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Semicrystallinity

The kind of single crystals discussed above are all made starting from solution. In industrial practice, bulk polymeric products are generally made from the melt, and [Pg.317]

Typically, a semicrystalline polymer has an amorphous component which is in the elastomeric (rubbery) temperature range - see Section 8.5.1 - and thus behaves elastically, and a crystalline component which deforms plastically when stressed. Typically, again, the crystalline component strain-hardens intensely this is how some polymer fibres (Section 8.4.5) acquire their extreme strength on drawing. [Pg.319]

The plastic deformation of such polymers is a major research area and has a triennial series of conferences entirely devoted to it. The process seems to be drastically different from that familiar from metals. A review some years ago (Young 1988) surveyed the available information about polyethylene the yield stress is linearly related to the fraction of crystallinity, and it increases sharply as the thickness [Pg.319]

The mechanical behavior of polymers, as well as many other topics in polymer engineering, are presented in an up-to-date way in a book by McCrum et al. (1998). [Pg.321]

Leaving aside rayon and artificial silks generally, the first really effective polymeric textile fibre was nylon, discovered by the chemist Wallace Hume Carothers (1896-1937) in the Du Pont research laboratories in America in 1935, and first put into production in 1940, just in time to make parachutes for the wartime forces. This was the first of several major commodity polymer fibres and, together with high-density polyethylene introduced about the same time and Terylene , polyethylene tereph-thalate, introduced in 1941 (the American version is Dacron), transformed the place of polymers in the materials pantheon. [Pg.321]


An essential component of cell membranes are the lipids, lecithins, or phosphatidylcholines (PC). The typical ir-a behavior shown in Fig. XV-6 is similar to that for the simple fatty-acid monolayers (see Fig. IV-16) and has been modeled theoretically [36]. Branched hydrocarbons tails tend to expand the mono-layer [38], but generally the phase behavior is described by a fluid-gel transition at the plateau [39] and a semicrystalline phase at low a. As illustrated in Fig. XV-7, the areas of the dense phase may initially be highly branched, but they anneal to a circular shape on recompression [40]. The theoretical evaluation of these shape transitions is discussed in Section IV-4F. [Pg.544]

Lamellar morphology variables in semicrystalline polymers can be estimated from the correlation and interface distribution fiinctions using a two-phase model. The analysis of a correlation function by the two-phase model has been demonstrated in detail before [30,11] The thicknesses of the two constituent phases (crystal and amorphous) can be extracted by several approaches described by Strobl and Schneider [32]. For example, one approach is based on the following relationship ... [Pg.1407]

Chlorinated Terpenes. A group of incompletely characterized insecticidal compounds has been produced by the chlorination of the naturally occurring terpenes. Toxaphene [8001-35-2] is prepared by the chlorination of the bicycHc terpene, camphene [79-92-5] to contain 67—69% chlorine and has the empirical formula C QH QClg. The technical product is a yellowish, semicrystalline gum (mp 65—90°C, d 1.64) and is a mixture of 175 polychloro... [Pg.279]

The semicrystalline, ethylene-based ionomers of commerce are flexible, transparent polymers notable for high strength and elasticity in both soUd and molten states. The ionic bonding is completely reversible (8) and has a strong influence on properties, even at temperatures well above the melting point. [Pg.404]

Polyethylene (PE) is a genetic name for a large family of semicrystalline polymers used mostiy as commodity plastics. PE resins are linear polymers with ethylene molecules as the main building block they are produced either in radical polymerization reactions at high pressures or in catalytic polymerization reactions. Most PE molecules contain branches in thek chains. In very general terms, PE stmcture can be represented by the following formula ... [Pg.367]

