Polymer specification

The present review is devoted to recent advances, mainly concerning the characterization of semicrystalline polymers, specifically polyethylene (PE) by means of microindentation hardness. The author has chosen to organize the chapter as follows ... 

The ultimate goal of bulk modification endows with the polymer-specific surface composition or a specific property for a given application. The bulk modification can be classified into blending, copolymerization, interpenetrating polymer networks (IPNs), etc. 

A monthly publication of Bill Brothers. It has articles on process production and manufacturing engineering. In a fall issue on plastics technology, it gives detailed equipment specifications, polymer specifications, and lists of equipment and chemical suppliers. 

Dynamics of a Supercooled Polymer Melt Above the Mode-Coupling Critical Temperature Cage Versus Polymer-Specific Effects. 

Polymer-Specific Effects of Bulk Relaxation and Stringlike Correlated Motion in the Dynamics of a Supercooled Polymer Melt. 

Finally, we turn from solutions to the bulk state of amorphous polymers, specifically the thermoelastic properties of the rubbery state. The contrasting behavior of rubber, as compared with other solids, such as the temperature decrease upon adiabatic extension, the contraction upon heating under load, and the positive temperature coefficient of stress under constant elongation, had been observed in the nineteenth century by Gough and Joule. The latter was able to interpret these experiments in terms of the second law of thermodynamics, which revealed the connection between the different phenomena observed. One could conclude the primary effect to be a reduction of entropy... 

Note 1 Chelating polymers mostly act as ion-exchange polymers specific to metal ions that form chelates with chelating ligands of the polymer. 

Polymer Specific gravity Mooney viscosity Tensile strength, MPa Elongation, % Ash, % Acetone extract, %... 

Due to these different primary structures of the main chain, important modifications and a broad variety of systems is realizable. While linear polymers can be essentially characterized by the number of the monomer units, for branched and crosslinked systems e.g. the way of branching and their quantity is of significance for the polymer specific properties. In cases of crosslinked systems the molecular dimension is the macroscopic dimension of the sample. 

In conclusion, it has to be emphasized, that the l.c. side chain polymers in principle exhibit field effects like l-l.c. s, assuming that the flexible spacer is sufficiently long. The applicability of polymers in high performance display technology seems to be less practicable due to the high viscosity. On the other hand, the polymer specific glass transition enables the realization of storage elements an information, put in by an electric field in the l.c. state, can be durably frozen in. 

W. Koch, W. Risse and W. Heitz, Makromol. Chem., Suppl. 12 (Polym. Specific Prop.), 1985, 105. 

The calculation of the solubility of gases and other small molecules in various polymers showed that for each polymer the relative solubility of the compounds was well predicted, but one polymer-specific correction had to be fitted. The results of this study are shown in Fig. 10.8. The correction constant may have to do with the missing combinatorial term, or with free-volume effects in polymers, or with structural differences of polymers, or with a combination of several such effects. The lack of a temperature dependence suggests that it is mainly of entropic nature. Unfortunately, no clear relationship between the value of... 

Fig. 10.8. Calculation of the solubility of gases in 24 different polymers, ranging from polyethylene to nitrocellulose [120], One polymer-specific constant has to be adjusted in order to achieve good results. Experimental data are taken from Pauli [121] (HDPE = high density polyethylene, POP = polyfoxyethylene glycol), PDMS = poly(dimethylsiloxane), PTFE = poly(tetrafluoroethylene)).

The concept of polymer free volume is illustrated in Figure 2.22, which shows polymer specific volume (cm3/g) as a function of temperature. At high temperatures the polymer is in the rubbery state. Because the polymer chains do not pack perfectly, some unoccupied space—free volume—exists between the polymer chains. This free volume is over and above the space normally present between molecules in a crystal lattice free volume in a rubbery polymer results from its amorphous structure. Although this free volume is only a few percent of the total volume, it is sufficient to allow some rotation of segments of the polymer backbone at high temperatures. In this sense a rubbery polymer, although solid at the macroscopic level, has some of the characteristics of a liquid. As the temperature of the polymer decreases, the free volume also decreases. At the glass transition temperature, the free volume is reduced to a point at which the... 

Polymer Specific gravity Specific heat kJ/kg/K Thermal conduc. W/m/K Coeff. therm. expan. /tm/m/K Thermal diffusivity (m2/s)10 7 Max temp. °C... 

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