Synergistic Effects and Mechanism of Modified Silica Sol Flame Retardant Systems on Silk Fabric

The nano-silica sol was prepared by sol-gel method, and the boric acid, urea, cyanoguanidine, melamine cyanurate (MCA), 1-hydroxyethane 1,1-diphosphonic acid (HEDP), and 6H-dibenz (C,E) (1,2) oxaphosphorin-6-oxide (DOPO) were added to the silica sol to modify the flame retardant through physical doping and chemical bonding. According to the formula proposed by Lewin, the calculation of flammability parameters were obtained by the limiting oxygen index meter, the micro calorimeter, the vertical burner, and the thermogravimetric analyzer proved that there was a synergistic or additive effect between the B/N/P flame retardant and the silica sol. Fourier transform infrared (FT-IR) spectrum, scanning electron microscopy, and pyrolysis gas chromatography-mass spectrometry were used to characterize the morphology, structure, and pyrolysis products of treated silk fabric and residues after combustion. The results show that the flame retardancy of silica-boron sol is mainly caused by endothermic reaction and melt covering reaction. Silicon-nitrogen sol acts as a flame retardant through endothermic reaction, release of gases, and melting coverage. Silicon-phosphorus sol achieves flame retardancy by forming an acid to promote formation of a carbon layer and melting coverage. Silica sol and other flame retardants show excellent flame retardanty after compounding, and have certain complementarity, which can balance the dosage, performance, and cost of flame retardants, and is more suitable for industrial development.

Download Full-text

The Flammability of Polyacrylonitrile and Its Copolymers I. The Flammability Assessment Using Pressed Powdered Polymer Samples

Journal of Fire Sciences ◽

10.1177/073490419301100505 ◽

1993 ◽

Vol 11 (5) ◽

pp. 442-456 ◽

Cited By ~ 14

Author(s):

Jun Zhang ◽

Michael E. Hall ◽

A. Richard Horrocks

Keyword(s):

Flame Retardant ◽

Flame Retardancy ◽

Flame Retardants ◽

Oxygen Index ◽

Char Residue ◽

Acrylic Polymer ◽

Limiting Oxygen Index ◽

Convenient Means ◽

Burning Rates ◽

Polymer Flammability

This paper is the first in a series of four which investigates the burning behaviour and the influence of flame retardant species on the flam mability of fibre-forming polymer and copolymers of acrylonitrile. A pressed powdered polymer sheet technique is described that enables a range of polymer compositions in the presence and absence of flame retardants to be assessed for limiting oxygen index, burning rate and char residue deter minations. The method offers a rapid, reproducible and convenient means of screening possible flame retardant systems, and LOI values compare favourably with those of films and fabrics comprising the same polymeric type. Burning rates, however, are sensitive to changes in physical sample character such as form (film vs. powder sheet) and density. Thus the technique forms an excellent basis for the generation of burning data which will enable comprehensive studies of acrylic polymer flammability and flame retardancy to be undertaken.

Download Full-text

Flame Retardant Polypropylenes: A Review

Polymers ◽

10.3390/polym12081701 ◽

2020 ◽

Vol 12 (8) ◽

pp. 1701 ◽

Cited By ~ 2

Author(s):

Farzad Seidi ◽

Elnaz Movahedifar ◽

Ghasem Naderi ◽

Vahideh Akbari ◽

Franck Ducos ◽

...

Keyword(s):

Flame Retardant ◽

Flame Retardancy ◽

Flame Retardants ◽

Cone Calorimetry ◽

Research Papers ◽

Limiting Oxygen Index ◽

Wide Range ◽

Pp Composites ◽

Calorimetry Data

Polypropylene (PP) is a commodity plastic known for high rigidity and crystallinity, which is suitable for a wide range of applications. However, high flammability of PP has always been noticed by users as a constraint; therefore, a variety of additives has been examined to make PP flame-retardant. In this work, research papers on the flame retardancy of PP have been comprehensively reviewed, classified in terms of flame retardancy, and evaluated based on the universal dimensionless criterion of Flame Retardancy Index (FRI). The classification of additives of well-known families, i.e., phosphorus-based, nitrogen-based, mineral, carbon-based, bio-based, and hybrid flame retardants composed of two or more additives, was reflected in FRI mirror calculated from cone calorimetry data, whatever heat flux and sample thickness in a given series of samples. PP composites were categorized in terms of flame retardancy performance as Poor, Good, or Excellent cases. It also attempted to correlate other criteria like UL-94 and limiting oxygen index (LOI) with FRI values, giving a broad view of flame retardancy performance of PP composites. The collected data and the conclusions presented in this survey should help researchers working in the field to select the best additives among possibilities for making the PP sufficiently flame-retardant for advanced applications.

