Article
Polymer Science
Hideto Tsuji, Kazumasa Iguchi, Yuki Arakawa
Summary: The research studied the effects of different molecular weights of crystalline blocks but similar overall molecular weights on the crystallization behavior, structure, morphology, and thermal properties of PLLA-b-PDLLA/PDLA-b-PDLLA blends. It was found that the incorporated long amorphous PDLLA blocks facilitated unique SC crystallization in the blends with different crystalline block fractions.
Article
Polymer Science
Steffen M. Weidner, Andreas Meyer, Hans R. Kricheldorf
Summary: L-lactide was polymerized in toluene using tin(II) 2-ethylhexanoate as the catalyst. The crystalline properties of the resulting polyLAs were studied under different concentrations, reaction times, and temperatures. It was found that the presence of solvent promoted cyclization, leading to the formation of cyclic polylactides. A new hypothesis for the crystal growth of cyclic polyLAs was proposed.
Article
Engineering, Chemical
Zun Yuan, Yalong Liu, Lin Ye, Phil Coates, Fin Caton-Rose, Xiaowen Zhao
Summary: In this study, a two-stage solid phase hot drawing technology was established to achieve a high degree of molecular orientation for poly(lactic acid)-b-poly(lactide-co-caprolactone) block copolymer. The evolution of the oriented crystalline/two-phase separated structure during drawing was studied. The results showed that by adjusting the draw ratio and temperature, the properties and structure of the material can be effectively controlled.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2022)
Article
Polymer Science
Tien-Wei Shyr, Huan-Chieh Ko, Tzong-Ming Wu, Meifang Zhu
Summary: The study found that different storage conditions can lead to varying levels of hydrolysis and degradation in polylactide samples, affecting their thermal stability and crystallization behavior. Hydrolysis results in shortened molecular chains, increased nucleation, decreased melting points, and increased melting enthalpy, impacting the formation of homocrystals in the samples.
Article
Chemistry, Multidisciplinary
Wei Wang, Angelo Saperdi, Andrea Dodero, Maila Castellano, Alejandro J. Muller, Xia Dong, Dujin Wang, Dario Cavallo
Summary: This study investigates the crystallization behavior of a soluble nucleator TMC-328 in a PLLA matrix at different temperatures. The nucleator forms fibrous structures via self-assembling, which develop into interconnected networks as temperature decreases. The density of TMC-328 crystal nuclei and crystallization rates exhibit power law dependence on supersaturation, while solid-melt interfacial energy and critical nucleus properties have been determined for the first time. The presence of TMC-328 fibrils enhances PLLA crystallization rate due to increased nucleating surface area.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Polymer Science
Wenze Li, Mengyao Wang, Huan Luo, Yanhua Niu, Yajiang Huang, Guangxian Li
Summary: This study investigates the crystallization behaviors of stereocomplex and homochiral crystals by blending high molecular weight PLLA with low molecular weight PDLA and its diblock copolymers. It was found that the introduction of different sequences can inhibit the crystallization kinetics of the blends, with the formation of sc crystalites prior to hc ones. Additionally, micro phase separation between PLA and PDMS segments was observed to weaken the competition between sc and hc crystals.
Article
Polymer Science
Beata Misztal-Faraj, Marcelina Ciupak, Ryszard Pecherski, Leszek Jarecki
Summary: The study analyzes the development of polymorphic composition in the isothermal crystallization process of unstressed amorphous PLLA, and predicts the relationship between the transformation degree of individual polymorphs and crystallization temperature as well as the overall transformation degree.
Article
Biotechnology & Applied Microbiology
Tiantang Fan, Jingwen Qin, Xiao Meng, Jiafeng Li, Qing Liu, Guannan Wang
Summary: PLPG membranes with sc-PLA improved the crystallizing behavior of PLLA segments, increased thermal stability and degradation ability, and showed low cytotoxicity.
