Silica and Clay Dispersed Polymer Nanocomposites

Preparation, Properties and Applications

Md Rezaur Rahman

• Publisher: Woodhead Publishing
• Year: 2018
• Print ISBN: 9780081021293
• eBook ISBN: 9780081021309
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

The production of 'polymer nanocomposites' has recently gained considerable attention from both the academic and industrial community, especially in the area of nanoscience. This is mainly due to their enhanced improvements in physico-mechanical, thermal and barrier properties compared to micro and more conventional composites. Their nanoscale dimensions, biodegradable character, cost-effectiveness and sustainability have constituted a stimulus for this increasing interest. Currently there is no limit to the possibility of applications. However, despite all this progress, it is still difficult to achieve uniform dispersion between the filler and the matrix, as agglomerations form far too easily and the production of polymer nanocomposites with high mechanical and thermal properties is still limited.The authors of this proposed book, are of the opinion, that with the increase in scientific publications and the rapid progress in processing possibilities to produce nanocomposites based on various nanoscale fillers (silica/clay), a book that collects all of these scientific findings in one place would be timely and of great interest to both students and scientific researchers, who are concerned with the production, and application of nanocomposites as new innovative materials.The authors aim is to present the latest research findings on the fabrication, properties and applications of nanofillers as reinforcement in polymer nanocomposites. Particular emphasis will be placed on the introduction of various nanofillers (silica/clay) into different elastomeric polymer matrices that will enhance the properties of these materials and their applications. The book will provide an up-to-date review of major innovations in the field and act as a reference for future research in materials science and engineering, which is highly topical due to the demand to produce more sustainable and eco-friendly innovative advanced materials from elastomeric polymers.- Emphasis on silica/clay as outstanding reinforcing potential in elastomeric polymer matrices- Up-to-date on the most relevant innovations in the field of silica/clay nanocomposites and their extensive applications in advanced material science- Establishes the most suitable fabrication methods, properties and applications as a solid foundation in materials science and engineering disciplines- Includes the incorporation of dual nanofillers that significantly improve the properties of nanocomposites

1

Introduction and reinforcing potential of silica and various clay dispersed nanocomposites

Md. Rezaur Rahman; Josephine Lai Chang Hui; Sinin bin Hamdan Department of Chemical Engineering and Energy Sustainability, Faculty of Engineering, University Malaysia Sarawak (UNIMAS), Kota Samarahan, Sarawak, Malaysia

Abstract

Polymer nanocomposites were fabricated with the introduction of different types of fillers into various types of polymers via suitable techniques. Polyvinyl alcohol/fumed silica/clay (PVA-fsi-clay) nanocomposites, polyvinyl alcohol (PVA)/silica/clay (PVA-si-clay) nanocomposites, phenol formaldehyde/fumed silica/clay (PF-fsi-clay) nanocomposites, styrene-co-glycidyl methacrylate/fumed silica/clay (ST-co-GMA-fsi-clay) nanocomposites, and polylactic acid/fumed silica/clay (PLA-fsi-clay) nanocomposites were prepared via solution-intercalation film-casting, solution intercalation, condensation polymerization, and free radical polymerization. All the nanocomposites undergo physical, mechanical, thermal, and morphological analysis. The nanocomposites were characterized by Fourier-transform infrared spectroscopy, X-ray fluorescence, scanning electron microscopy, adsorption isotherm, tensile testing, thermogravimetric analysis, and moisture absorption. All the nanocomposites showed better properties compared to the conventional polymer, as well as the polymer composites.

Keywords

Polymer; Nanocomposites; Thermogravimetric analysis (TGA); Scanning electron microscopy (SEM); Mechanical Properties

Acknowledgments

The authors are grateful for the support of the Ministry of Higher Education Malaysia, Grant No. ERGS/02 (08)/860/2012 (12).

