An Overview of the Potential of UV Modification of Polypropylene

Abstract

Summary: UV radiation with a photoinitiator has been utilized to modify polypropylene (PP). Factors affecting solid state photomodification were studied and the optimal processing conditions for formation of three different structures (degraded, long chain branched and crosslinked) in PP were determined. A long radiation time (more than 5 minutes) is required to form long chain branched PP (LCBPP) and this exposure time is even higher for production of crosslinked PP (XPP). Trimethylolpropane triacrylate (TMPTA) was utilized to decrease UV radiation duration. Optimal concentrations of TMPTA and photoinitiator for formation of long chain branched and crosslinked PP were determined. Finally, a setup was suggested for continuous photomodification of PP using a twin screw extruder. In this design, PP strands are irradiated directly after the die. Optimal photoinitiator (benzophenone) concentration, coagent (TMPTA) concentration and radiation time required to form controlled rheology (CRPP) or long chain branched PP or crosslinked PP were identified.

Improving melt strength of polypropylene by minimal branching and blending

“…Branching can be done directly during polymerization [3][4][5] or by post-reaction processing. The most frequently used post-reaction mechanisms are irradiation 6,7 and reactive processing. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Particularly, reactive processing has aroused great interest because of its flexibility and relatively low cost as it can be implemented on an extruder, which is the most common equipment in industrial plastic processing.…”

Design of polymeric materials: Experiences and prescriptions

“…An additional bonus of the systematic design approach was that this process could be scaled up from bench scale to commercial scale. [39,40]…”

Branched Propylene Derivatives by Radical-Mediated Grafting of an Acrylate-Functionalized Nitroxyl

“…The saturated hydrocarbon structure of PP limits its modification chemistry to radical-mediated reactions initiated by peroxide thermolysis, photoinitiator activation, mechanical shear, or high energy irradiation. , We are concerned with high temperature, melt-state chemistry that can be carried out in conventional polymer processing equipment. These operations are complicated by the susceptibility of tertiary alkyl macroradical intermediates to β-scission, which can lead to extensive losses of melt viscosity .…”