IRANIAN POLYMER JOURNAL
Year:2022 | Volume:31 | Issue:12|Papers Count:11

The uniform dispersion of polysilsesquioxane (POSS) in the matrix and strong interfacial bonding polysilsesquioxane (POSS) particulate and epoxy chains are critical for achieving epoxy/POSS with enhanced thermal and mechanical properties. In this study, polysilsesquioxane (POSS) reinforced bio-based cardanol NC-514 s epoxy elastomeric network was prepared, and the effects of POSS content on the mechanical and thermal properties of the as-prepared sample were investigated. Polysilsesquixane (POSS) modification biobased cardanol NC-514 s epoxy elastomeric (POSS-NC) was characterized by Fourier transform infrared spectroscopy, and scanning electron microscopy, respectively. Mechanical tests showed that the tensile strength, Young's modulus, and elongation-at-break of the prepared materials increased with an increase of POSS content. DSC and TGA analyses showed the increased trend of glass transition temperature with the addition of POSS. Typically, the epoxy thermoset without/with 10% (by wt) POSS increased tensile strength from 1. 18 to 3. 69 MPa, and Young's modulus from 1. 08 to 2. 71 MPa, increased elongation from 100. 85 to 122. 61% and increased glass temperature from 24. 2 to 48. 0 º, C by DSC and 32. 5 to 45. 1 º, C by DMA, respectively. This novel POSS reinforced bio-based renewable cashew phenol epoxy elastomer provided an ideal candidate for toughening epoxy-based thermosetting materials, showing the potential application of bio-based epoxy-based composite materials.

The conventional metal coil springs can be coated with a layer of rubber to improve the suspension characteristics of rolling stock in terms of stiffness capabilities and vibration attenuation. Here, by means of a hyperelastic finite element analysis and also introducing a modeling concept of three springs in parallel, the significance of mechanisms contributing to the axial stiffness of rubberized coil springs (RCS) are well disclosed. The stiffness share resulting from the rubber–, metal bonded interface was found to be remarkable (79% of the total RCS stiffness), much greater than the role played by a bare rubber or a metal coil spring. This contribution was elucidated by the stress field of shear-combined compression within the rubber layer. The model was the next ended to systematically examine the impact of material and structural factors influencing the RCS stiffness. In particular, the impacts of rubber hardness, rubber thickness, coil wire diameter, number of active coils, and coil outer diameter on the RCS stiffness were inspected. The rubber hardness significantly contributed to the axial stiffness of the part, while the rubber thickness revealed only a marginal effect. Interestingly, increasing the number of active coils though reduces the stiffness of the metal coil spring, it still augments the axial stiffness of the RCS.

This study developed a novel temperature-sensitive Pluronic F127 (PF127) gel-containing curcumin (CRC)/thiolated chitosan (TC) nanoparticles (NPs) (PF127-CRC–, TCNPs) for vaginal applications and examined the effect of two effective parameters on curcumin (CRC) release from thiolated chitosan nanoparticles (CRC–, TCNPs). Administering medication through a non-mucoadhesive conventional vaginal dosage form often requires high doses, resulting in decreased patient compliance and adverse events. Hydrogels have the potential to deliver a variety of therapeutic agents in a sustained, localized manner. Nanoparticle-loaded gel combines the advantages and benefits of both nanoparticle and gel technology. The efficiency of drug entrapment and loading was calculated, and by increasing the amount of CRC, entrapment efficiency (EE) and loading efficiency (LE) also increased. CRC release profiles were examined at three different pH values (4. 5, 5 and 5. 6) and they decreased as the pH of the release medium increased (VFS). PF127-CRC–, TCNPs were synthesized and the gelation temperatures of 18% and 21% gel formulation were 23. 17 °, C and 17. 78 °, C, respectively. The viscoelastic modulus measurements revealed a low dependence, indicating high gel elasticity, thus, improving the formulation residence time. The CRC releases from PF127-CRC–, TCNPs and a free-CRC-PF127 gel were compared, and the results indicated that PF127-CRC–, TCNPs release the drug more slowly. MTT tests were performed on the HeLa cell line and analyzed. The result of this study indicated that thermosensitive PF127-CRC–, TCNPs are a promising carrier that may be used in parenteral formulations for cervical cancer prevention.

