Swelling temperature

This technique involves the dispersion of a nanomaterial in a monomer (Fig. 4.8). This step requires a certain amount of time that depends on the polarity of the monomer molecules, the surface treatment of the nanomaterial, and the swelling temperature. For thermoplastics, the polymerization can be initiated either by the addition of an agent or by an increase in temperature. For thermosets such as epoxies or unsaturated polyesters, a curing agent or peroxide can be added in order to initiate the polymerization. Functionalized nanomaterials can improve their initial dispersion in the monomer and consequently in the composites. In the case of layered materials, such as clays or graphene, the most important step is the penetration of the monomer between the sheets, thus allowing the polymer chains to exfoliate the material. The... 

Excess pressure applied to gel Degree of swelling as function of time Gas constant Rate of swelling Temperature... 

Up till now there is only few safe knowledge about stress-induced deformations (E-modulus, creep) and stress-independent deformations (shrinkage, swelling, temperature-expansion). But due to long experiences with other mortars containing polymers (e.g. lightweight mortars with expanded polystyrene as aggregate, polymer modified cement mortars PCC), basic problems are not to be expected. 

The maximum temperatures permissible for homopolymers in a number of diluents are listed in Table 75. These temperatures were determined in two ways, first, by laboratory swelling tests of a homopolymer in the particular hydrocarbon and, second, by actual experience in the production of homopolymers with the hydrocarbons in a pilot slurry reactor. Also shown in Table 75 is the degree of branching of each hydrocarbon, which is defined as the ratio of the number of methyl carbon atoms to the total number of carbon atoms. The swelling temperature correlates nicely with this ratio. Isobutane was chosen for commercial use as the best compromise between being highly branched and not too expensive. It permits a maximum operating temperature of about 111 °C for polyethylene homopolymer. 

FIGURE 230 The swelling temperature of polymers in isobutane, plotted here against the polymer density, provides the operations guideline for HDPE manufacture with Cr/silica. 

H2SO (0.1M) LI C10 (0.2M) Value determined after 13 hours swelling Temperature 25 C. 

The effect of variation different operational conditions such as swelling temperature, reswelling ability and pH on the swelling process has been investigated. In addition, effect of hydrogels particle size on the swelling behavior has also been investigated. 

Figure 18.3 Series of diffraction spectra /(s) of a DOPC sample that was heated at t = 20 mm within 2 min from 20°C to the final swelling temperature of 35°C. / scattering intensity, reciprocal spacing j = 1/rf = 2sin(0/A) DOPC water = 0.8 100 (by weight).

Table A.34 Chemical resistance of fluoropolymers S = swelling temperature is provided in [32], temperature is not provided in [1039]...

Fig. 13 Influence of swelling temperature on the relationship between the modulus and swelling of a crosslinked gelatin film.

Molecular weight Room temperature Substituent content Swelling Temperature... 

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