Wiley

Two phosphorus‐containing heterocyclic flame retardants ‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and 2,8‐dimethyl‐phenoxaphosphin‐10‐oxide (DPPO) ‐ and their derivatives were characterized and incorporated in the backbone of epoxy novolac to obtain flame‐retardant epoxy resins. The structures and spectroscopic data including high‐resolution mass spectroscopy of these flame retardants were determined. Flame‐retardant epoxy resins with a phosphorus content of up to 2% based on heterocyclic DOPO and DPPO were cured with 4,4′‐diaminodiphenylmethane (DDM), and their features were examined by UL 94, LOI, and DSC. In this manner, high‐performance polymers with glass transition temperatures around 190°C and the UL 94 rating V0 were obtained. These polymers were compared with epoxy resins incorporating diphenyl phosphite and diphenyl phosphate, which are nonheterocyclic and do not pass the UL 94 test up to 2% phosphorus. DPPO has a similar flame retardancy like the commercially available DOPO. Furthermore, to explain the difference in the efficiency of the tested flame retardants, key experiments for the determination of the active species during the flame‐retarding process were performed and the PO radical was identified. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.

The polymerization (polymer deposition) rate of styrene in an electrodeless glow discharge from styrene vapor and a mixture of styrene vapor and gas (H₂, He, A, and N₂) was investigated. The rate of polymerization, R, was found to be independent of the discharge power. The rate of polymerization of the pure monomer was found to be proportional to the square of monomer pressure p_M. The addition of gas increased the rate of polymerization depending upon the partial pressure of the gas, p_x, and R can be generally expressed by R = a[p_M]²{1 + b[p_x]}. The value of b is dependent of the type of gas and follows the order of N₂, > A > He > H₂. The distribution of polymer deposition was found to be nearly independent of the partial pressure of the gas and of the discharge power with N₂ and H₂ as plasma gas; however, with He and A, the distribution is highly dependent on the partial pressure of the gas and on the discharge power. The study strongly suggests that polymerization occurs in the vapor phase and that the growing polymer radicals deposit on the surface of the discharge vessel, yielding highly crosslinked polymer deposition.

The polyvinyl alcohol/chitosan/graphene oxide/Ag composite films are facilely fabricated as active multifunctional food packaging materials. The AgNPs of less than 10 nm immobilized onto CS/GO matrices are in situ synthesized by using NaBH₄ as a reductant. The effect of different amounts of Ag and CS:GO weight ratios on the mechanical properties, water resistance, optical properties, thermal stability, and antibacterial activities of various films are systematically investigated. The composite film obtained at 0.5 wt% AgNP loading and a CS:GO ratio of 5:1 demonstrates significantly improved tensile strength (33.07 MPa, 1.7 times higher), reduced water swelling (2.4 times lower), increased contact angle (71.08° vs. 53.54°), and enhanced thermal stability compared to the neat PVA film. Additionally, these composite films exhibit excellent bacterial killing and inhibition activities against Escherichia coli and Staphylococcus aureus , with zones of inhibition of 10.09 nm and 12.66 mm, respectively. Interestingly, no viable bacteria were found with the film‐forming dispersion at 10 μg/mL. Furthermore, the fabricated films exhibit excellent UV‐blocking effects, sufficiently protecting exposed green plums from UV damage for 10 days. The membrane‐packed acerola fruits also demonstrate better freshness, slower ripening rate, and no signs of microbial growth as compared to those packed with commercial polyethylene film.

