Long Chain Branching, Part 2 – Experimental results

Hypothesis:  long chain branching of LLDPEs can improve melt strength in terms of drawability.

 We irradiated 3 LLDPE feedstocks with an electron beam and compared the properties of the 3 processed resins to a LDPE Control.  The starting samples were:

Radiation Processing

We dosed the samples with a 150kW, 4.5 MeV electron beam accelerator.  The electron beam irradiation initially breaks the polymer chains, creating free radicals that subsequently reform as long chain branches.  Improvements in melt behavior are attributed to this branched structure.

Observations

We observed a decrease in melt index and an increase in melt tension as dose was increased.  For LLDPE sample B, at dose level 3 the melt index and melt tension are equivalent to the LDPE Control.  This indicates that the desirable melt strength properties of LDPE can be imparted into LLDPE.

In Part 3 of this study we will blend these dosed samples with polyethylene to increase the properties of the alloy.

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