Introduction To Polymer Matrix Composites
1Introduction to polymer matrix composites1.1 IntroductionMaterials are the basis for improving human production and living standards. Theyprovide milestones in human progress. Humans have been accessing and using materials for several thousand years. Looking over the history of human civilization,we will find that its development is about human access and use of materials usingsocial productive forces, science and technology. It reflects human ability to understand and transform nature. Whenever there is a new epoch-making material,productivity will also receive a huge development and human society will leapforward. Therefore, materials have become a symbol of the progress of humancivilization, and have become milestones for dividing eras of human history. Fromthe material point of view, human society has experienced the Stone Age, BronzeAge, and Iron Age. High-performance plastics and composites, which appearedin the 20th century, have infiltrated to the national economy and people’s lives invarious fields with a rare rate of development in the history. They have become thesubstitutes for traditional materials, showing improved performance. Now, withthe rapid development of science and technology, materials play an important rolein the national economy and defense. New materials are the basis of new technologies, and materials science, energy technology and information science havebecome the three pillars of modern science and technology.Materials science is the integrated discipline. It is closely related to a wide rangeof other disciplines. It explains the laws of materials’ macroscopic properties fromthe chemical composition and the principle of internal structure, and then develops a set of principles in designing, manufacturing and using new materials withfrom the chemicalspecific properties. It mainly includes three parts contents:point of view , the relationship of the chemical composition of materials and eachcomponent is researched, and the relationship between the composition and performance is researched, and the preparation methods of materials are researched;from the physical point of view, the performance of material is studied, and therelationship between the internal structure of materials (the combination of atomsand molecules, the arrangement distribution in space and the state of aggregation)
21 Introduction to polymer matrix compositesand performance is studied;under the guidance of chemical and physical theory, the technical problems which related to the preparation and application ofmaterials are researched.There are many different types of materials. Basically, they can be divided intothree types of materials with vastly different performance by the way the atomsmetallic maor molecules are bonded together (the main combination bonds):organic polymer materiterials, metal elements are combined by metal bonds;als, non-metallic elements are bonded covalently to macromolecular compounds;ceramic materials, non-metallic elements and metal elements are combined bycovalent bonds, ionic bonds, or a mixture of the two bonds. From the servicestructural materials;performance point, there are two main types of materials:functional materials. For structural material, its mechanical properties, such asstrength, stiffness, deformation and so on, are majorly considerd, while for functional material, its sound, light, electricity, heat and magnetic properties are mainlyused. In this case, we should know the behavior of materials in sound, light, electricity, heat and magnetic field.As the rapid development of modern science and technology, there are moreharsh special requirements for materials. The research of material is graduallybreaking away from the track of researching by experiences and fumbling methods. It develops in the direction of material designing according to the designedproperties. The composite material which is made of metallic, non-metallic andpolymeric material by certain processes, can retain the advantages of the originalcomponents, overcomes some shortcomings and show some new properties. Theemergence and development of such composite materials is a classic example ofmaterial designing.Composite material is a multi-phase system consisted of matrix material andreinforcing material. Matrix material is a continuous phase, and it includes metalmatrix composite materials, inorganic non-metallic matrix composite materialsand polymer matrix composites by the different matrix materials. Reinforcingmaterial is a dispersed phase, usually fibrous materials such as glass fiber, organicfiber and so on. We only discuss polymer matrix composites in this book.Polymer matrix composite material is the one that uses organic polymer as matrix and fiber as reinforcement. Strength and modulus of fiber are much higherthan the matrix material normally. This makes fibers the main load-bearing component. However, there must be a matrix material with good adhesion propertiesto firmly bond fibers together. At the same time, the matrix material can serveto uniformly distribute the applied load, and transfer the loads to fiber. In addition, some properties of composite materials mainly depend on the characteristicsof the matrix material. As a result, in composite materials, the performance offiber, matrix and the interface between them directly impact on the performance ofcomposite materials.
