Article
Polymer Science
Katalee Jariyavidyanont, Mengxue Du, Qiang Yu, Thomas Thurn-Albrecht, Christoph Schick, Rene Androsch
Summary: The bulk enthalpy of melting of α-crystals of poly (L-lactic acid) (PLLA) was evaluated using fast scanning calorimetry (FSC). The results showed that the melting enthalpy of PLLA was 104.5 +/- 6 J g(-1) when melting occurs at 180-200 degrees C, with the analysis based on a two-phase structure and the absence of a vitrified rigid amorphous fraction (RAF). It was also confirmed that the RAF formation and vitrification were suppressed by controlling the crystallization process and using FSC for cooling.
MACROMOLECULAR RAPID COMMUNICATIONS
(2022)
Article
Polymer Science
Apisit Banpean, Hideaki Takagi, Nobutaka Shimizu, Noriyuki Igarashi, Shinichi Sakurai
Summary: The study focused on the confined crystallization of PEG in PLLA spherulite in a PLLA/PEG blend specimen using SAXS/WAXS measurements. The results showed suppression of PEG lamellae growth in the thickness direction due to space confinement by preformed PLLA lamellae, while also observing more regular stacking in the blend specimen.
Article
Polymer Science
Alexis Theodorou, Vasilios Raptis, Chrissie Isabella Maria Baltzaki, Thrassyvoulos Manios, Vagelis Harmandaris, Kelly Velonia
Summary: In this study, we performed synthetic experiments and kinetic modeling calculations to investigate the polycondensation process of lactic acid and the formation of poly(lactic acid) (PLA). The results showed that under optimized conditions, PLLA with a weight-average molecular weight of 161 kDa could be obtained. The kinetic parameters obtained from the optimization accurately reproduced the experimental data.
Article
Polymer Science
Amit Kumar Pandey, Hideaki Takagi, Noriyuki Igarashi, Nobutaka Shimizu, Shinichi Sakurai
Summary: The addition of SFN was found to enhance the formation and crystallizability of SC crystals in the PLLA/PDLA (50/50) blend, while suppressing HC crystallization. This finding is significant for the performance and applications of the material.
Article
Polymer Science
Igor O. Pariy, Roman Chernozem, Polina Chernozem, Yulia R. Mukhortova, Andre G. Skirtach, Vladimir V. Shvartsman, Doru C. Lupascu, Maria A. Surmeneva, Sanjay Mathur, Roman A. Surmenev
Summary: This work extensively characterized the effect of reduced graphene oxide (rGO) content on the morphology, structure, thermal and piezoelectric behavior of piezoelectric poly-L-lactide (PLLA) scaffolds. It was found that the addition of rGO enhanced the piezoelectric response of PLLA scaffolds, making them suitable for tissue engineering applications.
Article
Polymer Science
Qianjin Zhu, Kaixin Chang, Liyan Qi, Xinyi Li, Woming Gao, Qinwei Gao
Summary: In this study, PLLA films were surface-modified using different solutions, leading to changes in their structure and properties. The modification with PDLA weakened the crystal structure of the films, while modification with PDLAG increased the stereocomplex (SC) structure and decreased the homogeneous crystal (HC) structure.
Article
Thermodynamics
Todsapol Kajornprai, Kalyanee Sirisinha
Summary: The influence of post-process annealing treatment on the structural and thermal behaviors of poly(L-lactic acid)/poly(butylene succinate) (PLLA/PBS) blend was investigated. It was found that the temperature and addition of plasticizer can significantly affect the crystalline structure and melting behavior of the samples. Multiple melting behaviors observed were attributed to simultaneous melting, recrystallization, and remelting of PLLA and PBS crystals in the blends.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Polymer Science
Deyu Niu, Hai Wang, Ye Ma, Pengwu Xu, Jiaxuan Li, Weijun Yang, Tianxi Liu, Kohji Tashiro, Pieter Jan Lemstra, Piming Ma
Summary: In this study, a new crystal modification of poly(glycolic acid) (PGA) named β-form was reported, which is different from the previously known α-form. The β-form of PGA was obtained during isothermal crystallization in a specific temperature range (around 60°C) after prestretching the amorphous samples. It was found that the orientation of PGA amorphous chains in the β-form better fits the chain conformation, resulting in a lower energy barrier for β-form formation compared to the α-form. The study also revealed a solid-solid phase transition from β-form to α-form in the temperature range of 80-120°C with consistent crystalline orientation degree. This research contributes to a better understanding of the polymorphism and phase transition of PGA, providing insights for controlling its final performance through crystalline structure.
