Hybrid composite materials, which combine two or more types of fiber in a single matrix, have currently drawn the interest of researchers. This research investigates the tensile and impact properties of hybrid kenaf/glass reinforced metal laminates ( FML s) with different fiber orientations and stacking configurations. FML s were formed by sandwiching the annealed aluminum 5052 sheets to the composite laminates using hot press molding compression technique. The tensile test was performed at a quasi‐static rate of 2 mm/min with reference to ASTM E8 whereas Charpy impact test was conducted using impact pendulum tester according to ASTM E23. Results showed that improvement in tensile and impact strength was observed in hybrid FML s compared to kenaf fiber reinforced FML s. Fiber orientation of ±45° reduced the tensile strength but increased the impact strength of FML s in comparison with fiber orientation of 0°/90°. Overall, hybrid FML s incorporated with a fiber stacking sequence of glass/kenaf/glass showed superior characteristic in tensile and impact performance.
An innovative strategy for the generation of chondrocytes was thoroughly studied in this paper. Polyetherimide-modified polysaccharides of Porphyra yezoensis (pmPPY) served as a nonviral gene vector and delivered Sox9 plasmid to directly reprogram mouse embryonic fibroblasts into chondrocytes. The gene transfer efficiency was evaluated through ELISA, RT-PCR, and Western blot. The induced chondrocytes were identified through toluidine blue, Safranin O, and the immunostaining. The expression level of collagen II was finally evaluated through western blot. The pSox9/pmPPY nanoparticles (1:50) showed lower cytotoxicity as well as greater gene transfection efficiency than Lipofectamine 2000 and polyetherimide (PEI) (p<0.05). The results of toluidine blue, Safranin O, and the immunostaining of collagen II further showed that the normal MEFs were successfully reprogrammed into chondrocytes. These findings indicate that pmPPY could be a promising gene vector for the generation of chondrocytes via single-gene delivery strategy, which might provide abundant chondrocytes for cartilage repair.
Four-needle zinc oxide whisker (T-ZnOw) incorporated into microcrystalline cellulose/maleic anhydride grafted polypropylene/random copolymer polypropylene (MCC/PP-g-MA/rPP) composite was prepared by melt blending. 5wt% PP-g-MA was used as a coupling agent to improve the interfacial compatibility between fillers and rPP. The effect of T-ZnOw on MCC/PP-g-MA/rPP composite was investigated by mechanical testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Addition of T-ZnOw enhanced the mechanical properties of composites with tensile and flexural strengths increasing by 10% and 6%, respectively. SEM studies showed an improvement in the compatibility of fracture surfaces, which was evident from the absence of gaps between fillers and rPP. Additionally, initial thermal decomposition temperature and maximum weight loss temperature of T-ZnOw/MCC/PP-g-MA/rPP composite were both higher than those of MCC/PP-g-MA/rPP composite. Thermal degradation kinetics suggested that T-ZnOw has a weak catalytic effect on MCC, resulting in the early degradation of MCC and adhesion to the surface of rPP. Because of the presence of inorganic whiskers, the remaining weight percent was more than that of other composites at the end of the reaction. Crystallization temperature of the T-ZnOw/MCC/PP-g-MA/rPP composite was almost 3 similar to 5 degrees C higher than that of MCC/PP-g-MA/rPP composite and close to the crystallization temperature of pure rPP.
In the current research, the sonochemically prepared magnetite nanoparticles (MNPs) were silylated with triethoxyvinylsilane to produce a core–shell structure containing vinyl moieties on the surface. The radical polymerization of the silylated product with acrylic acid in the presence of N , N ‐methylenebisacrylamide, as the cross‐linker, led to the formation of novel magnetic hydrogel nanocomposites (MHNCs) in which some of polyacrylic acid (PAA) chains were chemically grafted onto MNPs (PAA‐grafted MNPs). Vibrating sample magnetometry showed the unique phenomenon of superparamagnetism for the prepared MNPs, silylated MNPs, and PAA‐grafted MNPs. Batch adsorption experiments were carried out for the removal of methylene blue (MB) using pure hydrogel and MHNCs as an adsorbent. The effects of contact time, PAA‐grafted MNP content, adsorbent mass, and initial pH value of the dye solution on adsorption were investigated. Results showed the MHNC containing 10 wt% of PAA‐grafted MNP (MHNC 10 wt%) had the maximum adsorption capacity. It was observed that the adsorption kinetics of MB followed pseudo–second‐order kinetics. The adsorption equilibrium data obeyed Langmuir isotherm, and the maximum adsorption amount of MB reached 507.7 mg g –1 for MHNC 10 wt%. It was shown that the adsorbed MB could be desorbed from the MHNCs by using methanol solution containing acetic acid and the nanoadsorbents could be recycled.
