AlBr3 impact on the thermal degradation of P(S-co-MMA): a study performed by contemporary techniques

Pyrolysis of copolymer, [P(S-co-MMA)], in the presence of AlBr₃ was inspected in an inert atmosphere. Five different proportions (copolymer/additive) were chosen. Films were cast from common solvent. It was noticed that copolymer showed more stability on the basis of T _0, however, regions of stability were also observed for the blends. Copolymer showed T ₀ at 260?°C, whereas blends started degrading around 70?°C. T _max was the same for the copolymer and the blends. Low-temperature decompositions of blends were attributed to the generation of free radicals (Br^?) and the zones of stabilizations were assigned to the formation of a ??complex type?? structure between Al and the carbonyl oxygens of MMA units. Degradation products were collected and identified employing Py-GC?CMS technique. Intermediates (solid) at different temperatures (300, 350 and 400?°C) were examined through FTIR spectroscopy. In the light of gathered data, a degradation mechanism was proposed. New products were encountered, viz., bromobenzene, ??brominated?? anhydride ring, etc., which established the chemical interactions between the constituents of the blends, i.e., copolymer and additive. Anhydride rings were absent when poly (methyl methacrylate) was pyrolyzed in the presence of AlBr₃. Oligomers of styrene were not found hinting at the involvement of additive in ??targeting?? the degrading styrene units. The blends indicate 2?C7% residue of original mass; the additive exhibits 9% while the copolymer does not leave residue at the completion of the TG run. The presence of char in the residues of blends suggests that the additive imparts stability to the copolymer. Horizontal burning rate was lowest (6 times less than that of neat copolymer) for [P(S-co-MMA):AlBr₃, 87.5:12.5%], thereby revealing the efficiency of the additive as thermal stabilizer. The highest activation energy was calculated for the copolymer (169.46?kJ/mol) and the range of this parameter for the blends was found from 52.72 to 27.14?kJ/mol.     

Oxidative stability enhancement of broiler bird meats with α-lipoic acid and α-tocopherol acetate supplemented feed

Depression of meat quality is known to be caused by lipid peroxidation occurring in meat. Supplementation of antioxidants in feed decreases lipid peroxidation and improves the oxidative stability of meat after slaughtering. The present study demonstrated that meat obtained from broiler birds fed feed supplemented with α-tocopherol acetate (200 mg/kg feed) along with α-lipoic acid (25, 75, or 150 mg/kg feed) exhibited increased oxidative stability and reduced fat content. The total phenolic content and α-lipoic acid content increased in the meat as the concentration of α-lipoic acid supplementation increased. The protein content in the meat was not changed by the supplementation of α-lipoic acid and α-tocopherol acetate. The results of DPPH and TBA assays demonstrated that feed supplemented with α-lipoic acid and α-tocopherol acetate also enhanced the antioxidant activity of broiler meat. On the other hand, the meat from broiler birds fed feed supplemented with oxidised oil (4% in feed) reduced its oxidative stability.     

The photoinduced charge transfer mechanism in aligned and unaligned carbon nanotubes

Using time-resolved reflectivity measurements on unaligned and aligned bundled single-wall carbon nanotubes with a pump energy of 1.55 eV, quasi-resonant with the second Van Hove singularity of semiconducting tubes, a positive sign of the transient reflectivity is detected in unaligned nanotubes. In contrast a negative sign is detected in aligned nanotubes. This discovery addresses a long-standing question showing that in unaligned nanotubes the stronger intertube interactions favor the formation of short-lived free charge carriers in semiconducting tubes. A detailed analysis of the transient reflectivity spectral response shows that the free carriers in the photo-excited state of semiconducting tubes move towards metallic tubes in about 400 fs.     

Rotary cement kiln coating estimator: Integrated modelling of kiln with shell temperature measurement

Coating thickness protection in the burning zone of a rotary cement kiln during operation is important from the viewpoint of the kiln productivity. In this paper, an integrated model is presented to estimate the coating thickness in the burning zone of a rotary cement kiln by using measured process variables and scanned shell temperature. The model can simulate the variations of the system, thus the impact of different process variables and environmental conditions on the coating thickness can be analysed. The presented steady‐state model derived from heat and mass balance equations uses a plug flame model for simulation of gas and/or fuel oil burning. Moreover, the heat transfer value from shell to the outside is improved by a quasi‐dynamic method. Therefore, at first, the model predicts the inside temperature profile along the kiln, then by considering two resistant nodes between temperatures of the inside and outside, the latter measured by shell scanner, it estimates the formed coating thickness in the burning zone. The estimation of the model was studied for three measured data sets taken from a modern commercial cement kiln. The results confirm that the average absolute error for estimating the coating thickness for the cases 1, 2, and 3 are 3.26, 2.82, and 2.21 cm, respectively.     