The chemical iadustry manufactures a large variety of semicrystalline ethylene copolymers containing small amounts of a-olefins. These copolymers are produced ia catalytic polymerisation reactions and have densities lower than those of ethylene homopolymers known as high density polyethylene (HDPE). Ethylene copolymers produced ia catalytic polymerisation reactions are usually described as linear ethylene polymers, to distiaguish them from ethylene polymers containing long branches which are produced ia radical polymerisation reactions at high pressures (see Olefin POLYMERS, LOWDENSITY polyethylene). [Pg.394]

Polyamides, often also lefeiied to as nylons, are liigli polymers which contain the amide repeat linkage in the polymer backbone. They are generally characterized as tough, translucent, semicrystalline polymers that ate moderately low cost and easily manipulated commercially by melt processing. [Pg.215]

Nylon-6 [25038-54-4] was first made in 1899 by heating 6-aminohexanoic acid (143), but its commercially feasible synthesis from caprolactam was discovered by Paul Schlack at 1. G. Farbenindustrie in 1938. Like nylon-6,6, it is a tough, white translucent, semicrystalline sofld, but melts at a lower temperature (T = 230° C. The physical properties and primary producers of nylon-6 are Hsted in Tables 9 and 10, respectively. [Pg.233]

Because of the capacity to tailor select polymer properties by varying the ratio of two or more components, copolymers have found significant commercial appHcation in several product areas. In fiber-spinning, ie, with copolymers such as nylon-6 in nylon-6,6 or the reverse, where the second component is present in low (<10%) concentration, as well as in other comonomers with nylon-6,6 or nylon-6, the copolymers are often used to control the effect of sphemUtes by decreasing their number and probably their size and the rate of crystallization (190). At higher ratios, the semicrystalline polyamides become optically clear, amorphous polymers which find appHcations in packaging and barrier resins markets (191). [Pg.238]

In addition to the semicrystalline nylons, which comprise the vast majority of commercial resins, nylon is also available in an amorphous form that gives rise to transparency and improved toughness at the expense of high temperature properties and chemical stress crack resistance. Table 2 shows the properties of some different polyamide types. [Pg.267]

Physical Form. Eor compounders, physical form is an important characteristic. They prefer sohd, free-flowing, nondusty materials whereas polymer manufacturers prefer materials that are Hquid and easily emulsified. Undesirable are semicrystalline materials which may stratify during storage. Also, substances to be avoided are highly viscous Hquids and low melting resins which block upon storage. [Pg.246]

Crystallinity. Generally, spider dragline and silkworm cocoon silks are considered semicrystalline materials having amorphous flexible chains reinforced by strong stiff crystals (3). The orb web fibers are composite materials (qv) in the sense that they are composed of crystalline regions immersed in less crystalline regions, which have estimates of 30—50% crystallinity (3,16). Eadier studies by x-ray diffraction analysis indicated 62—65% crystallinity in cocoon silk fibroin from the silkworm, 50—63% in wild-type silkworm cocoons, and lesser amounts in spider silk (17). [Pg.77]

A crystalline or semicrystalline state in polymers can be induced by thermal changes from a melt or from a glass, by strain, by organic vapors, or by Hquid solvents (40). Polymer crystallization can also be induced by compressed (or supercritical) gases, such as CO2 (41). The plasticization of a polymer by CO2 can increase the polymer segmental motions so that crystallization is kinetically possible. Because the amount of gas (or fluid) sorbed into the polymer is a dkect function of the pressure, the rate and extent of crystallization may be controUed by controlling the supercritical fluid pressure. As a result of this abiHty to induce crystallization, a history effect may be introduced into polymers. This can be an important consideration for polymer processing and gas permeation membranes. [Pg.223]


See other pages where Semicrystallinity is mentioned: [Pg.1406]    [Pg.1406]    [Pg.2534]    [Pg.2535]    [Pg.878]    [Pg.878]    [Pg.234]    [Pg.272]    [Pg.313]    [Pg.385]    [Pg.386]    [Pg.367]    [Pg.380]    [Pg.380]    [Pg.470]    [Pg.125]    [Pg.135]    [Pg.135]    [Pg.149]    [Pg.149]    [Pg.151]    [Pg.154]    [Pg.220]    [Pg.220]    [Pg.238]    [Pg.266]    [Pg.267]    [Pg.269]    [Pg.272]    [Pg.289]    [Pg.292]    [Pg.302]    [Pg.423]    [Pg.441]    [Pg.445]    [Pg.447]    [Pg.340]    [Pg.302]   
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Aging semicrystalline polymers

