Polyolefins, preferably polyethylene, having a density of about 0.86 to about 0.93 g/mL, having three or more branches of the formula (CH2CH2)mH wherein m is an integer of one or more, provided that said branched polyolefin has one or both of the following properties: said branched polyolefin contains less than 2 methyl groups per 1000 methylene atoms and at least 30 total branches per 1000 methylene groups; said branched polyolefin contains less than 0.3 branches of the formula —(CH2)5H per 1000 methylene groups; and in said branched polyolefin the level hexyl+branches is at least 80% of the level of ethyl branches, and said polyolefin contains less than 2 methyl branches per 1000 methylene groups or less than 0.3 branches of the formula —(CH2)4CH3 per 1000 methylene groups or both, thereby allowing good seals to be formed rapidly. This is advantageous when heat sealing these polyolefins, for example in the form of single or multilayer films.