Bimodal distribution, high density

The mode, the most commonly occurring (most popular) value in a distribution, passes through the peak of the relative distribution curve, i.e. it is the value at which the frequency is a maximum (Figure 2.6). More than one high density region may be present in which case the distribution is said to be multi-modal, i.e. bimodal, trimodal and so on. 

Figure 8.28 shows the pore size distributions for the PS formed on highly doped / -Si at different current densities." For the PS formed on heavily doped silicon, the pores at a given HF concentration have a narrower distribution at lower current at a given current density, the distribution is narrower at lower HF concentrations. A bimodal distribution of pore diameter is gena-ally associated with two-layer PS on lowly doped / -Si and iUmninated n-Si. The PS formed on p-Si has also been found to have a bimodal distribution of particles sizes small spherically shaped particles with a diameter of a few nanometers and large cylindrically shaped particles oriented with their axis perpendicular to the surface.The distribution of pore size with multiple peaks may be attributed to the fact that PS may have a surface micropore layer and smaller branched pores. Due to the hierarchical structure of the branched pores, the distribution of pore diameters for highly branched PS is found to be fractal-like. ° ... 

Application The UNIPOL Polyethylene (PE) Process produces the widest array of linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE) and high-density polyethylene (HOPE) having unimodal or bimodal molecular weight distribution (MWD) using a single, low-pressure, gas-phase reactor. 

Alathon L 4903. A high molecular-weight, high density copolymer with broad bimodal molecular weight distribution. This resin exhibits excellent machine-direction tear in an HMW-HD resin as well as low gel levels. 

Shen, H.-W. Luan, T. Xie, B.-H. Yang, W. Yang, M.-B., Rheological Behaviors and Molecular Weight Distribution Characteristics of Bimodal High-Density Polyethylene. J.Appl. Polym. Sci. 2011,121,1543-1549. 

Polymerizations with SSC (2). Previously NaSS-styrene copolymer latexes have been made, but <3% of NaSS could be incorporated without simultaneous formation of a soluble polyelectrolyte or a bimodal distribution of particle sizes (15-17), Hence, a lipophilic monomer that is freely miscible with styrene and VBC must be employed in order to achieve a high charge density styrenesulfonate latex. 

Figure 13.31 Environmental stress cracking resistance (ESCR) plotted against strain-hardening modulus for a range of EIDPEs, both catalyst based with broad molecular weight distribution, and bimodal. Points labelled reproducibility are repeated tests on the same sample. (Reproduced from Kurelec, L, Teeuwen, M., Schoffeleers, El. et al. (2005) Strain hardening modulus as a measure of environmental stress crack resistance of high density polyethylene. Polymer, 46, 6369. Copyright (2005) Elsevier Ltd.)...

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