Enhancement of Flame Retardancy of Colorless and Transparent Semi-Alicyclic Polyimide Film from Hydrogenated-BPDA and 4,4′-oxydianiline via the Incorporation of Phosphazene Oligomer

Abstract

Enhancement of flame retardancy of a colorless and transparent semi-alicyclic polyimide (PI) film was carried out by the incorporation of phosphazene (PPZ) flame retardant (FR). For this purpose, PI-1 matrix was first synthesized from hydrogenated 3,3′,4,4′-biphenyltetracarboxylic dianhydride (HBPDA) and 4,4′-oxydianiline (ODA). The soluble PI-1 resin was dissolved in N,N-dimethylacetamide (DMAc) to afford the PI-1 solution, which was then physically blended with PPZ FR with the loading amounts in the range of 0–25 wt.%. The PPZ FR exhibited good miscibility with the PI-1 matrix when its proportion was lower than 10 wt.% in the composite films. PI-3 composite film with the PPZ loading of 10 wt.% showed an optical transmittance of 75% at the wavelength of 450 nm with a thickness of 50 μm. More importantly, PI-3 exhibited a flame retardancy class of UL 94 VTM-0 and reduced total heat release (THR), heat release rate (HRR), smoke production rate (SPR), and rate of smoke release (RSR) values during combustion compared with the original PI-1 film. In addition, PI-3 film had a limiting oxygen index (LOI) of 30.9%, which is much higher than that of PI-1 matrix (LOI: 20.1%). Finally, incorporation of PPZ FR decreased the thermal stability of the PI films. The 10% weight loss temperature (T10%) and the glass transition temperature (Tg) of the PI-3 film were 411.6 °C and 227.4 °C, respectively, which were lower than those of the PI-1 matrix (T10%: 487.3 °C; Tg: 260.6 °C)

Colorless and transparent semi‐alicyclic polyimide films with intrinsic flame retardancy based on alicyclic dianhydrides and aromatic phosphorous‐containing diamine: Preparation and properties

“…However, it could not apparently reduce the smoke releasing of the PI films during the forced combustion. It has been revealed in our previous work that incorporation of some specific phosphorus‐containing flame retardant, such as polyphosphazene (PPZ) into the semi‐alicyclic PI films could efficiently prohibit the releasing of smoke 23 . Thus, it might be quite beneficial for the practical application of the current PI films by addition of a small amount of flame retardants with the smoke‐suppression effects in the formulation.…”

“…Thus, the Kapton films have been widely used in high‐tech fields as thermal‐insulating components or flame‐resistant materials 22 . However, when the pyromellitic dianhydride (PMDA) units in Kapton was replaced with hydrogenated pyromellitic dianhydride (HPMDA) which is another commercially available PI film, poly(hydrogenated pyromellitic dianhydride‐co‐4,4′‐oxydianiline) (HPMDA‐ODA, tradename: Neopulim, commercialized by Mitsubishi Gas Chemical, Japan), the LOI value of the PI film decreases to only 27.4% and a flame retardant grade of UL94 Not VTM‐2 23 . That is to say, the Neopulim film (HPMDA‐ODA) is combustible although it has been widely used in advanced optoelectronic fields due to the excellent optical transparency and good thermal stability 24,25 .…”

Biodegradable Flame Retardants for Biodegradable Polymer

“…Abiotic is a chemical process where photo-degradation and decomposition of the material at elevated temperatures and reactions with other compounds may occur that can change the materials intrinsic properties [ 18 ]. Moreover, non-biodegradable halogenated FRs may find their way into the environment through wastewater streams of the industries that produce them or through adsorption into the dust particles at the manufacturing facilities where they are incorporated directly to various products [ 19 ]. Once these FRs enter the environment, they can easily attach to any airborne particle and can travel distances far from their emission or production sites.…”

Soluble and transparent polyimides with high Tgs from a new semi-aliphatic diamine with cyclohexyl and ortho-methyl groups

“…and attract much attention in the fields of science and industry. [1][2][3][4] Unfortunately, the rigid backbones of conventional aromatic PIs often result in the difficult processing of them in solution or molten state. In addition, it is easy to form intramolecular and intermolecular charge-transfer complex (CTC) that usually causes the low transparency and deep color of PI films.…”

“…In order to decrease the cost and further enhance the T g s of PIs, we intend to use methyl instead of tert-butyl. 3,35 Herein, a new semi-aliphatic diamine 4,4 0 -(cyclohexylmethylene)bis(2-methylaniline) with cyclohexyl and orthosubstituted methyl groups was designed and synthesized through Mannich and rearrangement reactions. Then a series of soluble and transparent PIs with high T g s were prepared from CHMBMA and five commercial aromatic dianhydrides via the high-temperature one-step method.…”