ABSTRACTNacre, the iridescent material found in the innermost layer of seashells, having high strength and toughness was obtained from relatively weak constituents. The excellent mechanical performance of this biological material originates from its hierarchically ordered arrangement of well-tailored hard and soft building blocks. Incorporating these structures into composites is as alluring as conventional engineering materials often sacrifice strength to improve toughness. The unique mechanical properties originated from multiscale deformation regime involving solid-state self-organization process lead efficient energy dissipation which leads to high toughness, these multiscale biological assemblies inspire new synthesis route of complex materials. In this review, we study various mechanisms involved in toughening, methods used in mimicking nacre structure and various strategies for fabricating nacreous architecture which has gleaned new avenues for self-standing, strong, and advanced toughened material.

ABSTRACTСomposite based on polyimide and bismuth silicate Bi12SiO20 was fabricated by joint dispergating of the polymer matrix and finely-dispersed filler with subsequent solid-phase compaction. The results of acoustic tests of polymer composite show that optimum rate of composite filling with modified sillenite is 70 wt%. The introduction of the proposed filler in an amount of 70 wt% almost 4 times increases the modulus of elasticity of the polymer composite as compared to the pure polyimide. The developed polymer composite has high constructional, dielectric, thermophysical properties due to the significant intensification of physicochemical interaction in mechano-thermo-activated system «polymer–filler».

ABSTRACTAmino-modified polylactic acid (EPLA) nanofibre microspheres with a high porosity, large specific surface area, strong adsorption capacity, and rich in active amino groups were developed for drug delivery applications. Alendronate, a well-known antiresorptive agent, was chosen as a model drug to evaluate the loading capacity and release properties of the prepared EPLA microspheres. SEM micrographs clearly showed that the drug was loaded into the microspheres within the pores between the nanofibers and as well as being adsorbed on their surface. XRD and FTIR spectra analyses also confirmed drug loading. UV/Vis-absorption spectrophotometry was used to study the impact of various parameters, including adsorption time and initial concentration and pH value of the alendronate solution, on the microsphere drug-loading capacity. Under optimum conditions, EPLA microspheres exhibited a high alendronate adsorption capacity of up to 503 mg/g. In vitro release studies showed that alendronate-loaded EPLA nanofibre microspheres exhibited a perfect release performance, with alendronate being released in a sustained manner for approximately 15 days without any obvious initial burst. Therefore, EPLA nanofibre microspheres hold great potential as efficient, controlled release drug delivery carriers of alendronate.

ABSTRACTThe investigation mainly focuses on the effect of polyamide 6 (PA6) and phosphorus based flame retardants (FRs) on improving the flame retardancy of polypropylene (PP). The flame retardant properties have been studied by limiting oxygen index, vertical burning test tests and cone calorimeter testing. The results demonstrate that PA6 and FRs can greatly improve the flame-retardant and thermal properties of PP. It’s found that the addition of PA6/APP/FRs can promote the formation of stable intumescent char layers. Those indicate that the flame retardancy of PA6/APP/FRs/PP composites is improved by the condensed-phase action of PA6/APP/FRs.

ABSTRACTA decline in the world’s freshwater resources poses a major domestic and industrial challenge. Amelioration efforts that proffer possible water management and reclamation technology is therefore, of utmost priority. One of the most promising solutions to water conservation is to recycle wastewater. The use of polymeric nanocomposites (PNCs) in water treatment/remediation processes provides possible solution to recycling. This overview focused on PNCs; to highlight trends in their fabrication, characterization and application procedures for wastewater remediation and monitoring. Key issues bothering on the regeneration and reuse of PNCs were discussed, along with projections for their rational design for safe application.

ABSTRACTHumic acid amide (HA-amide) was prepared by amidation of HA and dodecylamine (DDA) with carbonyl diimidazole (CDI) as coupling reagent. Furthermore, HA-amide was added to poly (lactic acid) (PLA) as a nucleating agent to prepare poly (lactic acid)/humic acid amide composites (PLA/HA-amide) by melt blending. The structure and performance of PLA/HA-amide composites were investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and rheological analysis. Non-isothermal crystallization kinetics showed the HA-amide enhanced the crystallization rate of PLA. The results of crystallization behavior of PLA/HA-amide composites showed that HA-amide was an efficient nucleating agent of PLA.

