Article
Polymer Science
Mengxue Du, Katalee Jariyavidyanont, Regine Boldt, Muhammad Tariq, Matthieu Fischer, Yvonne Spoerer, Ines Kuehnert, Rene Androsch
Summary: This study analyzed the formation of crystal nuclei in injection-molded poly (L-lactic acid) (PLLA) and found that the number of nuclei varied in different regions of the molded component due to varying shear rates. The simulation results showed that the higher shear rate near the surface caused a higher number of nuclei in the skin region compared to the core region. However, shear-induced nuclei formation was also observed in the core region. By comparing the cold-crystallization kinetics and morphology with non-injection molded PLLA, it was concluded that both the skin and core regions had shear-induced nuclei formation. The simulated shear-rate data exceeded the critical specific work of flow for shear-induced nuclei formation in all regions of the component. This study demonstrates the importance of understanding the crystallization kinetics of shear and quiescent melt in PLLA for predicting structure formation in industrial processing.
Article
Polymer Science
Mengxue Du, Katalee Jariyavidyanont, Ines Kuehnert, Regine Boldt, Rene Androsch
Summary: The study found that in poly (l-lactic acid), the formation of crystal nuclei can be influenced by the variation of shear-induced specific work of flow in terms of time and rate. Different mass-average molar masses of PLLA materials showed different shear-induced crystal nucleation capabilities.
Article
Biochemistry & Molecular Biology
Mohamed Aouay, Albert Magnin, Jean-Luc Putaux, Sami Boufi
Summary: The nucleating aptitude for poly-L-(lactic acid) (PLLA) of various biobased nanoparticles with different morphologies and surface properties was investigated in this study. The results showed that cellulose nanofibrils and cellulose nanofibrils without lignin exhibited the lowest crystallization half-time and the most effective nucleating ability. Additionally, the surface energy components of the nanofillers were found to be related to their nucleating ability. The rheological properties of different compositions, as well as the mechanical and optical properties of films with and without annealing treatment, were also studied.
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
(2022)
Article
Polymer Science
Alessandra Longo, Ernesto Di Maio, Maria Laura Di Lorenzo
Summary: This article presents a novel method to enhance and control bubble nucleation in PLLA foaming without relying on external nucleating agents. The method involves annealing amorphous PLLA at temperatures close to its glass transition and foaming it after sorption of CO2. The resulting foam has a bimodal morphology with bubbles of different sizes.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2022)
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
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
Polymer Science
Biao Yang, Huifang Wang, Xinyu Wan, Baomin Fan, Hui Sun
Summary: D-mannitol (DM) and xylitol (Xy) were melt-blended with poly(L-lactic acid) (PLLA) as nucleation accelerants, and the nonisothermal crystallization behavior was studied. The crystallization temperatures of polyol-modified PLLAs were 10-15? higher than those of neat PLLA in the cooling rate range of 5-20 degrees C at 1% dosage. Xy was more effective than DM in promoting crystallization. It increased the crystallinity of PLLA to about 40% within the 1%-5% dosage, and the activation energy of nonisothermal crystallization followed the order: neat PLLA > PLLA/DM > PLLA/Xy. Polyols provide an efficient and biosafety approach to improve the performance of PLA by promoting its crystallization through a mechanism different from heterogeneous nucleation.
POLYMERS FOR ADVANCED TECHNOLOGIES
(2023)
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
Biochemistry & Molecular Biology
Wei-Wei Chang, Jinye Niu, Hui Peng, Weifeng Rong
Summary: In this study, selective formation of stereocomplex (sc) crystallization and suppression of homocrystallization (hc) in high-molecular-weight (HMW) PLLA/PDLA blends were achieved by adding C70 as a nucleator. Fourier-transformed infrared spectroscopy analysis revealed improved intermolecular interactions and inhibited molecular chain diffusion and mobility, leading to accelerated sc crystallization. The addition of C70 also resulted in a higher thermal stability compared to the neat PLLA/PDLA blend.
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
(2023)
Article
Polymer Science
Prasong Srihanam, Yaowalak Srisuwan, Theeraphol Phromsopha, Apirada Manphae, Yodthong Baimark
Summary: In this study, the phase compatibility and mechanical properties of flexible poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA)/thermoplastic starch (TPS) blends were improved by adding citric acid (CA) as a compatibilizer. The crystallinity of PLLA-PEG-PLLA matrix was suppressed and the thermal stability was enhanced by CA modification of TPS. The compatibility between TPS and PLLA-PEG-PLLA phases was improved, and the blends exhibited increased tensile strength, elongation at break, and Young's modulus with higher CA content.