Nanocomposites of poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP)/silver‐doped zinc oxide (Ag‐doped ZnO) ternary blends were prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and conductivity studies. The FTIR and UV spectrum indicated the intermolecular interaction between the polar part of blend and the metal oxide nanoparticles. SEM and XRD patterns ascertained the structurally ordered arrangements of nanoparticles within the polymer matrix. The DSC results showed that the addition of Ag‐doped ZnO particles to PVA/PVP decreases the thermal behavior such as glass transition and melting temperature of the blend. The TGA study indicated that the composites attained better thermal resistance than a pure blend and the thermal stability of the composite increases with an increase in the concentration of nanoparticles. The electrical properties such as AC conductivity and dielectric properties of the composites were increased with an increase in content of nanoparticles up to a certain concentration (5 wt%), and thereafter the value was found to decrease.
In this work, successful efforts have been performed for solubility enhancement of acyclovir. pH‐sensitive β‐Cyclodextrin‐g‐poly methacrylic acid (MAA) hydrogel microparticles were developed. β‐Cyclodextrin, MAA, N , N ‐methylene bisacrylamide were used as polymer, monomer, and cross‐linker, respectively. Nine different formulations (BM‐1 to BM‐9) were prepared by aqueous free radical polymerization. Developed microparticles were characterized for FTIR, Differential Scanning Calorimetry/Thermo Gravimetric Analysis, PXRD, energy‐dispersive x‐ray spectroscopy, SEM, TEM, optical microscopy, zeta sizer, percent equilibrium swelling (%ES), solubility studies, and in vitro drug release studies. Higher swelling results (83.68%) were obtained at pH 7.4 in less than 3 h. Porous surfaces with drug were seen in TEM images. Maximum release was observed at pH 7.4 (89.51%). Solubility enhancement was 7.38‐fold in water as compared to pure acyclovir. Thermal stability of grafted microparticles was increased up to 440.13°C. A potential approach for solubility enhancement was successfully developed.
In this work, successful efforts have been performed for solubility enhancement of acyclovir. pH-sensitive -Cyclodextrin-g-poly methacrylic acid (MAA) hydrogel microparticles were developed. -Cyclodextrin, MAA, N,N-methylene bisacrylamide were used as polymer, monomer, and cross-linker, respectively. Nine different formulations (BM-1 to BM-9) were prepared by aqueous free radical polymerization. Developed microparticles were characterized for FTIR, Differential Scanning Calorimetry/Thermo Gravimetric Analysis, PXRD, energy-dispersive x-ray spectroscopy, SEM, TEM, optical microscopy, zeta sizer, percent equilibrium swelling (%ES), solubility studies, and in vitro drug release studies. Higher swelling results (83.68%) were obtained at pH 7.4 in less than 3 h. Porous surfaces with drug were seen in TEM images. Maximum release was observed at pH 7.4 (89.51%). Solubility enhancement was 7.38-fold in water as compared to pure acyclovir. Thermal stability of grafted microparticles was increased up to 440.13 degrees C. A potential approach for solubility enhancement was successfully developed.
