Cyclodextrins and Cyclodextrin Derivatives as Green Char Promoters in Flame Retardants Formulations for Polymeric Materials. A Review

Abstract

Polymers are intrinsically flammable materials; hence, fire retardance (FR) is required in their most common applications (i.e., electronic and construction, to mention some). Recently, it has been reported that cyclodextrin (CD) and cyclodextrin derivatives are beginning to be introduced into Intumescent Fire Retardant (IFR) formulations in place of pentaerythritol, which is used in IFRs that are currently on the market. Since IFRs are of less environmental concern than their hazardous halogen containing counterparts, the use of natural origin compounds in IFRs provides a way to comply with green chemistry issues. BCD and BCD derivatives presence in IFR mixtures promotes a higher yield of blowing gases and char when polymeric materials undergo combustion. Both processes play important roles in intumescence. The key rule to obtain in insulating compact char is the good dispersion of the nanoparticles in the matrix, which can be achieved by functionalizing nanoparticles with BCD derivatives. Moreover, CD derivatives are attractive because of their nanosized structure and their ability to form inclusion complexes with many compounds used as FR components, reducing their release to the environment during their shelf life of FR items. Often, fire retardance performed by BCD and BCD derivatives accompanies other relevant properties, such as improved mechanical resistance, washability resistance, self healing ability, thermal conductivity, etc. The application of CD fire retardant additives in many polymers, such as poly(lactic acid), poly(propylene), poly(vinyl acetate), poly(methyl methacrylate), linear low density poly(ethylene), polyamides, and polyesters are comprehensively reviewed here.

Modification of Silk Yarn with β‐Cyclodextrin Nanoparticles: Preparation, Characterization, and Natural Dyeing Properties

“…-CDs may enhance the action of the condensed phase and reduce the time-to-ignition. These results have been reported by Zhang et al [58] and Luda et al [59] They have explained that -CDs can promote the formation of a stable and compact carbonaceous char.…”

“…[ 58 ] and Luda et al. [ 59 ] They have explained that β‐CDs can promote the formation of a stable and compact carbonaceous char.…”

Fire-Safe Polymer Composites: Flame-Retardant Effect of Nanofillers

“…Recently, increasing environmental legislations have prohibited or limited the application of halogen-containing flame retardants to polymeric materials [ 217 , 218 , 219 , 220 ]. Therefore, hydrated fillers, such as ATH and MDH, have attracted interest as flame retardants for polymers.…”

Progress in Biodegradable Flame Retardant Nano-Biocomposites

“…The usage of nano calcium carbonate yields better flammability properties when combined with polyphosphates, due to its intumescent behaviour [ 199 , 200 ]. Carbohydrates, such as cyclodextrin nanosponges and nano lignin, seem to be very useful components in flame retardant systems [ 201 , 202 ]. Lignin is seen as an efficient bio-based carbonization agent in intumescent systems.…”