Article
Polymer Science
Ying Zheng, Cai-Liang Zhang, Yong-Zhong Bao, Guo-Rong Shan, Peng-Ju Pan
Summary: Through treating PLLA with CO2 at different pressures and temperatures, this study found that PLLA can transform between complex crystalline states and conventional crystalline states, with the complex crystals having weaker interchain interactions. Additionally, the complex crystals transform into thermally stable crystals above 50 degrees Celsius, and they generally exhibit lower crystallinity and a plasticizing effect of CO2.
CHINESE JOURNAL OF POLYMER SCIENCE
(2021)
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
Jingyue Yan, Yi Zheng, Yeqiang Zhou, Yang Liu, Hong Tan, Qiang Fu, Mingming Ding
Summary: Poly(L-lactic acid) (PLLA) is a promising substitute for commercial petrochemical-based polymers due to its renewability, biodegradability, biocompatibility, and high mechanical performance. Fourier transform infrared (FTIR) spectroscopy is a simple and efficient technique to characterize the multiscale structures of PLLA, providing important insights into crystal modifications, phase transitions, chain orientation, crystallinity, crystallization kinetics, etc. This review examines the band assignments of PLLA in different states and highlights the contributions of FTIR to the structural characterization of PLLA, which can enhance researchers' understanding and encourage further advanced studies on PLLA and other macromolecules.
Article
Polymer Science
Yaowalak Srisuwan, Yodthong Baimark
Summary: In this study, high-molecular-weight poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) triblock copolymer (PLLA-PEG-PLLA) was used as a biodegradable bioplastic. However, its high cost and poor thermal stability limited its applications. Native cassava starch was blended to reduce the production cost and improve the thermal stability. The interaction between starch and PEG increased the thermal stability and phase adhesion, resulting in flexible and hydrophilic films with potential applications in biomedical, packaging, and agricultural fields.
Article
Engineering, Biomedical
Katalee Jariyavidyanont, Qiang Yu, Albrecht Petzold, Thomas Thurn-Albrecht, Rainer Gluege, Holm Altenbach, Rene Androsch
Summary: The Young's modulus of alpha '- and alpha-crystals of poly (L-lactic acid) (PLLA) has been estimated based on dynamic-mechanical analysis. The modulus increases with the crystal fraction in the assessed range and is slightly higher than the modulus of the unaged glassy amorphous phase. The average modulus seems to be controlled by weaker interchain secondary bonding rather than the modulus in the chain direction.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2023)
Review
Polymer Science
Maria Laura Di Lorenzo, Rene Androsch
POLYMER INTERNATIONAL
(2019)
Article
Polymer Science
Irene Bonadies, Alessandra Longo, Rene Androsch, Dieter Jehnichen, Michael Gaebel, Maria Laura Di Lorenzo
EUROPEAN POLYMER JOURNAL
(2019)
Article
Thermodynamics
Maria Laura Di Lorenzo, Alessandra Longo
THERMOCHIMICA ACTA
(2019)
Article
Chemistry, Physical
Maria Laura Di Lorenzo, Alessandra Longo, Rene Androsch
Article
Polymer Science
Xavier Monnier, Dario Cavallo, Maria Cristina Righetti, Maria Laura Di Lorenzo, Sara Marina, Jaime Martin, Daniele Cangialosi
Article
Chemistry, Physical
Monika Dobrzynska-Mizera, Monika Knitter, Aneta Wozniak-Braszak, Mikolaj Baranowski, Tomasz Sterzynski, Maria Laura Di Lorenzo
Article
Chemistry, Physical
Monika Dobrzynska-Mizera, Monika Knitter, Salvatore Mallardo, Maria Cristina Del Barone, Gabriella Santagata, Maria Laura Di Lorenzo
Summary: Bio-based composites made of PLLA and CD-Lim were prepared by melt extrusion, with the successful encapsulation of volatile d-limonene molecules within beta-cyclodextrin cages. Despite some limonene release during high-temperature processing, the filler's good dispersion acted as a nucleating agent favoring PLLA crystal growth. Thermomechanical analysis confirmed the lowered glass transition temperature and constant stiffness of the modified materials, which are crucial in PLLA-based formulations.