1.2The definition of composite materials31.2 The definition of composite materialsThe term of composite materials was firstly used in abroad in the 1950s, and ithas been used domestically from about the 1960s. Composite material is a kind ofcomplex multi-component multi-phase system, and it is difficult to be defined accurately. A concise definition is shown: composite material is a multi-phase combination material of two or more component materials with different properties anddifferent forms through compounding processes, it not only maintains the maincharacteristics of the original component, but also shows new character which arenot possessed by any of the original components. Composite materials shouldmicroscopically it is non-homogeneous mahave the following characteristics:there are big differences in the performanceterial and has a distinct interface;the formed composite materials should have a greatof component materials;the volume fraction of component materials areimprovement in performance;larger than 10%. According to this definition, composite materials in a wide rangeof areas, straw mud wall, steel bar reinforced concrete, and tire cord, etc. all belongto the scope of composite materials.From analysis of the composition and the internal structure of composite materials we found that it includes three basic physical phases. One is called matrixphase which is continuous, another is called reinforcement which is scattered andsurrounded by the matrix. The other is called composites’ interface which is aninterface between reinforcement phase and matrix phase. For further study onmicro-structure level, we found that, owing to the complex physical and chemicalreasons in compounding process, the reinforcement phase and the matrix phasenear the interface become a complex structure which is different from both of thematrix phase and the reinforcement phase of their own. And at the same time,we found that the structure and morphology have an impact on macroscopic performance of composites, so the microscopic area near the interface changes instructure and properties. Thus it becomes the third phase of composites, whichis called interphase. Therefore, composite material is composed of matrix phase,reinforcement phase and interphase. The structure and the nature of these threephases, their configuration and interaction, as well as the relative content determine the performance of composite materials.“Material Dictionary” edited by Changxu Shi gave a more comprehensive andintegrity definition on composite material: “Composite materials are new materials that are combinations of different types of materials, such as organic polymers,inorganic non-metal or metal and so on, through compound technology. It not onlyretains the key feature of the original component materials, but also gets the performances that are not depicted by the original components through the combinedeffects. Materials designing can make the performance of each component to mutual supplement and interrelate to each other, thus produce a new superiority of
41 Introduction to polymer matrix compositesperformance, which has essential differences from general materials mixed simply.” The definition stresses the important feature of composite materials that theyare designable. In industry, composite materials are usually referred to the materials with excellent integrated performance which is made of reinforcement withhigh-strength, high modulus and brittleness, and matrix material with low modulus and toughness by a certain processing process. Composite materials discussedin modern materials science are generally referred to as fiber, sheet, and particle reinforced, or self-reinforced polymer matrix, ceramic matrix or metal matrixcomposites. This definition grasps the essence of the composite materials, namelythe enhancing concept by enhancer. The fiber is the most widely used and the mosteffective reinforcement, so the composite material that people often talk about is anarrow meaning of composite materials, i.e. fiber-reinforced composite materials,which are discussed in this book.1.3 Naming and classification of composite materials1.3.1Naming of composite materialsThe development of many new materials is before their scientific name, so traditionally we often firstly use a number of popular names. For example, domesticcomposite material with glass fiber and resin began to appear in the 1950s, whichis called the “glass steel”, and its other names are: glass fiber reinforced plastics(GFRP), glass plastics, glass cloth laminates, and glass fiber composite materials.For the same kind of materials, if they have many names and some names areeven inaccurate or misleading, it is easy to cause confusion. This is certainly notdesirable to the application and development of materials.Composite materials can be named by reinforcement and the matrix material.According to the type of matrix materials, there are metal matrix composite material, aluminum matrix composites, polymer matrix composite material, and epoxyresin matrix composite material. Polymer matrix composites are often named bythe type of their reinforced fiber, such as glass fiber composite material (commonly known as glass fiber reinforced plastics), carbon fiber composites, and hybrid fiber composites. More specifically, the name of the reinforcement is putthe front of the name of the matrix material, along with “composite material” onthe back. For example, composite material with E-GF and epoxy resin can benamed “E-glass fiber epoxy composite material”. For convenient writing, it canalso be written as abbreviation of the reinforcement and matrix materials, witha “/” separating them, along with “composite material” on the back, and so theformer “E-glass fiber epoxy composite material” is briefly called “E-GF/epoxycomposite material” (traditionally called epoxy GFRP). Composite material ofcarbon fiber and metal matrix is called “metal matrix composites”, and can alsobe written as “carbon/metal composite material”. Carbon fiber reinforced carbon
