So I am fairly new to inkscape but have generally taught myself for the most part over the past few months. For the work I am currently doing I use inkscape to either modify graphs from excel or make simple diagrams from scratch.

However the most recent issue I have run into I am unable to figure out. For the images I am working at they are requested to be of specific dimensions, in this particular case with a maximum width of 90 mm. I then export the image as a .png only to find it is too blurry and pixelated for the lettering and smaller details to be visible. I have not found any other way of exporting the image to a better quality and even trying to import the .svg file into GIMP and edit it there does not seem to help. Any advice on how to export these smaller images in better quality would be greatly appreciated.

Check this page for more details.

Sicne you're creating the diagrams in Inkscape, it would be easiest and most productive if you'd export those as png's on 300dpi and than scale it down to the desired size, in mm's, in Gimp.