Can air travel cause packaging air pads to burst or deflate? This question is a new cross-post from the physics stack exchange: https://physics.stackexchange.com/questions/265884/can-a-decompressed-airplane-cargo-hold-cause-packaging-air-pads-to-burst-defla

I received a parcel from Germany to Chile. The contents were severely bruised due to a lack of packaging material. On second inspection I found a bunch of deflated air pads.

It was a personal shipment, the air pads were used and potentially not in pristine condition, but there were several brands of them, a manufacturing defect can be ruled out. It seems most of them burst, while at least one still had some air remaining and just had a leak that required a bit of pressure to release more air. Surprisingly there was very little air remaining, maybe 20% of the maximum volume.

The contents were light, I doubt they could have damaged a pad at all, let alone destroy them all. Could this phenomena be caused by a pressure difference between the air inside the packs and the cargo plane's hold? It seems a bad explanation considering the popularity of the packaging material.

I did check for needles and dead chicken. ;-)
Simple answer: yes, air travel can deflate or pop air pillows. 

Longer answer: Cargo holds are at the same pressure as the rest of the airplane, it's part of the pressure vessel. Generally airplanes are pressured to about 8000ft, so the air is a lot thinner and therefore there will be a higher pressure differential between the air in the pads and the air in the hold. Thin plastic is somewhat porous and will leak some air, the rate this happens will be faster when there's a higher pressure differential. This differential is known to pop these air pillows to the point many will not use them when shipping by air. Styrofoam, cellulose pops, or crumpled paper are the preferred method. 

You can see these forces at work next time you fly yourself by taking an empty disposable plastic water bottle on board. Seal it with the cap at airport altitude before departure. After takeoff as the airplane climbs the plastic will bulge as the cabin pressure drops, and when you uncap it you will probably hear a hiss. Seal it back up and then during descent the bottle will crumple as the air pressure increases.