Epoxy curing by polyaniline (PANI) – Characterization and self-healing evaluation

Polyaniline (PANI) was synthesized by chemical oxidative polymerization of aniline dissolved in aqueous phosphoric acid. The polymer was characterized by UV–Visible spectroscopy (UV–Vis), thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopic (FTIR) techniques. Hardener free epoxy coating was formulated with 10% PANI. The curing process of epoxy resin by PANI was analyzed using FTIR and a suitable mechanism of curing was suggested. The corrosion protective performance of conventional polyamide cured epoxy and PANI cured epoxy coating on steel has been assessed in 3% NaCl by electrochemical impedance spectroscopy (EIS). The self-healing property of the PANI cured epoxy coating on steel in 3% NaCl was studied by scanning vibrating electrode technique (SVET).     

Synthesis,structural and morphological characteristics,magnetic and optical properties of Co doped ZnO nanoparticles

Zn_1−xCo_xO (x==0.05, 0.10, 0.15) nanoparticles have been synthesized by an alternative wet-chemical synthesis route using the SimAdd technique. The as-obtained powders were investigated by FT-IR spectroscopy, X-ray diffraction and thermal analysis correlated with evolved gas analysis (TG–DTA–FT-IR) in order to determine their chemical nature, crystalline structure and to establish the decomposition sequences. The precipitates are generally amorphous, but low-intensity reflection peaks assigned both to the zinc oxalate dihydrate, and zinc hydroxide can be observed in the recorded patterns, indicating that hydroxy-oxalate precipitates were obtained. The structure, morphology and magnetic properties of the thermally treated samples have been investigated by X-ray diffraction, FT-IR, HRTEM, SAED, UV–vis and EPR. XRD studies reveal a hexagonal wurtzite-type structure for all Zn_1−xCo_xO samples. TEM investigations show particle size between 28 and 37 nm, with spherical and polyhedral shapes and with tendency to form aggregates. The presence of a Co₃O₄ secondary phase was evidenced by XRD, UV–vis and EPR for the Zn_0.85Co_0.15O sample. The ferromagnetic behavior of the samples was revealed. The paper highlights that by varying the cobalt concentration it is possible to modulate the structural, morphological, optical and magnetic properties.     

增塑熔纺聚丙烯腈纤维的预氧化过程

以增塑熔纺聚丙烯腈(PAN)纤维为研究对象,借助于傅里叶变换红外光谱对其结构以及预氧化过程中官能团的变化进行了分析研究,并进一步研究了预氧化温度和时间对反应程度的影响。研究结果表明:熔纺PAN纤维在纺丝过程中已发生了部分环化,其环化度为0.18;反应程度随着预氧化温度的升高逐渐增大,但在230℃之后变化不明显;预氧化时间对预氧丝的反应程度具有类似的影响,在预氧化20 min时反应程度迅速增大,但进一步延长预氧化时间,预氧丝的反应程度增幅较小。     

高纯六氟乙烷中氯化氢的傅里叶变换红外定量分析

电子行业用作清洗和蚀刻的特种气体六氟乙烷对杂质组分HCl的含量要求严格控制在一定范围,本文建立了用傅里叶变换红外光谱仪分析其中HCl杂质的分析方法,并实现了对产品中HCl的定量分析。     

Use of Fourier transform infrared spectroscopy to study ageing characteristics of asphalt binders

The present study aims at studying ageing characteristics of conventional bitumen, polymer modified bitumen (PMB) and warm mix asphalt (WMA) by using FTIR. Results of obtained FTIR spectrum were quantified by calculating different indices and finally based on these indices ageing index of the binders for short- and long-term ageing were calculated. Results showed ageing increased amount of complex and high molecular weight components of the binders. PMB was found to have greater ageing resistance than conventional asphalt binders. In case of WMA, results found to be inconclusive, requiring further investigation.     

Properties and carbonization behavior of asphalt modified with the THF-soluble fraction of a coal liquefaction residue

This study focuses on the effects of the tetrahydrofuran-soluble fraction of direct coal liquefaction residue as a modifier to modify asphalt with formaldehyde. The properties and carbonization behavior of matrix asphalt and the modified asphalts were studied. The results indicate that the ductility properties of modified asphalts have been effectively improved. The morphology of modified asphalts without the addition of formaldehyde is a set of uniform distribution point, and it is converted from linear distribution to clustered distribution observed in fluorescence microscope images with the increase of the adding amount of formaldehyde.     

