Flame‐retarded polyolefin systems of controlled interphase

Abstract

The principle of multilayer interphases was proposed earlier for modifying the mechanical properties and UV stability of various multicomponent polymer systems. This paper focuses on the applicability of this principle for improving the performance of intumescent flame‐retardant systems using melamine‐treated ammonium polyphosphate, silicone modified polyol + ammonium polyphosphate, and silicone modified nanoparticles in polypropylene. The structure–property relationship of the formed systems was studied. A melamine layer of 1.45 nm thickness was formed around ammonium polyphosphate in order to improve the hygrothermal stability, but this layer was not shear‐resistant enough. An interphase formed using a special silicone additive is more stable and acts with the intumescent flame‐retardant system synergistically. The advantageous interfacial structure is quite complex in this case: polyphosphate particles are surrounded with a macromolecular layer formed from polyol, silicone, and reactive surfactant in order to ensure good stability, efficiency and compatibility. AFM, XPS and a Cone Calorimeter were used for determining the structure and flame‐retardancy of these systems. Nanocomposites combined with silicone‐containing intumescent system were developed in order to avoid dipping at ignition in the vertical position. SAXS and µ‐TA methods were used for determining the structure of this material. Copyright ­© 2003 John Wiley & Sons, Ltd.

Swelling of organoclays in styrene. Effect on flammability in polystyrene nanocomposites

“…According to Levchik and Weil [19] flame retardancy achieved with nanocomposites alone is not enough for the ignition resistance inferred by the UL-94 test and they suggest a better approach to combine the nanocomposite with another flame retardant, such that the nanocomposite provides the base reduction in flammability, and the secondary flame retardant provides the ignition resistance. Several papers [20][21][22] investigated the effect of the chemical and physical structure of polymer/clay interfaces on the flammability of polymer composites and nanocomposites. Some of these papers showed that the clay/polymer nanocomposite improved not only the cone calorimetry results, but the UL94 performance as well.…”

Flame‐Retarded Poly(propylene) with Melamine Phosphate and Pentaerythritol/Polyurethane Composite Charring Agent

“…With three basic components, i.e., acid catalyst, char‐forming agent, and blowing agent involved, an IFR system can undergo an intensive expansion to form a protective foam char layer, which effectively holds back the transfer process of the heat and fuel during combustion, subsequently leading to a quick self‐extinguishment of the burning materials 4,5. Ammonium polyphosphate/melamine/pentaerythritol (APP/ME/PER) and melamine phosphate (MP)/PER are typical IFR systems for flame‐retarded PP,6–13 in which PER acts as a small molecular charring agent but brings some instability problems, e.g., (1) poor water‐resistance due to its moderate water‐solubility, (2) easy migration and blooming due to its poor compatibility with PP matrix, and (3) thermal instability due to the chemical reaction, e.g., esterification of PER with acid component MP in the intumescent system during incorporation with PP at processing temperature. In order to solve these problems, some new charring agents were developed to replace traditional PER.…”

Extrusion with ultrasound applied on intumescent flame‐retardant polypropylene

“…These systems have been formulated with various polymers, such as PU, EVA, SBR, PE, LDPE, PLA [4–9], with particular attention to polypropylene compounds. These works are diverse, including the synthesis of an intumescent system by reactive extrusion [10–12], the incorporation of different nanofillers in the intumescent system [13–16] and the formation of an interfacial layer containing intumescent flame‐retardant compounds [17]. In addition, thermal degradation and the combustion behavior of a novel intumescent system [18] were also given attention, among others.…”