples under the coexistence of shear and pressure and explore the crystallization behavior of SC. Differential scanning calorimetry and synchrotron radiation were used to investigate the combined effect of shear flow and pressure on SC crystallization. The results show that shear flow was helpful for SC formation. Shear flow promoted the phase mixing of the polymer blends and improved the nucleation efficiency of SC. Pressure had a negative effect on SC formation because of the decrease in free volume. Regard to polylactide homogeneous (HC), pressure played a positive role on HC formation. Pressure suppressed the formation of SC network which could impede HC generation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46378.

show abstract

Δ G^{*} = 32 \frac{σ^{2} σ_{e}}{Δ F^{2}},

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flow‐induced crystallization of polylactide stereocomplex under pressure

Song

Zhao

Yang

et al. 2018

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Except for the unbalanced surface stress, another factor that should be considered is volume shrinkage. The Sc crystal is proposed to be the β ‐form with 3 1 helical conformation, while homopolymer crystallizes into a form with 10 3 helical conformation . That means the density will increase when Sc crystal forms, resulting in volume shrinkage.…”

Section: Discussionmentioning

confidence: 99%

The sunken morphology of poly(lactic acid) stereocomplex spherulite

Liu

Zhang

Wei

et al. 2019

Polymer International

View full text Add to dashboard Cite

The mechanical properties and microstructure of poly(lactic acid) (PLA) stereocomplex spherulite at the micrometric scale were investigated using nanoindentation and synchrotron radiation scanning X-ray microdiffraction, which exhibits a new growth habit with more and more compact lamellae. Using atomic force microscopy and laser scanning confocal microscopy, a unique sunken morphology was found. Unbalanced surface stress and volume shrinkage are proposed as the main factors for the sunken morphology, which is also contributed by a novel growth regime driven by the hydrogen bonding between two PLA enantiomers.

show abstract

“…) and stereocomplex crystallites ( χ st ) ( Eq . ) were calculated :

χ_{h c} true(% true) = \frac{I_{h c}}{I_{h c} + I_{s t} + I_{a m o r}} \times 100

χ_{s t} true(% true) = \frac{I_{s t}}{I_{h c} + I_{s t} + I_{a m o r}} \times 100

where I hc is the integrated scattering intensity of the reflections of homocrystals, i.e.16.5° and 18.8°

,

I st is the sum of the areas under the scattering intensity peaks for the stereocomplex crystallites reflections, i.e. 11.9°, 20.7°, and 23.9° , I amor is the integrated intensity of the amorphous halo.…”

Section: Methodsmentioning

confidence: 99%

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

Pholharn

Srithep

Morris

2017

Polymer Engineering & Sci

View full text Add to dashboard Cite

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

show abstract

Enhancement of stereocomplex formation in poly(l-lactide)/poly(d-lactide) mixture by shear

Cited by 62 publications

References 56 publications

Flow‐induced crystallization of polylactide stereocomplex under pressure

Flow‐induced crystallization of polylactide stereocomplex under pressure

The sunken morphology of poly(lactic acid) stereocomplex spherulite

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

Contact Info

Product

Resources

About