Preface

Thermal analysis (TA) is a group of techniques which are based on simultaneous measurement of the temperature and a physical property of the sample, and these techniques allow to characterize the thermal properties of materials and the thermal effects occurring during chemical reactions and physical processes. As such, thermal analysis methods find broad use in all fields of materials science, chemical engineering and technology, as well as physical chemistry and soft matter physics. One of the important classes of materials that has received increasing attention in recent years are polymeric materials, including pristine polymers, polymer composites, nanocomposites and biocomposites, organic-inorganic hybrids, blends, and interpenetrating polymer networks. Thermal analysis methods substantially contribute to the better understanding of fundamental issues related to glass transition, crystallization, oxidation, and kinetics of decomposition and curing. Evaluation of the thermal properties of polymeric materials, such as degradation behavior, thermal stability, and phase transitions, is of primary importance for numerous applications that have to meet the strict requirements of, e.g. aviation industry.

This book describes recent developments in the area of thermal analysis of polymeric materials, arranged in four parts, focused on methods, fundamentals, materials, and applications. To start with methods, thermal analysis methods have been described in a historical perspective, and on examples of thermogravimetry, differential scanning calorimetry, and thermomechanical analysis, specific features of TA techniques are discussed, as well as their classification provided. Important issues of instrument calibration and sample preparation, as well as the role of various factors on the course of thermal analysis profiles, are also outlined. In the second chapter, the modulated temperature differential scanning calorimetry (MT-DSC) technique developed in the 1990s has been described. The unique feature of this method is that by applying a periodic modulation with a small amplitude to the temperature scan, one can separate the total heat into two types of heat flow, namely the reversing heat flow (sensitive to periodic temperature modulation) and the nonreversing heat flow (insensitive to periodic temperature modulation). Such separation can provide additional information, e.g. on polymer glass transition, enthalpy relaxations, and melting/recrystallization effects. Chapter 3 is devoted to the fast scanning calorimetry (FSC), in which micromachined sensors are applied that enable ultra-high scanning rates and very high sensitivity. Under these conditions, the kinetics of crystallization and melting processes in rapidly crystallizing materials can be studied, as well as atypical gelation effects, to name a few. The combination of FSC with a structural characterization technique, e.g. WAXD or AFM, allows a deep insight into the various processes (bio)macromolecules undergo. Chapter 4 deals with hyphenated thermal analysis techniques, which link the advantages of thermal analysis methods, such as TG or DSC, with IR spectroscopy features. Such coupled thermoanalytical techniques are useful tools in studying online various thermally induced chemical reactions, such as polymerization and crosslinking.

On the fundamentals, the connection between relaxation phenomena and glass transition in (polymeric) glasses is discussed in Chapter 5. The main a relaxation contribution to the vitrification and physical aging processes, also in a relatively narrow range around the calorimetric Tg, is presented; moreover, secondary mechanism in non-equilibrium dynamics is discussed, too. Chapter 6 is devoted to polymer crystallization, including crystal nucleation (also studied by the FSC technique), growth, crystallization in polymer blends, and crystallization in industrial processing by, e.g. extrusion and injection molding. Within this technologically important topic, discussion on flow-induced crystallization has been provided. In Chapter 7, principles and models associated with the polymer curing kinetics are presented. By using isoconversional and model-fitting approaches to perform kinetic analysis, it is possible to determine kinetic parameters in the mixed kinetic-diffusion regime and get an in-depth look into the complex process of cross-linking polymerization. The heat capacity of polymeric materials is one of the most important quantities that characterize the thermodynamic properties in advanced thermal analysis, and it has been thoroughly discussed in Chapter 8. Calorimetric techniques, such as DSC, MT-DSC, and FSC, and advanced thermal analysis make it possible to separate reversible and irreversible processes in the entire temperature range for the determination of thermodynamic and apparent heat capacities of polymeric systems. The thermo(oxidative) stability of polymeric materials, understood as the ability of a material to preserve its properties, especially mechanical properties, at elevated temperature and in an oxidative environment, is the subject of Chapter 9. The main concepts of the thermo(oxidative) behavior of polymers, good experimental practice, current testing procedures involving the use of hyphenated techniques and protocols for the determination of the oxidation induction time and thermo(oxidative) characteristics of different polymeric materials, including pristine polymers, blends, and composites, have been critically presented.

In the field of materials, the application of thermal analysis methods, particularly DSC and MT-DSC, for the investigation of the properties of liquid crystalline polymers, has been presented in Chapter 10. DSC is a useful tool to determine, e.g. the liquid crystalline transitions of mesogenic diepoxides-containing compositions and curing conditions of liquid crystalline polymer networks, modified by various fillers, crosslinked in magnetic field. In Chapter 11, thermal analysis of polymer nanocomposites and hybrid materials has been described. The influence of nanofillers and inorganic components on thermal degradation behavior, glass transition region, and thermomechanical properties has been discussed, along with the presentation of current challenges and future research directions. Chapter 12 titled "Biocomposites and Biomaterials" focuses on the application of thermal analysis techniques, such as TG, DSC, and DMA, to study the properties of biomaterials, including thermal stability, purity, and phase transitions. Useful information on the curing parameters of bone cements that contain phase-change materials, as well as on the determination of the water content in hydrogel biomaterials, is also given. Thermal analysis methods for the characterization of polymer additives are presented in Chapter 13, which contains a wealth of valuable information on the application of TA methods for the characterization of additives that are widely used in the fabrication and processing of polymeric materials. Thermal stability and decomposition behavior of flame retardants, (nano)fillers, pigments, stabilizers, antioxidants, processing aids, etc. need to be checked before they are admixed to the polymer matrices, and thermal analysis techniques are indispensable tools in that respect.

In the Application part, thermal analysis in polymers recycling has been discussed in Chapter 14. Circular economy strategy and protection of the environment require proper characterization, identification, and quality control of the recycled polymers, as well as development of more efficient mechanical and chemical recycling routes of polymer wastes; in both these areas, TA and coupled thermoanalytical methods are vastly used. Chapter 15 deals with application of thermal analysis methods for life-time predictions; such predictions are of primary importance to foresee the durability of polymers employed in structural applications and to plan the environmentally safe disposal of polymer wastes after their lifetime. In Chapter 16 application of thermal analysis methods - (modulated temperature) differential scanning calorimetry, thermogravimetry alone or coupled with spectroscopic techniques for evolved gas analysis, as well as dynamic mechanical analysis, for the characterization of organic and polymeric materials used in electrolytes and batteries, photovoltaic and solar cells, and as phase-change materials for thermal energy storage, has been discussed. Thermal analysis of pharmaceutical glasses stabilized by polymers is presented in Chapter 17, which outlines the role of thermal analysis techniques in studying drug-polymer interactions that govern the dissolution behavior and storage stability. The influence of the thermal history on the product performance and the stabilization effect of the amorphous drugs by the polymers are discussed, too. In Chapter 18 titled "Thermal Analysis in Aerospace and Automotive Sectors" coupled techniques, such as TGA-MS, TGA-FTIR, and TGA-GC/MS, are shown to be versatile thermoanalytical tools that produce quantitative and qualitative information on volatile products released during thermal decomposition of advanced polymeric materials used in aerospace and automotive sectors. Finally, in Chapter 19, the application of thermal analysis methods for the characterization of textiles and fibers has been described. Textiles used, for example, in firefighting, aerospace and metallurgy/mining industries need to meet strict thermal stability requirements; polymer products can be...