Comparative study of filler influence on polylactide photooxidation

Polylactide (PLA) based nanocomposites of organically modified montmorillonite and micro-talc based micro- composites were prepared with different compositions and were UV-light irradiated under artificial accelerated conditions representative of solar irradiation. The chemical modifications resulting from photo-oxidation were followed by infrared (IR) and ultraviolet (UV)-visible spectroscopies. The infrared analysis of PLA photooxidation shows the formation of a band at 1847 cm-1 due to the formation of anhydrides. The filler addition provokes an increase of anhydride formation rate dependent on filler nature, amount and dispersion degree on the matrix. The main factors that influence oxidation rate are the total extension of polymer/filler interfacial area and the presence of transition metal impurities of clays

MWNT Surface Self-Assembling in Fire Retardant Polyethylene-Carbon nanotubes nanocomposites

Multiwall carbon nanotubes (MWNT) were melt blended at different concentration with linear low density polyethylene (LLDPE). The nanotubes impart the fire-retardant characteristics to the polymer by formation of a thin protective film of MWNT/carbon char generated on the surface of the nanocomposites. The film formation mechanism is discusse

Crystallization kinetics of poly(lactic acid)-talc composites

The crystallization kinetics of Poly(lactic acid) / talc composites were determined over a range of 0 wt.% to 15 wt.% of talc. Talc was found to change the crystallization kinetics. The presence of talc increases the crystallization rate and this increase is related to talc concentration and to crystallization temperature. In order to understand the effect of talc and PLA crystallinity on mechanical properties, dynamic mechanical thermal analyses were performed on Poly(lactic acid) / talc composites before and after an annealing process. It was demonstrated that the presence of crystals improves thermo-mechanical properties but in order to achieve good results at high temperatures the reinforcing effect of a filler such as talc is necessar

Simple Method for the Preparation of Composites Based on PA6 and Partially Exfoliated Graphite

In the present work, the preparation of composite systems based on polyamide 6 (PA6) and exfoliated graphite was attempted by applying a simple procedure, which consists of a preliminary dispersion/exfoliation of graphite in the monomer, namely, ε- caprolactam (CL), and a subsequent polymerization of the above system. Atomic force microscopy (AFM) demonstrated specific interactions between CL and graphite surface. The dispersion of graphite in the monomer and polymer was assessed by scanning (SEM) and transmission (TEM) electron microscopy, while mechanical tests allowed to evaluate the influence of graphite on the polymer properties

Synergistic effects of zinc borate and aluminiumtrihydroxide on flammability behaviour of aerospaceepoxy system

The flame retardancy of mono-component epoxy resin (RTM6), widely used for aerospace composites, treated with zinc borate (ZB), aluminium trihydroxide (ATH) and their mixtures at different concentrations have been investigated by morphological and thermal characterization. Cone calorimeter data reveal that combustion behaviour, heat release rate peak (PHRR) and heat release rate average (HRR Average) of RTM6 resin decrease substantially when synergistic effects of zinc borate and aluminium trihydroxide intervene. Thermogravimetric (TGA) results and analysis of the residue show that addition higher than 20% w/w of ZB, ATH, and their mixture greatly promotes RTM6 char formation acting as a barrier layer for the fire development. Depending upon the different used flame additives, SEM micrographs indicate that the morphology of residual char could vary from a compact amalgam-like structure, for the RTM6+ZB system, to a granular structure, characterized by very small particles of degraded resin and additive for the AT

Mechanical and barrier properties enhancement in film extruded bio-polyamides with modified nanoclay

The plastics industry is increasingly oriented towards the use of bio-based polymers replacing the fossil-based ones. Bio-based polyamides (PAs) in the film packaging application are not still used and need enhancement to overcome some drawbacks. In this scenario, fully (PA10.10) and partially (PA6.10) bio-based PAs were extruded in a laboratory sheet-casting machine. The materials used to obtain films were previously melt blended with modified clay in a twin-screw extruder. The resulting films were morphologically investigated through the scanning electron microscope. The magnifications show agglomerated particles and the packed layers are preferentially aligned in the extrusion machine direction. X-rays confirm that 5 wt% of clay content is difficult to exfoliate in such matrices. The crystallinity was studied by using X-ray diffraction (XRD) and differential scanning calorimetry. The XRD results show coexisting a and ¿ phases in the PA6.10 while the presence of only ¿ in the PA10.10. The presence of clay platelets constrains the crystallites formation, especially in the more polar PA6.10, resulting in changes in the type and the amount of crystals. The mechanical analysis data showed that 5 wt% of clay induced significant improvement in Young's modulus (+68 and + 14%), a slight increase in the tensile yield stress (+21 and + 5%) and only a surprisingly small decrease in the deformation at break (-15 and -24%) for PA10.10 and PA6.10, respectively. Furthermore, the addition of clay gave the best oxygen barrier properties reaching a value of 1.8 ± 0.2 cm3 × mm/m2 × day × atm comparable to a commercial PA6 film used in the packaging field.Peer ReviewedPostprint (published version

Optimization of pyrolysis-gas chromatography/mass spectroscopy parameters in order to obtain nanoplastics calibration curves

The issue of plastic pollution is one of the challenges of the coming years. When it comes to agriculture, this material is widely used, although its degradation leads to formation of micro- and nanoplastics, whose impact is being studied within the Minagris project. In particular, the identification and quantification of nanoplastics in soil can be challenging due to their size, which is below the special resolution of several techniques typically used for the characterization, as Raman or μ-FTIR analysis. Furthermore, the presence of organic matter or biological agents makes these techniques unsuitable for this purpose. Pyrolysis-gas chromatography/mass spectroscopy enables to investigate nanosized plastic samples with low limit of detection (LOD) and limit of quantification (LOQ). In this work, some of the main types of plastic used in farming have been tested at the nanoscale; with optimized parameters of py-GC/MS, calibration curves of these polymers have been obtained, in order to test out the likelihood of analysing them not only qualitatively, but also quantitively. Strong linear correlation has been found between the peak areas of the markers of each polymer and its quantity under analysis, an outcome that may be useful for real nanoplastic samples