New bisphenol novolac epoxy resins for marine primer steel coating applications

Bisphenol derived from reaction of phenol with benzaldehyde was prepared in the presence of sulfuric acid as catalyst. Bisphenol novolacs were synthesized in both melting and solution processes using p-formaldehyde and formalin solution in the presence of oxalic acid catalyst. ¹H NMR analysis shows a high methylene bridge contents using the novolacs synthesized in a melting process. The bisphenol novolac epoxy resin was prepared by reaction with epichlorohydrine in the presence of sodium hydroxide as a catalyst. The prepared novolac epoxy resins were cured with 1,2-amino ethyl piperazine (AEP) as a curing agent. The cured resins were evaluated as organic coating for steel. The mechanical properties of the cured epoxy resins were evaluated by measuring both impact resistance and hardness. The chemical resistances of the cured resins were evaluated through salt spray resistance, hot water immersion, solvent resistance, acid and alkali resistance measurements. The data indicate that the cured epoxy resins have excellent chemical resistances as organic coatings among other cured resins.     

ATH浓度对PP/ATH复合材料力学性能的影响(英文)

ATH被广泛添加到聚丙烯(PP)中用于制成阻燃复合材料。PP/ATH复合材料比纯PP材料更具防火性。材料中成分的比例最终取决于应用要求。已有文献对这种复合材料的阻燃性能的提高进行了研究,但对机械强度的影响还没有涉及。本文研究了ATH浓度对PP/ATH复合材料的影响,利用实验测试、ASTM分析公式和有限元方法研究了材料的拉伸、弯曲和断裂特性。研究结果表明:增加ATH对材料的机械强度有不利的影响。     

Effect of concentration of ATH on mechanical properties of polypropylene/aluminium trihydrate (PP/ATH) composite

Aluminium trihydrate (ATH) is being extensively added to polypropylene (PP) to make a fire retardant composite. Blends of PP/ATH composite are more fire resistant as compared to pure PP. Percentage proportion of both the constituents in the final composite depends upon the application. Improvement in the fire retardant properties of such composites have been studied and published in literature but effects on mechanical strength have not been addressed. The effect of concentration of ATH on the strength of PP/ATH composite was presented. The tensile, flexural and fracture properties were studied and discussed. Experimental tests, ASTM analytical formulae and finite element approach were used. It has been found that increase in ATH has an inverse effect on the mechanical strength.     

Fabrication of binary metal doped CuO nanocatalyst and their application for the industrial effluents treatment

Herein, we fabricated the binary transition metal (Ce & Zn) doped CuO nanocatalyst via a single step facile co-precipitation technique by using liquid ammonia as a pH regulator and precipitating agent. The structural, morphological, and compositional studies of the fabricated samples were completed via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and EDX techniques, respectively. The impact of binary metal-doped CuO nanocatalyst on the optical band-gap was examined via the UV-Visible spectroscopic technique. The photocatalytic aptitude of the fabricated pristine and binary metal-doped CuO nanocatalyst was examined against the 5-ppm aqueous solution of MB dye. The obtained results revealed that the doped sample removes 81.64% MB dye, via adsorption (32.65%) and degradation (48.99%) processes, while in comparison the pristine CuO sample removes just 38.77%. The superior adsorption and degradation aptitude of the binary metal-doped sample can be ascribed to its higher surface area and tuned band-gap, respectively. Moreover, the kinetic study of the degradation process also displayed that the doped sample degrades the MB dye with a higher value of the rate constant (0.0137 min^?1) than that of pristine CuO photocatalyst (0.0049 min^?1). The tuned band-gap and nanoarchitecture morphology of the doped CuO not only facilitate the excitation process but also assist in the transportation of the photo-induced species towards the surface of the photocatalyst. The observed superior photocatalytic activity of the binary metal-doped CuO photocatalyst showed its exceptional aptitude for the treatment of toxic industrial effluents.     

Crystal structure of τ5–TiNi2−xAl5 (x = 0.48) and isotypic {Zr,Hf}Ni2−xAl5−y

The crystal structure of the compound in the Al-rich region of the Ti–Ni–Al system, τ₅–TiNi_2?xAl₅, x = 0.48, has been derived from X-ray powder and single crystal, neutron powder and electron diffraction (space group I4/mmm, a = 0.3984(2) nm, c = 1.4073(3) nm, R_F2 = 0.0133). Titanium atoms were unambiguously located from neutron powder data. τ₅ is isotypic with the crystal structure of ZrNi₂Al₅. Detailed transmission electron microscopy (TEM) in several crystallographic directions confirmed the lattice parameters and crystal symmetry. Although occupancy of Ni in the 4e site revealed a defect (occ. = 0.76), no significant homogeneity region was observed for this phase at 1020°C. Rietveld analyses of X-ray powder diffraction data for the Zr- and Hf-homologues confirmed for both compounds isotypism and revealed defects in the Ni sites and to a lesser extent also in the Al sites: ZrNi_2?xAl_5?y, x = 0.4, y = 0.4 and HfNi_2?xAl_5?y, x = 0.5, y = 0.2. The crystallographic relations among the structure types of Cu, TiAl₃, ZrNi₂Al₅ and Zr(Ni,Ga)₇ have been defined in terms of a Bärnighausen scheme.     

Chitosan-Based Smart Polymeric Hydrogels and Their Prospective Applications in Biomedicine

With increasing scientific research, knowledge, and socioeconomic awareness, research, and industrial communities are now much more interested in biopolymers-based composite materials with multifaceted functionalities. Biopolymers are easily obtainable, economical, non-hazardous, and abundant. Several natural and synthetic polymers have been used to prepare hydrogels, microbeads, and microfibers for controlled drug release. Due to marvelous properties, chitosan has been widely explored for medical and pharmaceutical applications. In recent years, considerable attention has been paid to the chitosan-based hydrogels for biomedical applications, especially for transplantation, and for improving interfacial interactions for the living tissues. Hydrogels can be synthesized by co-polymerization, condensation, and cross-linking. This review spotlights recent advances in physicochemical characteristics, modification strategies, and smart blended hydrogels for an array of biomedical and pharmaceutical applications. The whole discussion reveals that among all the biopolymers, chitosan is the finest carrier for biomedical applications.