Article
Polymer Science
Alessandra Longo, Giovanni Dal Poggetto, Mario Malinconico, Paola Laurienzo, Ernesto Di Maio, Maria Laura Di Lorenzo
Summary: This work presents the enhancement of crystallization rate of poly (L-lactic acid) (PLLA) by introducing optically pure short chain branches. The synthesized graft copolymer demonstrates faster crystallization rate compared to commercial PLLA and a binary blend with the same composition. The short branches play a crucial role in promoting crystal nucleation and growth.
Review
Polymer Science
Serena Coiai, Maria Laura Di Lorenzo, Patrizia Cinelli, Maria Cristina Righetti, Elisa Passaglia
Summary: Poly(lactic acid) (PLA) is a widely produced biobased, biodegradable and biocompatible polyester. Although it shares similarities with petroleum-based polymers, its high brittleness and low toughness limit its utilization, prompting the blending with other biobased and biodegradable polymers. By incorporating appropriate additives and solid nanoparticles, the toughness and ductility of PLA can be improved, enhancing its mechanical performance, thermal stability and gas/vapor barrier properties.
Article
Polymer Science
Alessandra Longo, Ernesto Di Maio, Maria Laura Di Lorenzo
Summary: This article presents a novel method to enhance and control bubble nucleation in PLLA foaming without relying on external nucleating agents. The method involves annealing amorphous PLLA at temperatures close to its glass transition and foaming it after sorption of CO2. The resulting foam has a bimodal morphology with bubbles of different sizes.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2022)
Article
Polymer Science
Maria Cristina Righetti, Maria Laura Di Lorenzo, Dario Cavallo, Alejandro J. Muller, Massimo Gazzano
Summary: The structural evolution of poly(butylene succinate) (PBS) crystals was studied using synchrotron wide-angle and small-angle X-ray scattering (WAXS and SAXS) analysis after crystallization at 100 degrees C. Isothermal crystallization of PBS resulted in a single lamellar population. The temperature-dependent WAXS/SAXS analysis revealed the development of an additional crystal population characterized by thicker lamellae upon heating, leading to a dual lamellar population. The derived temperature dependence of the lamellar thickness for the two different crystal populations provided structural information that elucidated the multiple melting behavior of PBS.
Article
Polymer Science
Alessandra Longo, Ernesto Di Maio, Fanfan Du, Rene Androsch, Maria Laura Di Lorenzo
Summary: This study compared the cold crystallization of poly(l-lactic acid) (PLLA) containing α-mesophase with fully amorphous PLLA by mild CO2 treatment. CO2-induced mesophase developed in surface-near regions of the PLLA disks, while the core remained amorphous. Cold-crystallization of CO2-treated PLLA resulted in the formation of conformationally disordered α'-crystals.
Article
Materials Science, Multidisciplinary
Fanfan Du, Irene Bonadies, Alessandra Longo, Harald Rupp, Maria Laura Di Lorenzo, Renei Androsch
Summary: Fibers consisting of PLLA and mosquito-repellent IR3535 were successfully prepared by solution electrospinning. The incorporation of more than 40 m% of IR3535 into PLLA fibers was achieved. IR3535 facilitated the crystallization of PLLA and had a plasticizing effect on PLLA, leading to a decrease in the glass transition temperature. The slow release of IR3535 from PLLA/IR3535 fibers suggests their potential use as a long-lasting repellent-delivery system for combating diseases caused by mosquito bites.
ACS APPLIED POLYMER MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Maria Cristina Righetti, Maria Laura Di Lorenzo, Patrizia Cinelli, Massimo Gazzano
Summary: The study quantified the temperature evolution of the constrained or rigid amorphous fraction (RAF) of PBS, indicating that at room temperature and at human body temperature, all amorphous fraction is mobile. This information is important for the development of PBS products for various applications.
Proceedings Paper
Materials Science, Composites
Maria Laura Di Lorenzo, Rene Androsch
9TH INTERNATIONAL CONFERENCE ON TIMES OF POLYMERS AND COMPOSITES: FROM AEROSPACE TO NANOTECHNOLOGY
(2018)