Nanostructured Polymer Blends

Sabu Thomas, Robert Shanks, Sarath Chandran

• Publisher: William Andrew
• Year: 2013
• Print ISBN: 9781455731596
• eBook ISBN: 9781455731602
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Over 30% of commercial polymers are blends or alloys or one kind or another. Nanostructured blends offer the scientist or plastics engineer a new range of possibilities with characteristics including thermodynamic stablility; the potential to improve material transparency, creep and solvent resistance; the potential to simultaneously increase tensile strength and ductility; superior rheological properties; and relatively low cost. Nanostructured Polymer Blends opens up immense structural possibilities via chemical and mechanical modifications that generate novel properties and functions and high-performance characteristics at a low cost. The emerging applications of these new materials cover a wide range of industry sectors, encompassing the coatings and adhesives industry, electronics, energy (photovoltaics), aerospace and medical devices (where polymer blends provide innovations in biocompatible materials). This book explains the science of nanostructure formation and the nature of interphase formations, demystifies the design of nanostructured blends to achieve specific properties, and introduces the applications for this important new class of nanomaterial. All the key topics related to recent advances in blends are covered: IPNs, phase morphologies, composites and nanocomposites, nanostructure formation, the chemistry and structure of additives, etc. - Introduces the science and technology of nanostructured polymer blends – and the procedures involved in melt blending and chemical blending to produce new materials with specific performance characteristics - Unlocks the potential of nanostructured polymer blends for applications across sectors, including electronics, energy/photovoltaics, aerospace/automotive, and medical devices (biocompatible polymers) - Explains the performance benefits in areas including rheological properties, thermodynamic stablility, material transparency, solvent resistance, etc.

Chapter 1

Polymer Blends

Chandran C. Sarath*†, Robert A. Shanks† and S. Thomas*, *Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, India, ^†Applied Sciences, RMIT University, Melbourne, Australia

Miscibility and compatibility in polymer blends is a topic of great academic and industrial importance. This is because miscibility and compatibility contribute to morphology, properties, and performance. Miscibility results in one phase; compatibility creates a disperse phase with size and stability determined by interfacial interactions. Miscible polymer properties are averaged similar to a plasticizer polymer, and compatible polymers retain properties of each component, such as toughening or reinforcement. With miscible polymer blends the continuous phase dominates properties; the disperse phase contributes via stress transfer. This chapter revisits the criteria for miscibility or compatibility in polymer blends and the contributors of compatibility compared with miscibility and incompatibility. Development of copolymers and their blending with thermosets and thermoplastics result in complex two-phase morphologies. The dynamics of phase separation observed in polymer blends leading to different morphologies and the criteria for phase separation is explained. A nanometer-dispersed phase requires strong interfacial interactions to stabilize the large interfacial area, and this is favored by rapid spinodal phase separation compared with size diminution by high shear. Nanoblends open up a new arena for polymer blends, and research shows that nanoblends have outstanding optical and mechanical properties.

Keywords

Miscibility; Polymer blends; Compatibilizer; Flory–Huggins theory; Cross-linking; Nanoblends

Chapter Outline

• 1.1 Introduction 1
• 1.2 Polymer–Polymer Miscibility Theory 4
  • 1.2.1 Macromolecular Solubility 4
  • 1.2.2 Binodal Phase Separation 6
  • 1.2.3 Spinodal Phase Separation 7
  • 1.2.4 Nanophase Separation 7
  • 1.2.5 Blends of Semicrystalline Polymers 7
• 1.3 Incompatible Polymer Blends 8
• 1.4 Miscible Polymer Blends 8
  • 1.4.1 Interactions and Miscibility 8
  • 1.4.2 Loss of Desirable Properties 9
• 1.5 Cross-Linking of Miscible Polymer Blends 10
  • 1.5.1 Cross-Linking of the Major Phase 10
  • 1.5.2 Cross-Linking of the Minor Phase 10
• 1.6 Compatible Polymer Blends 11
  • 1.6.1 Compatible Polymers 11
  • 1.6.2 Shear-Induced Colloid Formation 11
• 1.7 Nanophase Blends 12
  • 1.7.1 Properties of Nanoblends 12
• 1.8 Conclusion 12
• References 13

1.1 Introduction

The art of mixing different materials was known to mankind from the Bronze Age. Concrete, metal alloys, and fiber composites that are considered to be typical examples were introduced [1]. In the early stages of polymer industry the major polymers used were wood, natural rubber, and gutta-percha along with natural fibers such as cellulose, protein fibers, and leather. The year 1846 witnessed the first polymer blend (natural rubber blended with gutta-percha) which was reported in the patents of Hancock and Parkes [1]. A single rotor masticating machine was used for the blending process. This was followed by the slow development of blending technology. In the first half of the twentieth century great progress in the polymer industry led to the development of a wide range of new polymers. Later the depletion of economic ways to develop new monomers, and the fact that newly developed monomers gave rise to polymers with intermediate properties as compared with the existing polymers, led to the development of polymer blending [2]. The last 80 years show an exponential increase in the number of polymer blend patents and literature; the number almost doubled after 1993 [3]. Thus, polymer blends are a class of materials in which at least two polymers are combined together resulting in a new material with different physical properties [4].

The important advantages of polymer blending can be summarized as:

• • Development of new properties or improvement of existing properties to meet specific needs
• • Material cost reduction with little or no loss of properties
• • Material processability improvement
• • Meeting the needs of emerging industries by surpassing the polymerization step

Polymer blends can broadly be classified into three categories:

1. 1. Miscible polymer blends
2. 2. Compatible polymer blends
3. 3. Immiscible polymer blends

The main differences and the important conditions for miscibility are shown in Table 1.1.

Table 1.1

The Variation of Properties for Polymer Blends in Relation to their Miscibility

Miscible Blends	Partially Miscible Blends	Immiscible Blends
Homogenous	Partial phase separat...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• List of Contributors
• Chapter 1. Polymer Blends
• Chapter 2. Characterization of Nanostructured Materials
• Chapter 3. Theoretical Modeling of Nanostructured Formation in Polymer Blends
• Chapter 4. Compatibilization as a Tool for Nanostructure Formation
• Chapter 5. Nanofilled Thermoplastic–Thermoplastic Polymer Blends
• Chapter 6. Nanostructure Formation in Thermoset/Block Copolymer and Thermoset/Hyperbranched Polymer Blends
• Chapter 7. Nanostructure Formation in Block Copolymers
• Chapter 8. Significances of Nanostructured Hydrogels for Valuable Applications
• Chapter 9. WITHDRAWN: Nanostructured Liquid Crystals
• Chapter 10. Nanostructured Hydrogels
• Chapter 11. Nano/Micro and Hierarchical Structured Surfaces in Polymer Blends
• Chapter 12. Degradation Behavior of Nanocomposite Polymer Blends
• Chapter 13. New Applications of Nanoheterogeneous Systems
• Chapter 14. Blend of Silicon Nanostructures and Conducting Polymers for Solar Cells
• Chapter 15. Conductive Polymer Composites and Blends: Recent Trends
• Index