Amorphous and semicrystalline thermoplastic

Amorphous matrix with semicrystalline reinforcement

Amorphous phase in semicrystalline polymers

Amorphous versus semicrystalline

Birefringence semicrystalline polymers

Blends of Amorphous and Semicrystalline Polymers

Blends of Semicrystalline Polymers

Chain orientation semicrystalline polymers

Continuous semicrystalline

Continuous semicrystalline structure

Copolymers impact resistance, semicrystalline polymers

Craze in semicrystalline thermoplastics

Crazing, in semicrystalline

Crazing, in semicrystalline thermoplastics

Creep semicrystalline polymers

Crystalline-amorphous features semicrystalline

Crystallinity glass transition temperature, semicrystalline

Deformation Behavior of Semicrystalline Polymers

Deformation Response of Semicrystalline Thermoplastics

Deformation mechanisms semicrystalline polymers)

Deformation of Semicrystalline Polymers

Deformation of Unoriented Semicrystalline Polymers

Degradation semicrystalline

Dielectric semicrystalline polymer blends

Differential scanning calorimetry semicrystalline polymers

Disordered regions, semicrystalline polymer

Examples of modulus variations versus temperature for an amorphous and a semicrystalline thermoplastic

Factors That Influence the Mechanical Properties of Semicrystalline Polymers

Folded-chain model, semicrystalline

Fractionation, semicrystalline polymers

Fringed micelle model, semicrystalline

Glass transition temperature semicrystalline

Heat capacity semicrystalline polymers

High density polyethylene Semicrystalline polymers, properties

Hydrogels semicrystalline poly

Hysteresis semicrystalline polymer

Impact resistance semicrystalline polymers

Lamellar peaks semicrystalline polymers

Lamellar semicrystalline structure

Lamellar spacing semicrystalline polymers

Macromolecules, semicrystalline polymer

Materials properties, impact resistance semicrystalline polymers

Melt spinning semicrystalline polymers

Melting temperature of semicrystalline

Methods of Analysis Used for SAXS on Semicrystalline Polymers

Microstructure of Semicrystalline Polymers

Model studies semicrystalline films

Modulus Semicrystalline polymer

Multicomponent semicrystalline polymers

Nanocomposites semicrystalline thermoplastic

Nylon semicrystalline

Physical aging semicrystalline polymers

Physically cross-linked semicrystalline

Physically cross-linked semicrystalline properties

Plastic Deformation of Semicrystalline Polymers

Plastic deformation of semicrystalline

Plastic deformation semicrystalline polymers

Plastics semicrystalline polymer

Poly /polylactide semicrystalline

Polyamide Semicrystalline polymers, properties

Polyesters semicrystalline polymers, properties

Polyethylene semicrystalline

Polyethylene semicrystalline nature

Polymer blends semicrystalline

Polymer semicrystalline oriented

Polymer semicrystalline, morphological

Polymers semicrystalline state

Polyphosphazene), semicrystalline

Polypropylene resins semicrystalline

Refractive indices semicrystalline polymers

Relaxation processes semicrystalline polymers

Relaxation processes, in semicrystalline

Relaxation processes, in semicrystalline polymers

Relaxations in semicrystalline polymers

Resins semicrystalline polymer

Rigid-amorphous fraction, RAF, in semicrystalline polymers

Semiconductors Semicrystalline polymers

Semicrystalline

Semicrystalline PEEK

Semicrystalline PP

Semicrystalline Segmented Poly(Ether

Semicrystalline Stmcture

Semicrystalline blends

Semicrystalline block

Semicrystalline block composition

Semicrystalline block copolymers

Semicrystalline block copolymers, variation

Semicrystalline copolymers

Semicrystalline definition

Semicrystalline domains

Semicrystalline engineering

Semicrystalline engineering thermoplastics