Lightweight sound insulation materials have received much attention. In this study, a series of superfine metal powder (SFM)/nitrile-butadiene rubber (NBR)-polyvinyl chloride (PVC) microcellular foaming materials were prepared with NBR-PVC as matrix and SFM as modifiers by employing the method of molding foaming. Analysis on the morphology of cross section, pore size, and pore distribution possessed by SFM/NBR-PVC was conducted by scanning electron microscopy (SEM), as well as the image processing software of Image-Pro. Then detailed discussion on the effect of SFM with different mass fractions in the matrix on the foaming quality was provided. In the meanwhile, the performance of sound insulation was tested by four-channel impedance tube system. The results show significant improvement for foaming quality and sound insulation performance of NBR-PVC microcellular foaming material through the addition of SFM. In comparison with the pure NBR-PVC materials, the microcellular foaming material exhibits the best performance of foaming quality and sound insulation when the SFM content in matrix is 30 wt%. It is shown that the average pore diameter and the foaming capacity decrease by 60% and 31%, respectively, while the surface density increases by 131%. In the meantime, the sound insulation index of SFM/NBR-PVC microcellular material increases by 7.2 dB to 30.5 dB, which conforms to the requirements of new lightweight sound insulation materials in modern time. Finally, the mechanism of the optimization conducted for sound insulation performance after the addition of SMF is explained.
The present work endeavors fabrication of fast dissolving buccal film of clonidine hydrochloride by employing quality by design (QbD) based approach. The total nine formulations were prepared according to formulation by design helped by JMP software 13.2.1. The patient oriented quality target product profiles were earmarked and on that basis critical quality attributes were identified. Preliminary screening studies along with initial risk assessment eased the selection of film-forming polymer (HPMC E 15) and plasticizer (PEG 400) as CMAs for formulation of films. A 3(2) full factorial plan was utilized for assurance of impact, i.e., HPMC E15 (X-1) and PEG 400 (X-2), as independent variables (factors) on thickness (mm) (Y-1), disintegration time (s) (Y-2), folding endurance (Y-3), and tensile strength (kg) (Y-4). Furthermore, prediction profiler assists in predicting composition of best formulation encompassing desired targeted response. The optimized formulation (F6) showed fast drug dissolution (>90%) within 8 min, and solid state characterization by DSC, XRD revealed excellent film characteristics. In a nutshell, the fast dissolving buccal film for clonidine hydrochloride was successfully developed assisted by QbD approach with markedly improved biopharmaceutical performance as well as patient compliance.
Cross‐linking of superabsorbent hydrogels based on poly(acrylamide‐ co ‐sodium alginate) is carried out using 60 Co γ‐radiation. Hydrogels of PAM /NaAlg with 1.5:0.5 and 1.0:1.0 w/v concentrations showed good gel contents of 87 and 66 (%) and swelling degrees in water of 3.7 and 5 (g/g) after 40 min, respectively. The chemical structure of the hydrogel is confirmed by FTIR , XRD , and ESR . The morphology of the hydrogel is observed using scanning electron microscopy. Intramolecular H‐bonding in the hydrogel network is confirmed by TGA and DSC . The pH ‐responsive swelling behavior of ( PAM ‐ co ‐NaAlg) hydrogels is tested in different pH ranges showing higher swelling capacities in basic than in acidic media. This property proposes the use of ( PAM ‐ co ‐NaAlg) hydrogel as internal curing agent for concrete. The hydrogel is examined with cement weight ratios of (0.1–0.5) wt%. The study shows that cement with ( PAM ‐ co ‐NaAlg) hydrogel improves the compressive strength of cement at 0.1 and 0.2 wt%.
The purpose of the present work is to develop a new biomaterial with suitable melt strength, stiffness‐to‐toughness balance, and the required thermal performance for food packaging applications. The study is dedicated to investigating a new physical compatibilization approach of biosourced materials as well poly (lactic acid) ( PLA ) and polyamide 11 ( PA 11) in comparison with the chemical compatibilization through addition of a multifunctionalized epoxide. For this reason, this paper deals with gaining better understanding physical compatibilization in the biosourced blend with the incorporation of an acrylic melt strength enhancer into PLA / PA 11 blend. The main focus of this paper is studying how physical compatibilization improves melt strength in comparison with chemical approach. Hitherto, the chain extension–branching balance was demonstrated to be difficult to be controlled and decoupled from chemical compatibilization at the polymer–polymer interface. Hence, the physical approach is presented as an original route in this work to develop a PLA ‐based blend with good film blown processability and engineering properties. Morphological, rheological and thermomechanical properties of the new obtained biosourced blends were studied. The physical compatibilization effect was confirmed by the tuning interfacial properties. The extensional rheology highlighted that melt strength for the physical blends was also improved without any pronounced strain hardening in comparison with reactive blends. Besides, a great enhancement of the blowing processing windows of physically PLA ‐ PA 11 compatibilized blend was highlighted while higher blow‐up ratio and take‐up ratio values were obtained. Overall, a correlation between the obtained thermal and crystalline properties was performed for the optimal biosourced blown film.
