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-Combination of at least two components, a matrix/ reinforcements.
-This combination creates a material that has properties greater than or equal to the sum of the parts.
Isotropic vs. Anitropic
-Isotropic: Strength is the same in all directions.
-Anitropic: Strength is greatest in a certain direction.
Natural and Synthetic composites
-Synthetic: Plie wood, Carbon Fibers (man made)
Classification of Composites
Fiberous: Reinforced Plastics
Laminar: Composed of layers or piles of matrix
Particulate: Particles dispersed in the matrix
-Binder to the reinforcer
-Transfer loads across the structure
-Protects the reinforcement from outside environment
Major classes of Matrices
Considerations in determining proper matrix
Bond well with reinforcements
Sources of matrix
Starting material that is changed into a new material by means of further processing and use of additives.
Use of Thermoplastic polymers
Ceramic Composites: Very brittle, high temperature resistant material. Can be the matrix only but in many cases is both the matrix and the reinforcer.
Use of Thermoset Polymers
Melamine-Phenolic: Produced by combining a one-stage phenolic with melamine resin, not used for large volume applications and are generally produced in black or dark colors.
Co-polymer vs. Alloy
Co-polymer: The combination of two or more monomers
Alloy: The combination of two or more basic polymers into a mechanical mix
Various Thermoset polymers used in composites
Advantages of Thermoplastics in composites
-Ease of repairability
-Improved impact strength
-No need to refrigerate
-Much quicker processing time
Disadvantages of Thermoplastics in composites
-Overall lower high temperature properties
-Still some problems with fiber adherence
-Higher material cost
-Lack of tacticity/ flexibility in prepreg from
Advantages of Thermosets in composites
-Higher temperature properties
-Lower material cost
-Good fiber adherence
-Better tacticity/ flexibility
Disadvantages of Thermosets in composites
-Lower impact strength
-More difficult to repair
-Have to refrigerate
-Longer processing time
-Hard to recycle
Four methods of impregnating reinforcement to make prepreg