Spherulite growth of l-lactide copolymers: Effects of tacticity and comonomers

Tsuji, Hideto; Tezuka, Yasufumi; Saha, Swapan K.; Suzuki, Masakazu; Itsuno, Shinichi

doi:10.1016/j.polymer.2005.03.069

Cited by 128 publications

(133 citation statements)

References 35 publications

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“…This led to macroscopic defects in the spherulites in figure 2. The spherulites of PLLGA85/15 do not possess periodical distinction rings, which indicates the absence of periodical twisting of lamellae along the direction of the radius [16]. In the process of spherulite growth, they can release energy, which can act as an exothermic peak in some DSC thermograms.…”

Section: Discussionmentioning

confidence: 99%

Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l‐lactide‐co‐glycolide)

Zhao

Wang

Huang

et al. 2010

Cryst. Res. Technol.

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We investigated the effect of isothermal annealing on the degree of crystallinity and mechanical properties of a random copolymer-poly(l-lactide-co-glycolide) (PLLGA)-with monomer molar ratios of 85/15 (PLLGA85/15) by performing polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction, and studying the tensile properties. Isothermal annealing of PLLGA at 130 °C was conducted to improve the degree of crystallinity of the copolymer; the maximum degree of crystallinity (44.5%) was achieved after 60 min of annealing. The crystal size/perfection was observed to increase with annealing time. The highest tensile strength of 65.8 MPa was achieved after 80 min of annealing. However, the degree of crystallinity and tensile strength can only reach to certain extent.

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Section: Discussionmentioning

confidence: 99%

Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l‐lactide‐co‐glycolide)

Zhao

Wang

Huang

et al. 2010

Cryst. Res. Technol.

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“…An interesting morphology of which the center is spherulite and the outer is dendrite was formed at T c = 115 °C shown in Figure 18d. When crystallized at a higher temperature, T c > 115 °C, the crystallization behavior and the crystalline morphologies are absolutely different from those at low T c [7,[44][45][46][47]. Dense dendrites were formed at 120 °C, as shown in Figure 18e,f; the morphologies composed by the main branches were star-shaped, and the second branches grew along the main branches.…”

Section: Soft Confined Crystallization and Microphase Separation-detementioning

confidence: 97%

“…The morphologies evaluate from radial spherulite, banded spherulite at low T c , to dense branches, dendrite and fractal dendrite at high T c . It has been reported that the crystallization behavior of PLA can be classified into the low and high temperature ranges based on the crystallization modification, nucleation, and growth rate [7,44,47,[49][50][51][52][53][54], but such distinguished morphological evolution with T c has never been investigated. We speculated that the T c -dependent morphological behavior of the asymmetric copolymers is the result of soft confinement crystallization.…”

Section: Soft Confined Crystallization and Microphase Separation-detementioning

confidence: 99%

Crystallization Behaviors and Structure Transitions of Biocompatible and Biodegradable Diblock Copolymers

Xue

Jiang

2014

Polymers

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Biocompatible and biodegradable block copolymers (BBCPs) containing crystalline blocks become increasingly important in polymer science, and have great potential applications in polymer materials. Crystallization in polymers is accompanied by the adoption of an extended conformation, or often by chain folding. It is important to distinguish between crystallization in homopolymers and in block copolymers. In homopolymers, chain folding leads to metastable structures introduced by the crystallization kinetics. In contrast, equilibrium chain folding in diblocks can be achieved as the equilibrium number of the folds is controlled by the size of the second block. The structures of BBCPs, which are determined by the competition between crystallization, microphase separation, kinetics and processing, have a tremendous influence on the final properties and applications. In this review, we present the recent advances on crystalline-crystalline diblock copolymer in our group.

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“…Huang et al [12] showed that when the D-lactic acid isomer composition in an L chain increases, the T c at maximal crystal growth rate decreases, indicating that samples with a higher D-isomer concentration crystallize more slowly. In 2005, Tsuji et al [13] completed this study and described the transition of growth rate regimes.…”

Section: Introductionmentioning

confidence: 99%

Amino acids and poly(amino acids) as nucleating agents for poly(lactic acid)

Carbone

Vanhalle

Goderis

et al. 2014

Journal of Polymer Engineering

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Abstract:In industry, rapid crystallization is often required. At present, the crystallization rate of poly(lactic acid) (PLA) is too low compared to industrial needs. In this paper, amino acids such as glycine and L-alanine and poly(amino acids) like polyglycine and poly-DL-alanine are considered as heterogeneous crystallization nucleating agents. The impact of adding these bio-based additives on the isothermal crystallization behavior of PLA was quantified and compared at different concentrations by using the so-called Lotz efficiency scale, which here is based on isothermal DSC measurements. In addition, rheological and rheo-optical techniques were used to monitor the isothermal crystallization. Our results indicate that polyglycine possesses a significant nucleating ability (60.5%) which is comparable to the industrially used talc (81.1%).

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Spherulite growth of l-lactide copolymers: Effects of tacticity and comonomers

Cited by 128 publications

References 35 publications

Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l‐lactide‐co‐glycolide)

Effect of isothermal annealing on degree of crystallinity and mechanical properties of poly(l‐lactide‐co‐glycolide)

Crystallization Behaviors and Structure Transitions of Biocompatible and Biodegradable Diblock Copolymers

Amino acids and poly(amino acids) as nucleating agents for poly(lactic acid)

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