Prospects of non-edible neem (Azadirachta indica) oil in Bangladesh: performance and emission evaluation in a direct injection diesel engine

Transition to alternative energy is receiving serious attention globally and in this very way, biodiesel from inedible neem can be an alternative to conventional liquid fuels as it contains 30–45%?wt of oil. In this study, esterification and transesterification reaction of methanol and triglycerides at a molar ratio of 7:1 was done and maximum 96% by volume biodiesel was extracted. Physiochemical properties of neem biodiesel lies within ASTM standards and Fourier transform infrared spectroscopy analysis of neem biodiesel reveals the presence of strong esters and the alkane group. The maximum efficiencies were found to be 22.8% and 22.3%, whereas minimum brake specific fuel consumptions were observed to be 0.57 and 0.59?kg/kW-hr for diesel and B20, respectively. Moreover, B20 provides less emission of HC, CO_x and increase in NO_x. Taking all into consideration, if at least 60% of the arid lands is utilised to cultivate neem trees then it will minimise the import of fossil fuel to an extent of 8.75%.     

Simplified structure of the condensed phase of fire retarded PA6 nanocomposites in TGA as related flammability

This paper concerns with the analysis of the nature of the mass residue of PA6 and its nanocomposites in nitrogen. To assess the structure of the condensed phase during pyrolysis, this study presents thermal (by TGA in nitrogen) and condensed phase analysis of the residue (by FTIR-ATR) of PA6 nanocomposites consisting of phosphorous based flame retardants (FR) and/or nanoparticles (based on modified Montmorillonite clay). The thermal analysis reveals that the nanoparticles do not change the pyrolysis kinetics of PA6 whereas the FR does. The FR and NC used in the polymer nanocomposites (PNC) are capable of changing the structure of the char compared with pure PA6, where the char structure consists of polycyclic aromatic hydrocarbons (PAH) whereas the PA6 does not leave any considerable amount of mass residue. This residue analysis for decomposition samples in TGA in Nitrogen of the PA6/FR/NC composites complements previously published work for gas phase analysis ( FTIR-gas) as well as cone calorimeter characterization for their flammability. The overall aim, addressed here also, is to find out to what extent microscale measurements (e.g. TGA/FTIR/DSC/ATR) can be used a priori to delineate the flammability of polymer fire retarded composites. It is shown that FTIR-gas and FTIR (ATR) residue can be used to determine the fire retardant action (solid and/or gaseous) only qualitatively.     

Functional properties of sonicated and non-sonicated extracted leaf protein concentrate from Diplazium esculentum

Leaf protein concentrate of edible fern Diplazium esculentum was extracted using sonication and non-sonication methods and its functional properties were evaluated. The leaf protein concentrate contained 34.28 and 9.89% protein for sonicated and non-sonicated extractions, respectively. Sonication yielded (36.36%) better emulsion activity over non-sonication (31.10%). Foaming capacity was also found better in sonication (7.27%) over non-sonication (6.99%), and oil absorption capacity also improved in sonication (7.55 g of oil/g) over its counterpart (7.41 g of oil/g). Contact angle experiments with the leaf protein concentrate evidenced the enhancement of more hydrophilicity of the sonicated sample. Thermal properties of the leaf protein concentrate with sonication evidenced more stability (55.58 and 95.95°C) over the non-sonicated (46.75 and 75.60°C). Fourier transform infrared spectral analysis with the leaf protein concentrate of Diplazium esculentum was used to assess the secondary structural data such as α-helix and β-sheets. The various percentages of secondary structures of protein in sonicated and non-sonicated samples were 49.06 and 69.16% for α-helix, 33.59% and 17.02% for β-sheet and 42.02 and 35.68% for turn, respectively. The results of the present investigation showed credible evidence to support that sonication method of extraction of leaf protein concentrate was better in terms of protein yield and functional properties as compared to the non-sonication. The sonicated extracted leaf protein concentrate has the potential for developing value added products.