Design and Performance of a Laboratory Spray Dryer to Realize Evaporation-Induced Self-Assembly of Nanoparticles

This work discusses the design, development, and performance of an indigenous laboratory spray dryer with a relatively slow drying rate. The drying time of droplets of colloidal silica (5 wt%) and sodium chloride solution (20 wt%) in this spray dryer was nearly 10 s. The present system was composed of a four-jet compressed air nebulizer that generates a droplet size of 2–5 µm with a nebulization rate of nearly 60 mL/h. The generated powder can be collected using a cyclone or a wire mesh collector. Design and characterization of this system as well as characterization of the micrometric self-assembled powder grains obtained by this spray dryer are discussed.     

Monitoring the Key Components and Elimination of Asphaltenes Precipitation in Crude by a New Alternative Route

The crude composition was determined by distillation on a true boiling point apparatus individually. Then crude naphthas were introduced to a gas chromatograph and asphaltenes were determined by extraction. Quantities of key components were calculated by prescribed mathematical equations. On the basis of relative quantities of key components, 21 blends of 12 crudes were prepared caused asphaltenes precipitation in desalter. Seven blends remained successful, causing no further asphaltenes precipitation, and one of the successful blends was chosen to prepare a batch of 55,000 barrels and was passed through desalter. No further asphaltenes precipitation was found during the whole operation.     

Reinforcement effect of nanodiamond on properties of epoxy matrix

Epoxy/nanocrystalline diamond nanocomposites composites were prepared by dispersing ultrasonically, 0.4, 0.7, 1.0, and 4.0 wt% acid‐treated nanocrystalline diamond (NCD) powder in epoxy matrix. Fourier infrared spectroscopy was utilized to study the moieties attached to the nanodiamond particles. The trace elements present in NCD powder before and after acid treatment were analyzed by ion beam techniques. Thermomechanical properties of the nanocomposites showed that incorporation of low content (0.4 wt%) of nanodiamond powder into epoxy matrix enhanced the storage modulus, loss modulus, and hardness by ∼68, ∼55, and ∼86%, respectively, over neat epoxy. By increasing the concentration of modified NCD to 0.7 wt% resulted in lower values of hardness and thermomechanical properties but still remain higher than neat epoxy. An increasing trend in properties was again observed at 4 wt% concentration of modified nanofiller. The glass transition temperature was up shifted to ∼110°C over neat epoxy. The mechanisms responsible for enhanced properties of epoxy matrix are also discussed in detail. POLYM. COMPOS., 34:811–818, 2013. © 2013 Society of Plastics Engineers     

Comparison of artificial neural network and adaptive neuro-fuzzy inference system for predicting the wrinkle recovery of woven fabrics

The aim of this study was to compare the artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models for predicting the wrinkle recovery of polyester/cotton woven fabrics. The prediction models were developed using experimental data-set of 115 fabric samples of different constructions. Warp and weft yarn linear densities, ends/25 mm and picks/25 mm, were used as input/predictor variables, and warp and weft crease recovery angles (CRA) as output/response variables. It was found that the prediction accuracy of the ANN models was slightly better as compared with that of ANFIS models developed in this study. However, the ANFIS models could characterize the relationships between the input and output variables through surface plots, which the ANN models could not. The developed models may be used to optimize the fabric construction parameters for maximizing the wrinkle recovery of polyester/cotton woven fabrics.     

Feasibility study of use of recycled High Density Polyethylene and multi response optimization of injection moulding parameters using combined grey relational and principal component analyses

Usability of recycled High Density Polyethylene (HDPE) as substitute for virgin HDPE is investigated. Optimization design of the injection moulding parameters for recycled HDPE products is presented. Tensile, compressive and flexural strengths are selected to evaluate the process performance and the corresponding moulding parameters are melt temperature, holding pressure, injection time, and holding time. Optimal combination of injection moulding parameters is determined using Grey relational analysis. The principal component analysis is applied to evaluate the weighting values corresponding to various performance characteristics. Tensile, compressive and flexural strengths of the recycled HDPE are found close to that of virgin HDPE. Thus, recycled HDPE is a good substitute for virgin HDPE. Optimal combination of the process parameters for the multi-performance characteristics of the recycled HDPE is the set with melt temperature at 240 °C, holding pressure at 255 N/m², injection time at 0.6 s and holding time at 30 s.