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102. Synergistic effects of boron-doped silicone resin and a layered double hydroxide modified with sodium dodecyl benzenesulfonate for enhancing the flame retardancy of polycarbonate

Author

Jiang Yi, Chen Yilong, Shao Zehui, Hongsheng Luo, Zhifeng Hao, Ke Yong, Ming Sun, and Qian Yu

Subjects
chemistry.chemical_classification, Thermogravimetric analysis, Materials science, General Chemical Engineering, Composite number, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Limiting oxygen index, chemistry.chemical_compound, chemistry, Cone calorimeter, Silicone resin, Hydroxide, Fourier transform infrared spectroscopy, 0210 nano-technology, Fire retardant, Nuclear chemistry
Abstract

To improve the flame retardancy of polycarbonate (PC), a novel and environmentally friendly flame retardant was synthesized by combining boron-doped silicone resin (BSR) with a layered double hydroxide (LDH) modified with sodium dodecyl benzenesulfonate (SDBS) which was denoted as DBS-LDH/BSR. The structure of the hybrid was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), which indicated that BSR was successfully combined with DBS-LDH. X-ray diffraction (XRD) studies showed that the reaction of BSR occurred only on the surface of DBS-LDH. In addition, scanning electron microscopy (SEM) was used to further verify the combination of DBS-LDH with BSR. PC exhibited the optimum flame retardancy following the incorporation of 10 wt% DBS-LDH/BSR (5 wt% DBS-LDH and 5 wt% BSR). Based on thermogravimetric analysis, the char residue of this PC composite in air at 750 °C increased to 3.60 wt%. Mechanical test showed that the DBS-LDH/BSR could affect the mechanical properties after incorporation into PC. According to the UL-94 vertical burning test, the flame retardant rating of the PC composite improved to V-0. Furthermore, the limiting oxygen index (LOI) value of the PC composite increased to 34%. According to the cone calorimeter test, the peak heat release rate (PHRR) dramatically decreased by 44%. The morphology of the PC composite after combustion was characterized by SEM, which revealed that the pores of the composite were smaller than those of pure PC. This result was attributed to the limited spread of oxygen and heat permeation. Thus, both DBS-LDH and BSR contributed to the synergistic effects of reducing the fire hazard of PC.

Published
2018

105. Foreword

Author

Farahani, Mohammad Reza, primary, Liu, Jia-Bao, additional, and Shao, Zehui, additional

Published
2019
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123. L(2,1)-labeling of the strong product of paths and cycles

Author

Shao, Zehui and Vesel, Aleksander

Subjects
teorija grafov, mathematics, matematika, graph theory, označitev točk, udc:519.17
Abstract

An L(2,1)-labeling of a graph G = (V, E) is a function f from the vertex set V(G) to the set of nonnegative integers such that the labels on adjacent vertices differ by at least two and the labels on vertices at distance two differ by at least one. The span of f is the difference between the largest and the smallest numbers in f(V). The ƛ-number of G, denoted by ƛ(G), is the minimum span over all L(2,1)-labelings of G. We consider the ƛ-number of Pn ☒ Cm and for n ≤ 11 the ƛ-number of Cn ☒ Cm. We determine ƛ-numbers of graphs of interest with the exception of a finite number of graphs and we improve the bounds on the ƛ-number of Cn ☒ Cm, m ≥ 24 and n ≥ 26.

Published
2017

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