posted 09-26-2003 11:10               

Executive Summary of the Zylon issue.
By Kevin McClung
Pres/Sr. Engineer
MD Labs

Second Chance was the first manufacturer to offer Zylon vests, as they had a two year armor exclusive with Toyobo when Toyobo introduced the material. They started offering it in 1998. The Zylon vests promised to be thinner and lighter than any previously made.
What they didn't know then was to what degree the Zylon suffered from heat/humidity and light degradation problems. Neither were they required to by NIJ, so they didn't bother to do any analysis of the new, relatively unknown material.

Since polymers tend to have some form of degradation under certain conditions, and this is well known in the engineering community, rational and responsible engineering practice would of course require some due diligence in this area prior to warrantying the material for a given length of time, such that research would be accomplished proving the material would actually fullfill the promised performance expectations over the duration of the warranty.

They found out by 2000 because of some inhouse testing and a university study by a PhD chemist, and then they intentionally suppressed the data. They chose to gamble officer's lives against their immense profits. The Zylon degradation curves were dismissed as "inconsistant" because of their spotty testing and poor engineering practices.

Vests that cost them approximately $100-150.00 to make are selling for $750-1400.00. They have now sold about 200,000 Zylon vests in the U.S. and abroad. Even at the low end of sales ($750.00 X 200K), that would be about one and a half BILLION dollars in sales for Second Chance alone.
In 2000, they knowingly chose their obscene profits over Officer safety.

By 2001, Toyobo had published extensive data on the heat and humidity degradation over time, as well as light induced degradation. They have updated that information several times, and provided it to their Zylon customers. We have that information directly from Toyobo.
Despite the ample warnings from Toyobo, most of the other manufacturers brought out Zylon vests to remain competitive with Second Chance, who shamelessly touts their "Leadership in the Industry".
Honeywell began making their Z-Shield product to compete with the woven versions of Zylon.
(This Z-Shield product is now sold exclusively to Armor Holdings)

Since then no less than three internationally known armor manufacturers and three materials houses have publicly decried the use of Zylon in soft body armor as unsafe. Numerous other credible scientific researchers have also come out with evidence that Zylon suffers sufficient degradation through normal wear to cause as much as 30% loss of V50 values in as little as six months of wear!
This means that level IIA Zylon vests over six months old and Level II vests over a year old have about a 60% chance of being penetrated by any 9mm round.
This assertion is born out by data collected after the officer shootings and tests done independantly by several police agencies, as well as data collected during NIJ certified lab retests of aged armor.

Nevertheless, Second Chance, Armor Holdings, Point Blank and several others continue to offer the Zylon material in soft body armor, despite the recent spate of injury and death as a result of Zylon armor failures.

About Zylon PBO Fiber:
First, the good news:

Zylon fiber is amazingly strong when new.

Roughly twice the tensile strength of p-aramids like Kevlar and Twaron.

This would ideally allow construction of thinner, stronger vests that are amazingly light and flexible.

Here's some more poop on the origins of Zylon, acquired in a MK1/mod0 Google search.
http://www.sri.com/about/timeline/pbz.html

PBZ High-Performance Polymers

SRI chemists patented a class of high-performance polymers called PBZs. This technology had been licensed for commercialization to Dow Chemical, which sold its interest in PBZ to Toyobo Company, Ltd., a leading fiber producer in Japan. Toyobo began commercial production under the name Zylon(tm) in 1998. Zylon(tm), also called PBO after its chemical structure, poly(p-phenylene-2,6-benzobisoxazole), is a member of the PBZ class.

In other words, Dow dumped the material when they found it to be essentially unmarketable, and in all probability not capable of being developed to a degree that would allow it to be safely used in any conventional engineering application.

Brand new level IIIA vests of Zylon based materials are usually capable of defeating threats that would ventilate other vests made of competing materials like P-Aramid or UHMWPE.

Although backface deformation would still be extreme in these situations, the brand new Zylon panels can often remain intact where other vests would have failed.

The Zylon based vests are super light, very comfortable, and very expensive.

Several companies are currently manufacturing vests made of this PBO material, either in whole or in part.

Second Chance, Point Blank, Armor Holdings/ABA/Xtreme Armor/Safariland are a few of the companies currently advertising the use of Zylon based materials in some of their vests.

They make sweeping promises of a new age of more wearable vests and increased user safety.

Now the Bad News:

They are NOT really delivering what they claim they are.

Toyobo of Japan has published a PDF document (September, 2001) regarding the strengths and inherent weaknesses of Zylon (PBO fiber).

Apparently, the material is twice as strong in tensile as p-aramids like Kevlar and Twaron when it is new, but manifests some very serious strength degradation issues with exposure to any visible light, or heat and humidity.

Read this PDF, and then come back for the rest of this. (You will need Adobe Acrobat 5.0 or later to download it)
http://www.toyobo.co.jp/e/seihin/kc/pbo/technical.pdf

The Adobe PDF file at the Toyobo site shows, among other things:

1) Degradation of as much as 65% strength loss over six months (evidently a day/night inclusive time line) exposure to sunlight, at northern latitudes.

