Influence of Change of Si/Al Ratio on the Synthesis of Mesoporous Aluminosilicates and Flexural Strength of Novolac Composites

Beata Strzemiecka,Adam Voelkel,Mariusz Sandomierski

doi:10.1007/s10904-019-01076-5

Abstract

Fillers used in phenol–formaldehyde resins should have high thermal stability, be cheap and do not have a negative impact on the resin crosslinking process. These features have mesoporous aluminosilicates which are used in many industries. In this work, effective and simple synthesis of mesoporous materials (with a different Si/Al ratio) from a solid source of silicon has been presented. Materials were used as fillers for phenol–formaldehyde composites. Synthesized mesoporous aluminosilicates have been characterized using Scanning electron microscopy, Energy dispersive spectrometry, Transmission electron microscopy, X-ray Difractometry, Nitrogen adsorption/desorption measurements and Inverse gas chromatography. The properties of the obtained materials are closely related to the amount of aluminum and silicon in the tested materials. All synthesized materials have a larger specific surface area than the substrates used during the synthesis. The mechanical properties of the novolac composites were tested using three-point flexural test. The composite with aluminosilicate which have the lower surface area has the highest flexural strength and it is higher than the strength of the composites with substrates.

Highlights

One of the most commonly used types of organic binders in abrasive tools are phenol–formaldehyde resins [1]
Phenol–formaldehyde resins represent 2% of the world’s polymer production. They are divided into novolacs which are synthesized using an excess of phenol to formaldehyde under acidic conditions and resoles which are obtained using an excess of formaldehyde to the phenol under basic conditions [2]
Along with the increase in the aluminum content in the materials, the content of sodium increases. It results from the structure of aluminosilicates, the main element of this structure are TO4/2 tetrahedra, where T is silica or aluminum

Summary

Introduction

One of the most commonly used types of organic binders in abrasive tools are phenol–formaldehyde resins [1]. Phenol–formaldehyde resins represent 2% of the world’s polymer production. They are divided into novolacs which are synthesized using an excess of phenol to formaldehyde under acidic conditions and resoles which are obtained using an excess of formaldehyde to the phenol under basic conditions [2]. Resole is cured by heat, acids and bases while novolac is cured using cross-linking agent (urotropine) [3]. Their wide application in abrasive tools is associated with high hardness, thermal stability, chemical resistance and their ability to cure by heating which facilitates production processes [3, 4]. The last component should have high thermal stability, be cheap

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