Blends highly drawn

According to the theory of continuous fiber composites [40], not only 3 but also the Poisson s ratio are expected to obey the rule of mixtures. This is verified in Figure 14.24, confirming that highly drawn blends of PC and Vectra B behave like continuous fiber... 

One exception to the above mentioned trend in physical properties of immiscible blends is in the utilization of liquid crystal polymers as a reinforcement for a more flexible thermoplastic polymer. The fact that LCP s can act as reinforcing agents in a blend has led some workers to model the mechanical behavior of the blends using theories of composites. Thus, Dutta et al. (1990) showed that the moduli values of highly drawn melts that contain liquid crystal polymers can be treated effectively by a simple rule of mixtures. That is, the modulus of a blend is given by... 

Figuie 1 (a) Effect of elongational drawing on the elastic modulus ( ) of extruded PP/LCP blends, (b) Morphology of highly drawn PP/LCP 80/20 blend (LCP = Vectra A950, Hoechst Celanese) [4]. 

Figure 11.5. SEM micrographs of drawn PP/PET (70/30 wt%) blend after etching of the PP matrix of samples taken at various stages of the cold drawing (a) at the beginning of drawing, (b) at lower draw ratios, (c) at higher draw ratios, and (d) at highest draw ratios, (insertion) -nanoflbrils of PET obtained from highly drawn PP/PET blend (fibers of 30 i,m diameter) after removing of PP...

It is important to note that the materials displayed in Figures 11.10(a), (d) and (e) consist of highly drawn blends, but they by no means represent composite material because... 

It is important to note here that the materials displayed in Figures 5.8a, d and e consist of highly drawn blends but by no means do they represent a composite material. The isotropic state (matrix) is obtained only after thermal treatment at temperatures between the two melting t peratmes of two blend constituents (in the present case PP and PET with = 170 and 250 C, respectively). As a result of such treatment, the lower-melting component (PP) is converted into an isotropic matrix reinforced with PET fibrils. Such a composite structure is demonstrated in Figures 5.8b, c and f at diffeient magnifications. 

For the isolation of the neat nanofibrils one can use the two rather different materials—the highly drawn polymer blend or the sheet (film) after compression molding. Either of these two materials has to be subjected to extraction of the major component using selective solvent. The rest represents parallel aligned neat nano-or microfibrils. 

Fig. 12.5 SEM micrographs of the various stages of pieparation of nanofibrillar SPCs a ciyo actured surface made parallel to the draw direction of nanofibrillar polymer-polymer composite based on LLDPE/PVDF highly drawn blend subjected to compression molding, b neat PVDF nanofibrils after extraction with selective solvent of IXDPE from the IXDPEfPVDF polymer-polymer composite (a), c cryofractured cross section of nanofibrillar single polymer composite prepared via compression molding of the parallel aligned neat PVDF nanofibrils (b), d surface of the nanofibrillar SPC shown in (c) demonstrating the adherence of PVDF nanofibrils due to surface premelting only...

Types of internal enamel for food containers include oleoresins, vinyl, acryflc, phenoHc, and epoxy—phenoHc. Historically can lacquers were based on oleoresinous products. PhenoHc resins have limited flexibiHty and high bake requirements, but are used on three-piece cans where flexibiHty is not required. Vinyl coatings are based on copolymers of vinyl chloride and vinyl acetate dissolved in ketonic solvents. These can be blended with alkyd, epoxy, and phenoHc resins to enhance performance. FlexibiHty allows them to be used for caps and closures as weU as drawn cans. Their principal disadvantage is high sensitivity to heat and retorting processes this restricts their appHcation to cans which are hot filled, and to beer and beverage products. 

The company claims easy processing results from the high compatibility of the blend components. The formulation consists of more than 10% PLA (purchased from NatureWorks LLC) plus a biodegradable co-polyester and special additives. FKuR says a special combination of compatibilisers permits coupling between the PLA and the co-polyester. The compound is homogeneous, which allows the film to be drawn down to 8 microns. Film up to 110 microns thick is 90% degraded after twelve weeks in composting conditions. 

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