Download Full-text

Flame Retardant Polyethylene with Intumescent System Containing Macromolecule-Encapsulated Low Molecular Weight Charring Agent

Polymers and Polymer Composites ◽

10.1177/096739110701500709 ◽

2007 ◽

Vol 15 (7) ◽

pp. 591-596 ◽

Cited By ~ 1

Author(s):

Meifang Liu ◽

Xing Huang ◽

Yuan Liu ◽

Qi Wang

Keyword(s):

Flame Retardant ◽

High Performance ◽

Flame Retardants ◽

Synergistic Effects ◽

Thermoplastic Polyurethane ◽

Esterification Reaction ◽

Limiting Oxygen Index ◽

Charring Agent ◽

Optimum Formula ◽

Intumescent System

Intumescent flame retardants are important halogen-free products used in polyethylene. However, their thermal stability and water-resistance are major shortcomings. In this work, a composite charring agent, pentaerythritol (PER) encapsulated by thermoplastic polyurethane (TPU) was used in an intumescent system to improve the flame retardancy of high density polyethylene (HDPE). The encapsulation of macromolecular charring agent TPU can effectively suppress the esterification reaction of PER and acid source in the intumescent system during processing. It can also remarkably decrease the water absorption, thus producing flame retardant HDPE with high performance. The synergistic effects of other common flame retardants including melamine phosphate, melamine polyphosphate and ammonium polyphosphate with TPU-encapsulated PER, as well as the ratio of charring agent to acid source were investigated so as to determine the optimum formula for use in HDPE. The flame retardant HDPE can reach limiting oxygen index of 33 and achieve UL-94 V-0 rating at 3.2 mm thickness when the ratio of MP/composite charring agent is 2:1 w/w.

Download Full-text

Synergistically improved flame retardancy of the cotton fabric finished by silica-coupling agent-zinc borate hybrid sol

Journal of Industrial Textiles ◽

10.1177/15280837211028800 ◽

2021 ◽

pp. 152808372110288

Author(s):

Dan Li ◽

Zhen-hua Wang ◽

Yuan-shu Zhu ◽

Fei You ◽

Song-tao Zhou ◽

...

Keyword(s):

Cotton Fabric ◽

Flame Retardancy ◽

Coupling Agent ◽

Coupling Effect ◽

Synergistic Effects ◽

Sol Gel ◽

Cotton Fabrics ◽

Silica Sol ◽

Zinc Borate ◽

Limiting Oxygen Index

The sol-gel process has been applied to cotton fabrics to cover the fibers with a silica-based film, which can improve their thermal oxidation and combustion behaviors. Silica sol, silane coupling agent 3-glycidoxypropyltrimethoxysilane (KH560) and flame retardant zinc borate (ZB) are used together to prepare SiO2-KH560-ZB hybrid sol, which is then finished on the surface of cotton fabric through impregnation and baking. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), limiting oxygen index analysis (LOI) and microscale combustion calorimetry (MCC) are used to characterize functional groups, thermal stability and flammability properties of finished fabrics. Surface morphology of sol modified cotton fabrics are analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX). Results show the sols are successfully converted into gel coatings onto cotton fabrics, and continuous smoldering phenomenon of resulted fabrics disappears. ΔLOI/Δm of SiO2-KH560-ZB coated cotton fabric reaches the highest of 0.37%/g, char residue rate is as high as 28.43% and the peak heat release rate (PHRR) is reduced by 26.9% (83.7 W/g). KH560 has a significant coupling effect on combining components in the sol system and increases compatibility between sols and cotton fabrics. ZB (cooling, separation, dilution and suppression), silica sol (physical barrier) and KH560 show excellent synergistic effects in enhancing overall flame retardancy.

Download Full-text

Silica precursor as synergist for cotton flame retardancy

International Journal of Clothing Science and Technology ◽

10.1108/ijcst-03-2016-0036 ◽

2016 ◽

Vol 28 (3) ◽

pp. 378-386 ◽

Cited By ~ 5

Author(s):

Ana Marija Grancaric ◽

Lea Botteri ◽

Jenny Alongi ◽

Anita Tarbuk

Keyword(s):