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
(2022)
Article
Engineering, Chemical
Jiewei Hu, Jin Chen, Tao Yang, Pengbo Wang, Jie Min, Qiang Fu, Jie Zhang
Summary: Entanglement of polymers can lead to increased viscosity and decreased flowability, negatively affecting their crystallization behavior. This study demonstrates that disentanglement of polymers, specifically Poly(L-lactide) (PLLA), can improve flowability and crystallization ability without the need for additives. By utilizing a self-designed polymer melt disentanglement machine, the researchers effectively promoted polymer disentanglement, resulting in lower viscosity, higher melt flow rate, accelerated crystallization kinetics, and improved heat resistance and mechanical properties of the PLLA material. This research provides new insights for resolving the conflict between mechanical properties and processing flowability, as well as expanding the application range of PLLA.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Megha D. Deokar, Baijayantimala Garnaik, Swaminathan Sivaram
Summary: Well-defined six-arm star-branched bio-degradable block copolymers were prepared using controlled ring-opening polymerization and a sequential monomer addition method. The study found that the sequence of enchainment could be changed by reversing the order of monomer addition, resulting in different crystalline or amorphous blocks. However, disruption of the block structure was observed in one of the copolymers due to competing transesterification reactions. Differential scanning calorimetry studies showed interesting phase morphologies in these sequence-controlled block copolymers. Blending these copolymers with a commercially sourced polymer led to improved tensile toughness in the blend.
Article
Polymer Science
Hanying Li, Dapeng Hu, Min Chen, Songyan Lu
Summary: This study systematically investigates the formation mechanism of nested spherulite in poly(L-lactic acid) and finds that these spherulites originate from fractional precipitation of high-molecular weight polymer chains. The insights provided by this work offer a novel perspective for polymorphism formation and a facile strategy to tailor polymorphs for PLLA and other polymers.
Article
Polymer Science
Lidong Feng, Xinchao Bian, Gao Li, Xuesi Chen
Summary: By investigating the thermal properties, morphology, and thermal stability of PLLA/PDLA blends, a new stereoamorphous mesophase (sam-PLA) structure was discovered, and the relationship between different phases in the PLLA/PDLA blends was explored.
Article
Chemistry, Physical
Giulia Giubertoni, Michiel Hilbers, Federico Caporaletti, Peter Laity, Hajo Groen, Anne Van der Weide, Daniel Bonn, Sander Woutersen
Summary: Two-dimensional infrared spectroscopy on polymer films reveals the relationship between hydrogen-bond structure and viscoelastic response. The increase in hydrogen bond number during deformation is largely reversible, however, the 2DIR spectrum shows that the distribution of hydrogen bond strengths becomes slightly narrower after a deformation cycle, possibly explaining the strain-cycle induced softening of polyurethane. These results demonstrate the ability of rheo-2DIR spectroscopy to bridge the gap between molecular structure and macroscopic elastic properties of (bio)polymers.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Applied
Yaowalak Srisuwan, Yodthong Baimark
Summary: This paper reports a study on flexible polymer blends made from PLLA-PEG-PLLA and TPS. The addition of TPS suppressed crystallizability of PLLA and PLLA-PEG-PLLA matrices, while greatly increasing the thermal stability of PLLA-PEG-PLLA. The PEG middle-blocks enhanced phase compatibility between PLLA-PEG-PLLA and TPS, resulting in ductile and flexible blend films.
CARBOHYDRATE POLYMERS
(2022)
Article
Engineering, Chemical
Jing Jiang, Lian Yang, Caiyi Jia, Yongjun Cao, Yuhui Qiao, Jianhua Hou, Qian Li, Xianhu Liu
Summary: This study reports a facile, efficient, and easy-to-scale-up strategy for producing lightweight and strong foamed polypropylene (PP) composites. By combining in situ polyethylene terephthalate (PET) fibrillation (INF) with chemical foam injection molding (CFIM) technologies, lightweight porous components with improved mechanical strength were successfully fabricated.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
