Elsevier

Applied Surface Science

Volume 252, Issue 22, 15 September 2006, Pages 7771-7773
Applied Surface Science

Short communication
Influence of chemical composition of filler's surface on the burning of foam plastics

https://doi.org/10.1016/j.apsusc.2005.09.054Get rights and content

Abstract

The influence of additives such as TiO2, Al2O3 and their mechanical mixture as well as aluminium oxide, the surface of which contains phosphorous and titanium-oxide nanostructures, on the combustibility of foam plast (trade mark PEN-I), produced on the basis of epoxide novolak block-copolymers, was studied. It was stated that the incorporation both phosphorous-containing and titanium-containing oxides in the composition results in significant (in two to five times) decreasing of the samples’ combustibility. The probable mechanism of inhibition of burning process for those combustion retarders was discussed.

Introduction

A wide use of dispersed inorganic fillers in polymer composition materials makes it possible to increase significantly their characteristics. It is caused by orienting influence of a filler surface at contact and interaction with polymers as well as by alteration of macromolecules mobility in the interfacial layers [1].

Chemical nature of filler is one of the fundamental characteristics that determine its reactivity. Taking into consideration physical–chemical processes occurring at the interface it is obvious, that chemical composition of the filler surface and its specific surface are important factors in controlling polymer material properties. Introduction into polymers the fillers with definite surface chemical properties can give rise to acceleration or retarding of different stages of the destruction process and alteration of the mechanism of such transformations. Efficiency of forming surface depends on precise control of chemical composition, uniform distribution of functional additives on the surface and strength of their connection with surface.

At the present time the method of molecular layering (ML) is one of the most interesting means of surface designing [2], [3], [4], [5]. The basic idea of the ML method is consists in consecutive escalating of structural unit's monolayers of the set chemical composition on the solid matrix surface. The analysis of the experimental data obtained at present time show that the method involved can be used for performing chemical assembly of micro- and macro-surface structures by assembling one an atom layer after another using multiple alternating sequences of chemical reactions according to a given programme. Under optimal regimes the method involved furnishes uniform coating with introduced additives of whole surface, strong (chemical) links of the additives with the surface, accuracy in prescribing the composition on molecular level, designing of multicomponent structures using sufficiently simple apparatus for performing the process [2].

The given paper deals with the results on studying the combustibility of a foam plast of make PEN-I based on epoxide novolak copolymer with the fillers, the surface of which is modified by phosphorus and titanium compounds by ML method.

Section snippets

Materials and methods

Oxides of aluminium and titanium were used as the fillers of the polymer materials. Their specific surface measured by low temperature air adsorption is in the range of 20–25 m2/g. Synthesis of element oxide groups on the surface of fillers were carried out in the installation of a flow type including a system of drying gas-carrier (air), a capacity with low molecular mass reagents, a glass reactor with indirect heating and system of absorbing gaseous products of reaction. Chlorides of titanium

Combustibility of the filled foam plasts

The results of tests on combustibility of the samples of foam plast of the make PEN-I filled with aluminium oxide containing phosphorus and titanium nanostructures on the surface are shown in Table 1. The extend of the filling for all compositions was 16% (mass). It should be noted that increasing of aluminium oxide concentration beyond 16% produces sharp degradation of the foam plast physical–mechanical characteristics (the apparent density, the limit of elasticity under compression and the

Conclusions

The experimental data presented in the paper show the efficiency of the preliminary surface treatment of polymer materials’ fillers by ML method. In doing so, to achieve the optimum results it is necessary to take into account not only chemical nature of a modified reagent that determines the mechanism of its inhibiting action, but also the method of its introduction into polymer matrix. For example, the fire protective action of phosphorus containing additives appears to be more advantageous

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