Thermal Properties ◽

Synergistic Effect ◽

Flame Retardant ◽

Flame Retardancy ◽

Flame Retardants ◽

Ammonium Polyphosphate ◽

Limiting Oxygen Index ◽

Excellent Thermal Stability ◽

Content Type ◽

Silica Precursor

Purpose – The cotton and its blends is the most commonly used textile material in the design and production of protective clothing. However, as the cellulose textiles are the most flammable materials it is necessary to improve its flame retardancy. The government regulations have been the driving force for developing durable flame retardants finishes for textile, to improve its performance and to reduce the negative impact on the environment. The paper aims to discuss these issues. Design/methodology/approach – This paper investigates the effect of silica precursor (tetraethoxysilane – TEOS) added in bath with conventional flame retardant urea/ammonium polyphosphate in full and half concentration for achieving environmental-friendly cotton flame retardancy. Silica precursors have excellent thermal stability and high heat resistance with very limited release of toxic gases during the thermal decomposition. Synergistic effect between urea/ammonium polyphosphate and TEOS has been calculated. Thermal properties of treated cotton fabrics were determined by limiting oxygen index (LOI), thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). Findings – TEOS, significantly improves the flame retardancy of cotton when added in the bath with conventional flame retardants urea/ammonium polyphosphate by increasing the LOI values and other thermal properties as increasing char residue measured by TGA and higher heat release rate measured by MCC. Originality/value – This paper represent a good synergistic effect between urea/ammonium polyphosphate and TEOS. This phenomena is evident in better thermal properties when TEOS was added in the bath with conventional flame retardant especially for half concentration of urea/ammonium polyphosphate.

Download Full-text

Investigation on the effect of supported synergistic catalyst with intumescent flame retardant in polypropylene

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0225 ◽

2021 ◽

Vol 41 (4) ◽

pp. 281-288

Author(s):

Hongmei Peng ◽

Qi Yang

Keyword(s):

Heat Release ◽

Flame Retardant ◽

Flame Retardancy ◽

Flame Retardants ◽

Supported Catalyst ◽

Intumescent Flame Retardant ◽

Limiting Oxygen Index ◽

Polypropylene Composites ◽

Cone Calorimeter Test ◽

Microscale Combustion Calorimetry

Abstract In this paper, cerium nitrate supported silica was prepared as a new type of catalytic synergist to improve the flame retardancy in polypropylene. When 1% of Ce(NO3)2 supported SiO2 was added, the vertical combustion performance of UL-94 of polypropylene composites was improved to V-0, the limiting oxygen index (LOI) was increased to 33.5. From the thermogravimetric analysis (TGA), the residual carbon of C and D was increased by about 6% at high temperature compared with B. When adding supported catalyst, the heat release rate (HRR) and total heat release (THR) were significantly reduced according to the microscale combustion calorimetry (MCC), the HRR of sample E with 2% synergist was the lowest. The combustion behaviors of intumescent flame retardant sample B and sample D were analyzed by cone calorimeter test (CCT), the HRR of sample D with supported synergist was significantly reduced, and the PHRR decreased from 323 kW/m2 to 264 kW/m2. The morphologies of the residue chars after vertical combustion of polypropylene composites observed by scanning electron microscopy (SEM) gave positive evidence that the supported synergist could catalyze the decomposition of intumescent flame retardants into carbon, which was the main reason for improving the flame retardancy of materials.

Download Full-text

Various Combinations of Flame Retardants for Poly (vinyl chloride)

Open Chemistry ◽

10.1515/chem-2019-0105 ◽

2019 ◽

Vol 17 (1) ◽

pp. 980-987

Author(s):

Ayşe Çetin ◽

S.Gamze Erzengin ◽

F. Burcu Alp

Keyword(s):

Flame Retardant ◽

Flame Retardants ◽

Synergistic Effects ◽

Thermal Analyses ◽

Thermal Characteristics ◽

Holistic Approach ◽

Heat Stability ◽

Softening Temperature ◽

Zinc Borate ◽

Limiting Oxygen Index

AbstractVarious combinations of zinc borate (ZB), alumina trihydrate (ATH) and magnesium hydroxide (MH) were used to retard the flammability of PVC composite. Flame retardancy of samples were investigated with limiting oxygen index (LOI) test. Further testing was achieved to expose the individual and synergistic effects of flame retardant additives on heat stability, Vicat softening temperature, fusion time, microstructure, mechanical and thermal characteristics. Microstructural and thermal analyses were performed by scanning electron microscopy and TG/DTA respectively. The LOI results showed that, high levels of ZB-ATH combination provided the highest LOI value of 53.4%. Although ZB and its combinations improved the fire performances of composites, they caused a small reduction at tensile strengths. When compared with plain PVC, flame retardant composites had better thermal stability. In addition to the advantages of ZB, when test results were evaluated with a holistic approach ZB-ATH-MH combination was understood to be an effective flame retardant alternative with this research.

