In the present study, we investigated the possibility of value-added recycling of ultrafine ground tire rubber (uGTR) produced from water jet milling, with an average particle size of a few tens of microns. Our goal was to compare the properties of blends with different uGTR and conventional fine ground tire rubber (fGTR) contents prepared by blending with low-density polyethylene (LDPE). We also aimed to explore the property changes caused by the larger specific surface area due to the size effect. Samples were prepared with a hydraulic press after internal mixing. In the case of ground tire rubber (GTR) filled mixtures, the tensile properties showed rubber-like characteristics: with a significant decrease in modulus, elongation at break remained high, and tensile strength slightly decreased. The fracture surfaces of the samples were analyzed by scanning electron microscopy (SEM), wherein the case of materials made with uGTR showed better adhesion between the phases. In order to investigate the interfacial adhesion between the GTR and LDPE, we performed dynamic mechanical thermal analysis (DMTA). The glass transition peak of the uGTR shifted to a higher temperature and the storage modulus was higher than in the case of samples containing fGTR. Finally, we determined the Shore D hardness of the materials, which decreased with increasing GTR content, but hardness was greater in the case of uGTR samples. The better mechanical properties of blends containing uGTR were explained by better interfacial adhesion between the two phases due to the significantly higher specific surface area compared to fGTR.

Fused filament fabrication (FFF) is an additive manufacturing technology in which a fused filament is deposited in a controlled manner over or adjoining previous deposited filaments, leading to construction of a structural part. This study aims to characterise the extent of fusion bonding between individual filaments using printed single-layer films, which helps understand the process–structure–property relationship, optimising process parameters (i.e. deposition speed and extrusion temperature) involved in the FFF process. For a brittle polylactic acid (PLA) and a ductile polypropylene (PP), single-layer double-edge notched tensile (DENT) specimens with sharp cracks parallel to the deposition direction was fabricated using FFF of different extrusion temperatures (from 200 °C to 260 °C) and deposition speeds (from 30 mm/s to 90 mm/s). The fracture toughness (K_c), defined as the critical stress intensity factor at the critical load for brittle fracture of PLA and the specific essential work of fracture (w_e), as an indicator of the fracture toughness for ductile fracture of PP, were characterised. The results demonstrate that this methodology proved to be an effective tool to identify the effects of process parameters on fusion bonding in the FFF process, showing the strong sensitivity of fracture toughness, either K_C for PLA or w_e for PP, to the extent of fusion bonding between individual filaments.

Tribo-electric nanogenerator proved a better alternative energy resource for many electronic accessories because of its flexible nature and optimized device properties. It opens up the use of polymer materials (PMs) for harvesting mechanical energy. The disadvantage of the Tribo-Electric Nano Generator (TENG) is likely lower durability, limited short circuit output current, structural changes, post-stress conditions, etc. The purpose of this review article is more focused on systematic and detailed descriptions of TENGs. It gives an overview of tribo-electric polymer-based material formation and triboelectricity generation, structural modes of tribo-electric polymer-based nanogenerators, and its comparisons, measurement, and quantification of tribo-electric polymer-based nanogenerators based on structural and load conditions. Also, this article focused on TNEG efficiency enhancement techniques using various charge control circuit techniques. Possible applications of TNEG for various self-powered devices such as sensor, actuators and bio-harvesting utilities are discussed in detail.

A fast-swelling porous poly (acrylic acid co-acrylamide) crosslinked by N-Maleyl chitosan superabsorbent hydrogels were prepared by free radical graft copolymerization reaction for partially neutralized acrylic acid (AA), acrylamide (Am) using ammonium persulphate (APS) as an initiator, and N-Maleyl chitosan (N-MACH) as crosslinker. The structure of the synthesized hydrogels were investigated by FTIR spectroscopy and scanning electron microscope (SEM). Acetone and sodium bicarbonate were used as porosity generator (porogens) during the polymerization process. Surfactant (span 80) was used as a micelle template and foam stabilizer. The swelling studies showed improvement of hydrogel behavior with increasing of crosslinker concentration. Otherwise, the porous structure and swelling rate of the hydrogels improved by the incorporation of acetone and NaHCO₃. While the incorporation of span 80 in the gelling process can enhance the porosity structure. Morphological studies showed that the porosity generators and surfactant created highly porous structures. The density of all the highly porous superabsorbents hydrogels (HPSH) synthesized was ranged from 0.6 to 1.04 g/cm³. These HPSHs exhibited a higher rate of swelling at time range from 28 to 269 min.

Studies on modeling and optimization of alkali treatment, investigation of experimental uncertainty and sensitivity analysis of alkali treatment factors of natural fibers are important to effective natural fiber reinforced polymer composite development. In this contribution, response surface methodology (RSM) was employed to investigate and optimize the effect of varied treatment factors (sodium hydroxide concentration (NaOH) and soaking time (ST)) of the alkali treatment of Ampelocissus cavicaulis natural fiber (ACNF) on the tensile strength (TS) of alkali treated ACNF reinforced polyester composite. RSM and multi gene genetic programming (MGGP) were comparatively employed to model the alkali treatment. The best model was applied in Oracle Crystal Ball (OCB) to investigate the uncertainty of the treatment results and sensitivity of the treatment factors. Results showed that increased NaOH and ST increased the TS of the alkali treated ACNF reinforced polyester composite up to 28.3500 MPa before TS decreased. The coefficient of determination (R²) and root mean square error (RMSE) of RSM model were 0.8920 and 0.6528 while that of MGGP were 0.9144 and 0.5812. The optimum alkali treatment established by RSM was 6.23% of NaOH at 41.99 h of ST to give a TS of 28.1800 MPa with a desirability of 0.9700. The TS of the validated optimum alkali treatment condition was 28.2200 MPa. The certainty of the experimental results was 71.2580%. TS was 13.8000% sensitive to NaOH and 86.2000% sensitive to ST. This work is useful for effective polymer composite materials production to reduce the enormous material and energy losses that usually accompany the process.

Azidoethyl-2-bromo-2-methylpropanoate (AEBMP) has been synthesized from 2-azidoethanol and 2-bromo-2-methylpropionyl bromide under nitrogen atmosphere. The azido end-functional polystyrene (PS-N₃) has been synthesized by Atom Transfer Radical Polymerization (ATRP) technique using AEBMP initiator and styrene in conjugation with Cu(1)Br-bipyridine catalyst at 100°C. The polymerization was performed at three different periods of time, and it was found that both yield and number average molecular weight were increased linearly with increasing reaction time. Thermogravimetric analysis showed that the polystyrene is stable up to 300°C. The molecular weight of the polystyrene was determined using Gel Permeation Chromatography (GPC), and structures of the initiator AEBMP and polystyrene (PS-N₃) were characterized by ¹H NMR and FT-IR spectroscopy.