Some nanomechanical properties and degree of branching of electron beam modified polyamide 6

Evaluation of Cross-Linked Polyamide 6 Micro-Indentation Properties: TAIC Concentration and Electron Radiation Intensity

Nowadays, technical practice puts emphasis on improving selected material properties of polymers which could lead to new applications. Material properties can be modified in numerous ways, among which is radiation treatment. This study looks into the influence of beta radiation on several properties of polyamide 6, e.g., indentation hardness, modulus and creep. Main changeable parameters were the concentration of triallyl isocyanurate (TAIC), which promotes cross-linking, and intensity of radiation. The concentration was in the range from 2 to 6 wt.%, while the radiation dose was 0, 66, 99 and 132 kGy. The treated materials were measured for indentation hardness, modulus and creep. Degree of cross-linking was verified by thermo-mechanical analysis (TMA), while degradation processes was investigated by Fourier-transform infrared spectroscopy (FTIR). The results indicate that electron radiation positively affects the tested material properties. The best results were seen in polyamide with 6 wt.% of TAIC, which demonstrated a 38% improvement in mechanical properties after exposure to 132 kGy. This improvement in properties affects the final parts and their application (e.g., in the automotive industry-engine parts; in electrical engineering-insulation of wires and cables; and in industry-pipes for underfloor heating, etc.).

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

In-situ fibrillated polytetrafluoroethylene (PTFE) enhanced nanocomposites were successfully prepared by mixing thermoplastic polyether ester elastomer (TPEE) and PTFE using a twin-screw extruder. Well-dispersed, long aspect ratio PTFE nanofibrils with a diameter of less than 200 nm were generated and interwoven into networks. Differential scanning calorimetry and in-situ polarized optical microscopy showed that the PTFE nanofibrils can greatly accelerate and promote crystallization of the TPEE matrix and the crystallization temperature can be increased by 6 °C. Both shearing and elongational rheometry results confirmed that the introduction of PTFE nanofibrils can significantly improve the rheological properties. The remarkable changes in the strain-hardening effect and the melt viscoelastic response, as well as the promoted crystallization, led to substantially improved foaming behavior in the continuous extrusion process using supercritical CO2 as the blowing agent. The existing PTFE nanofibrils dramatically decreased the cell diameter and increased cell density, together with a higher expansion ratio and more uniform cell structure. The sample with 5% PTFE fibrils showed the best foaming ability, with an average diameter of 10.4-14.7 μm, an expansion ratio of 9.5-12.3 and a cell density of 6.6 × 107-8.6 × 107 cells/cm3.

Towards High-performance Materials Based on Carbohydrate-Derived Polyamide Blends

A bio-derived monomer called 2,3:4,5-di-O-isopropylidene-galactarate acid/ester (GalXMe) has great potential in polymer production. The unique properties of this molecule, such as its rigidity and bulkiness, contribute to the good thermal properties and appealing transparency of the material. The main problem, however, is that like other biobased materials, the polymers derived thereof are very brittle. In this study, we report on the melt blending of GalXMe polyamides (PAs) with different commercial PA grades using extrusion as well as blend characterization. Biobased PA blends showed limited to no miscibility with other polyamides. However, their incorporation resulted in strong materials with high Young moduli. The increase in modulus of the prepared GalXMe blends with commercial PAs ranged from up to 75% for blends with aliphatic polyamide composed of 1,6-diaminohexane and 1,12-dodecanedioic acid PA(6,12) to up to 82% for blends with cycloaliphatic polyamide composed of 4,4′-methylenebis(cyclohexylamine) and 1,12-dodecanedioic acid PA(PACM,12). Investigation into the mechanism of blending revealed that for some polyamides a transamidation reaction improved the blend compatibility. The thermal stability of the biobased PAs depended on which diamine was used. Polymers with aliphatic/aromatic or alicyclic diamines showed no degradation, whereas with fully aromatic diamines such as p-phenylenediamine, some degradation processes were observed under extrusion conditions (260/270 °C).

Plasticizing of chitosan films with deep eutectic mixture of malonic acid and choline chloride

Chitosan (CS) films containing deep eutectic solvent (DES) based on malonic acid (MA) and choline chloride (ChCl) were successfully prepared by solution casting method by using DES content ranging from 0 to 82 wt%. A strong interaction of CS with the components of DES was demonstrated by analyses of water sorption isotherms, atomic force microscopy and FTIR results. The plasticizing effect of the MA and ChCl mixture on the CS matrix was shown by static bulk mechanical measurements, thermal analysis and quantitative nanomechanical mapping (QNM). Elongation at break increased from 3 to 62% at increase of DES content from 0 to 67 wt%, while further increase of DES content led to the decreasing of maximal elongation. Introduction of DES into CS films led to the appearance of glass transition temperature in the region +2 - -2.3 °C. QNM results indicated homogeneity of the films containing up to 75 wt% of DES.