Effects of three surfactant types of anionic, cationic and non-ionic on tensile properties and fracture surface morphology of epoxy/MWCNT nanocomposites

Three types of surfactants were used to enhance the dispersion of multi-wall carbon nanotubes (MWCNTs) in the epoxy matrix. MWCNTs were separately treated with non-ionic (polyoxyethylene octyl phenyl ether, Triton X-100), cationic (hexadecyl-trimethyl-ammonium bromide, CTAB) and anionic (sodium dodecyl sulfate, SDS) surfactants and their effects were evaluated on the dispersion state and surface chemistry, as well as on the tensile properties and tensile fracture surface morphology of MWCNTs/epoxy nanocomposites. The active surfaces of the carbon nanotubes were characterized by FTIR. The non-ionic surfactant, Triton X-100, had the best effect on dispersion of the MWCNT in the epoxy matrix, thus, positively affecting the tensile parameters of the corresponding nanocomposites which were attributed to the ??bridging?? effects between the MWCNT and epoxy, introduced by the hydrophobic and hydrophilic heads of the corresponding surfactant. Presence of MWCNTs as reinforcing agent increased the elastic modulus of nanocomposites, indicating the improved interfacial adhesion between CNTs and polymer matrix. The regions of nucleation and propagation of cracks were clearly seen in the SEM micrographs of the tensile fracture surface of the nanocomposites. The cracks deviated on reaching the carbon nanotubes. The dispersing aiding capabilities of the three surfactants used in the present study were as follows: cationic?<?anionic?<?non-ionic.     

Characterization of multiwalled carbon nanotube filled,palm‐oil‐based polyalkyds: Effects of loading and in situ reaction

In this study, the contribution of multiwalled carbon nanotubes (MWCNTs) was studied for the evaluation of the performances of polyalkyd‐based films produced from dehydrated palm oil. Initially, different percentages of MWCNTs, including 0.5, 1.0, and 1.5 wt %, were considered for loading into the resin with the help of sonication. Additionally, a 1.0 wt % loading was considered for in situ conditions during the esterification process to achieve better dispersion and obtain improved properties of the film. The loading was evaluated by different performance tests, such as those of tensile, elongation, pencil hardness, swelling ratio, gel content, wettability, chemical resistivity, adhesion, and surface morphology. The results of mechanical testing showed that the addition of 1.0 wt % MWCNTs enhanced the tensile strength by 50%, whereas in situ conditions were found to be favorable for significantly improving the tensile strength by 75%. Moreover, the wettability, surface morphology, and thermal properties were also found to be in favor of in situ conditions for the dispersion of the MWCNTs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42934.     

Quantifying Thermally Induced Flowability of Rennet Cheese Curds

Conversion of liquid milk to cheese curds is the first stage in cheese manufacture. Changing the rigidity of cheese curds through heating and pH control is an established method for preparing fresh curds, whereas a similar method to prepare fully coagulated curds is largely unknown. This study elucidated the effect of temperature variation on the viscoelastic moduli of fully coagulated curds under different pH conditions. The results showed that Rennet curds treated at pH 4.8 exhibited drastic changes in the viscoelasticity at 43°C, above which the degree of fluidity exceeded the degree of rigidity. The viscoelastic moduli exhibited exponential decay as a function of temperature, which was independent of pH.     

Functional genomics of commercial baker's yeasts that have different abilities for sugar utilization and high-sucrose tolerance under different sugar conditions

In the modern baking industry, high-sucrose-tolerant (HS) and maltose-utilizing (LS) yeast were developed using breeding techniques and are now used commercially. Sugar utilization and high-sucrose tolerance differ significantly between HS and LS yeasts. We analysed the gene expression profiles of HS and LS yeasts under different sucrose conditions in order to determine their basic physiology. Two-way hierarchical clustering was performed to obtain the overall patterns of gene expression. The clustering clearly showed that the gene expression patterns of LS yeast differed from those of HS yeast. Quality threshold clustering was used to identify the gene clusters containing upregulated genes (cluster 1) and downregulated genes (cluster 2) under high-sucrose conditions. Clusters 1 and 2 contained numerous genes involved in carbon and nitrogen metabolism, respectively. The expression level of the genes involved in the metabolism of glycerol and trehalose, which are known to be osmoprotectants, in LS yeast was higher than that in HS yeast under sucrose concentrations of 5-40%. No clear correlation was found between the expression level of the genes involved in the biosynthesis of the osmoprotectants and the intracellular contents of the osmoprotectants. The present gene expression data were compared with data previously reported in a comprehensive analysis of a gene deletion strain collection. Welch's t-test for this comparison showed that the relative growth rates of the deletion strains whose deletion occurred in genes belonging to cluster 1 were significantly higher than the average growth rates of all deletion strains.