Search results for "Polyester"
showing 10 items of 221 documents
Reprocessed polylactide: Studies of thermo-oxidative decomposition
2012
The combustion process of virgin and reprocessed polylactide (PLA) was simulated by multi-rate linear non-isothermal thermogravimetric experiments under O2. A complete methodology that accounted on the thermal stability and emission of gases was thoroughly developed. A new model, Thermal Decomposition Behavior, and novel parameters, the Zero-Decomposition Temperatures, were used to test the thermal stability of the materials under any linear heating rate. The release of gases was monitored by Evolved Gas Analysis with in-line FT-IR analysis. In addition, a kinetic analysis methodology that accounted for variable activation parameters showed that the decomposition process could be driven by …
Synthesis, thermal properties and X-ray structural study of weak C–H⋯OC hydrogen bonding in aliphatic polyester dendrimers
2004
Dendritic polyester compounds based on polyol with three, four and six reactive hydroxy groups as a molecular core, chloroacetyl chloride (or bromoacetyl bromide) and sodium metal enolate were prepared by a simple two-step synthetic procedure. The compounds were characterised by using the NMR and MS techniques, and the thermal properties were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The structures of the crystalline compounds were determined by X-ray single crystal diffraction. Detailed analysis of the structures showed that the self-complementarity of the molecules together with a multitude of weak C-H⋯O=C hydrogen bonding results in crystal…
Preparation, characterization and in vitro test of composites poly-lactic acid/hydroxyapatite scaffolds for bone tissue engineering.
2018
Abstract In this work, the possibility to produce composite Poly-L-lactic acid (PLLA)/Hydroxyapatite (HA) porous scaffolds via Thermally Induced Phase Separation (TIPS) for bone tissue engineering applications was investigated. Several PLLA/HA wt/wt ratios (95/5, 90/10, 70/30, 50/50, 34/66) were tested and the as-obtained scaffolds were characterized via Scanning Electron Microscopy, Wide Angle X-Ray Diffraction, Thermogravimetric analysis, Gas Pycnometry, Differential Scanning Calorimetry and mechanical compression test. Morphological analysis revealed an open structure with interconnected pores and HA particles embedded in the polymer matrix. Finally, cell cultures were carried out into t…
Structural, mechanical and thermal behavior assessments of PCL/PHB blends reactively compatibilized with organic peroxides
2018
Abstract The efficiency of two commercially available organic peroxides, dicumyl peroxide (DCP) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB), during reactive processing of poly(e-caprolactone)/poly(3-hydroxybutyrate) (PCL/PHB) blends was investigated. The changes in chemical structure of PCL/PHB blends, as a function of organic peroxide type (DCP/BIB) and content (in range: 0–1.0 parts by weight - pbw), were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis combined with infrared spectroscopy, and headspace analysis combined with gas chromatography with flame ionization detector. Performance properties of PCL/PHB blends were evaluated based on diffe…
Combining in the melt physical and biological properties of poly(caprolactone) and chlorhexidine to obtain antimicrobial surgical monofilaments.
2012
Bacterial infections on a sutured wound represent a critical problem, and the preparation of suture threads possessing antimicrobial properties is valuable. In this work, poly(caprolactone) (PCL) monofilaments were compounded at the concentration of 1, 2 and 4 % (w/w), respectively, to the antiseptic chlorhexidine diacetate (CHX). The incorporation was carried out in the melt by a single-step methodology, i.e. “online” approach. Mechanical tests revealed that the incorporation of CHX does not significantly change tensile properties of PCL fibres as the thermal profile adopted to prepare the compounded fibres does not compromise the antibacterial activity of CHX. In fact, CHX confers to comp…
In vitro degradation of porous PLLA/pearl powder composite scaffolds
2013
Abstract The in vitro degradation behavior of poly- l -lactide (PLLA), PLLA/aragonite pearl powder and PLLA/vaterite pearl powder scaffolds was investigated. The scaffolds were soaked in phosphate buffer solution (PBS) up to 200 days. Scanning electron microscopy (SEM), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) were used to observe any degradation of the scaffolds. Degradation behaviors such as changes in pH, porosity, bulk density, water absorption, weight loss and mechanical properties were discussed. The results show that a gradual increase of the pH in composite scaffolds can decrease the rate of hydrolysis of PLLA. PLLA/vaterite and PLLA/aragonite…
Vascular Endothelial Growth Factor-Releasing Microspheres Based on Poly(ε-Caprolactone-PEG-ε-Caprolactone)-b-Poly(L-Lactide) Multiblock Copolymers In…
2020
Pancreatic islet transplantation is a promising advanced therapy that has been used to treat patients suffering from diabetes type 1. Traditionally, pancreatic islets are infused via the portal vein, which is subsequently intended to engraft in the liver. Severe immunosuppressive treatments are necessary, however, to prevent rejection of the transplanted islets. Novel approaches therefore have focused on encapsulation of the islets in biomaterial implants which can protect the islets and offer an organ-like environment. Vascularization of the device’s surface is a prerequisite for the survival and proper func- tioning of transplanted pancreatic islets. We are pursuing a prevascularization s…
MRI-visible nanoparticles from hydrophobic gadolinium poly(ε-caprolactone) conjugates
2015
International audience; In this work we report on the synthesis of two hydrophobic and degradable gadolinium poly(ε-caprolactone) conjugates and their use for the preparation of MRI-visible nanoparticles intended for diagnosis applications. Advantage has been taken from functional poly(ε-caprolactone)s (PCL) bearing propargyl (PCL-yne) or amine groups (P(CL-co-NH2VL)) to yield conjugates by following two strategies. In a first approach, an azido-chelate of gadolinium (Gd(III)) has been conjugated by CuAAC to PCL-yne to yield a polymeric chelate containing 2.6 wt% of Gd(III). In a second approach, a dianhydride Gd(III)-ligand was reacted with P(CL-co-NH2VL) to yield, after complexation with …
Photo-Oxidative and Soil Burial Degradation of Irrigation Tubes Based on Biodegradable Polymer Blends
2019
: Irrigation tubes based on biodegradable polymers were prepared via an extrusion-drawing process by Irritec and compared to conventional pipes made of high-density polyethylene (HDPE). A commercial polylactide/poly (butyleneadipate-co-butyleneterephthalate) (PLA/PBAT) blend (Bio-Flex®
Antibacterial performance of solvent cast polycaprolactone (PCL) films containing essential oils
2013
Abstract The increase of consumer demand for higher quality and longer shelf-life in foods, while reducing the use of non-compostable packaging materials, has encouraged research on biopolymers incorporating natural antimicrobial compounds. Cinnamaldehyde (CNMA) and allyl isothiocyanate (AITC) were incorporated into polycaprolactone (PCL) films by solvent casting. The release study was carried out by means of ATR and transmission FTIR spectroscopy and showed high volatility of the essential oils during the film forming process. While only negligible quantities of AITC were retained in the polymer matrix after film curing, the release of CNMA was prolonged for at least 50 h at room temperatu…