Semicrystalline films

Semicrystalline materials

Semicrystalline miscible polymer blends

Semicrystalline morphology

Semicrystalline network

Semicrystalline plastics

Semicrystalline poly

Semicrystalline polyamide resins

Semicrystalline polycarbonate, thermal

Semicrystalline polymer 986 INDEX

Semicrystalline polymer amorphous phase

Semicrystalline polymer high-molecular poly ethylenes

Semicrystalline polymer physical properties

Semicrystalline polymer systems

Semicrystalline polymer thermal properties

Semicrystalline polymer-containing

Semicrystalline polymers

Semicrystalline polymers OsO4 staining

Semicrystalline polymers block copolymers

Semicrystalline polymers chain conformations

Semicrystalline polymers conditions

Semicrystalline polymers crazing

Semicrystalline polymers crystallization

Semicrystalline polymers crystallization behaviors

Semicrystalline polymers crystallization under flow

Semicrystalline polymers crystallization under quiescent

Semicrystalline polymers dielectric properties

Semicrystalline polymers elastic properties

Semicrystalline polymers experimental

Semicrystalline polymers first-order transitions

Semicrystalline polymers glass transition

Semicrystalline polymers glass transition temperature

Semicrystalline polymers high-performance

Semicrystalline polymers homopolymers

Semicrystalline polymers injection molding

Semicrystalline polymers interfacial phase

Semicrystalline polymers lamellae

Semicrystalline polymers linear viscoelasticity

Semicrystalline polymers matrix mechanics

Semicrystalline polymers mechanical properties

Semicrystalline polymers melting

Semicrystalline polymers melting range

Semicrystalline polymers molding

Semicrystalline polymers molecular architecture

Semicrystalline polymers morphological effects

Semicrystalline polymers optical properties

Semicrystalline polymers oxidative degradation

Semicrystalline polymers peak with

Semicrystalline polymers properties

Semicrystalline polymers reflections

Semicrystalline polymers secondary transitions

Semicrystalline polymers spherulites

Semicrystalline polymers thermodynamics

Semicrystalline polymers toughening

Semicrystalline polymers toughness enhancement

Semicrystalline polymers transitions

Semicrystalline polymers transport properties

Semicrystalline polymers widths

Semicrystalline polymers yield stresses

Semicrystalline polymers yielding behavior

Semicrystalline polymers, creep deformation

Semicrystalline polymers, effect

Semicrystalline polymers, thermal analysis

Semicrystalline polyolefins

Semicrystalline polyurethane

Semicrystalline region

Semicrystalline solid

Semicrystalline state

Semicrystalline structure

Semicrystalline thermoplastic appearances

Semicrystalline thermoplastic matrix

Semicrystalline thermoplastic polymers

Semicrystalline thermoplastic polymers, characteristic

Semicrystalline thermoplastics

Semicrystalline thermoplastics polymerization

Semicrystalline thermoplastics synthesis

Semicrystalline thermoplastics, crazing

Semicrystalline thermoplastics, crazing fracture

Semicrystalline, arrangement

Semicrystalline, arrangement molecules

Shear Deformation in Semicrystalline Polymers

Small-Angle X-ray Scattering for Morphological Analysis of Semicrystalline Polymers

Small-angle scattering semicrystalline polymers

Standard semicrystalline state

Structure formation in semicrystalline diblocks

Subject semicrystalline

The Semicrystalline State

Thermoforming semicrystalline plastics

Toughness semicrystalline matrix

Toughness semicrystalline polymers

Transparent semicrystalline polymer

Viscoelasticity semicrystalline polymers

Working with Semicrystalline Polymers

Yield behavior semicrystalline polymers

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