Average cell diameter

Gendron and Vachon (36), reviewing Park s research (274) on PP foam, defined a foamability factor F from the tan S of the PE melt (at 190 °G and 1 Hz), the average cell diameter D and the foam density p as ... 

The foamed, non-crosslinked resin particles, which have a bulk density of not greater than 0.045 g/cu.cm. and an average cell diameter of at least 200 pm, include PP to which a vinyl comonomer is graft polymerised in such an amount that the weight ratio of the PP to the graft polymer of the vinyl comonomer is in the range of 97 3 to 65 35. They are produced by graft polymerisation at a... 

LDPE/EVA blend was irradiated using gamma-irradiation and then expanded by heat as a foamed material. The EVA content in the blend was optimised to form a gel. The effects of atmospheres and of irradiation dose rate were studied. The ETIR spectra of the foam revealed the oxidation level. The relations between gel fraction of LDPE/EVA blend, expansion ratio, apparent density, average cell diameter and tensile properties of the foam are discussed. 8 refs. 

The more complex machines (e.g. Coulter counter model ZM) have variable upper and lower thresholds and will measure cell number with automatic coincidence correction if required and average cell diameter or volume. When coupled with the Channelizer 256... 

Nucleating Agent Density, g/cm Void Content, % Average Cell Diameter, jam Surface Quality... 

At the slower depressurization rate O.lMPa/min, the difference of foaming temperatures, 40 °C and 20 °C, could not create big difference in cell diameter and cell density for the samples of PS/MMA, 2/1 and 3/1. On the other hand, the sample of PS/MMA ratio, 1/1, shows large changes in number average cell diameter as well as density when decreasing temperature from 40 °C to 20 °C. 

The average cell diameter was reduced to 50 nm when the depressurization rate was increased to 0.5MPa/min. The cell diameter was not changed so much with the weight ratio of PS/PMMA while the number density was increased from 20 to 80 pm as the PS content was increased. The dispersity of PMMA domains in PS and the difference between the plasticization effect of CO2 on PMMA and that on PS can create the nanoscale cell structure. Figure 7 shows the CO2 induced reduction of glass transition temperature of PMMA and those of PS [8]. As can be seen in Fig. 7, when the CO2 sorption pressure was 8.6 MPa, Tg of PMMA decreases to 0 °C while that of PS decrease to 30 °C. When foamed at temperature 40 °C after dissolving CO2 at 8.6 MPa, the... 

With the increase of silicon dioxide content, the average cell diameter of silicone rubber foam decreases (Table 2). The foam density declines to a minimum value, then increases (Figure 2). This is also because with the increase of silicon dioxide content, the elastic modus of rubber melt increases, the bubble expanding is suppressed, and the expansion ratio is decreased. With... 

Irradiation dose before foaming (kGy) Average cell diameter (gm) Foam density (g/cm ) Tensile strength (MPa) Tensile modulus (MPa) Elongation at break (%)... 

Table 2. Effect of silicon dioxide content on average cell diameter of silicone rubber foam...

Figure 4. Average cell diameters for all experimental settings versus melt temperature (Filled points denote heterogeneous foams).

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