Chain Extension of Polyamide 6 Using Bisoxazoline Coupling Agents

The chain extension behaviors of 2,2′-(1,3-phenylene)bis(2-oxazoline) (MPBO) and 2,2′-bis(2-oxazoline) (BOZ) were studied to evaluate the coupling effect on polyamide 6 (PA6) in a Haake Rheocord mixer and an extruder. The coupling results showed that there existed an optimal dosage of chain extender, lack of which caused deficiency of chain extension and excess of which led to more blocking reaction. The effect of chain extension with MPBO was shown to be inferior to BOZ. When the optimum amount of chain extenders was added in PA6, the intrinsic viscosity of the polyamide 6 increased from 1.632dl/g to 1.787dl/g(MPBO) and 2.031dl/g(BOZ), respectively. The reaction time decreased very fast with an increase in the temperature. The chain-extended products dissociated at high temperature; the degradation is suggested to proceed from the onset of the chain extension reaction, as do the coupling and blocking reactions. Furthermore, the effects of MPBO and BOZ on the thermal and mechanical properties of chain-extended PA6 were also investigated.     

A Sensitive Spectrophotometric Method for the Determination of Some Imidazoline Derivatives by 2,6-Dichlorophenol-Indophenol

Abstract

A new and highly sensitive method is presented for the spectrophotometric determination of four imidazoline derivatives: antazoline hydrochloride, tolazoline hydrochloride, xylometazoline hydrochloride and naphazoline nitrate. The method is based on the reaction of the corresponding drug base with 2,6 - dichlorophenol -indophenol (DGPIP) in chloroform to give a blue chromogen exhibiting a maximum at 588 - 603nm. The method could be applied for the quantitative determination of the above drugs either pure or in their pharmaceutical preparations (tablets and nasal drops). The results obtained are accurate and have good reproducibility.     

On two epireflective subcategories of the category of 2T 0-fuzzy bitopological spaces

In the space of absolutely summable sequences the total variation of a sequence becomes a natural norm, and is a measure of smoothness. This norm is preserved by the so-called LU LU-smoothers, in that the variation of the image plus the variation of the difference is equal to the variation of the original sequence. This surprising property is useful for strategies for the removal of impulsive and other random noise. Strong shape preserving properties of these smoothers are derived in the process of proving this. The results shed light on similar properties of the popular median smoothers, as well as their sometimes enigmatic behaviour.     

Mesoporous Carbon@Titanium Nitride Hollow Spheres as an Efficient SeS2 Host for Advanced Li–SeS2 Batteries

The introduction of a certain proportion of selenium into sulfur‐based cathodes is an effective strategy for enhancing the integrated battery performance. However, similar to sulfur, selenium sulfide cathodes suffer from poor cycling stability owing to the dissolution of reaction intermediate products. In this study, to exploit the advantages of SeS₂ to the full and avoid its shortcomings, we designed and synthesized a hollow mesoporous carbon@titanium nitride (HMC@TiN) host for loading 70 wt % of SeS₂ as a cathode material for Li–SeS₂ batteries. Benefiting from both physical and chemical entrapment by hollow mesoporous carbon and TiN, the HMC@TiN/SeS₂ cathode manifests high utilization of the active material and excellent cycling stability. Moreover, it exhibits promising areal capacity (up to 4 mAh cm⁻²) with stable cell performance in the high‐mass‐loading electrode.