1.1 Introduction

Polymers are chain substances that consist of bonding of similar monomer units in a molecular state (Chu, 2010). Polymer nanocomposites are fabricated by incorporation of nanosized fillers or a reinforcing agent. The production of polymer nanocomposites has gained attention from both researchers and manufacturers due to its outstanding performance. Polymer nanocomposites are important in nanoscience due to the significant improvement in physicomechanical, thermal, and barrier properties compared to microcomposites or conventional composites (Pukánszky, 2005). However, the application of the polymer nanocomposites is limited to certain fields. In polymer nanocomposites, it is difficult to achieve uniform dispersion between the filler and matrix, as it forms agglomerations easily (Chu, 2010). To obtain excellent properties of nanocomposites, preparation and the structural relationships between the polymer matrix and fillers should be highly studied (Pukánszky, 2005).

Silica, fumed silica, and clays are referred to as reinforcing agents. Silica and fumed silica are widely used as filler embedded in a polymer matrix to improve the mechanical and morphological properties (Conradi, 2013). Clay is widely applied onto polymer matrix, as the hydrophobic clay enhances the strong interaction with hydrophilic polymer matrix (Roelofs & Berben, 2006). The clay with weak bondings between the layers expands the clay galleries and enhances the intercalation in the polymer nanocomposites. Clay is used as a filler material in small amounts due to its availability, low cost, and high surface-to-volume ratio (Greesh, 2011). It leads to a better reinforcement due to its large interface and evenly distributed nanosized particles. The nanofillers are dispersed in polymer matrix to form polymer nanocomposites. Polymer matrix is the continuous constituent that is found in higher quantities in the nanocomposites. It helps to bind and distribute the fillers uniformly in the nanocomposites (Thomas, Kuruvilla, Malhotra, Goda, & Sreekela, 2012, Chapter 1).

A polymer such as PVA functions as polymer matrix. It is a hydrophilic polymer that has high solubility in aqueous solution with low degrees of hydrolysis (Kokabi, Sirousazar, & Hassan, 2007). PVA performs better when crosslinking with fillers; it has advantages such as compatibility, excellent film foaming, it is nontoxic, and a simple chemical structure (Rosi, Iskandar, & Abdullah, 2014). It is widely applied in adhesives, paints, plastics, coatings, and others. PVA nanocomposites are applied in pharmaceutical and biomedical tools due to their outstanding properties (Tanigami, Yano, Yamaura, & Matsuzawa, 1995). However, PVA has limitations, such as thermal reversibility and low mechanical strength (Rosi et al., 2014).

PF is another common polymer produced by polycondensation of phenol and formaldehyde in acidic or basic catalyst at low molecular weight that is used as a polymer matrix in polymer nanocomposites (Edoga & Kovo, 2006). PF is one of the thermosetting polymers that can be applied as a bonding agent and binders in coatings, as PF has good mechanical and thermal properties. However, PF has limited usage due to its brittleness and poor adhesion properties (Inamdar & Rathod, 2013).

ST-co-GMA is a polymer matrix that undergoes polymerization with the introduction of an initiator (Ma, Shi, & Song, 2014). This polymer resin can be applied in paper strength additive (Zhang & Tanaka, 2001). ST-co-GMA matrix has good mechanical and thermal properties as well as better water resistance from acids and deionized water (Garg & Srivastaba, 2014). However, ST-co-GMA is unable to be widely applied due to its high toxicity and low polymerization temperature (El-Demerdash, Sadik, & El-Maghraby, 2008).

PLA is another polymer matrix. It is a thermoplastic with high strength that can be easily modified by simple hydrolysis of the ester bond without any enzyme (Garlotta, 2002). PLA is used as packaging material for construction, tissue regeneration, and scaffolds for bone reconstruction (Ray, 2012). Recently, PLA has been applied in green plastics. PLA nanocomposites can also be applied in biomedical fields, as they have bioadsorbable characteristics (Lim, Kim, Han, Khan, & Seo, 2014).

In this study, selected polymers such as PVA, PF, ST-co-GMA, and PLA are used as polymer matrix, while silica/fumed silica and clay are chosen as fillers. The fabricated nanocomposites are characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), scanning electron microscopy (SEM), adsorption isotherm, tensile testing, thermogravimetric analysis (TGA), and moisture absorption test.

