Binary-hooking

Several approaches to the description of molecular entanglements in polymers are available at present. A brief outline will be given here. The best known is the version of the binary hook [9,10] with some network features. At temperatures (T) exceeding the temperature of glass transition (Tg) for the polymer, the network density V(,i, is usually determined in the framework of the rubber-like elasticity, while for Tentanglement network is proven both theoretically and... 

The density of exceeds that of the macromolecular binary hooking network by, approximately, an order of magnitude. 

The cluster model [1] doesn t prohibit simultaneous existence of the molecular binary hooking network in the polymer Its density V, i, can be determined from the relationship [23] ... 

This formula has been shown to coincide with the experiment at i< 3 (Figure 9.1) even better than Equation (9.3). At A, > 3, both equations give somewhat overestimated results, indicating that using the rate k 0 at high strains is necessary due to possible breakdown of binary hooking junctions especially for chains with low molecular mass [28]. 

The macromolecular binary hooking network density was determined as follows [70] ... 

The seeds role at amorphous pol5miers structure formation is played by nodes of macromolecular binary hooking network wife density Then at seeds high concentration it can be written [197] ... 

FIGURE 84 The dependence of macromolecular binary hooking s network density on macromolecular coil intersections number N., for PAST. 

Further it is supposed that the macromolecular entanglements (traditional macromolecular binary hookings [10]) network is formed by just such contacts of fractals (macromolecular coils), therefore the indicated network... 

Where A/ is molecular weight of a chain part between entanglements traditional nodes ( binary hookings ), which is equal to 1390 g/mole for low-density polyethylenes [17]. 

As it is known [5], in amorphous phase two types of macromolecular entanglements are present traditional macromolecular binary hooking and entanglements, formed by nano clusters, networks density of which is equal to and v, respectively. value is determined within the framework of mbber high-elasticity conception [2] ... 

As alternative the authors of Ref. [28] assumed, that besides the indicated above binary hooking netwoik in polymers glassy state another entanglements type was available, nodes of whieh by their structure were similar... 

For the observed distinetions explanation it is necessary to point out, that the Eqs. (2.8) and (2.12) take into consideration only molecular characteristic, namely, maeromolecule flexibility, characterized by the value C. Although the Eq. (2.12) takes into account additionally topological factor (traditional macromolecular binary hooking network density v ), but this factor is also a function of [40, 42], The Eqs. (2.16) and (2.5) take into account, besides C, the structural organization of HDPE noncrystalline regions within the frameworks of cluster model of polymers amorphous state structure [5] or fractal analysis with the aid of the value [22], Hence, HDPE noncrystalline regions structure appreciation changes sharply the dependence DJJ). 

As the estimations have shown [26], the theoretical values E E7) are a little smaller than elasticity modulus experimental magnitudes. This assumes one more structural factor availability, influencing on the value E. This factor can be traditional macromolecular binary hooking network, which can... 

Lately the large attention is given to macromolecular entanglements fluctuation network influence on crazes formation process in polymers [20], Much less is known about entanglements network influence on shear deformation zones (ZD) formation processes, which by their essence are crazes, without microvoids. The authors of Ref [21] fulfilled quantitative estimation of such influence on deformation processes in ZD on the example of polyarylatesulfone (PASF) samples in the form of films with a sharp notch. In this analysis two models of macromolecular entanglements network were used of binary hooking s [20] and cluster ones [22], The PASF films were prepared with the aid of nine various solvents that allows their structure wide enough variation [21]. 

FIGURE 5.4 The dependences of limiting draw ratio in ZD on molecular weight of polymer chain par between nodes of cluster network A/j (1) and macromolecular binary hooking s network Af (2) for PAST films, prepared from various solvents [21],... 

Let us note that to obtain the similar dependence with macromolecu-lar binary hooking network notions using is impossible, since its density (and, hence, chain part length between binary hooking s) is independent on testing temperature [14],... 

Table 1.4 The values of molecular weight Af of chain parts between nodes of the binary-hooking network for HOPE and PC according to the literary ...

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