RTPP has short branches in the polymer's main chains because of its copolymerization with ethylene and butene, whereas the HPP structure is linear without branches, leading to its low melt viscosity and strength.
On the other hand, the TPGDA-modified RTPP can hardly improve its melt viscosity.
As compared to HPP, RTPP may have the ability to create more active sites on its main chains, since RTPP has many short branches.
From these considerations, an intrinsic grafting of HDDA on RTPP may be more dominant than on HPP while suppressing homopolymerization because of the inactivity of HDDA, leading to a remarkable enhancement of the melt viscosity of the RTPP, as shown in Fig.
On the other hand, MWD of the RTPP modified with 1.
The MWD is very similar to the modified RTPP (line A) that has considerable amount of huge molecule in the polymer.
However, the melt viscosities of the RTPP modified with 1.
At 10 kGy irradiation, the modified RTPP and HPP represent each different MWD, as shown in lines D and E in Fig.
As shown in the photographs, cells foamed in virgin HPP are easily broken and attain irregular shapes in the course of the foaming process (A), whereas virgin RTPP can create large size foams because of its original melt-viscous property (B).