2) 65+% degradation in 100 hours under exposure to Xenon lights at 83C, and signifigant degradation after minimal exposure to two 35 watt fluorescent lamps.

Interestingly, the degradation curves for 100 hours under Xenon at 83C and "six months sunlight" are nearly identical, as layed out in their graphs. Both show very sharp downward curves upon initial exposure, and then decreased degradation rates as time goes on, but NEVER stop degrading during the term of the experiment.

Bear in mind that the six months of daylight would include 1/2 of that time in near total darkness (night), and about 50% of the remaining time might be strong, direct sunlight. The 50% strength loss occurs in sunlight right at the two month point.(Do the math)

Taken on the average, about 150-300 hours of exposure to strong white light
(6.5-12.5 full 24 hour days) appears to cause an average of 50% degradation in tensile strength in Zylon. Higher temperatures accelerate this degradation.

Also noted by Toyobo is signifigant degradation due to exposure to humidity.

Toyobo specifically warns against exposing Zylon any exposure to humidity.

Toyobo also specifically warns against exposing Zylon to any visible light.

Oddly enough, the material seems nearly impervious to outright immersion in water, but humidity just kills it.

This is due to phosphoric acid that is entrapped in the PBO fiber during the fiber manufacturing processes. These acids/chemicals are activated by the water vapor, and then begin eating away at the material or otherwise altering its structure sufficiently to allow the documented loss of strength. The acid is hygroscopic, so it draws and condenses atmospheric moisture.

The strong capilary quality of the fiber feeds the moisture to the rest of the fiber structure, even when it is encased in plastic laminate, as in the Z-Shield material. The exposed cut ends act like soda straws, pulling the wearer's body moisture into the vest.
"Water proof" GoreTex carriers do not help. They are specifically designed to allow transpiration of water vapor.

Given the fact that the armor made from Zylon is tendentially engineered for minimal bulk and maximum wearability under the entirely erroneous assumption that Zylon (as currently packaged) retains all of its "as manufactured" strength after manufacture and wear, the amount of safety margin built in for acrued light, heat and humidity induced strength degradation over time is minimal as well.

Imagine how humid it is between a vest and its sweaty wearer at any given moment.

Approximately 100% relative humidity, day or night, rain or shine. This has been measured in laboratory and field conditions by the use of hygrometers placed inside the uniform of Officers wearing armor.

Then realize that a Goretex cover is specifically designed to allow the transpiration of water vapor.

Guess where the water vapor will migrate to? Straight to the acids in the fiber. The acid is hygroscopic. It attracts water vapor.

Compound that with use/storage in very humid areas, and compound it again by use in elevated temperatures.

Bad news.

Merely sealing it into thermoplastic elastomer (TPE) sheets (Z-Shield type technology) won't help much at all. There is a large body of data showing the strong capillary quality of the fiber.

Exposed fiber ends on the cut TPE laminate material (Z-Shield) edges will, quite literally, suck water vapor as it becomes available.

[ J. Appl. Polym. Sci. Vol.80, 1030 (2001) An Analysis of Capillary Water Behavior in Poly-p-Phenylenebenzobisoxazole Fibers T. Kitagawa, K. Yabuki ]

Further, the Toyobo PDF document specifically WARNS against any exposure to or storage and use in visible light, and any exposure to "high humidity", even at "room temperatures".

Despite these published warnings from the material's manufacturer, no armor maker using Zylon has made any attempts (to date) to keep the Zylon from any exposure to bright work lights during both storage and manufacturing procedures.

Zylon users and OEM armor material fabricators have made no attempts to prevent similar hazardous exposure issues with humidity during their manufacturing processes.

Note that there is NO data shown in the Toyobo document to indicate:

1) That there is any recovery of strength after exposure to light/heat/humidity ceases.
Once some quantity of strength is gone, it is gone for good.

2) None of Toyobo's published data indicates that degradation of strength ceases entirely after exposure to degrading influences ceases.
Zylon gets a sort of ongoing "cancer" from exposure to light and/or water vapor, as opposed to just getting a "sunburn" or fagged out from the humidity.

3) None of Toyobo's published data indicates that drying out the Zylon recovers its strength.
In point of fact, the drying techniques possible for wearers in the field would entail turning the liquid water on the vest into water vapor in order to dry the vest... thereby causing increased exposure to humidity.

4) None of Toyobo's published data shows that a combination of humidity and light exposure would not compound the degradation curves manifested in the other tests. Data does exist to show that greater heat compounds the humidity issue though.

We know for a fact that the Zylon materials used by armor manufacturers are not currently handled and stored in totally dark, zero humidity conditions during fabrication of armor panels, and in laminated variants it is exposed by the laminate material manufacturer to heat sufficient to bond it to the TPE sheets used in the laminate material.

All of these conditions are PROVEN to cause degradation of Zylon...

So, this begs the question:

Just how bad is the degradation by the time the user gets his vest, and how long can he expect it to stop the rated threats?