1.4Molding methods of composite materials5matrix composite material is called “carbon/carbon composite” or “C/C composite material”. The above-mentioned nomenclature can also be addressed usingcommodities trademark directly, for example, T300/648, M40/5208, S-GF/5245C,Kevlar49/QY8911, HT3/5405 and so on.1.3.2Classification of composite materialsThere are many ways to classify composite materials. For example, in accordancewith the reinforcing principle, there are diffusion-enhanced composite materials,particle-enhanced composite materials and fiber-reinforced composite materials.Based on different application requirement, there are structural and functionalcomposite materials. Functional composite materials, in accordance with its function, can also be divided into electrical functional composite materials, thermalfunctional composite materials, optical functional composite materials, and so on.According to different preparation processes, it is classified as laminated composite materials, winding structural composites, pultrusion composite materials,textile structural composite materials and so on.According to the meaning of composite materials and its naming principles inthis book, the classification of composite materials is shown in follows.Metal(1) Classification in accordance with the type of matrix material.inorganic non-metallic matrix composite mamatrix composites (MMC’s);polymer matrix composites (PMC’s). The most important inorganicterials;non-metallic matrix composite materials are ceramic matrix composites (CMC’s)and carbon-based composite materials such as C/C composite materials. In thepolymer matrix composite materials, there are thermosetting resin-based composite materials and thermoplastic resin-based composite materials, as well as onecomponent polymer matrix composite materials and polymer blends matrix composite materials.Con(2) Classification in accordance with the form of dispersed phase.fibrous fabric, braid reinforcedtinuous fiber-reinforced composite materials;sheet reinforced composite materials;short fiber orcomposite materials;whisker reinforced composite materials; particle reinforced composite materials;nanometer particle reinforced composite materials.Car(3) Classification in accordance with the type of reinforcing fibers.glass fiber composite materials;organic fiberbon fiber composite material;boron fiber or silicon carbide fiber composite materials;composite materials;hybrid fiber composite materials.1.4 Molding methods of composite materialsThere are many processing methods of composite materials, and big differences indifferent types of molding processes of composite materials. The molding process
61 Introduction to polymer matrix compositesabout hand lay-up fiber reinforced plastics (FRP) (Fig. 1.1) is a typical process ofpreparing thermosetting polymer matrix composites. We see that there are manymanual labours in process. Compounding of fibers and resins and curing reactionprocess of resin system are the forming processes of composite materials and at thesame time, the formation processes of composite material products. Preparation ofmaterials and products completes in the same process, which is another characterthat the composite materials are different from metallic materials.Mold preparationCoating releaseagentResin glue preparationCutting glass clothHand lay-up pre-moldingCuringDemouldingFinishingProductsFig. 1.1 Technique flow chart of FRP by hand lay-up.1.5 Characteristics of composite materialsFrom the classification of composite materials, we already know that there’s a widerange of composite materials. It is a truism that different types of composite materials have different performance characteristics. However, composite materialsalso have some common characteristics. Polymer matrix composites, because oftheir inherent characteristics, have become the fastest growing and most widelyused composite materials. Compared with traditional materials such as metals,polymer matrix composites have the following characteristics.1.5.1High specific strength, high specific modulusThe prominent advantages of polymer matrix composite materials are their highspecific strength and high specific modulus. The specific strength is the ratio ofstrength and density and the specific modulus is the ratio of modulus and density, and the dimensions or units are both length. Under the premise of equalweight, they are indices of measuring bearing capacity and stiffness properties ofthe material. Such properties are very important for aerospace structural materialsto work in the air or the space. Table 1.1 lists the specific strength and specificmodulus of several common structural materials, in which carbon fiber resin matrix composites shows higher specific modulus and specific strength. The highspecific strength and high specific modulus of composite materials result fromhigh-performance and low-density of reinforcing fibers. As a result of relativelylow modulus, high density of glass fiber, the specific modulus of the glass fiberresin matrix composites is slightly lower than metallic materials.
