Highly efficient halogen-free flame retardants of thermally-oxidized polyacrylonitrile copolymers containing bio-derived caffeic acid derivatives

2020 ◽  
Vol 11 (41) ◽  
pp. 6658-6669
Author(s):  
Jongho Kim ◽  
Nam-Ho You ◽  
Bon-Cheol Ku

Polyacrylonitrile (PAN) copolymer with catechol comonomer is utilized as a precursor for the production of high-performance flame retarding fibers and is also widely used for clothing fibers.

2013 ◽  
Vol 1492 ◽  
pp. 161-166 ◽  
Author(s):  
Ruchi Bakshi ◽  
Sethumadhavan Ravichandran ◽  
Weeradech Kiratitanavit ◽  
Jayant Kumar ◽  
Ramaswamy Nagarajan

ABSTRACTIncreasing awareness of toxicity of halogenated flame retardants (FRs) has resulted in stringent regulations that require the elimination of their use in plastics. Consequently, there is considerable interest for the development of new varieties of high performance FRs. Here, we report the synthesis of new class of polyphenol based FR additives. Preliminary investigations indicate that these FR materials can possibly work through a combination of radical scavenging and char-formation. The thermal stability and char yield of polyphenol samples were investigated by thermogravimetric analysis (TGA). Thermal characterization indicated that these polymers produce significant amount of carbonaceous char upon combustion.


2010 ◽  
Vol 9 (1) ◽  
pp. 137-141
Author(s):  
M. Amzad Hossain ◽  
Zhari Ismail

This paper presents the studies performed on extraction of Orthosiphon stamineus, Benth by using different solvent for the identification and quantification of the caffeic acid derivatives such as caffeic acid  and rosmarinic acid which confers to the leaves of this plant with remarkable pharmaceutical properties. High performance thin-layer chromatographic (HPTLC) allows the identification and the quantification of more than 20 samples in the same chromatographic run. The analysis of the samples requires 15-30 min compared with more than 2 h using a typical HPLC method. Using the techniques of the HPTLC and the UV-VIS spectra we have found that the extraction of this herb plant contain, the caffeic acid and rosmarinic acid ranging between 0.029% up to 0.506% and up to 0.24% to 2.24% respectively.     Keywords: Caffice acid derivatives, quantification, Malaysian Orthosiphon stamineus, HPTLC


Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2145 ◽  
Author(s):  
Quanyi Liu ◽  
Donghui Wang ◽  
Zekun Li ◽  
Zhifa Li ◽  
Xiaoliang Peng ◽  
...  

With the increasing emphasis on environmental protection, the development of flame retardants for epoxy resin (EP) has tended to be non-toxic, efficient, multifunctional and systematic. Currently reported flame retardants have been capable of providing flame retardancy, heat resistance and thermal stability to EP. However, many aspects still need to be further improved. This paper reviews the development of EPs in halogen-free flame retardants, focusing on phosphorus flame retardants, carbon-based materials, silicon flame retardants, inorganic nanofillers, and metal-containing compounds. These flame retardants can be used on their own or in combination to achieve the desired results. The effects of these flame retardants on the thermal stability and flame retardancy of EPs were discussed. Despite the great progress on flame retardants for EP in recent years, further improvement of EP is needed to obtain numerous eco-friendly high-performance materials.


Author(s):  
Bhanu Sood ◽  
Michael Pecht

Abstract Failures in printed circuit boards account for a significant percentage of field returns in electronic products and systems. Conductive filament formation is an electrochemical process that requires the transport of a metal through or across a nonmetallic medium under the influence of an applied electric field. With the advent of lead-free initiatives, boards are being exposed to higher temperatures during lead-free solder processing. This can weaken the glass-fiber bonding, thus enhancing conductive filament formation. The effect of the inclusion of halogen-free flame retardants on conductive filament formation in printed circuit boards is also not completely understood. Previous studies, along with analysis and examinations conducted on printed circuit boards with failure sites that were due to conductive filament formation, have shown that the conductive path is typically formed along the delaminated fiber glass and epoxy resin interfaces. This paper is a result of a year-long study on the effects of reflow temperatures, halogen-free flame retardants, glass reinforcement weave style, and conductor spacing on times to failure due to conductive filament formation.


Author(s):  
G. G. Vokin

The article describes the approach and topical issues of synthesis of highly efficient transportable systems for search and determination of coordinates in the areas of elements falling, separated from the missiles, taking into account the dislocation of pre-empted areas of fall and physical conditions in their territories. The principles of these systems are based on the rational integration of traditional and non-traditional information sensors of different physical nature, which record the moments of landing of separated parts of the missiles.


Author(s):  
Guillem Romero-Sabat ◽  
Elena Gago-Benedí ◽  
Joan Josep Roa Rovira ◽  
David González-Gálvez ◽  
Antonio Mateo ◽  
...  

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