In this study, wood polymer composites (WPC) were produced by polypropylene (PP) as the matrix material and 30 wt% olive wood flour (OWF) as the filler material, for injection applications. Various treatments of OWF—, including single treatment or co-modifications using the silane treatment, heat treatment, and maleic anhydride grafted polypropylene (MAPP) compatibilizer—, were used to improve PP/OWF compatibility and mechanical properties. Structural and thermal characterization of the OWF after treatment has been implemented using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). FTIR and energy-dispersive X-ray (EDX) analyses revealed the interactions between OWF and silane coupling agent. Silane and heat treatments increased the thermal stability of OWF. Results of mechanical tests revealed that the OWF increased Young's modulus values of PP/OWF composites with respect to those of pure PP, while their tensile and impact strengths decreased. Moreover, heat and MAPP treatments enhanced the mechanical properties. Heat treatment introduced higher toughness in PP/OWF composites compared to the other treatments. Scanning electron microscopy (SEM) showed the evidence of the improved interfacial adhesion and consequently mechanical properties of the PP/OWF composites by the used treatments. A further enhancement in mechanical properties was recorded for these wood polymer composites with co-modifications of OWF with MAPP.

The utilization of biopolymers as a packaging material has received enormous attention, owing to the arising pressure on global warming and environmental pollution. Polylactic acid (PLA) is identified as a promising biopolymer with good processability amidst other biopolymers. However, due to its poor barrier property and brittle nature, its use is limited. To alleviate the properties of polymer composites, plasticization and reinforcement with nanoparticles are carried out in this study. Nanoparticles derived from naturals resources (almond shell wastes) are utilized for the present research due to the ecological concerns associated toward the usage of synthetic nanoparticles. Almond shell nanoparticles with an average particle size of 197 nm were prepared by ball milling and then ultrasonication. The influence of plasticizers, such as glycerol, sorbitol, polyethylene glycol, clove oil and polycaprolactone on the properties of biodegradable PLA films was investigated. The results revealed that PLA films blended with 10% (by w/w) naturally derived clove oil improved the elongation by 377. 19% and the tensile strength up to 19. 75 MPa. The PLA composite films with varied proportions of almond shell waste nanoparticles (0. 25–, 1. 0% by wt) were developed. At optimum loading, the tensile strength of PLA/0. 75% (by wt) nanoparticle film increased to 25. 09 MPa, and its water vapor permeability was reduced to 0. 25 , × , 10–, 10 gPa−, 1 s−, 1 m−, 1 with the addition of 1% filler. The PLA films incorporated with nanoparticles displayed low transparency, increased water solubility and biodegradability compared to a neat PLA film. The results obtained demonstrated that the PLA developed, using almond shell wastes, is a better alternative to synthetic plastics in the packaging industries.

Making use of water-soluble polymers as films, membranes, and coatings for aqueous applications has increased over the years, owing to their environmentally benign nature and biodegradability. Interaction of solvent (i. e., water) with highly polar polymers, i. e., water-soluble polymers, results in weakening of cohesive forces between the polymer molecules and increase in the solvent–, polymer interaction forces due to the formation of strong hydrogen bonds and polar–, polar interactions. This, in turn, leads to the formation of highly swollen polymer gels. The present work focuses on the preparation of water-insoluble ionic thin films using water-soluble blends of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA), by adopting an environment friendly approach. For this purpose, solutions containing varied PVA and PAA contents were prepared in water, and the resulting clear solutions were cast to make films. The cross-linking of cast films were carried out at different temperatures and cross-linking durations. With increasing the cross-linking temperature, properties of the thin films, such as percentage swelling, molecular weight between cross-links, and mesh size, decreased, while cross-link density, gel content, thermal stability and Tg increased. The thin film obtained using solution containing 50% (by wt) of PAA and 50% (by wt) of PVA, and cross-linked at 140 °, C, showed optimum swelling properties. Further, cation exchange membranes and thin film composite membranes were fabricated using ion exchange resin and polysulfone substrate membrane, respectively. The composite membrane cross-linked at 140 °, C exhibited 95. 1% rejection of Na2SO4. Finally, PVA–, PAA/polysulfone composite nanofiltration membranes demonstrated Na2SO4/NaCl selectivity in the range of 2. 14 to 2. 6.

