Effect of Process Conditions on the Properties of Resorcinol-Formaldehyde Aerogel Microparticles Produced via Emulsion-Gelation Method.

Seeni Meera Kamal Mohamed,Charlotte Heinrich,Barbara Milow

doi:10.3390/polym13152409

Seeni Meera Kamal Mohamed, Charlotte Heinrich + Show 1 more

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https://doi.org/10.3390/polym13152409

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Journal: Polymers	Publication Date: Jul 22, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: German Aerospace Center

Abstract

Organic aerogels in the form of powder, microgranules and microsized particles receive considerable attention due to their easy fabrication, low process time and costs compared to their monolithic form. Here, we developed resorcinol-formaldehyde (RF) aerogel microparticles by using an emulsion-gelation method. The main objective of this study is to investigate the influence of curing time, stirring rate, RF sol:oil ratio and initial pH of the sol in order to control the size and properties of the microparticles produced. The emulsion-gelation of RF sol prepared with sodium carbonate catalyst in an oil phase at 60 °C was explored. RF microparticles were washed with ethanol to remove the oil phase followed by supercritical and ambient pressure drying. The properties of the dried RF microparticles were analyzed using FT-IR, N2 adsorption isotherm, gas pycnometry, wide angle X-ray scattering and scanning electron microscope. RF microparticles with high surface area up to 543 m2/g and large pore volume of 1.75 cm3/g with particle sizes ranging from 50–425 µm were obtained.

Highlights

Aerogels are ultra-lightweight materials with a highly open porous nature with more than 90% v/v of empty space
We report the preparation of RF aerogel microparticles by using an emulsion-gelation method
The effects of curing time, stirring rate, sol:oil ratio and initial pH of the sol were investigated on the microparticle formation and its structural and adsorption properties

Summary

Introduction

Aerogels are ultra-lightweight materials with a highly open porous nature with more than 90% v/v of empty space They are defined as interconnected solid colloidal or polymeric nanoparticles expanded throughout their volume by gas [1]. This contributes to their interesting properties such as high surface area, ultra-low thermal conductivity, low density, high porosity, etc. The foundry industry can take considerable advantage of, e.g., energy efficiency by using open porous nanostructured materials like aerogels as binders and additives for sand cores and molds [9,11]. High temperature stable aerogels present in the sand cores could be able to absorb gases evolved during the decomposition of polymeric resins employed as sand grain binders [13]

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