Nearly 10 years back, I built my own stand to put my handheld solar charger on at my home indoor environment when I am not using it on the go. As part of the construction, I used some pink erasers to hold it at the desired angle. Fast forward to today, and those pink erasers are now looking white and are quite hard, dry, and brittle. What happened?
Well, first of all, clearly those erasers are some sort of “fake” rubber. If you’ve ever had a “rubber band” that “dried up” and became brittle, you probably know what happened given your chemical knowledge. The “rubber band” was actually, literally, plastic, and plasticizers were added to it to make it softer and more flexible. Over time, those plasticizers leaked out into the atmosphere which caused the band to loose its flexibility while also making an environmental pollutant in the process. Now, you’re telling me that the material is turning white? Well, then we have yet more information at our disposal. We know that PVC plastic is a white powder, and pigmets are added to it to make it other colors. Indeed, the vast majority of historic “synthetic rubbers” may have been made out of PVC and laden with plasticizers given that many of these old kinds of things were prone to the same fate when exposed to the elements.
How does natural rubber latex compare to synthetic rubber? Natural rubber latex is generally softer and more gummy than synthetic rubber. If you’ve ever used a “gummy eraser” before, that’s more similar to how an eraser made out of natural rubber latex would feel like and work.
On a related note, your “latex free” rubber bands may actually be more dangerous than you think. By substituting natural rubber latex with plastics laden with plasticizers, you may be exposing yourself to more endocrine disruptors. Endocrine disruptors negatively affect everyone, but latex may only negatively affect who are allergic. Also, that eraser dust that you sometimes accidentally breathe in when using a pencil eraser? Well, well, that’s an easy and ripe path for those endocrine disruptor phthalate plasticizers to enter directly into your blood stream, similar to how inhaling lead vapor (i.e. from soldering with leaded solder) can cause lead to enter directly into your blood stream. Yeah, you know it’s bad for your health because it hurts if you inhale eraser dust, so you try to avoid it, but maybe you were unaware of exactly how dangerous inhaling eraser dust can be. Likewise, the reason why car tires are classified as hazardous waste and must be disposed of properly is because they are made of synthetic rubber, possibly laden with endocrine disruptor plasticizers that can cause serious environmental and human health damage if released improperly to the environment.
In the old days, people previously used real, natural rubber latex a lot more often in construction. Some political history can explain the primary motivation why people switched by far and large to synthetic rubbers. Before World War II, Goodyear had a large rubber tree plantation in Vietnam where they produced a lot of the rubber used by industrialized countries in less favorable climates for growing rubber trees like North America and Europe. During World War II, Japan seized the area and basically cut off the rubber supply to northern countries. At this time, these countries had to look for alternative sources for rubber, and the one that emerged was synthetic rubbers produced from petroleum. Ever since then, the vast majority of rubbers have been synthetic rubbers, and nowadays synthetic rubbers are generally preferred to natural rubber latex because it can be made to be harder and stronger. Also, the softness can be adjusted simply by adjusting the proportion of plasticizers injected into the manufacturing process.