Conductive biopolymer hydrogels have received wide attention due to their wide applications, including biomedical applications. Biopolymers are biocompatible and degradable, but show poor electrical properties. The present paper attempts to make a conductive biopolymer hydrogel composite using conductive polymers by adding nanoparticles of CoFe2O4 to biopolymer hydrogel matrix developed by synthetic methodology, i. e. in situ procedures. The nanoparticles of CoFe2O4 (10–, 60 mg) prepared by the co-precipitation method were loaded to gum ghatti (GG)-grafted poly(N-isopropyl acryl amide-co-acrylic acid) (P(NIPA-co-AA)), which was prepared by in situ polymerization technique by applying ammonium persulphate (APS) as free radical initiator. All materials were well characterized by FTIR, XRD, TGA and SEM. The DC electrical conductivity of all materials was investigated. The outcomes of FTIR, XRD and SEM demonstrated that CoFe2O4 nanoparticles could be successfully loaded on GG-g-P(NIPAM-co-AA). The electrical conductivity of GG (2. 1808 , × , 10−, 9 S/cm) increased after grafting of P(NIPAM-co-AA). Immobilization of CoFe2O4 contributed to improve the electrical conductivity of GG-g-P(NIPAM-co-AA). Loading 10 mg CoFe2O4 showed the highest electrical conductivity (5. 3364 , × , 10−, 9 S/cm) compared to loading 20, 30, 40, 50 and 60 mg CoFe2O4 nanoparticles. It can be concluded that higher loading of nanoparticles can exhibit insulation property or high loading may attract more aggregation of nanoparticles that might cause lower electrical conductivity.

In situ preparation and functionalization of poly(vinyl chloride) (PVC) nanofibers were investigated by a combination of copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) click chemistry and electrospinning methods. For CuAAC click reaction, the azido groups were installed on the PVC via nucleophilic substitution reaction with sodium azide. Various experimental conditions including concentration of clickable compounds, applied voltage, collector charge and feeding speed were intensively investigated by both spectral and microscopic analyses. The efficiency of CuAAC click reactions was monitored by Fourier transform infrared spectroscopy (FTIR) spectroscopy through the decrease of the azide band of the azido-functionalized PVC in its spectrum. The increase on phenylacetylene concentration from one-to twofold as clickable compound, applied voltage from 25 to 35 kV and the decrease feeding speed from 0. 5 to 0. 1 mL/h gradually improved the CuAAC click efficiency between azido-functionalized PVC (PVC-N3) and phenylacetylene (PA). The best CuAAC click efficiency was found as 70% with optimized condition (6: 2: 0. 01 , = , azide-functionalized PVC: phenylacetylene: copper(II) sulfate, 35 kV voltage, negatively charged collector and 0. 1 mL/h feeding speed). In addition, the proton nuclear magnetic resonance (1H NMR) spectroscopy confirmed the chemical structure of the clicked product of PVC-N3 and phenylacetylene (PA) and CuAAC click efficiency was calculated from the corresponding peaks as 69. 2%. The diameters of nanofibers produced by either electrically positive or negative charged collectors were also investigated by scanning electron microscopy and their diameter distributions were found as 10–, 370 and 20–, 400 nm, respectively. The in situ functionalization of PVC-N3 led to obtain improved thermal properties of the clicked product based on differential scanning calorimeter (DSC).

