Burbujas de vidrio, materiales compuestos a partir de las mismas y método de fabricación de burbujas de vidrio

The present disclosure provides a plurality of glass bubbles having an average true density of up to about 0.55 grams per cubic centimeter and a size distribution including a median size in a range from about 15 micrometers to 40 micrometers. A hydrostatic pressure at which ten percent by volume of the plurality of glass bubbles collapses is at least about 100 megapascals. In some embodiments, the plurality of glass bubbles is a graded fraction preparable by classifying a second plurality of glass bubbles, wherein the second plurality of glass bubbles has a higher percentage of glass bubbles with a size of up to ten micrometers than the first plurality of glass bubbles. Composites including the plurality of glass bubbles are also disclosed.