Matrix fibril

Composite fibers have been produced for a number of years to create structures with enhanced properties or combinations of properties. Different configurations of the materials selected for composite fibers are matrix-fibril, side-by-side, and skin-core. In the latter configuration, the core component can be made to dominate the mechanical properties of the fiber, while the skin controls surface properties. This permits decoupling of the two types of properties and closer control of the overall characteristics of the final product. 

Kadler, K. (1994). Extracellular matrix fibril forming collagen. Protein Profile 1, 519-638. 

Yuan, X., Downing, A. K., Knott, V., and Handford, P. A. (1997). Solution structure of the transforming growth factor beta-binding protein-like module, a domain associated with matrix fibrils. EMBO J. 16, 6659-6666. 

Bicomponent fibres are sjmthetic fibres composed of two firmly but separately combined polymers of different chemical and physical structures. The structure of the bieomponent depends on the shape of the spinnerette orifice (side-by-side, sheath eore, matrix - fibril and multi-fibrillary) and the type of spinning method. Due to the structural differences, the two components shrink differently on heat treatment and form crimp and greater bulk in the fibre. The first fully synthetic bicomponent was an acrylic (Sayelle, Orion 21). The use of sheath-core fibres composed of nylon 6,6 and nylon 6 (Heterofil, ICI) for floor coverings is described. 

Behmlander, R.M. and Dworkin, M. (1994). Biochemical and structural analyses of the extracellular matrix fibrils ofMyxococcus xantkus. J. Bacterial. 176,6295-6303. 

In bicomponent spinning, two strongly bonded (but separable) polymers of different chemical and/or physical structure are processed into single filaments by means of special spinnerets, e.g. side-by-side type (S/S), core-cover type (C/C) or matrix/fibril type (M/F) (see Fig. 2.2). Bicomponent spinning offers the best opportunities for the production and development of micro- and nanofibres by the use of matrix/fibril... 

Blends of two fiber-forming polymers can be used to spin several types of two-component fibers (Allied Chemical Corp., n.d. Buckley and Phillips, 1969 Cresentini, 1971 Fukuma, 1971 Hayes, 1969 Mumford and Nevin, 1967 Papero et ai, 1967 Pollack, 1971). As shown in Figure 9.3, the two components may be arranged as mated half-cylinders, in a skin-core configuration, or in a matrix-fibril configuration. The first two configurations are referred to as bicomponent, the last as biconstituent fibers. 

Figure 9.3. Classification of bicomponent and biconstituent fibers. (Allied Chemical Corp., advertising literature) (A) Bicomponent system (B) skin-core system (C) matrix-fibril system.

Figure 38-5. Diagram of the cross section and length section of bicomponent fibers. S/S, side by side C/C, core/cover M/F, matrix/fibril.

Fig. 7. Electron micrograph of a single nucleolar gene isolated from Triturus viridescetis. RNA polymerase molecules are seen on the DNA axis at the base of each matrix fibril. (By courtesy of Dr. O. L. Miller, Jr., reprinted from /. Cell Physiol. Suppl. i 74, 225 (1969).]...

It is generally accepted [16] that the mechanical properties of the MFC, with optimized composition made under best processing conditions, are superior to those of the corresponding neat matrix material due to the high aspect ratio (AR) of the crystalline and oriented microfibrillar reinforcement, and in view of the various possibilities to strengthen the matrix-fibril interface by compatibilization or transcrystallization. All of the systematic mechanical studies on MFC were made with systems based on polyolefin matrices reinforced by PET microfibrils and no such studies are available for PE/PA MFC systems. 

Antia, M., Baneyx, G., Kubow, K.E., Vogel, V., 2008. Fibronectin in aging extracellular matrix fibrils is progressively unfolded by cells and ehcits an enhanced rigidity response. Faraday Discuss 139 (229—249), 419—420 discussion 309—325. 

If the phase morphology is fine disperse, the particle distances are reduced and the stress state is changed to a one-dimensional stresses. If the dispersed phase has no intensive interactions with the matrix, than the PP matrix fibrillates between the drops. This mechanism leads to higher specimen deformability, thus higher maximum extension at break. 

Matrix fibril (M/F) polyblend type where many fine fibrils of one polymer are dispersed randomly in size and location but with axial ahgnment in a matrix of another component. 

Several reinforcement techniques have been introduced for the fabrication of composite fibres, such as (i) the introduction of thermotropic liquid crystalline polymers (TLCP) to produce a matrix-fibril stmcture, (ii) use of multiphase polymer blends and hard/soft segmented thermoplastics, and (iii) bicomponent extrusion, where different polymers are brought in contact as separate streams just before the spinnerette to produce a sheath-core structure (Salem, 2000). However, the inapplicability of these techniques to high-commodity commercial polymers and other serious drawbacks has limited the appeal. For instance, fabrication of TLCP is very expensive and postprocessing may destroy its unique matrix-fibril structure. Incomplete microphase separation in some polymer blends often leads to a less desirable morphology in multiphase fibres and bicomponent spirming is sensitive to differences in viscosity between the polymers. 

Polymers used for the manufacture of commodity fibres are also used in the production of multiconstituent fibres, sometimes in conjunction with a modified commodity polymer or a specialty polymer. These fibres consist of two or more polymers forming separate phases. There are essentially two types of such fibres. In the first type, each polymer occupies a discrete region of the fibre cross-section e.g. sheath/core-type fibres, where the sheath is a lower melting homopolymer or copolymer such fibres are used for thermal bonding). In the second type, the components are dispersed in a random way throughout the fibre, typically forming a matrix/fibril arrangement e.g. incorporation of dyeable polymer fibrils into polypropylene which forms the matrix). Detailed description of these fibres can be found elsewhere. 

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