Agnieszka Piegat

Effect of carbon nanotube modification on poly (butylene terephthalate)-based composites

The influence of the chemical modification of carbon nanotubes on the mechanical, thermal and electrical properties of poly(butylene terephthalate)-based composites was investigated. Polymer composites based on poly(butylene terephthalate) were obtained via in situ polymerisation or extrusion. Commercially available multi-walled carbon nanotubes (Nanocyl NC7000) at different loadings (mass %: 0.05, 0.25, 1, 2) were used as fillers. The functionalisation process took place under a chlorine atmosphere followed by a reaction with sodium hydroxide. The effect of carbon nanotube modification was analysed according to the changes in the polymer thermal and mechanical properties. An addition of modified carbon nanotubes in the amount of 0.05 mass % improved the mechanical properties of the composites in terms of both Young’s modulus and tensile strength by 5–10 % and 17–30 % compared with composites with unmodified carbon nanotubes and neat poly(butylene terephthalate), respectively. The in situ method of composite preparation was a more effective technique for enhancing the matrix-filler interactions, although a significantly lower amount of fillers were used than in the extrusion method.

The effect of carbon nanoparticles on biological properties of polyester nanocomposites

The aim of present study was to determine the hemocompatibility, cellular response of endothelial cells and bacterial adhesion to a new polyester nanocomposite. The carbon nanoparticle nanocomposite was prepared via in situ polymerization of monomers to obtain material of hardness 55 Sh D similar to polyurethanes used in medical applications, for example, in heart-assisting devices. The carbon nanoparticle-containing polyester exhibits markedly reduced bacterial colonization, as compared to commercially available polyurethanes. Further the nanocomposite possesses markedly improved hemocompatibility, as determined by flow cytometry, and robust endothelialization. Possible explanations for these beneficial properties include surface nanoroughness of carbon nanoparticle-containing nanocomposites and presence of fatty acid sequences within polymer structure.

Enzymatic Degradation of Poly(butylene succinate) Copolyesters Synthesized with the Use of Candida antarctica Lipase B

Biodegradable polymers are an active area of investigation, particularly ones that can be produced from sustainable, biobased monomers, such as copolymers of poly(butylene succinate) (PBS). In this study, we examine the enzymatic degradation of poly(butylene succinate-dilinoleic succinate) (PBS-DLS) copolymers obtained by “green” enzymatic synthesis using lipase B from Candida antarctica (CALB). The copolymers differed in their hard to soft segments ratio, from 70:30 to 50:50 wt %. Enzymatic degradation was carried out on electrospun membranes (scaffolds) and compression-moulded films using lipase from Pseudomomas cepacia. Poly(ε-caprolactone) (PCL) was used as a reference aliphatic polyester. The degradation process was monitored gravimetrically via water uptake and mass loss. After 24 days, approx. 40% mass loss was observed for fibrous materials prepared from the PBS-DLS 70:30 copolymer, as compared to approx. 10% mass loss for PBS-DLS 50:50. Infrared spectroscopy (FTIR) and size exclusion chromatography (SEC) analysis were used to examine changes in chemical structure. Differential scanning calorimetry (DSC) and scanning light microscopy (LSM) revealed changes in degree of crystallinity, and changes in surface morphology, consistent with a surface erosion mechanism. We conclude that the obtained copolymers are suitable for tissue engineering applications thanks to tuneable degradation and lack of acidification during breakdown.

Thermoplastic Elastomers: Materials for Heart Assist Devices

Heart assisting devices have become a standard element in clinical practice and provide support for the traditional methods of treating heart disease. Regardless of the construction of VAD (ventricular assist devices), there are crucial requirements that have to be met by the construction materials: high purity, desired physical, chemical and mechanical properties, easy fabrication and high stability and susceptibility to sterilization. They must not cause thrombosis, destroy cellular elements, alter plasma protein, destroy enzymes, deplete electrolytes, cause immune response and cancer, and must not produce toxic and allergic reactions, when they are applied in direct contact with biological tissues and fluids. This paper provides an overview of the polymeric materials as construction materials for cardiovascular support systems, focusing on the group of thermoplastic elastomers, mainly polyurethane and polyester based ones. It also highlights the advantages and disadvantages of currently used materials and the progress in the design of new materials with potential application in the biomedical field.

Morphology of polyamide 6 confined into carbon nanotubes

Abstract The preparation of polymer nanocomposites filled with carbon nanotubes requires the nanotubes to be uniformly dispersed and compatible with the polymer matrix. In this work we report a preparation method of polyamide 6 (PA 6) based nanocomposite containing multi-walled carbon nanotubes (MWCNT) without any additional surface modification and obtained by in situ polymerization, as a simple method for composites production. The process was assisted by ultrasounds prior to synthesis.With such a method, an interesting morphology of polyamide 6 confined into a multiwalled carbon nanotube as well as grafted on a carbon nanotube surface was observed. For comparative purpose, PA 6 nanocomposites were also prepared from commercially available master batch by melt compounding.

Silica-Polyester Nanocomposites Prepared by Polycondensation In Situ: Synthesis and Mechanical Properties

New multiblock polymer-matrix nanocomposites were prepared by the in situ polycondensation. Polymers containing 30% hard segments of poly (butylene terephthalate) (PBT) and 70% soft segments built up from dimerized fatty acid (DLA), were modified with silica nanopowder. The nanocomposite materials were prepared by polycondensation in situ with the use of two different catalysts. Two types of nanosilica (Evonic Aerosil R 972 hydrophobic, and Aerosil 130 - hydrophilic) in amount of 0.1, 0.2 and 0.3 wt. % were used. Physical and mechanical properties were examined. The results indicate a strong influence of transesterification stoichiometry and type of catalyst on physical and mechanical properties. The amount of nanofiller and its character (hydrophilic or hydrophobic) showed also an influence on mechanical properties of synthesized nanocomposites indicating the best mechanical properties for nanocomposite containing 0.1wt% hydrophobic silica nanopowder (over 70% increase in elongation and 30% increase in tensile strength).