Papers by Keyword: Poly(lactic acid) (PLA)

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Authors: B. Notario, Javier Pinto, E. Solórzano, J. Escudero, J. Martín de León, D. Velasco, Miguel A. Rodríguez-Pérez
Abstract: An own-designed pressure vessel with glass windows has been employed to perform an in-situ characterization of the temporal evolution of the crystallization process of an amorphous polylactic acid (PLA) under different controlled CO2 pressures and temperatures. It has been proven that crystallinity can be related to optical parameters such as transmissivity, obtaining information about the whole process by optical measurements. The method has the advantage of measuring in-situ over bulk samples with a non-destructive tool. The obtained results have shown some unexpected trends that have been explained taking into account the complex phenomena occurring during the crystallization process of PLA in the presence of CO2 at high pressure.
Authors: Mujtahid Kaavessina, Fitriani Khanifatun, Imtiaz Ali, Saeed M. Alzahrani
Abstract: Poly (lactic acid) was solvent-blended and formed as thin ribbons with different weight fraction of hydroxyapatite, namely 5, 10 and 20wt%. In-vitro biodegradability of biocomposites was performed in phosphate buffer solution (PBS) at 37°C. The presence of hydroxyapatite tended to increase biodegradability of poly (lactic acid) in its biocomposites. Thermal stability of biocomposites was always higher than that neat poly (lactic acid) either before and after hydrolytic degradation tests. After biodegradation tests, some micro-holes and cracks were appeared in the surface morphology of biocomposites as well as the increasing crystallinity occurred.
Authors: Zheng Guo, Jin Jing Chen, Pei Hua Zhang
Abstract: A tubal knitted scaffold fabricated from poly(lactic acid) (PLA) yarns was given in this work. The performance of the scaffold during degradation in vitro and the morphology of the scaffold with cells (monkey dermal fibroblasts) were examined. The scaffold fabricated from poly(glycolic acid) (PGA) yarns was manufactured as the control. Results showed that the PLA scaffold could keep much more tensile strength during degradation in vitro, compared with the PGA scaffold. However, cell attachment and proliferation on the PGA scaffold were better than on the PLA scaffold.
Authors: Yi Wang, Hong Song Fan, Yu Mei Xiao, Zhong Wei Gu, Xing Dong Zhang
Abstract: A new way to prepare polymer/hydroxyapatite(HA) composite scaffolds with 3-D interconnected macro and micro pores at room temperature was established, basically based on solvent-casting and particle-leaching together with foaming technique. With this method, Polylactide (PLA) / HA composites of porous architecture with macro pores (50~300)m, average 200)m) and micro pores (~10)m) on the skeleton were obtained. The bending strength and the compressive strength of the composite scaffold were reached to 11.5 MPa and 7MPa respectively with the porosity of approximate to 90%. The study supplied a new short time, low energyexpending method to prepare polymer/ceramic composite with high porosity and interconnected porous structure at room temperature.
Authors: Yun Qing Kang, Guang Fu Yin, Ke Feng Wang, Lin Luo, Li Liao, Ya Dong Yao
Abstract: The ability of apatite to form on the surface of biomaterials in simulated body fluid (SBF) has been widely used to predict the bone-bonding ability of bioceramic and bioceramic/polymer composites in vivo. Porous β-tricalcium phosphate/poly(L-lactic acid) (β-TCP/PLLA) composite scaffold was synthesized by new method. The ability of inducing calcium phosphate (Ca-P) formation was compared in static simulated body fluid(sSBF) and dynamic simulated body fluid (dSBF). The Ca-P morphology and crystal structures were identified using SEM, X-ray diffraction and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the typical features of bone-like apatite formation on the surface and the inner pore wall of β-TCP/PLLA. Ca-P formation on scaffold surfaces in dSBF occurred slower than in sSBF and was more difficult with increasing flow rate of dSBF. The ability of apatite to form on β-TCP/PLLA was enhanced by effect of each other that has different degradable mechanism. Porous β-TCP/PLLA composite scaffold indicates good ability of Ca-P formation in vitro.
