Tie-chain concentration

Figure 4, Bi-modal HDPE resins designedfor optimum stiffness, toughness and ESCR balance via optimizing tie-chain concentration...

The lower limit of integration of the numerator of Eq. (1) has occasionally been modified in applications of the tie chain model. Yeh and Runt [9] proposed that the diameter of gyration of a random coil in the melt must be greater than twice the long period in a given specimen in order to form tie molecules. For the HOPE samples in Table 1, the tie chain concentration was determined at various values of L equal to an integral multiple of Lp =L +L . The... 

The simple functional relationship between ESCR, tie chain concentration and permeability is proposed as shown below ... 

Figure 7 Relationship between tie chain concentration and ESCR...

The formation of the microstructure involves the folding of linear segments of polymer chains in an orderly manner to form a crystalline lamellae, which tends to organize into a spherulite structure. The SCB hinder the formation of spherulite. However, the volume of spherulite/axialites increases if the branched segments participate in their formation [59]. Heterogeneity due to MW and SCB leads to segregation of PE molecules on solidification [59-65], The low MW species are accumulated in the peripheral parts of the spherulite/axialites [63]. The low-MW segregated material is brittle due to a low concentration of interlamellar tie chains [65] and... 

The cluster model assumes availability in the amorphous polymers structure of local order domains (clusters), consisting of several densely packed collinear segments of different macromolecules (amorphous analog of crystallite with stretched chains). These clusters are connected between themselves by tie chains, forming by virtue of this physical entanglements network, and are surrounded by loosely packed matrix, in which all fluctuation free volume is concentrated [107],... 

The concentration of interlamellar tie chains in a given sample depends on molar mass, which determines the spatial distribution of the chains, and long period, i.e. the sum of crystal and amorphous layer thicknesses. Figure 7.33 shows two very... 

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