1.5Characteristics of composite materials7Table 1.1 Specific strength and specific modulus of some common used materials andfiber compositesDensity(g/cm3 )MaterialsSteelAluminum alloyTitanium alloyGlass fiber composite materialsCarbon fiber II/epoxy composite materialsCarbon fiber I/epoxy composite materialsOrganic fiber/epoxy compositesBoron fiber/epoxy compositesBoron fiber/aluminum matrix lasticmodulus(102 106 cm)1.31.72.15.310.36.71.06.63.8Specificmodulus(108 cm)2.72.62.52.09.7155.7107.5Good fatigue resistance and high damage toleranceThe fatigue failure of metallic materials is often of no obvious omen to the salienceof damage. The interface between fiber and matrix in composite materials can prevent the propagation of crack. The fatigue failure always initiates from the weaklinks of fiber. Crack growth or damage continues gradually for a long time, sothere is a significant harbinger before the final destruction. As we see from theS-N curve of fatigue properties, the fatigue strength of the majority of metallicmaterials is 30% to 50% of tensile strength, while the fatigue strength of carbonfiber/polyester composite material is 70% to 80% of its tensile strength, the proportion of glass fiber composite materials is between them.Unlike traditional materials, damage of composite material is not due to theunstable propagation of the main crack and then suddenly happening, but it experiences the development of a series of damages such as matrix cracking, interfacialdebonding, fiber pull-out and fiber split or break. A large number of independentfibers in matrix are typical mechanical statically indeterminate system. When asmall number of fibers fracture, the part of the load they bore will be transferredvia the matrix and quickly diffuse to other fibers. Composite materials will notlose the bearing capacity in short term. Composite material will not fracture withsome defects and cracks in it for a sudden development.1.5.3Good damping characteristicsThe natural frequency of vibration of forced structure relates to the shape of thestructure itself, as well it is proportional to the square root of the specific modulus of structural materials. Therefore, composite materials have a high naturalfrequency, and it’s not easy to have a resonance in general. At the same time, theinterface between the fiber and matrix in composite materials has a great ability
81 Introduction to polymer matrix compositesto absorb vibrational energy, resulting in a high vibration damping of materials.Once the vibration occurs, it can be stopped in a short time.1.5.4Multi-functional performance(1) High instantaneous temperature resistance and good ablation resistance.Thermal conductivity of FRP (fiberglass reinforced plastics) is only 1% of metalmaterials. It can also be made into the materials with high specific heat, highmelting heat and high vaporization heat. Thus, FRP can be used as the ablationresistant protective material for missile nose cone.(2) Superior electric insulation performance and high frequency dielectric properties. FRP is a superior insulating material in power frequency. Besides insulationproperty, FRP has good high-frequency dielectric properties as well. It can thus beused
6 1 Introduction to polymer matrix composites about hand lay-upfiber reinforced plastics (FRP) (Fig. 1.1) is a typical process of preparing thermosetting polymer matrix composites. We see that there are many manual labours in p
as reinforcements for polymer composites. This replacement could be again synthetic, petroleum-based polymer but prepared as fibers, micro- or nanofibrils. Of course, this approach is not as advantageous as using natural fibers that are biodegradable and eco-friendly. At the same time, the synthetic polymer-polymer composites seem to be much
5 NATURAL FIbRE-SYNThETIC poLYMER CoMpoSITES 28 5.1 Wood Plastic Composites 29 5.2 Natural Fibre Injection Moulding Compounds 30 5.3 Non-Woven Natural Fibre Mat Composites 32 5.4 Aligned Natural Fibre-Reinforced Composites 33 6 FULLY bIo-bASEd CoMpoSITES 34 6.1 Natural Fibre-Bio-based Polymer .
CONTENTS CONTENTS Notation and Nomenclature A Matrix A ij Matrix indexed for some purpose A i Matrix indexed for some purpose Aij Matrix indexed for some purpose An Matrix indexed for some purpose or The n.th power of a square matrix A 1 The inverse matrix of the matrix A A The pseudo inverse matrix of the matrix A (see Sec. 3.6) A1 2 The square root of a matrix (if unique), not elementwise
A Matrix A ij Matrix indexed for some purpose A i Matrix indexed for some purpose Aij Matrix indexed for some purpose An Matrix indexed for some purpose or The n.th power of a square matrix A 1 The inverse matrix of the matrix A A The pseudo inverse matrix of the matrix A (see Sec. 3.6) A1/2 The square root of a matrix (if unique), not .
CONTENTS CONTENTS Notation and Nomenclature A Matrix Aij Matrix indexed for some purpose Ai Matrix indexed for some purpose Aij Matrix indexed for some purpose An Matrix indexed for some purpose or The n.th power of a square matrix A 1 The inverse matrix of the matrix A A The pseudo inverse matrix of the matrix A (see Sec. 3.6) A1/2 The square root of a matrix (if unique), not elementwise
Important types of modified polymer systems include polymer composites, poly-mer–polymer blends, and polymeric foams. 1.3.1 Types and Components of Polymer Composites Polymer composites are mixtures of polymers with inorganic or organic additives having certain geometries (fibers, flakes, spheres, particulates). Thus, they consist of
Metal Matrix Nanocomposites (MMNC) Polymer Matrix Nanocomposites (PMNC) Metal matrix composites (MMCs) reinforced with nano-particles, also called Metal Matrix nano-Composites (MMnCs), and are being investigated worldwide in recent years, owing to their promising properties suitable for a large number of functional and structural applications. .
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