Multicomponent semicrystalline polymers

The interest in multicomponent materials, in the past, has led to many attempts to relate their mechanical behaviour to that of the constituent phases (Hull, 1981). Several theoretical developments have concentrated on the study of the elastic moduli of two-component systems (Arridge, 1975 Peterlin, 1973). Specifically, the application of composite theories to relationships between elastic modulus and microstructure applies for semicrystalline polymers exhibiting distinct crystalline and amorphous phases (Andrews, 1974). Furthermore, as discussed in Chapter 4, the elastic modulus has been shown to be correlated to microhardness for lamellar PE. In addition, H has been shown to be a property that describes a semicrystalline polymer as a composite material consisting of stiff (crystals) and soft, compliant elements. Application of this concept to lamellar PE involves, however, certain difficulties. This material has a microstructure that requires specific methods of analysis involving the calculation of the volume fraction of crystallized material, crystal shape and dimensions, etc. (Balta Calleja et al, 1981). 

Three main types of multicomponent polymer systems will be discussed (1) combinations of two or more semicrystalline polymers, (2) impact modified thermoplastics and (3) impact modified thermosets. The microstructure of semi-crystalline multicomponent polymers can often be determined by polarized light microscopy of thin... 

The first group are the semicrystalline homopolymers, while a second group would include a diverse collection of block polymers, blends, and segmented elastomers. The latter systems were emphasized at a symposium on "Multicomponent Polymer Systems organized as part of the 175th National Meeting of the American Chemical Society in Anaheim, March 13-17, 1978. 

The microstructure of semicrystalline multicomponent polymers can often be determined by... 

Applications and examples of microscopy imaging and analysis to multicomponent polymers follow. The microstructure of semicrystalline multicomponent polymers can often be determined by polarized light microscopy of thin sections. A blend of two polyacetals, a homopolymer and a copolymer, is shown in the micrograph of a thin section (Fig. 5.68). The structure is rather interesting... 

The first example is using light mieroscopy to provide an overview of the crystalline structure and even the blend morphology. Semicrystalline multicomponent polymers can appear very confusing in polarized light as the spherulitic texture and the dispersed phase textures are superimposed and may not be distinguishable. Comparison of polarized light (Fig. 5.77A) and phase contrast (Fig. 

---