Authors: Toru Tonegawa, Toshiyuki Ikoma, Tomohiko Yoshioka, Kazuo Shinozaki, Nobutaka Hanagata, M. Tanaka
Abstract: Insulin delivery carriers using low crystalline porous zinc hydroxyapatite (ZnHAp) microparticles with different crystal sizes and novel formulation method of poly (lactic acid) (PLA) have been developed to achieve the sustained-release of insulin. The adsorption isotherm curves of insulin dissolved into acetic acid of pH4.5 onto ZnHAp nanocrystals show non-Langmuir type due to the dissolution of the ZnHAp microparticles; the adsorption amounts were increased with the increase of crystalline sizes. The PLA formulation, coating the outer layer of microparticles, showed the apparent reduction of initial burst for insulin. The amounts of initial release of insulin decreased with the increase of crystalline sizes of ZnHAp, which could be attributed to the different meso-porous structure depending on its crystal sizes.
Authors: Han Yong Jeon
Abstract: In this study, concept of green geosynthetics was introduced in terms of biodegradability. Development of green geosynthetics, its background and technical concerns were discussed through some research results of PLA(polylactic acid) specimens. Test method for biodegradability of PLA(polylactic acid) as a green geosynthetics were considered and suggested based on composting method. Finally, the rest result shows that the concept of biodegradability for green geosynthetics is available in the environmental application. PLA 4032D/PBAT(80/20) blend shows improvement of environmental performance as a green geosynthetics application than PLA 4032D only used.
Authors: Yuan Yuan Chen, Luke M. Geever, Clement L. Higginbotham, Declan M. Devine
Abstract: Polylactic acid (PLA) is the most promising material in the biodegradable category. However, brittleness and poor thermal stability restrict its application. To overcome this limitation, PLA may be blended with other biodegradable materials to tailor its properties while maintain biodegradability. In this study a series of blends of PLA and poly (ε-caprolactone) (PCL) with various mass fractions were prepared by solution method and solvent casting. Films of each blend were formed when the solvent evaporated. Subsequently, tensile test samples were punched out of the film for testing and tensile testing, Fourier transform infrared spectrometry (FTIR), Differential scanning Calorimetry (DSC) and contact angle measurements were carried out. Since PCL is a ductile material, the two materials were blended together in an effort to improve the mechanical properties. However, on thermal analysis of the blends, two individual melting peaks were observed in the DSC thermograms. Furthermore, no significant shift in peaks was observed on the FTIR spectra, and clear droplets and boundaries between two components of the blend can be observed in morphology study, all indicated the immiscibility of PLA and PCL. Tensile test showed poor mechanical properties due to the poor adhesion of the two immiscible components of the blend, and the addition of PCL did not influence the wettability of the surface of the blends as there were no significant differences in contact angle measurements.
Authors: Hirotaka Maeda, Toshihiro Kasuga
Abstract: A new type of poly(lactic acid) (PLA)/calcium carbonates hybrid membrane incorporated with silicon, which is suggested to stimulate the formation of bones, was prepared using aminopropyltriethoxysilane (APTES) for bone repair materials. Carboxyl groups in PLA made a chemical bond with amino groups in APTES, resulting in the formation of the hybrid membrane. The membrane formed hydroxycarbonate apatite (HCA) on its surface after 3 days of soaking in simulated body fluid (SBF). X-ray energy dispersive spectroscopy showed the HCA layer includes Si with Ca and P. A result of osteoblast-like cellular proliferation on the substrates that the membrane coated with silicon-containing HCA had much higher cell-proliferation ability than the membrane.
Authors: Zhi Hua Cui, Jiang Chao Guo, Wei Guo Chen, Bing Tao Tang
Abstract: A series of phenylazo-β-naphthol-containing sulfonamide disperse dyes were applied to poly (lactic acid) fabric by exhaust dyeing. Their dye exhaustion, color strength and color fastness on poly (lactic acid) fabric were assessed. It was found that sulfonamide dyes, especially tertiary sulfonamide dyes, exhibited superior dye exhaustion, color strength and color fastness to washing and sublimation on poly (lactic acid) fabric in comparison to C.I. Solvent Yellow 14 bearing the same chromophore but without sulfonamide moiety.
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