1.2 Problem statement

Nowadays, polymer nanocomposites are materials with high demand due to their unique characteristics. However, the pure polymer matrices cannot be applied widely due to the limitations of their properties and environmental concerns. Pure polymers are hydrophobic in nature, and their drawbacks include low thermal resistance, low mechanical properties, and poor adhesion. Due to the drawbacks of pure polymers, single filler has been incorporated into the pure polymers to synthesize polymer nanocomposites. The incorporation of single filler has gradually improved either thermal or mechanical properties of the polymer nanocomposites. However, the physical and morphological properties of the single filler polymer nanocomposites have not been improved. To overcome the aforementioned problem, dual fillers such as silica/fumed silica (si/fsi) and clay are used as reinforcing agents to be incorporated into polymer matrices to enhance their physical, morphological, mechanical, and thermal properties. In this study, PVA, PF, ST-co-GMA, and PLA matrices were used to fabricate the nanocomposites.

1.3 Scope of the study

Due to their significant properties, especially their biodegradability and ecofriendliness, the research of polymer nanocomposites is of growing interest in the development of new materials. It is speculated that the hydrophilic nature of the pure polymers affects the resultant physical, mechanical, and thermal properties. According to the literature review and the aforementioned problem statement, there was no research reported on PVA-fumed silica-clay, PVA-silica-clay, PF-fumed silica-clay, ST-co-GMA-fumed silica-clay, and PLA-fumed silica-clay nanocomposites. Due to the research gap, the researcher is responsible for finding the appropriate solution.

1.4 Objectives of the study

The specific objectives of this study are:

1. a) To manufacture the polymer nanocomposites with various fillers loading.
2. b) To evaluate the physical, mechanical, morphological, and thermal properties of polymer nanocomposites.
3. c) To investigate the compatibility of dual fillers with various polymer matrices in the nanocomposites.
4. d) To compare the fabricated polymer nanocomposites with the existing nanocomposite materials.

1.5 Literature review

1.5.1 Clays and clay minerals

Clays are the main constituents of fine-grained rocks that exist in mudstones and shales from marine sediments and soils. Most clays are formed due to the weathering and secondary sedimentary processes (Bilotti, 2009).

Clay minerals are referred to as layered silicates due to their stacked structure of 1 nm silicate sheets with a variable basal distance. They belong to the structural family known as phyllosilicates. The fundamental building units of phyllosilicates consist of tetrahedral silica (Si) and octahedral alumina (Al). The tetrahedral sheets are composed of individual tetrahedrons where every silicon atom is equidistant from four oxygen or hydroxyls to balance the structure. They are arrang...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Preface
• 1: Introduction and reinforcing potential of silica and various clay dispersed nanocomposites
• 2: Preparation and characterizations of silica and various clay dispersed nanocomposites
• 3: Impact of nanoclay on physicomechanical, morphological, optical, BET isotherm, and thermal analysis of polyvinyl alcohol/fumed silica/clay nanocomposites
• 4: Polyvinyl alcohol/silica/clay nanocomposites: effect of clay on surface morphology, electrical and thermo-mechanical properties
• 5: Nanoclay dispersed phenol formaldehyde/fumed silica nanocomposites: effect of diverse clays on physicomechanical and thermal properties
• 6: Study on physical, mechanical, morphological and thermal properties of styrene-co-glycidyl methacrylate/fumed silica/clay nanocomposites
• 7: Physico-mechanical and thermal properties of clay/fumed silica diffuse polylactic acid nanocomposites
• 8: Biomedical and packaging application of silica and various clay dispersed nanocomposites
• 9: Durability and sustainability of the silica and clay and its nanocomposites
• 10: Low-density polyethylene/silica nanocomposites foams: Relationship between chemical composition, particle dispersion, cellular structure and physical, mechanical, dynamic mechanical, electrical, and thermal properties
• 11: The effect of clay dispersion on polypropylene nanocomposites: Physico-mechanical, thermal, morphological, and optical properties
• 12: Improvement of epoxy nanocomposites on physical, morphology, and mechanical properties as well as fracture behavior with the addition of mesoporous silica/nano-silica
• Index