What is photodegradable?
Stone Paper is Photodegradable.
This means it is decomposed by (direct) sunlight. Photodegradable plastic, in this case HDPE which we have in our Stone Paper notebooks and envelopes, has bonds in its structure that are weakened and broken by sunlight, the exact process is that it is oxidized by active UV light with oxygen.
Over time it completely degrades and is resorbed into the biosphere without adverse effects. This natural characteristic of HDPE is an advantage for Stone Paper.
Is Stone Paper biodegradable?
No it is not. For that we would need to add bacterias, which we don't.
HDPE more information around
HDPE is photodegradable by nature; it’s interesting to note that plastic manufacturers have been attempting to make polymers resistant to UV light degradation, in order to make certain plastic products more durable, especially when exposed to direct UV light (through the addition of carbon black or chemical UV inhibitors).
With the last decade’s environmental awareness and ecologically minded efforts, more and more environmentalists’ pressure has been exerted on numerous government officials, to choose better plastic for products which may end up in nature, so as to reduce and eventually eliminate harming nature because of our laziness or convenience. It’s interesting to note that laws have been passed requiring plastic rings connecting beverage cans to be either, bio, photo, or chemically degradable. he sun’s rays have capabilities in its ultraviolet light (UV light) and infrared radiation which bring about the incorporation of oxygen molecules into the plastic, a process known as oxidation. As more and more oxygen intermingles with the polymer in the plastic, it becomes brittle and easier to break into ever diminishing pieces.
Up to now, after many tests, the conclusion that spontaneous chemical plastic degradation does not seem feasible has been reached. Thus, photodegradation was explored, namely in plastics which are sensitive to UV degradation.
How quick is the degration process?
HDPE’s relatively quick photodegradation (the speed of course depends on the amount and thickness of HDPE; stone paper has a very low percentage and is not in bulky form) makes it a good environmentally minded choice. When it fully degrades there are no micro-plastics as the resin oxidizes into 1.4ppm of Nitrous Oxide and 65ppm of CO leaving only calcium carbonate behind. Recent research has concluded there are no halogens present.