Flame Retardancy of Wood Fiber Materials Using Phosphorus-Modified Wheat Starch

Abstract

Biopolymer-based flame retardants (FR) are a promising approach to ensure adequate protection against fire while minimizing health and environmental risks. Only a few, however, are suitable for industrial purposes because of their poor flame retardancy, complex synthesis pathway, expensive cleaning procedures, and inappropriate application properties. In the present work, wheat starch was modified using a common phosphate/urea reaction system and tested as flame retardant additive for wood fibers. The results indicate that starch derivatives from phosphate/urea systems can reach fire protection efficiencies similar to those of commercial flame retardants currently used in the wood fiber industry. The functionalization leads to the incorporation of fire protective phosphates (up to 38 wt.%) and nitrogen groups (up to 8.3 wt.%). The lowest levels of burning in fire tests were measured with soluble additives at a phosphate content of 3.5 wt.%. Smoldering effects could be significantly reduced compared to unmodified wood fibers. The industrial processing of a starch-based flame retardant on wood insulating materials exhibits the fundamental applicability of flame retardants. These results demonstrate that starch modified from phosphate/urea-systems is a serious alternative to traditional flame retardants.

Suitability and Modification of Different Renewable Materials as Feedstock for Sustainable Flame Retardants

“…All syntheses were carried through in a kneader as described in part 4. Based on former results [14] for synthesis of FR using starch, wheat protein and xylan a molar ratio (AGU:MAP:Urea) of 1:3:4 proved to be optimum. For modification, tannin ratio was 1:1:4.…”

“…It could be confirmed that the flame retardants act exclusively in the condensed phase. The investigations prove that starch-based flame retardants are suitable, representing an alternative to common flame retardants in the wood fiber industry [14]. Thus, further biopolymers were investigated in a similar manner to assess the influence of biopolymer nature.…”

“…The thermal degradation of wood fiber insulation material was described in a former work [14]. All flame retardants and the wood fiber insulation material were characterized using thermogravimetric analysis under air.…”

“…Basic material was an industrial wheat starch, because phosphat-carbamatation of starch is a well-known reaction [11,18] and was scaled up successfully [14]. Wheat protein has a high native nitrogen content of about 12 %.…”

Utilization of Hemicelluloses as Example for Holistic Recovery of Agricultural Residues

“…Based on former investigations using starch or other polysaccharides the modification of HC for application as flame retardant (FR) material was tested. Due to the high amount of reactive hydroxyl groups and the easy accessibility there are good conditions for an effective modification of HC.…”