This review provides a report on recent studies of composite materials based on a chitosan and collagen mixture due to their biocompatibility and bioactivity. Those natural polymers are most widely used to obtain biomaterials. However, the materials based on chitosan/collagen complexes present poor mechanical parameters, as well as high swelling behavior and enzymatic degradation rate. Such properties are considered problematic for the material clinical application. An increased interest in composite materials has been observed due to their enhanced physicochemical properties. A composite material preparation involves different compounds addition to natural polymers. Herein, the use of organic and inorganic additives has been reported. Moreover, the potential application of composite materials based on chitosan/collagen complexes in the tissue engineering science has been discussed.
Novatein thermoplastic protein was blended with modified polyethylene (containing either epoxy, carboxylic acid functionalities partially neutralised to produce zinc carboxylate salts, or maleic anhydride functionalities) to alter blend morphology and to manipulate thermal and mechanical properties. Up to 40 pph Novatein polyethylene ( PE ) was blended with Novatein by extrusion and injection moulding. Using zinc ionomer resulted in optimal properties and was compatible with a finely dispersed morphology at high content; high interfacial tension (σ) and a viscosity ratio (λ) of ~1 was observed. Unmodified blends and those containing epoxy functionalities showed co‐continuity at low PE content. Whilst co‐continuity appeared to increase impact resistance, other mechanical properties decreased due to lack of phase interaction. Maleic anhydride‐grafted‐polyethylene blends showed a finely dispersed PE phase, yet was less compatible. Zinc ionomer was deemed to be the most appropriate for modification of mechanical properties in Novatein.
The viscous flow activation energy and non-Newtonian index properties of polymer based on feature size were studied through a series of experiments on the rheological properties of amorphous polymer polymethyl methacrylate (PMMA), semi-crystalline polymer polypropylene (PP), and crystalline polymer high-density polyethylene (HDPE) using capillary die with hole diameters of phi 0.3 mm, phi 0.5 mm, phi 1.0 mm, and phi 2.0 mm. The results show that the viscous flow activation energy of PMMA decreases with the feature size under microscopic scale. And the viscous flow activation energy of PP and HDPE increases with hole diameters of the die. Under macroscopic scale, the difference in viscous flow activation energy of all polymer materials is significantly reduced with hole diameters of the die. For the non-Newtonian index of the three polymer materials, it decreases with the feature size under the microscopic scale while it increases or does not change with the feature size under the macroscopic scale. At the same time, for different high polymer materials, the viscous flow activation energy model (SVAE model) and non-Newtonian index model (SNNE model) based on feature size were established. Finally, the accuracy and effectiveness of the SVAE model and the SNNE model are verified by comparing with the traditional model and reference data. The viscous flow activation energy and non-Newtonian index values of the polymer material can be calculated conveniently and accurately.
The elongational flow behavior of polyethylene, polypropylene, polystyrene, poly(methyl methacrylate), and polycarbonate, temperatures from 70 to 290 degrees C and pressures up to 70MPa, is examined with the Yahsi-Dinc-Tav (YDT) model and its particular case known as the Cross model. The viscosity data employed in the range of 3-405 s-1 elongational rates were acquired from the literature at ambient and elevated pressures. The predictions and the fitting results of the proposed YDT model with the same measurement data are compared with the Cross model. The average absolute deviations of the viscosities predicted by the YDT model range from 0.54% to 9.44% at ambient and 1.95% to 6.28% at high pressures. Additionally, the linear formulations derived from the YDT model are employed to relate the viscosity with temperature and hole fraction (thermooccupancy function) at zero level of elongational rate and constant elongational rate along with constant elongational stress. The effects of the four viscosity parameters (such as transmission and activation energy coefficients in these equations) on the elongational viscosity are analyzed in detail and some conclusions on the structural differences for the polymers are discussed.