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
Polymer Science
Giulia Tamburini, Stefano Bertagnoli, Giulia Tarricone, Sergio Piva, Adele Sassella, Roberto Lorenzi, Alberto Paleari
Summary: A spectroscopic study on the initial stages of radiation-induced modifications in poly(lactic acid) (PLA) revealed the emergence of molecular unit perturbations, mainly related to methyl and carbonyl groups with the formation of C=C double bonds.
POLYMER DEGRADATION AND STABILITY
(2023)
Article
Biochemistry & Molecular Biology
Zhimin Dong, Yushuang Miao, Huashuai Cui, Qing Huang, Yiguo Li, Zongbao Wang
Summary: The microstructure of PGA and P(GA-co-LA) fibers used as surgical sutures plays a crucial role in determining their properties. Heat-setting at 120 degrees C was found to be more effective in enhancing fiber properties, especially due to crystal formation and perfection. The structural evolution during heating showed different behaviors between PGA and P(GA-co-LA) fibers, with differences in crystallite sizes, unit cell parameters, and crystal structure due to the presence of LA monomers.
Article
Polymer Science
Lidong Feng, Xinchao Bian, Gao Li, Xuesi Chen
Summary: The study shows that the compatibility between PLLA and PLDLA-m decreases as the L-lactate unit content in PLDLA-m decreases, impacting the crystallization and compatibility of the blends.
Article
Polymer Science
Apisit Banpean, Shinichi Sakurai
Summary: The study found that under specific conditions, PEG can only crystallize in the preformed spherulites of PLLA and not in the amorphous phase of the mixed PLLA/PEG matrix.
Article
Polymer Science
Charles J. McCutcheon, Boran Zhao, Christopher J. Ellison, Frank S. Bates
Summary: Adding PEO-PBO diblock copolymer significantly reduces the crystallization time and increases the ductility of PLLA blends without affecting the modulus. The block copolymer particles facilitate stress-induced cavitation and uniform crazing, leading to a 7-15 fold increase in tensile toughness of the blends.
Article
Polymer Science
Yangzhe Hou, Han Jia, Yamin Pan, Chuntai Liu, Changyu Shen, Xianhu Liu
Summary: This study successfully prepared brand-new porous PLA films with enhanced flexibility and heat resistance using blade coating and thermally induced phase separation methods. The resulting blend films showed improved mechanical properties and high porosity, making them suitable for microfiltration, packaging, and modified applications.
Article
Polymer Science
Yuanzhang Jiang, Xuyi Wang, Yanting Han, Dakai Gong, Yingchun Gu, Lin Tan
Summary: In this study, FeCl3 and poly(acrylic acid) (PAA) were doped into waterborne polyurethanes (WPUs) to create multifunctional materials with self-healing and antimicrobial properties. WPU/Fe/PAA-5.5, containing 5.5 wt % PAA, exhibited excellent mechanical properties, strong self-healing capabilities, and an impressive antimicrobial rate of over 90%. These supramolecular films were also highly recyclable through hot-pressing.
Article
Polymer Science
Longyu Tian, Min Wang, Guangming Liao, Baoliang Liu, Sujuan Zhang, Yucheng Sun, Zhen Meng, Jintao Zhang, Zaijun Lu
Summary: Two kinds of benzoxazine monomers were synthesized and used to prepare polybenzoxazine anion exchange membranes (AEMs) with quaternary ammonium functionalization. The LQPBZ AEM exhibited better ion conductivity and alkaline stability.
Article
Polymer Science
Claire A. Lemarchand
Summary: This study investigates the shock behavior of three different polymers through molecular dynamics simulations. The results reveal specificities in the shock behavior of polymers, including deviations from the linear relation between shock velocity and particle velocity, as well as differences in shear stress relaxation behind the shock front. It is found that the deviation of the Hugoniot locus is related to the change in the relative contribution of bonding and non-bonding potential energies, while polymers with higher glass transition temperatures exhibit slower shear stress relaxation.
Article
Polymer Science
Zengquan Liu, Xiaochun Yin, He Zhang, Shuo Gao, Qinglin Kuang, Yanhong Feng
Summary: A powder solid-state extension (PSSE) technology was proposed to address the high melt viscosity issue of UHMWPE. By uniaxial extension and sintering in the solid state, a highly self-reinforced material was prepared. X-ray diffraction and scattering techniques were used to study the structural evolution during the PSSE process, and a solid-phase induced transformation model was established.
Article
Polymer Science
Zhike Li, Anyu Luo, Rui Zhou, Xin Li, Haiyan Li
Summary: A novel high temperature resistance IL@SiO2 nanocapsules were successfully prepared and their friction and wear properties in PA6 composites were studied. The addition of IL@SiO2 nanocapsules reduced the friction coefficient and wear rate without affecting the mechanical properties of PA6. The synergy between the IL core and SiO2 wall in the nanocapsules improved the self-lubricating performance of the PA6 composites.
