Surface Chemical Modification And Mechanism Research Of Magnesium Aluminum Hydroxides Used For Flame Retardant Leather

This paper is concerned with a surface chemical modification method of magnesium hydroxide particle for leather flame retardant.Its characteristic is grafting polymer brushes into the surface of magnesium hydroxide particles by using atom transfer radical polymerization?ATRP?.In order to improve the compatibility of magnesium hydroxide particles[Mg?OH?₂]and leather,poly?glycidyl methacrylate??PGMA?grafted from magnesium hydroxide particles were synthesized via surface-initiated atom transfer radical polymerization?SI-ATRP?.In this work,two approaches for the immobilization of ATRP initiator on the magnesium hydroxide particles surface were compared and selected.The macroinitiators were analyzed by fourier transform infrared spectroscopy?FT-IR?,thermogravimetry?TGA?,scanning electron microscopy?SEM?,and X-ray photoelectron spectroscopy?XPS?.The density of initiator was significantly increased by the method of introducing more hydroxyl groups via ATRP of 2-hydroxyethyl methacrylate?HEMA?on the surface.The percentage of bromine atom for the initiator-functionalized magnesium hydroxide particles[Mg?OH?₂-g-PHEMA-Br]reached to 1.75%,compared to 0.48%for Mg?OH?₂-Br determined by XPS analysis.The surface-initiated ATRP of glycidyl methacrylate?GMA?can be conducted in a controlled manner,as revealed by the linear kinetic plot,linear increase of number average molecular weight?Mn?with monomer conversions,and the relatively narrow molecular weight distributions?PDI-1.5?of PGMA chains.The percentage of grafting PG?%?and the thickness of the grafted polymer layer increased with the increasing of polymerization time and reached to 116.6%and 197.6 nm after 300 min respectively.As for the polymerization with different initial monomer concentration,the number average molecular weights?Mn?and weight average molecular weights?Mw?of PGMA increased with the increasing of initial monomer concentration.LOI,vertical burning and smoke density test indicated that Mg?OH?₂-g-PHEMA-PGMA composite particles could increase the LOI of leather,decrease the flameless burning time and decrease the smoke density of leather.