The effect of mineral fillers on the rheological, mechanical and thermal properties of halogen-free flame-retardant polypropylene/expandable graphite compounds

AbstractMicro and nanocomposites of hydroxyl terminated polybutadiene (HTPB)-based polyurethanes (NPU) were obtained using five mineral fillers and Cloisite 20A nanoclay, respectively. Samples were prepared by the reaction of HTPB polyol and toluene diisocyanate (TDI), and the chain was further extended with glyceryl monoricinoleate to produce the final elastomeric polyurethanes. Mechanical and thermal properties were studied, showing that mineral fillers (20%w/w) significantly increased tensile strength, in particular nanoclay (at 5% w/w). When nanoclay-polymer dispersion was modified with a silane and hydantoin-bond promoter, elongation at break was significantly increased with respect to NPU with C20A. Thermal properties measured by differential scanning calorimetry (DSC) were not significantly affected in any case. The molecular structure of prepared micro and nanocomposites was confirmed by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Interaction of fillers with polymer chains is discussed, considering the role of silanes in compatibilization of hydrophilic mineral fillers and hydrophobic polymer. The functionalization of nanoclay with HMDS silane was confirmed using FTIR. Microstructure of NPU with C20A nanoclay was confirmed by Atomic Force Microscopy (AFM).

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Flame retardancy and thermal properties of rigid polyurethane foam conjugated with a phosphorus–nitrogen halogen-free intumescent flame retardant

Journal of Fire Sciences ◽

10.1177/0734904119890685 ◽

2020 ◽

Vol 38 (3) ◽

pp. 235-252

Author(s):

Zhaojun Lin ◽

Qianqiong Zhao ◽

Ruilan Fan ◽

Xiaoxue Yuan ◽

Fuli Tian

Keyword(s):

Thermal Properties ◽

Thermogravimetric Analysis ◽

Flame Retardant ◽

Polyurethane Foam ◽

Flame Retardancy ◽

Oxygen Index ◽

Carbon Layer ◽

Limited Oxygen Index ◽

Halogen Free ◽

Limited Oxygen

In this work, a halogen-free intumescent combining phosphorus and nitrogen, flame-retardant 2-((2-hydroxyphenyl)(phenylamino)methyl5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide (HAPO) was successfully synthesized. It had been synthesized by reaction of 5,5-dimethyl-1,3, 2-dioxphosphinane 2-oxide with Schiff base. Its chemical structure was characterized in detail by Fourier transform infrared spectroscopy, 1H NMR, and 31P NMR spectrum. The flame-retardant polyurethanes were prepared with different loadings of HAPO. The thermal properties, flame retardancy and combustion behavior of the pure polyurethane foam thermosets were investigated by a series of measurements involving thermogravimetric analysis, limited oxygen index measurement, UL-94 vertical burning test, and cone calorimeter test. The results of the aforementioned tests indicated that HAPO can significantly improve the flame retardancy as well as smoke inhibition performance of polyurethane foam. Compared with the PU-Neat, the limited oxygen index of flame-retardant polyurethanes (15%) thermoset was increased from 19.5% to 23.8% and its UL-94 reached V-0 rating. In addition, the cone test results showed that the heat release rate, total heat release, rate of smoke release, and total smoke production of flame-retardant polyurethanes (10%) were decreased obvious sly. The apparent morphology of carbon residue was characterized by scanning electron microscopy, and results revealed that the modified polyurethane foam can form dense carbon layer after combustion. Thermogravimetric analysis results also indicated that the char amount of flame-retardant polyurethanes was obviously increased compared with PU-Neat. Based on the above analysis, we can draw the conclusions which in the condensed phase, phosphorus-based acids from the degradation of HAPO, this could promote the formation of continuous and dense phosphorus-rich carbon layer. In the gas phase, the flame-retardant mechanism was ascribed to the quenching effect of phosphorus-based radicals and diluting effect by non-flammable gases.

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Synthesis, characterization, flame retardance and thermal properties of halogen-free expandable graphite/PMMA composites prepared from sol–gel method

Polymer Degradation and Stability ◽

10.1016/j.polymdegradstab.2008.03.030 ◽

2008 ◽

Vol 93 (7) ◽

pp. 1357-1363 ◽

Cited By ~ 32

Author(s):

Chen-Feng Kuan ◽

Wei-Hsin Yen ◽

Chia-Hsun Chen ◽

Siu-Ming Yuen ◽

Hsu-Chiang Kuan ◽

...

Keyword(s):

Thermal Properties ◽

Sol Gel ◽

Expandable Graphite ◽

Flame Retardance ◽

Gel Method ◽

Sol Gel Method ◽

Halogen Free

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Fabrication of cellulose-based halogen-free flame retardant and its synergistic effect with expandable graphite in polypropylene

Carbohydrate Polymers ◽

10.1016/j.carbpol.2019.02.088 ◽

2019 ◽

Vol 213 ◽

pp. 257-265 ◽

Cited By ~ 12

Author(s):

Zaihang Zheng ◽

Yuhang Liu ◽

Boya Dai ◽

Chunyu Meng ◽

Zhenxue Guo

Keyword(s):

Synergistic Effect ◽

Flame Retardant ◽

Expandable Graphite ◽

Halogen Free

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Studies of the Influence of Graphite on the Physical Mechanical and Thermal Properties of Polyurethane Foams for Construction Applications

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.887.399 ◽

2021 ◽

Vol 887 ◽

pp. 399-405

Author(s):

L.N. Shafigullin ◽

N.V. Romanova ◽

G.R. Shafigullina

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Absorption Coefficient ◽

Sound Absorption ◽

Polyurethane Foams ◽

Onset Temperature ◽

Sound Absorption Coefficient ◽

Expandable Graphite ◽

Mechanical And Thermal Properties ◽

Pu Foam

The paper shows the applicability of expandable graphite METOPAC EG 350-50 (80) in a rigid PU foam system as a substance that reduces the flammability (flame retardant) and improves the usability. The studies of the physical mechanical and thermal properties of PU foam with a higher graphite content revealed a higher normal sound absorption coefficient; insignificant influence on the thermal conductivity; a higher decomposition onset temperature; more difficult ignition. PU foam sample with a ratio of 15 graphite weight fractions to 100 polyol weight fractions has the highest physical mechanical and thermal properties, and, as compared to the starting PU foam, it features an increase in normal sound absorption coefficient by an average of 3 times; a decrease in the thermal conductivity by 8 %; an increase in the decomposition onset temperature by 6.7 °С. Therefore, the modification of PU foam with expandable graphite makes it possible not only to develop hardly combustible polyurethanes but also to improve its physical mechanical and thermal properties.

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