Shape retention

The mechanical properties of acryUc and modacryUc fibers are retained very well under wet conditions. This makes these fibers well suited to the stresses of textile processing. Shape retention and maintenance of original bulk in home laundering cycles are also good. Typical stress—strain curves for acryhc and modacryUc fibers are compared with wool, cotton, and the other synthetic fibers in Figure 2. 

It is generally accepted that, all other things being equal, the lower the secondary creep, the better the fiber is in terms of wear, shape retention, and crease resistance. This does not mean that glass, which has no secondary creep, is better in abrasion resistance than high tenacity viscose rayon, which has secondary creep, because the respective energy absorption capacities of these two materials, exclusive of secondary creep, are not equal. Nor does it mean that fibers that exhibit secondary creep are of no value. For fabrics to meet the requirements of wear, crease resistance, and shape retention, the load and extension yield points should not be exceeded during use. 

Acrylic Acrylonitrile units, 85% or more Warm, lightweight, shape-retentive, resilient, quick-drying, resistant to sunlight Carpeting, sweaters, skirts, baby cloths, socks, slacks, blankets, draperies Orion... 

Modacrylic Acrylonitrile units, 35%-85% Resilient, softenable at low temps., easy to dye, abrasion-resistant, quick drying, shape-retentive, resistant to acids, bases Simulated fur, scatter rugs, stuffed toys, paint rollers, carpets, hairpieces, wigs fleece fabrics Verel, Dynel... 

Figure 1. Shape retention during leaching (A Cu precursor)...

Melt-blown nonwoven fabric TPX are used as separator materials. They are thin, but sufficient in mechanical strength and possess superior shape retention at elevated temperatures. 

Molecules of solute travel as a zone in the chromatographic system. Recording of molecules eluting from the column yields a chromatogram (Fig. 1), whose characteristics are peaks. When peaks are symmetrical (Gaussian shape), retention times are taken at peak height. Since k is dimensionless, one can record retention distances or retention volumes on the chromatogram and... 

The versatility of the crosslinked structures opens a new broad avenue for their application in several areas. As mentioned above, corona-crosslinked PFS assemblies demonstrate excellent shape retention upon pyrolysis and permit the formation of ceramic replicas. We have also recently shown that in a common good solvent, the PFS chains in the microgel interior of xPMVS can serve as a microreactor forthe localized production of metal nanoparticles [25], We are also about to begin light scattering studies of PMVS micelles, before and after corona crosslinking, and hope to use these experiments to learn more about the self-assembled structures formed in dilute solution. 

Shape retention is a factor in almost all articles made from polymeric materials (cf. warping of plastic articles, deformation of films, etc.). In textiles the lack of shape retention is reflected in the sagging of curtains, the bagging of trousers, etc. Shape retention is determined by the viscoelastic properties of the polymer, especially under the influence of moisture plastic deformation and creep are highly undesirable, whereas resilience is favourable. 

Special forms of shape retention are wrinkle recovery and pleat and crease retention. 27.3.3.1. Wrinkle recovery (wrinkle fastness)... 

It may be concluded that shape retention, wrinkle recovery and pleat and crease retention depend on well-known viscoelastic properties the existence of a transition range, stress relaxation, creep and permanent deformation, and a possible resilience by a change in external conditions. 

Loss by wear is dependent on the coefficient of friction, the stiffness, the resilience and the degree of brittleness. In order to assess the resistance to wear it has to be ascertained whether this property is in equilibrium with other properties, e.g. colour fastness and shape retention. If the durability is determined by the resistance to wear, the aesthetic and use properties must remain virtually constant during the life of the product. 

Advantages of silicone water repellents include a high degree of water repel-lency at relatively low (0.5-1 % owf) on weight of fabric concentrations, very soft fabric hand, improved sewability and shape retention, and improved appearance and feel of pile fabrics. Some modified silicone repellents can be exhaust applied (to pressure-sensitive fabrics). 

A number of reviews of interest have appeared of both a specific and general nature. These include photoresponslve polymers with the main emphasis on phase transitions, memory and shape retention 2 , the kinetics of polyelectrolyte formation , molecular modelling for excimer formation , luminescent probes and molecular dynamics . The uses of thermally stimulated emission for monitoring radical decay and chemiluminescence of polymers... 

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