graphSE =
Plot[Sin[2 t \[Pi]], {t, -10, 18}, AspectRatio -> 1.2,
PlotStyle -> {Thickness[0.007]}, Axes -> False, PlotPoints -> 10^3];
Export[FileNameJoin[{NotebookDirectory[],
"SEgraphnotext" <> ToString[#] <> ".pdf"}], graphSE,
ImageSize -> #] & /@ {72, 96, 150, 300}