Styrene modified sulfur materials

Figure 4. Gel permeation chromatograms of the styrene-modified sulfur materials. Samples are identified by percentage of styrene used (w/w sulfur) and heating time at 140°C. (a)...

Figure 5. Shore D hardness vs. log time plots of modified sulfur materials. Samples are identified by percentage of modifier used (w/w sulfur) and heating time at 140°C. The onset of sample shattering is indicated by X. (a) Sulfur (b) 5% dicyclo-pentadiene, 3 hr (c) 10% dicyclopentadiene, 3 hr (d) 25% dicyclopentadiene, 3 hr (e) 5% styrene, 3 hr (f) 10% styrene, 3 hr (g) 25% styrene, 3 hr (h) 25% myrcene, 0.8 hr.

Compressive strength (Figure 6) of sulfur has a very high initial figure falling to a level at about 7000 kNm 2. The modified materials have much lower values, which with the lower levels of additive (5 and 10% styrene), increase rapidly after approximately two weeks, presum-... 

Dicyclopentadiene, dipentene, styrene, CTLA polymer, and methyl-cyclopentadiene dimer were used as modifiers. These modifiers are all available in commercial quantities at 5-12 cents/lb. All contain unsaturated double bonds suitable for direct reaction with sulfur. The materials used in this investigation were from the following sources ... 

Laboratory Reaction Tests. It was necessary to understand the reaction parameters for the modifiers dipentene, styrene, and dicyclopentadiene to aid future field stabilization tests. Laboratory tests were performed to define the typical character of the material in the liquid and solid state. The conditions necessary to form completely plastic noncrystalline sulfur with each modifier were also established. 

Sulfur can be fully plasticized by using the modifiers dipentene, styrene, and dicyclopentadiene. Sulfur can be plasticized with dicyclo-pentadiene at two minimum concentrations, as indicated in Table III 13% at reaction temperatures of < 140°C and 6% at reaction temperatures > 140 °C. This effect probably results from cracking of the dicyclopentadiene dimer molecule, which doubles the molecules available for reaction. The higher percentage dicyclopentadiene mixture was initially flexible. Upon aging, both plasticized materials became brittle. The reaction is exothermic and very difficult to control above 140 °C. When uncontrolled, extreme viscosity increases were encountered. 

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