Condensation polyurethanes with different hard segment (HS) content were prepared by condensation reaction of urea, phenol sulphonic acid and formaldehyde and tested for their mechanical, physical and thermal properties. Obtained polyurethane (PUR) films were first heated at 50uC for 120 min and then treated at 135uC for 15 min or 160uC for 10 min. The tensile strength of samples thermally treated at 50uC then at 135uC was 120% higher than for samples treated only at 50uC. The obtained polyurethanes exhibited segmented structures with phase separation between HSs and soft segments (SSs). Films containing 19 and 21%HSs heated at 50uC then 135uC exhibited acceptable mechanical properties and water resistance. The lower and higher end use temperatures of PUR films were affected mainly by the polymer composition. Moreover, the polyurethane samples containing 19 and 21%HSs have shown the highest decomposition temperature (i.e. .165uC), compared to 80uC for polymers with 32%HSs.

The present work investigates the properties and morphology of nanobent/poly(methyl methacrylate) (PMMA)/epoxy resin hybrid nanocomposites which were successfully prepared by solvent and ultrasonication methods. Nanobent ZS1 were added in amount of 1, 2, 3, and 4 wt% and 5, 10, and 15 wt% for PMMA. The fracture toughness (impact strength and critical stress intensity factor) and flexural properties were evaluated for epoxy composites. Obtained results showed improvement of the epoxy resin mechanical properties due to the addition of PMMA and nanobent. Composites containing 5 wt% of polymeric modifier or 1 wt% nanobent exhibited maximally improved properties. In the case of hybrid composites, synergistic effect was obtained with flexural strain at break and flexural energy to break of hybrid nanocomposite based on 1 wt% nanobent and 5 wt% PMMA. However, epoxy nanocomposites based on 2 wt% nanobent and 5 wt% PMMA showed synergism with IS and brittle fracture energy toward the composites with one modifier. Fourier transform infrared (FTIR) spectra analysis confirmed interactions between incorporated modifiers and reactive groups of the epoxy matrix. Moreover, scanning electron microscope (SEM) micrographs of hybrid epoxy nanocomposites exhibited a morphology with large plastic yielding associated with significant roughness of the fracture surface with embedment of nanobent in the polymer system. This study clearly demonstrates that the improvement of mechanical properties of the epoxy resin could be attributed to the synergistic toughening effect of PMMA and nanobent without deterioration of thermal stability. POLYM. COMPOS., 39:E2540–E2551, 2018. © 2018 Society of Plastics Engineers

The present work investigates the preparation of nonisocyanate polyurethane through condensation of oligomeric hard segments produced by using phenol sulfonic and hydroxybenzoic acids and soft segments obtained by transesterification reaction of polyoxypropylene glycol with ethyl urethane. Obtained nonisocyanate polyurethane films with different hard segments content were tested for their mechanical, physical and thermal properties. Polyurethane films containing p-hydroxybenzoic acid exhibited enhanced tensile strength and water resistance. The tensile strength increased by approximately 230% and water resistance by 35% with the addition of 30% p-hydroxybenzoic acid. Differential scanning calorimetry analysis confirmed the formation of segmented structures within the prepared condensation nonisocyanate polyurethane-based films. Moreover, Fourier transform infrared spectroscopy results analysis confirmed the chemical structure of condensation polyurethanes with characteristic groups of typical conventional polyurethanes.

AbstractThe present work investigates the adhesive properties and morphology of diglycidyl ether of bisphenol A nanocomposites modified with reactive butadiene acrylonitrile copolymers having different amine equivalent weight. Tensile adhesive strength and shear adhesive strength of epoxy resin were significantly increased due to reactive rubbers and nanoparticles (ZW1) incorporation to the epoxy matrix. Hybrid composites based on 1 wt% ZW1 and 10 wt% ATBN-16, 1 wt% ZW1 and 15 wt% ATBN-21 exhibited maximum adhesive strength in comparison with neat epoxy resin as well as epoxy nanocomposite containing 1% ZW1. Tensile adhesive strength of hybrid composites containing 1% ZW1 and 10% ATBN-16 as well as 1% ZW1 and 15% ATBN-21 was maximally enhanced. The fracture surfaces of epoxy hybrid composites showed significant plastic yielding together with delaminated and stratified structures, explaining thus the increase of the adhesive strength of tested composites. This finding was confirmed by FTIR spectra in terms of chemical reactions occurrence between the reactive rubbers and epoxy matrix.

The present study investigates the biodegradation of synthesized condensation nonisocyanate polyurethanes (NIPUs). It was prepared by reacting phenol sulphonic acid and oligooxypropylene diol and formaldehyde and contained different amounts of hard segments (HSs). Polyurethane samples were submitted to biodegradation with microorganisms R-14 and in garden soil. The tensile strength (TS), relative elongation at break and weight loss of the prepared samples were evaluated and their structure and morphology analysed. It was found that maximum decrease of the TS of all tested NIPU samples occurred only after 7 days of biodegradation. Maximum TS decrease attained was approximately 70% and 75%, respectively, for NIPU based on 0.8-mol and 1-mol HS. Moreover, significant decrease of relative elongation at break and weight loss values after biodegradation in culture R-14 for NIPU samples based on 0.9-mol HS and 1-mol HS was observed. Fourier transform infrared and scanning electron microscopic results confirmed that biodegradation occurred in urea or urethane groups. The glass transition of HSs decreased by at least 20°C due to biodegradation, suggesting that this later took place almost only in the crystalline region of NIPU samples.