Shear and extensional rheometry of PA6 reinforced with polyacrylic nanoparticles

Effects of Hybrid POSS Nanoparticles on the Properties of Thermoplastic Elastomer-Toughened Polyamide 6

In this study, polyamide 6 (PA6)/thermoplastic elastomer (TPE) blends were prepared to decrease the notch sensitivity of PA6 for automotive applications, and the morphological, rheological, mechanical, and thermal properties of PA6/TPE blends, which are partially miscible or immiscible depending on the TPE ratio, were significantly improved in the existence of polyhedral oligomeric silsesquioxane (POSS) nanoparticles with multiple reactive epoxy groups as compatibilizers. An unstable phase morphology was obtained with the addition of TPE into PA6 without POSS nanoparticles, whereas interfacial interactions between phases in the presence of POSS were enhanced as a result of a significant decrease in the average particle size from 1.39 to 0.41 μm. The complex viscosity value of the 70PA6/30TPE blend, which was 20 kPa/s-1 at 0.1 rad/s angular frequency, reached 380 kPa/s-1 with the addition of POSS due to the formation of long chains by the generation of graft and/or block copolymers, which resulted in a 65% increase in Young's modulus value. Most notably, the Izod impact strength of pure PA6, which was 10 kJ/m2, increased by 290% with the incorporation of POSS. It was confirmed by FTIR analysis that the reactive multiple epoxy groups of MultEpPOSS and EPPOSS nanoparticles react with the proper groups of PA6 and/or TPE, and also, a partial hydrogen bonding interaction occurs between PA6-TPE from the shifting of N-H and carbonyl peaks. In conclusion, it can be suggested that POSS nanoparticles can serve as highly effective compatibilizers for PA6/TPE blends and have potential commercial applications, especially in the automotive sector.

Is it Possible to Mechanical Recycle the Materials of the Disposable Filtering Masks?

In a singular period, such as during a pandemic, the use of personal protective masks can become mandatory for all citizens in many places worldwide. The most used device is the disposable mask that, inevitably, generates a substantial waste flow to send to incineration or landfill. The article examines the most diffused type of disposable face mask and identifies the characteristic of the constituent materials through morphological, chemical, physical, and thermal analyses. Based on these investigations, a mechanical recycling protocol with different approaches is proposed. Advantages and disadvantages of the different recycling solutions are discussed with considerations on necessary separation processes and other treatments. The four solutions investigated lead to a recycling index from 78 to 91% of the starting disposable mask weight. The rheological, mechanical, and thermo-mechanical properties of the final materials obtained from the different recycling approaches are compared with each other and with solutions present on the market resulting in materials potentially industrially exploitable.

Effect of elongational flow on immiscible polymer blend/nanoparticle composites: a molecular dynamics study

Using coarse-grained nonequilibrium molecular dynamics, the dynamics of a blend of the equal ratio of immiscible polymers mixed with nanoparticles (NP) are simulated. The simulations are conducted under planar elongational flow, which affects the dispersion of the NPs and the self-assembly morphology. The goal of this study is to investigate the effect of planar elongational flow on the nanocomposite blend system as well as to thoroughly compare the blend to an analogous symmetric block copolymer (BCP) system to understand the role of the polymer structure on the morphology and NP dispersion. Two types of spherical NPs are considered: (1) selective NPs that are attracted to one of the polymer components and (2) nonselective NPs that are neutral to both components. A comparison of the blend and BCP systems reveals that for selective NP, the blend system shows a much broader NP distribution in the selective phase than the BCP phase. This is due to a more uniform distribution of polymer chain ends throughout the selective phase in the blend system than the BCP system. For nonselective NP, the blend and BCP systems show similar results for low elongation rates, but the NP peak in the BCP system broadens as elongation rates approach the order-disorder transition. In addition, the presence of NP is found to affect the morphology transitions of both the blend and BCP systems, depending on the NP type.