Article
Polymer Science
Xin Liu, Xuhong Guo, Qi Liao
Summary: In this study, an algorithm for accurately estimating viscosity is developed using molecular dynamics simulations and the Green-Kubo formula. This algorithm can be applied to complex systems with long correlations, such as macromolecular and biological simulation systems.
Article
Polymer Science
Hao Pu, Yun-Lei Hou, Jing -Zhou Chen, Dong -Lin Zhao
Summary: The use of modified graphene improves the interfacial adherence of carbon fibers to epoxy resin, resulting in enhanced interfacial and bending properties of CF and matrix in CF/EP composites, as well as increased interlaminar shear strength and flexural strength.
Article
Polymer Science
Wei-Chung Ke, Jin-Wei Lin, Manohar Reddy Busireddy, Yueh-Hsing Lee, Jiun-Tai Chen, Chain-Shu Hsu
Summary: This study introduces a crosslinkable monomer, TAIC, to synthesize three crosslinked polyimide films, which exhibit improved thermal, mechanical, and dielectric properties. The introduction of TAIC enhances the tensile strength, reduces the dielectric constant and dielectric loss, and decreases the coefficient of thermal expansion of the polyimide films.
Article
Polymer Science
Alex Kwasi Kumi, Ruiling Fan, Ye Chen, Yumei Zhang
Summary: The difference in leaching of amylopectin from cellulose/amylopectin/1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) blends during regeneration in water and aqueous ethanol has been studied. Molecular dynamics simulations showed that the dissolution and regeneration mechanisms of amylopectin in [Bmim][Cl] are similar to cellulose in ionic liquids. Water regeneration leads to weak electrostatic interactions, resulting in high leaching of amylopectin. In contrast, ethanol-water interactions enhance electrostatic interactions among amylopectin chains, limiting amylopectin leaching in aqueous ethanol.
Article
Polymer Science
Xi Zeng, Junwei Zhou, Junbiao Peng, Chunsheng Zhang, Danling Wang, Yihu Song, Qiang Zheng
Summary: This study utilizes an oligomer deep eutectic solvent (DES) based on polyethylene glycol to regulate the vulcanization kinetics of rubber. The results show that the DES can accelerate vulcanization at low temperatures without affecting the crosslinking density and Mullins effect.
Article
Polymer Science
Qianqian Yue, Yongfei Peng, Xingjian Liu, Aihua He, Huarong Nie
Summary: The addition of metal deactivators can effectively suppress the aging of TBIR, prolong its lifespan, and have no negative effects on its physical and processing properties. These research findings are of great importance for improving the stability and aging resistance of polymers.
Article
Polymer Science
J. Gomez-Caturla, J. Ivorra-Martinez, R. Tejada-Oliveros, V Moreno, D. Garcia-Garcia, R. Balart
Summary: This work focuses on the development of environmentally friendly PLA formulations by using different esters derived from geraniol as plasticizers. The results show that these esters have good compatibility with PLA, and they can effectively enhance the elongation and plasticity of PLA, reduce its glass transition temperature, and slightly improve its water absorption capabilities.
Article
Polymer Science
Dandan Li, Zhaohui Lu, Zhao Ke, Ke Xu, Fengna Dai, Youhai Yu, Guangtao Qian, Chunhai Chen
Summary: In this study, cross-linked PI aerogel membranes with low dielectric constant and high moisture resistance were prepared by co-polymerization and scraping coating technology. The incorporation of fluorinated blocks and benzimidazole ring structures resulted in novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance.
Article
Polymer Science
Zhaoyang Chu, Qing Zhang, Haihua Luo, Han Zhou, Fapei Zhang, Wei Chen, Wenhua Zhang
Summary: Multi-physical fields solution processing strategy is a universal and facile method for preparing various conjugated polymer films and high-performance devices. In this study, we employed a combined microfluidic flow and ultrasonication strategy (FU) for processing CP solutions, and found a pronounced synergetic effect in promoting the pre-ordering of chains in solution. The conformation order and anisotropy of the solution were revealed through various characterizations. A non-classical nucleation model for polymer crystallization in non-equilibrium solution processing was confirmed. The roles of microfluidic flow and ultrasonication in chain aggregation and crystallization were addressed through multi-physical simulations. Compared to pristine solutions, the FU strategy showed improved solution anisotropy and crystallization kinetics, resulting in higher crystallinity in films and increased mobilities in OFET devices. The FU processing strategy provides a universal approach for regulating chain conformation and aggregation in conjugated polymer solutions.