Polyethylene in the presence of CTFE

Figure 1. Plot of Gf vs. dose in the irradiation of various polyethylenes in the presence of CTFE (( ) HDPE (O) LDPE ((D) BG-LDPE-1 (C) BG-LDPE-2 (9) BG-LDPE-3 (Q) IG-LDPE) and in vacuum ((A) LDPE (A) HDPE)...

Figure 2. Plot of Dg vs. dose in the irradiation of various polyethylenes in the presence of CTFE (symbols are the same as in Figure 1)...

These results lead to the consideration that the cross-linking of polyethylene in the presence of CTFE is not... 

Radiation-induced cross-linking of various polyethylenes in the presence of CTFE... 

Figure 5 shows the relationship between the gel fraction and the total consumption of the unsaturated groups (—A[U] expressed by equation (4)) in the irradiation of butadiene-and isoprene-grafted polyethylenes in the presence of CTFE. 

Radiation-Induced Cross-Linking in the Presence of CTFE/Butadiene Mixture. On the basis of the results mentioned in the previous section, it is concluded that in the irradiation of polyethylenes in the presence of CTFE the polyethylenes are mainly cross-linked through the addition reaction of the unsaturated groups contained in the main and the side chains of the polymers to the propagating graft chain radical of CTFE. Therefore, the radiation-induced cross-linking of polyethylene is expected to be accelerated by the presence of the mixture of CTFE and a diene monomer effectively than the presence of pure CTFE. 

The radiation-induced cross-linking of polyethylenes in the presence of CTFE/butadiene mixture with various compositions are shown in Figure 6. The overall degree of co-grafting decreased gradually with the increase in the mole fraction of butadiene in the mixture, while the gel fraction of the polymer was increased rapidly by the addition of a small amount of butadiene to CTFE and then decreased with the increase in butadiene mole fraction in the mixture. The maximum of the gel fraction was found at about 0.1-0.2 of butadiene mole fraction in the mixture. 

Role of Unsaturated Group in the Cross-Linking in the Presence of CTFE. In order to make clear the role of unsaturated group contained in polyethylene, the radiation-induced cross-linkings of the polyethylenes containing various concentrations of the unsaturated groups were carried out in the presence of CTFE. 

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