are thermally bonded which can be achieved at lower temperatures than for mipp alone the increased breadth of the thermal bonding window can provide that not only is the spp on the surface of the fibres melted but also some of the mipp tends to be melted to form bonds between adjacent fibres thus the incorporation of spp into mipp enables the maximum strength of the non woven fabric to be greatly increased as a result of this increased thermal bond formation between adjacent fibres in contrast znpp has a significantly higher melting point range than that for spp so that when the known znpp spp fibres are thermally bonded the thermal bonding and thus the tenacity are lower than for the mipp spp blends of the invention because the znpp does not contribute to the formation of thermal bonds the mipp employed in accordance with the invention has a narrow molecular weight distribution typically having a dispersion index d of from 2 to 3 5 more preferably from 2 to 3 the dispersion index d is the ratio mw mn where mw is the weight number average molecular weight and mn is the number average molecular weight of the polymer the mipp typically has a peak in the molecular weight distribution of 60 000 to 120 000 kda the mipp has a melting temperature in the range of from 140 u00b0 c to 155 u00b0 c the properties of two typical mipp resins for use in the invention are specified in table 1 in contrast the spp has a slightly broader molecular weight distribution than for the mipp wherein typically d may be around 4 and has a.