ABSTRACTRing-opening polymerization of ε-caprolactone was performed at 130°C, under partial vacuum in the presence of stannous octoate as the catalyst and 1,4-butanediol as the initiator. After the termination of polymerization by deionized water, a hydroxyl group formed at the end of the polymer chains. Structure of the synthetic poly(ε-caprolactone)-diols (PCL-diol), molecular weight, polydispersity index, and Cell viability were evaluated. Very narrow distribution in the molecular weight obtained for PCL-diols is due to a new method for synthesis. It was shown that by the increase in PCL-diols, the compatibility of human mesenchymal stem cells grew up.

ABSTRACTThe effect of three different organomodified nanoclays (Cloisite 20A, Cloisite 30B, and Nanomer I28E) as well as the effect of a compatibilizer (PEgMA) was studied, with the purpose of developing greenhouse cover films based on polyethylene/ethylene vinyl acetate blends. Three organomodified clays were analyzed. The influence of organomodifier clay on film optical, morphology, mechanical, and photo-oxidative degradation properties as well as the effect of incorporation of maleic anhydride-grafted polyethylene as a compatibilizer was studied. The combined effect of these nanoclays with two different UV-oxidative protection systems for polyethylene/ethylene vinyl acetate-nanostructured films was evaluated. Two types of UV stabilizer combination systems were studied; one with a combination of heat and light stabilizers of mixture of antioxidants (phenolic and metal deactivator, Irgatec NC66) with hindered amines, Tinuvin 494AR (designated as system-A) and other with a combination of metal deactivator antioxidant, Irganox MD1024 with hindered amines Tinuvin NOR 371 and benzophenones, Chimasorb 81 (designated as system-B). A strong influence is observed in the use of compatibilizing agent, type, and content of nanoclay in the degree of dispersion as well as in the photo-oxidation behavior. The structure obtained is very dependent on the modified clay used; mostly, intercalated–exfoliated clay structure is produced. The induction period for the photodegradation reaction to start is shorter in the samples with the nanoclay than in the pure polymer. There was a difference in the effectiveness of two stabilizing systems used. It was found a better performance for the stabilizer system-A, regardless of the type of clay used. These greenhouse cover films should allow the pass-through of visible light into the greenhouse during day but restrict the pass-through of the infrared radiation out of the greenhouse during night.

ABSTRACTPromising nanocomposites (EPDM-nRHP) were prepared from EPDM/ nanosized rice husk powder (nRHP) in the presence of HRH system as modifying dry bonding agent. HRH system comprised hydrated silica, resorcinol and hexamethylenetetramine. Different concentrations from nRHP were used for preparing such nanocomposites. The effect of nRHP was studied on the mechanical and dielectric properties of EPDM-nRHP nanocomposites whether in the presence or absence of HRH system. The presence of HRH modifying system enhanced the dispersion of nRHP in EPDM and consequently improved the mechanical and dielectric properties for the resulting EPDM-nRHP nanocomposites which may be used as electrical insulator.

ABSTRACTPolypropylene/styrene-butadiene-styrene fumed silica nanocomposites were mixed in a twin screw Brabender Plasticorder, the weight percent of the SBS was varied at (0, 5, 10, 20, and 40), and the fumed silica content was varied at (0, 0.05, 0.1, 0.5, 1, and 2) wt%. The thermal and morphological properties of these nanocomposites were studied using a differential scanning calorimetry and a polarized light microscopy. It has been found that the addition of styrene-butadiene-styrene or fumed silica nanoparticles alone to polypropylene did not change the melting temperature while the existence of both elements changed the melting temperature of polypropylene slightly. Also, increasing the percentage of fumed silica nanoparticles leads to an increase in the crystallization temperature while styrene-butadiene-styrene increment has no effect. The melting peaks obtained by the differential scanning calorimetry revealed that increasing the styrene-butadiene-styrene content reduces the percentage crystallinity as a result of increasing the amorphous portion. The addition of styrene-butadiene-styrene to polypropylene has a very slight effect on the relative percentage crystallinity when calculations are performed based on the quantity of polypropylene within the composite. Although fumed silica nanoparticles aided and accelerating the nucleation step but it could not increase the percentage crystallinity of polypropylene beyond the percentage crystallinity of neat polypropylene.