Download Full-text

A transparent and intumescent phosphaphenanthrene/phenylpyrazole-containing epoxy resin system and its flame retardancy

High Performance Polymers ◽

10.1177/0954008321992412 ◽

2021 ◽

pp. 095400832199241

Author(s):

Zijin Luo ◽

Zhe Chen ◽

Jun Wei ◽

Dongchao Wang ◽

Han Chen ◽

...

Keyword(s):

Flame Retardant ◽

Epoxy Resin ◽

Flame Retardancy ◽

Gas Chromatography Mass Spectrometry ◽

Control Group ◽

Pyrolysis Gas ◽

Limiting Oxygen Index ◽

Cone Calorimeter Test ◽

Epoxy Resin System ◽

Index Value

A novel intumescent flame retardant, PPMD, was designed from phosphaphenanthrene and nitrogen heterocycles through the two-step gut reactions of 1,4-phthalaldehyde and 3-methyl-1-phe-nylpyrazol-5-ylamine. After determination of its structure by nuclear magnetic resonance and Fourier-transform infrared analyses, PPMD was added to an epoxy resin (EP) to facilitate a curing process. Thus, EP/PPMD samples with excellent transparency and flame retardancy were acquired. For example, the EP sample satisfied the UL-94 V-0 standard and achieved a limiting oxygen index value of 30.5% because of the incorporation of 5 wt% PPMD. The cone calorimeter test of the EP/5% PPMD sample revealed that its total smoke production (TSP) and total heat release (THR) values of EP/5% PPMD was only 22.5% and 56.4% of the control group, respectively. Moreover, the average effective heat of combustion (av-EHC) value of EP/5% PPMD was reduced by 34.1%, indicating that PPMD possessed high flame-inhibition activity and smoke suppression efficiency. The flame-retardant mechanisms of PPMD were also investigated in gas phase by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and in condensed phase by XPS and IR.

Download Full-text

Intumescent Flame Retardant Mechanism of Lignosulfonate as a Char Forming Agent in Rigid Polyurethane Foam

Polymers ◽

10.3390/polym13101585 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1585

Author(s):

Weimiao Lu ◽

Jiewang Ye ◽

Lianghai Zhu ◽

Zhenfu Jin ◽

Yuji Matsumoto

Keyword(s):

Thermal Stability ◽

Flame Retardant ◽

Flame Retardancy ◽

Flame Retardants ◽

Hydroxyl Groups ◽

Condensed Phases ◽

Limiting Oxygen Index ◽

Cone Calorimeter Test ◽

Intumescent Flame Retardants ◽

Flame Retardancy Mechanism

Intumescent flame retardants (IFR) have been widely used to improve flame retardancy of rigid polyurethane (RPU) foams and the most commonly used char forming agent is pentaerythritol (PER). Lignosulfonate (LS) is a natural macromolecule with substantial aromatic structures and abundant hydroxyl groups, and carbon content higher than PER. The flame retardancy and its mechanism of LS as char forming agent instead of PER in IFR formulation were investigated by scanning electron microscopy, thermogravimetric analysis, limiting oxygen index testing and cone calorimeter test. The results showed LS as a char forming agent did not increase the density of RPU/LS foams. LOI value and char residue of RPU/LS foam were higher than RPU/PER and the mass loss of RPU/LS foam decreased 18%, suggesting enhanced thermal stability. CCT results showed LS as a char forming agent in IFR formulation effectively enhanced the flame retardancy of RPU foams with respect to PER. The flame retardancy mechanism showed RPU/LS foam presented a continuous and relatively compact char layer, acting as the effect of the flame retardant and heat insulation between gaseous and condensed phases. The efficiency of different LS ratio in IFR formulation as char forming agent was different, and the best flame retardancy and thermal stability was obtained at RPU/LS1.

Download Full-text

A bio-based phosphaphenanthrene-containing derivative modified epoxy thermosets with good flame retardancy, high mechanical properties and transparency

RSC Advances ◽

10.1039/d1ra05709j ◽

2021 ◽

Vol 11 (49) ◽

pp. 30943-30954

Author(s):

Wei Peng ◽

Yu-xuan Xu ◽

Shi-bin Nie ◽

Wei Yang

Keyword(s):

Mechanical Properties ◽

Flame Retardant ◽

Flame Retardancy ◽

Epoxy Resins ◽

Flame Retardants ◽

The Past ◽

Phosphorus Containing ◽

Modified Epoxy

Phosphorus-containing flame retardants have received huge interest for improving the flame retardant behavior of epoxy resins (EP) over the past few decades.

Download Full-text