With the push to create ever-thinner, ever-lighter concealable body armor, companies cast about for materials that had even better strength-to-weight ratios than UHMWPE. In the late 90’s, they believed they had found a miracle material.
Developed in the late 80’s by SRI International, and marketed by Toyobo a Japanese company, PBO Zylon [poly(p-phenylene-2,6-benzobisoxazole)] promised to be the holy grail of the armor industry. With nearly TWICE the strength and Young’s Modulus of Aramid, and over twice the decomposition temperature (1202 F), Zylon looked to be a champion. Armor companies immediately started producing high-end vests using the new material. Within a short time, laminates began to be used as well, with names such as Z-Shield and Z-Flex.
The armors produced were impressive, unbelievable even. Thinner, lighter, and more comfortable than anything produced up until that time. Nearly a quarter of a million vests were produced before the shine came off the rose.
Despite the impressive statistics put up by Zylon fiber, these were “ideal” numbers. After time in the environment (especially the harsh conditions body armor is subjected to), it was found that Zylon degraded at a horrifying rate. Light and humidity exposure caused as much as a 60% decrease in the effectiveness WITHIN AS LITTLE AS SIX MONTHS. Due to how the fiber was finished (a phosphoric acid scouring process), small amounts of water (such as the vapor found in human sweat) could react with trace quantities of phosphoric acid remaining on the fibers, and trigger those acids to break down the fibers. UV light accelerated the breakdown.
These dangerous properties were brought to light in 2000 by a researcher at a major University, and CONFIRMED by Toyobo in 2001 (who, to their credit, had never recommended this fiber for use in body armor). These findings were dismissed, and Zylon continued to be used in soft armor.
If not for the tireless efforts of individuals such as Kevin “Mad Dog” McClung and Dr. Gary Roberts, this dangerous material may still be used in vests. This in spite of at least 3 deaths directly attributed to Zylon breakdown, leading to vests failing during bullet impacts.
After these high profile failures, and do to the revelations of Zylon’s unsuitability, a rush for the door ensued. Zylon was pulled by numerous manufacturers, and it was decertified by the NIJ for use in armor. The trouble is, a lot of these vests still remain in circulation today, either because the wearer was not made aware of the issue, or unscrupulous sellers feel that making a quick buck selling, essentially, garbage, is more important than the wearer’s safety.
Zylon should never, EVER be used in armor. If you have a vest that contains ANY, it is not safe, even if it is only a small portion. Identification of this material is paramount, and I will be posting a tutorial in a future post to allow people to determine what their armor consists of.
So avoid Zylon, at all costs, and stay safe!
Next time: We look at hard armor. Same time, same channel!
d-rmor gear 