In this work, the effects of silane-modified aluminum oxide (m-Al2O3) and ethylene–, vinyl acetate grafted maleic anhydride (EVA-g-MAH)/m-Al2O3 hybrid fillers were studied on the mechanical and thermal properties of the ethylene–, vinyl acetate copolymer (EVA)/ternary polyamide (tPA) composites. Surface modification of the pristine Al2O3 was carried out with 3-aminopropyltriethoxysilane (APTES) to enhance dispersion and compatibility of the inorganic filler into the EVA/tPA matrix. These fillers in the range of 20–, 40 wt% were blended into the composites and their properties were evaluated. FTIR technique was used to investigate the treated Al2O3 fillers. Experimental results showed that the thermal stability and conductivity of EVA/tPA/(m-Al2O3/EVA-g-MAH) with a ratio of 42/18/40 wt% improved significantly up to a differences of 326 ℃,and 0. 178 W/m K compared to the neat EVA/tPA composite. Hybrid fillers modified with silane coupling agent and EVA-g-MAH were more effective to improve both tensile and tear strengths. The tensile strength of the EVA/tPA/(m-Al2O3/EVA-g-MAH) composite with a ratio of 49/21/30 wt% increased up to 66% compared to the neat EVA/tPA. Additionally, DSC analysis showed that the melting temperature was not significantly affected. The findings suggested that a silane modification and EVA-g-MAH compatibilizer approach for Al2O3 filler could be considered in the future research work to develop better thermally stable reinforced composites. As they showed great potentials in automotive and oil pipeline applications.

The present study focuses on the synthesis of phosphorus-containing epoxy resins and their use as reactive flame retardants. Phosphorus-functionalized epoxy resins were synthesized using different aliphatic diols. First, phosphorus was grafted by reacting phosphoryl chloride with three different aliphatic diols: 1, 5-pentanediol, 1, 4-butanediol, or 1, 3-propanediol. The ensuing phosphorus-triol compounds were epoxidized with epichlorohydrin in an alkaline medium. Fourier transform infrared and nuclear magnetic resonance spectroscopy confirmed the presence of the epoxy-end group in the structure of synthesized epoxy resins. The phosphorus-containing epoxy resins were mixed with diglycidyl ether of bisphenol A at a fixed mass ratio of 9: 1, and the hybrid formulations were cured with triethylene tetramine as a hardener. Their thermal behaviour was assessed by differential scanning calorimetry and thermogravimetric analysis. Furthermore, the hybrid epoxy resins were blended with nanoclay and applied as a finishing on the grain surface of the leather. Thermal analyses of the coated leather showed an enhancement of thermal performance with an increase of statistical heat resistant index temperature from 100 to 121 °, C. The flame retardation properties were also assessed and it was found that after coating leather with epoxy nanocomposites, the limiting oxygen index of leather increased from 26. 7 , ±,  , 0. 5 to 28. 6 , ±,  , 0. 7%, while the ignition time of 6. 0 s developed to 8. 1 s. Consequently, all the leather samples coated with phosphorus-based epoxy nanocomposites exhibited a self-extinguishing behaviour due to the synergistic effect of phosphorus atoms and clay nanoparticles.

Bio-based polyurethanes (PU) prepared through green routes using technical cashew nut shell liquid (TechCNSL) for anti-corrosive application could protect infrastructures and addresses environmental concerns. The synthesis was carried out in situ by an acid-catalyzed condensation reaction of TechCNSL and formaldehyde (F) at 120 °, C. The final structure was obtained through addition polymerization of TechCNSL-F with toluene diisocyanate (TDI) at room temperature (OH: NCO ratios: 1: 0. 8, 1: 1 and 1: 1. 2) to form TechCNSL-F-PU. The characteristic properties of the coatings were influenced as a function of free –, OH and –, NCO groups that is influenced by the composition of TechCNSL used. The high coating resistance (Rc) and change in solution resistance (Rs) values along with lower coating capacitance (Cc) values supporting sufficient protection ability and compactness to the metallic substrate was determined by non-destructive electrochemical impedance spectroscopy (EIS) studies. Structural and progress of the reaction was evaluated by ATR/FTIR, whereas XRD revealed the amorphous nature of the hydrophobic films/coatings with a contact angle of 100°,for TechCNSL-F-PU1: 1. The variation in thermal stability with TDI concentration and glass transition (Tg) temperature was based on the degree of cross-linking density of the systems. The degree of cross-linking was calculated through estimation of gel content, which varied from 96 to 98% based on the concentration of TDI with thermal stability by max 265 °, C. TechCNSL-F-PU1: 1 shows excellent films/coatings adhesion, anticorrosion performance, chemical and mechanical resistance in the various chemical environment (water, 3. 5% of HCl, NaCl and NaOH) and showed the best performance. These thermally stable and mechanically robust PU films/coatings can be projected for the corrosion protective applications.