Maleation of linear low-density polyethylene by reactive processing

The reaction of maleic anhydride (MAH) with molten 2 MI poly(ethylene‐co‐butene‐1) (LLDPE) at 160°C in the presence of peroxyesters (t1/2 < 10 s) as catalysts resulted in the formation of a mixture of cross‐linked and trichlorobenzene‐soluble LLDPE‐g‐MAH. The soluble fraction constituted more than 50% of the mixture and had an MI of 0.0 and an MAH content ranging from 0.3 to 1.8 wt %. The presence of tri(nonylphenyl) phosphite (TNPP) in the LLDPE–MAH–t‐butyl peroctoate (tBPO) reaction at 160°C increased the MI of the soluble product to 0.7–2. The amount of soluble polymer increased at higher TNPP concentrations while its MAH content ranged from 0.05 to 0.54 wt %, with most contents in the 0.2–0.3 wt % range. The color development that usually occurs in polyolefin–MAH reactions was reduced by the presence of TNPP. However, the reaction of TNPP with the peroxide and from the thermal decomposition thereof reduced the availability of the excited species necessary for the appendage of MAH units onto the polyofin.