The influence of heat treatment on moisture sorption behavior of moso bamboo (Phyllostachys pubescens), especially under dynamic sorption conditions, was investigated. Moso bamboo was heated to 180 and 200 degrees C for 8h to investigate the chemical components and sorptive behavior at sinusoidal relative humidity (RH) and constant humidity. The results of chemical components revealed that the content of holocellulose, -cellulose, and hemicellulose decreased while that of lignin increased slightly with increasing treatment temperatures. The results of static adsorption at constant RH showed that 200 degrees C treated bamboo exhibited the lowest moisture content and moisture sorption coefficient. The results of dynamic sorptive behavior indicated that the moisture content changed sinusoidally but lagged behind the triggering sinusoidal RH changes. Heat-treated bamboo presented greater phase lag and smaller amplitudes of moisture content and sorption hysteresis due to the hemicellulose removal.
The sulfonic containing polymer bead was synthesized using sodium p-styrenesulfonate (SSS) and N,N-methylenebisacrylamide (MBA) through inverse suspension polymerization and evaluated as catalyst for esterification of of n-octanol and acrylic acid. The influence of some principal factors, such as combination dispersant, crosslink agent content, posttreatment methods, and porogen types, was investigated in detail. The results showed that the morphology and characteristics of polymer beads were controllable. The polymer beads with 20wt% crosslink agent showed the best catalysis ability achieving almost 96% esterification conversion at the first time and 80% after 5 cycles.
Interfacial interaction between host matrix and nanofillers is a determinative parameter on the mechanical and thermal properties of nanocomposites. In this paper, we first investigated interaction between carbon nanotube (CNT) and montmorillonite clay (MMT) absorbing on epoxy surface in a theoretical study based on the density functional theory (DFT) calculations. Results showed the interaction energy of -1.93 and -0.11eV for MMT/epoxy and CNT/epoxy, respectively. Therefore, the interaction between epoxy polymer and MMT is of the chemisorptions type, while epoxy physically interacts with CNT. In addition, thermal and mechanical analyses were conducted on nanocomposites. In DSC analysis the glass transition temperature which was 70 degrees C in neat epoxy composite showed an improvement to about 90 degrees C in MMT nanocomposites while it was about 70 degrees C for CNT nanocomposites. Finally, mechanical properties were investigated and MMT nanocomposite showed a change in compressive strength which increased from 52.60 Mpa to 72.07 and 92.98 Mpa in CNT and MMT nanocomposites, respectively. Also tensile strength improved to the value of 1250.69 Mpa MMT nanocomposites while it was about 890 Mpa in both CNT nanocomposite and neat epoxy composite which corresponds to the calculation result prediction.
In this research, the effects of organic‐inorganic hybrid nanocomposites as novel nanostructure additives in paint compositions were studied. The silica modified TiO 2 nano structure was prepared by using sol–gel method. The TEM analysis indicated that these particles were in the range 10–15 nm. The organo silicone containing polymer was prepared by free radical polymerization process. The prepared polymer/mixed metal oxides nanocomposites were fabricated and demonstrated as nanostructure additives. The prepared nanocomposite was introduced into the road marking material formulation. In the first part of the current study, the prepared samples were evaluated by quality control experiment such as compatibility and color visualization tests. Also specific experiments such as hydrophobicity, adhesion, exposure to weathering conditions, self‐cleaning nature of the samples, gloss appearance, hardness of the prepared samples, anti‐pollution investigation, moisture resistance, and heat‐cold cycle's tests were evaluated. The environmental issue of the road marking material and also the dirtiness removal efficiency by using nanostructure coating was investigated. The prepared samples showed 4–7 mg weight loss per hundred square centimeters during the exposure to 300 h by 313 nm UVB irradiation. The best photocatalytic performance in road marking application was found for NA 3% sample.