Free radical hydrosilylation of polypropylene

Abstract

Hydrosilylation of terminal double bonds in polypropylene was investigated via a free radical process in the melt-phase. This process involved the following two reactions occurring in parallel: chain scission, which leads to formation of double bonds, and the addition of silyl radicals to such bonds. Fourier Transform Infrared Spectrometry (FT-IR) was used to follow silane incorporation and terminal double bond formation. The experimental trends were verified using elemental analysis obtained from energy dispersive x-ray analysis (EDX). Using a single screw extruder and a model silane compound, a 2 3 full factorial experiment design was implemented with the following investigated factors: residence time, silane concentration, and peroxide concentration. Statistical analysis of the FT-IR results, showed that, for the silane incorporation, residence time, peroxide concentration, and the interaction between the silane and peroxide concentrations had significant effects. The significant effects for the formation of terminal double bonds were residence time, silane concentration, and peroxide concentration. The experimental results have shown that melt-phase hydrosilylation of polypropylene can be accomplished through this noncatalytic free radical method.

Properties and Characterization of Filled Poly(Propylene) Composites Crosslinked Through Siloxane Linkage

“…During the silane-grafting process, PP chain scission is accompanied as a side reaction. [16,17] This would negatively influence the properties of the crosslinked product.…”

“…In the case of poly(propylene) (PP), it has been well established that PP mainly experiences chain scission reactions during peroxide modification, leading to a decrease in molecular weight and molecular weight distribution. Therefore, in order to perform crosslinking of PP, the silane-water crosslinking seems to be a promising technique.Silane-grafting and water-crosslinking of polyolefins have received much attention in recent years, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] not only for industrial applications but also in fundamental research, because of its various advantages, such as easy processing, low capital investment, and favorable properties in the processed materials. The properties of silane-crosslinked products were reported earlier to differ from those of peroxide crosslinked materials, in which the silane-crosslinked polymers were found to exhibit better thermal stability and higher energy storage capacity.…”

“…During the silane-grafting process, PP chain scission is accompanied as a side reaction. [16,17] This would negatively influence the properties of the crosslinked product.In this work, the silane-grafting and water-crosslinking of PP and PP composites filled with calcium carbonate (CaCO 3 ) are investigated. The extents of silane-grafting and degradation of PP as reported in terms of melt flow index (MFI) are demonstrated.…”

Trends in polymer chemistry 1997 Part 1: Pure research

“…With the continual development of the polyolefin market this group of materials has moved into the center of melt modification. For example, for the extension of the general properties of polypropylene, radical-initiated long chain branching reactions for the formulation of specific rheological properties [78] and graft reactions for functionalization using double bonds (either available or generated by a peroxidic decomposition), e. g. coupling of silanes [79], have been intensively investigated.…”

Sirolimus‐ versus paclitaxel‐eluting stents for coronary bifurcations intervention

“…Silane grafting and then water cross‐linking of polyolefins are a recently developed alternative approach [5–23] that has gained both academic and industrial interest because of its various advantages, such as easy processing, low capital investment, and favorable properties of processed materials. Compared with peroxide cross‐linked polymers, silane cross‐linked ones are found to exhibit better thermal stability and higher energy storage capacity [1].…”