Fibril elongation

Many examples exist of using this protein motif to construct hydrogels from protein or peptide assembly. For example, Dong et al., reported elongated fibrils with diameters as small as 4 nm by incorporation of charged amino acids in the... 

Gelatin is a natural material based on animal proteins. It is derived from collagen, which is elongated fibrils and mostly found in fibrous tissues such as tendon, ligament, and skin. It is commonly used for biomedical applications due to its biodegradability and biocompatibility in physiological environments, in contact with living tissues (Ofokansi et al., 2010). 

Using the unique and superior properties of LCPs to enhance the thermal and mechanical performance of various engineering resins, studies have been conducted since late 1980s (94-104). The LCP phase is preferentially oriented in the direction of flow. LCPs can also be viewed as a processing aid (lubricant), which effectively reduces the viscosity of the blends if the LCP content is low (32,94,96-99). It is foimd that the LCP domains do not always deform into fibrils as reinforced elements for some LCP/thermoplastic blends. One must provide adequate shear stress and torque history to deform LCPs into elongated fibrils. The rule of thumb is to have process conditions which yield the viscosity ratio of the dispersed LCP phase to the thermoplastic matrix to be lower than 1 (99,103). LCPs blends also suffer from poor adhesion strength between the LCP phase and the thermoplastic matrix. Forming cross-linkable LCP blends is one of the ways to overcome it... 

SEM micrograph showing the cross-section of fiber exhibiting the elongated fibrils. The fiber was obtained from spinning a 9% (w/w) cellulose solution at 30°C into methanol coagulant bath kept at -4°C with Dr above 2. Scale bar equals 10 pm. 

FIGURE 12.3 Schematic flow protocol used to create the elongated fibrils. 

To create a blend with a droplet matrix morphology, a prerequisite to form the elongated fibrils during the flow protocol, 1% emulsions of the caseinate-rieh phase in the alginate-rieh phase have been used. The low concentrations of the dispersed phase are ehosen to provide suflBeient transparency necessary to perform the optieal measurements. 

Whereas the dispersed phase is predominantly present as droplets in a continuous matrix when the flow intensity is rather mild, more intense shear or extension results in the formation of elongated fibrils. For Ca-numbers that largely exceed the critical value, the droplet dynamics is completely governed by the hydrodynamic forces [103]. If the viscosity ratio is sufficienfly close to 1, the dispersed domains will follow the principal stretch of the matrix and their shape can be described by means of the affine deformation equations. Elemans et al. found that the ratio CalCa rit should exceed 2 in order to obtain affine deformation for a system withp = 0.1 [104]. For highly extended domains, the aspect ratio LIB is generally used to quantify the droplet deformation rather than the deformation parameter D. In case of affine deformation, the following expression provides the evolution of the aspect ratio LIB in shear flow [103] ... 

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