Zhidong Han

Organosilicon Compounds as Polymer Fire Retardants

The use of organosilicon compounds as fire retardants in polymers is one of the promising ways to overcome health, safety, and availability concerns of traditional halogenated fire retardants. Several types of organosilicon compounds with different degrees of oxidation are currently available, including silanes, polysiloxanes, and polysilsesquioxanes, as well as structures containing heteroatoms in the main chain, such as polycarbosilane and polysilazanes. Dispersion of such compounds into organic polymers may affect the polymer behavior in case of fire by a condensed phase action, producing a ceramic thermally stable protecting phase during the early stage of combustion. This chapter reviews the use of organosilicon compounds as fire retardants in polymers, discussing present achievements and perspectives.Abstract The use of organosilicon compounds as fire retardants in polymers is one of the promising ways to overcome health, safety, and availability concerns of traditional halogenated fire retardants. Several types of organosilicon compounds with different degrees of oxidation are currently available, including silanes, polysiloxanes, and polysilsesquioxanes, as well as structures containing heteroatoms in the main chain, such as polycarbosilane and polysilazanes. Dispersion of such compounds into organic polymers may affect the polymer behavior in case of fire by a condensed phase action, producing a ceramic thermally stable protecting phase during the early stage of combustion. This chapter reviews the use of organosilicon compounds as fire retardants in polymers, discussing present achievements and perspectives.

Decoupled trends for electrical and thermal conductivity in phase-confined CNT co-continuous blends

Abstract In the present work, the morphology and the electrical and thermal conduction properties of co-continuous poly(vinylidene fluoride) (PVDF), maleated polypropylene (PPgMA) and multiwall carbon nanotubes (CNT) nanostructured blends are investigated. CNT preferentially locates in the PPgMA phase and clearly causes a refinement in the co-continuous structure. Electrical conductivity experiments show that nanocomposites are well above the percolation threshold and evidence for one order of magnitude enhancement in conductivity for the co-continuous nanocomposites compared to the monophasic nanocomposites with the same CNT volume fraction. On the other hand, thermal diffusivity enhancement for the co-continuous blends is found lower than that for the monophasic nanocomposites at the same CNT volume fraction. An explanation is proposed in terms of large interfacial area, causing phonon scattering at the interface between immiscible PVDF and PPgMA domains. Results described in this paper open the way to the preparation of high electrical and low thermal conductivity materials with possible application as thermoelectrics. Graphical Abstract