Synergistic effects of β‐cyclodextrin containing silicone oligomer on intumescent flame retardant polypropylene system

Abstract

The effects of b-cyclodextrin containing silicone oligomer(CDS), as a synergistic agent, on the flame retardancy and mechanical properties of intumescent flame retardant polypropylene composites were studied by adding different amounts of CDS in intumescent flame retardants. The limiting oxygen index (LOI), UL-94 test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were utilized to evaluate the synergistic effects of CDS in the composites. It was found that after a little amount of CDS partially replaced a charring-foaming agent (CFA) in IFR, LOI values of the composites were enhanced and they obtained a UL-94 V-0 rating. IFR system containing 6.25wt% CDS presented the best flame retardancy in PP. The experimental results obtained from LOI and UL-94, TGA, SEM, and mechanical properties indicated that the combination of CDS and CFA presents synergistic effects in flame retardancy, char formation, and mechanical properties of the composites. This is probably due to different structures of polyhydroxyl macromolecules (CDS and CFA), the existence of dimethyl silicone group in CDS, and the toughness of epoxy silicon chain in CDS. SEM results proved that the interfacial compatibility between IFR and PP was improved by CDS

Intumescence: Tradition versus novelty. A comprehensive review

“…Further improvements were achieved for PP by using CD with silicone oligomer, as reported by Wang and Li [110].…”

An intumescent flame retardant system using β‐cyclodextrin as a carbon source in polylactic acid (PLA)

“…Different from Wang et al . 19 and Alongi et al . 36, the present study is physically grinding CD with APP and/or MA without any chemical modification, aiming to form more simple and greener IFR complex systems.…”

Synergistic effect of phosphorus‐containing nanosponges on intumescent flame‐retardant polypropylene

“…T onset of the PP/IFR/P–NS composite was 11°C lower than that of PP/IFR, and two main stages of decomposition were observed, as shown in Figure 3(c). The first stage occurred roughly from 250 to 385°C and was ascribed to the char‐forming reaction and decomposition of the composite; the second stage was probably due to the destruction of the protective layer 18. The T max values of the two stages were 353 and 396°C; these values were 10 and 53°C higher than those of the PP/IFR composite, respectively.…”

“…This was because P–NS acted as a catalyst in the PP/IFR composite for char formation. When P–NS was more than 2.0 wt %, the esterification speed of the system did not match the foaming speed well; this destroyed the char swelling behavior of the composite and resulted in an unsatisfactory flame retardancy 18, 31. Therefore, on the basis of the results of the LOI and UL‐94 tests, an appropriate P–NS content of 2.0 wt % was optimum for the flame retardancy.…”

“…We suggest that this issue can be solved via the absorbance of RDP into nanosponges (NSs) synthesized by the crosslinking of β‐cyclodextrin (β‐CD) with epoxy. β‐CD, consisting of seven glucopyranose units, has been proven to be a good charring agent 17, 18. Besides, it is well‐known for forming an inclusion complex with various guest molecules because of its special molecular structures: a hydrophobic internal cavity and a hydrophilic external surface 16, 19, 20.…”