Nanocomposites consisting of poly(styrene‐b‐butadiene‐b‐styrene) (SBS) and polyhedral oligomeric silsesquioxanes (POSS) were prepared using a solvent dispersion method. Dumbbell‐shaped POSS fillers were prepared using diacyl chlorides to bridge the POSS molecules. Infrared spectroscopy confirmed functionalization. Scanning electron microscopy revealed an increase in filler aggregation with concentration, with preferential phase selectivity. Polydispersity increased with filler concentration while d spacing was influenced by phase selectivity and domain‐filler compatibility. Functionalized POSS improved thermal stability by imparting restrictions of SBS chain motions. Tensile stress–strain analysis revealed an increase in modulus, yield strength, and strain hardening with filler concentration, while creep deformation decreased and permanent strain increased with POSS content. Storage modulus, loss modulus, and glass transition temperature increased with filler content due to effective SBS–POSS interaction. Nanocomposite properties were influenced by filler concentration, the phase of the filler was dispersed throughout and the length of the alkyl “barbell” on the dumbbell‐shaped POSS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Using plant derived polymers for the composite production has been considering as an efficiently attempt to reduce the impacts from the environmental pollution as well as utilizes the benefits they can bring. Fully jute/polyamide 11 (PA11) biocomposites are green materials expected to own many outstanding advantages of both components for example, high‐mechanical performances and especially environmentally friendliness. However, to the best of our knowledge, these materials has not been studied so far. This work focuses on the further modification of alkaline pre‐treated jute fibers by using vinyltrimethoxysilane (VTMS) and evaluates the effect of silanization on the interaction and adhesion between jute fibers and PA11 resin as well as the characteristics of resulting composites. By using Fourier transform infrared, thermogravimetry, mechanical property analysis, color difference measurement, and scanning electron microscopy observations, the contribution of VTMS modification to the enhancement on the interfacial interaction and adhesion between fibers and PA11 resin proved clearly. The results showed that tensile strength, impact strength; and Young's modulus of silanized jute biocomposites increased by 44.1; 26.5 and 55.6%, respectively in comparison to those of untreated fiber biocomposites. Similarly, thermal stability, resistance to water absorption and weathering resistance of obtained biocomposites were improved.

Dispersive mixing is most efficiently accomplished with pure straining flow. Vorticity in the flow field inhibits this extending action; accordingly, the presence of shearing flow will decrease the overall effectiveness of dispersive mixing processes. A method to reduce the vorticity by inducing lubricated flow through development of a nonuniform distribution of the components of a polymer blend is described.

Dispersive mixing is most efficiently accomplished with pure straining flow. Vorticity in the flow field inhibits this extending action; accordingly, the presence of shearing flow will decrease the overall effectiveness of dispersive mixing processes. A method to reduce the vorticity by inducing lubricated flow through development of a nonuniform distribution of the components of a polymer blend is described.

In the present study the step response experiments were carried out with power law fluids in two helical coils to examine the suitability of axial dispersed plug flow model in describing the laminar dispersion of non‐Newtonian fluids in helical coils. The ranges of variables covered are 10 ≤ λ ≤ 100,0.01 ≤ N_Regen ≤ 2.5,0.001 ≤ N_De ≤ 0.77 and 0.035 ≤ τ ≤ 1.33. It is found that coiling results in reduced dispersion to that in a straight tube.

The current “gold standard” to treat bone lesions is allografts and autografts, both presenting important disadvantages such as risk of infection and morbidity. Synthetic grafts and scaffolds for bone regeneration represent a promising solution. Fused deposition modeling is a valid tool for developing synthetic bone grafts of complex shapes, which is a key issue. The possibility of building polylactic acid–nanohydroxyapatite (PLA/nanoHA) composites by 3D printing was systematically evaluated. PLA/nanoHA filaments for low‐cost 3D printers were produced by a multistep solvent‐free procedure and characterized by scanning electron microscopy, energy dispersive X‐ray spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry, and rheometry. TGA analysis confirmed the presence of the nanoHA amounts used in the composites, equal to 5 and 15 wt %. The glass‐transition temperature and degree of crystallinity of PLA are not influenced by presence of nanoHA, which remains substantially amorphous. The morphological analysis and compression testing on printed samples showed that nanoHA was uniformly dispersed within the PLA matrix and improved the PLA mechanical properties without changing the rheological performance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44656.

For the first time, soy protein isolate (SPI)/hydroxypropyl alkaline lignin (HPL) composites have been successfully prepared by mixing them in aqueous solution containing a small amount of glutaraldehyde as compatibilizer, and then compression‐molded to obtain plastic sheets. The structures of the SPI/HPL composites were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy, indicating the existence of amorphous networks and nanoscale HPL dispersion in the SPI matrix. When HPL content was lower than 6 wt %, the HPL‐domain occurred in SPI/HPL composites with a dimension of about 50 nm, indicating a high interfacial activity. Differential scanning calorimetry analysis showed that the glass transition temperature of the SPI/HPL sheets increased from 62.5 to 70.4°C with an increase of HPL content from 0 to 6 wt %. Moreover, the tensile strength of the SPI/HPL nanocomposite sheets with 6 wt % HPL and 3.3 wt % glutaraldehyde was enhanced from 8.4 to 23.1 MPa compared with that of the SPI sheets, suggesting that the nanoscale HPL dispersion significantly reinforced the SPI materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 334–341, 2006