Amorphous regions of polymers

Techniques Employed to Study the Amorphous Regions of Polymers... 

It should be emphasized that oxygen gas dissolves only in the amorphous regions of polymers, and can, therefore, oxidize the material only within the amorphous phase or on the surface. Also the extent of oxidation per unit of radiation dose is very dependent on the dose rate. The lower the dose rate the more time the oxygen has to diffuse into the plastic per unit of dose so that the net amount of oxidation for the same dose is much greater at low rates. 

Thus, amorphous regions of polymer, bounded by crystals, are macroreactors in which chain process of mechanodestruction and failure of material is being developed. Hence, decrease of the amount of polymer amorphous part will lead to strengthening of the fibre and improving its physico-mechanical characteristics. 

The importance of crystallinity in the present context is that it affects the properties of materials. "Whilst the amorphous regions of polymers are permeable to oxygen, water, carbon dioxide etc., the tighter packing of crystalline regions makes them impermeable, so that in a semicrystalline polymer the crystallites are impermeable barriers in the path of diffusing molecules. 

In crystalline polymers, the crystalline region remains unaffected, because plasticizers enter only the amorphous regions of polymers. 

Note that the Tg is a property of the amorphous regions of polymers however, since no polymer is 100% crystalline, the Tg is important for all polymeric materials. 

The Glass Transition The glass transition occnrs in amorphous regions of polymers. 

Effect of Fiber Properties. Acid dyes are attracted to the accessible amine ends of the nylon chains located in the amorphous regions of the fiber. Acid dye affinity of nylon can be adjusted by a dding excess diamine or diacid to the polymer salt or by changing the molecular weight in polymerization. A light acid-dyeable nylon-6,6 is spun with 15—20 amine ends, expressed in terms of gram equivalents per 10 g of polymer. A medium or... 

In these complexes, the cations coordinate with the oxygen atoms of the backbone and, under the influence of an electrical potential, they are transferred from an oxygen atom to another through the amorphous region of the polymer assisted by the segmental motion of the polymer backbone. 

Why does polymer degradation typically occur in the amorphous region of semicrystalline polymers rather than in the crystalline regions ... 

Experiments pertaining to a new system for the application of bromine to flame retardant polypropylene and foamed polystyrene are described. The FR compound, ammonium bromide, is formed in the amorphous regions of the polymer phase by the interaction of bromine sorbed on the polymer and ammonia, sorbed subsequently. Gaseous nitrogen which is also produced, expands and brings about the rearrangement of the chains to produce a porous structure. The ammonium bromide produced is finely divided and imparts FR properties to the polymer. 

Amorphous phase, of polymers, 20 400 Amorphous polymers, 10 203 crystallization of, 19 844 Amorphous red selenium, 22 74 Amorphous regions, in fibers, 11 171 Amorphous resins, use in thermoforming, 19 555... 

---