As it turns out, not very long at all. Only about six months on the outside.

Zylon may be a marvelous material when used within its very well documented limitations, but it is certainly obvious that NONE of the armor manufacturers or OEM material suppliers have taken all of those limitations into consideration during their design and packaging of the material for use as body armor.

Why?

Good question.

The answer? Money. Tons of it.

The armor makers were warned as early as 2000 that Zylon had serious degradation issues. [edited 2/20/2004 to add: Toyobo has now published correspondance with Second Chance showing that they were warned of light, heat and humidity issues in 1998]
The armor makers suppressed the data, and continued to make the Zylon armor because their profits were immense, and the NIJ required no post manufacture testing to ascertain environmental stability of the armor.

Toyobo told us that they sent their test data to all of their customers as it became available. The most damning data came from them in July, 2001. Over two years ago.

The manufacturers did nothing.

Note: In ascending order, the threat levels for soft concealable body armor are IIA, II and IIIA
A "IIA" vest will stop fewer threats and at lower velocities than a II, and a II stops less than a IIIA.

Forest Hills, Pa: Officer Limbacher was critically wounded after his Second Chance Zylon vest failed to stop a .40 caliber pistol round it was rated to stop. His level IIA vest was about six and a half months old.

Oceanside California: Officer Tony Zeppetella has died as a result of his Second Chance Zylon vest failing to stop rated 9mm rounds. His vest was about seven months old. He leaves a widow and an infant son behind. His level II Ultima Zylon vest was about seven months old.
[edited 2/20/2004 to add: the autopsy of Tony Zeppetella proves conclusively that the round that killed him was a 9mm round his vest was "rated" to stop, but which penetrated the vest, punctured his carotid and jugular, and shattered his seventh cervical vertebrae]

Both of these vests were well within their warranty life, and neither was over eight months old.

The tests done by Kent PD in Washington indicate that vests of approximately two years of age suffer a minimum of 40% strength/stopping ability (V50) loss at that latitude.

Vests worn in southern climes where more heat and humidity are present will degrade even faster.

Ravalli County, Montana: Another Second Chance Zylon vest was penetrated from the inside out by a .45 acp round. The .45acp is a very slow round, larger in diameter than most other pistol rounds. They are not known for deep penetration.

This .45acp penetration would be an impossibility with a new vest even in a IIA level, but the two year old Second Chance Ultima Zylon vest let the round through after it passed all ther way through the officer's shoulder and scapula. This was a level II vest that should have stopped that round quite easily. His vest was about two years old.

The preliminary analysis of this field data on wounded and killed officers indicates that a level IIA Zylon vest more than six months old has a greater than 50% chance of being penetrated by any 9mm round. Zylon vests of any threat level will degrade sufficiently in two years to be effectively useless against most rounds they are rated to stop.

There are three grades of Zylon, the "AS grade" being the lowest quality, and most susceptible to degradation due to it's molecular structure and affinity for attracting and bonding water molecules (hygroscopy). This is the grade in use by all of the armor manufacturers, despite data that higher grades (in ascending order, H and HM grades) would have slightly longer lifespans.

There are over 150,000 Zylon based vests in use in the U.S. today, and over 70,000 in Germany.

About three out of four Zylon vests in the U.S. were made by Second Chance. The balance made by their competitors.

Zylon vests cost roughly twice the price of competing woven kevlar/aramid products. The profits on this are so immense that the armor makers will do anything to keep making Zylon.

Even risk their customer's lives.

Kent Washington tests:
http://64.177.53.248/ubb/Forum5/HTML/000346.html

Limbacher shooting, Pennsylvania
http://www.pittsburghlive.com/x/tribune-review/s_142385.html

Toyobo Technical Data PDF
http://www.toyobo.co.jp/e/seihin/kc/pbo/technical.pdf
http://www.bsstgmbh.de/BSSTV20/html/english/eS010702.htm

US Armor refuses to use Zylon:
http://64.177.53.248/ubb/Forum5/HTML/000356.html

Nov 20, 2002 Interview with Richard Davis, President of Second Chance:
http://64.177.53.248/ubb/Forum5/HTML/000297.html

(carefully read the parts in bold face)

Comprehensive discussion of Zylon and armor issues at MD Labs Forum at Tactical Forums.com
http://64.177.53.248/cgi-bin/tacticalubb/forumdisplay.cgi?action=topics&forum =M.D.+Labs+&number=5

Please feel free to call me at any time with any questions or requests for elaborations.

Please bear in mind that all of my most dire predictions about Zylon armor have proven to be absolutely correct.

I can also provide access to other expert witnesses to corroborate my data and analysis or provide references for my personal credibility in this matter.

Thank you for your attention to this matter.

Kevin McClung
Pres/Sr. Engineer
MD labs
8333 pecos Drive #4
Prescott Valley, AZ. 86314

928-772-3021 Office

928-899-4552 Cell/24 hour message

*****************************************

[edited to correct typos and add newly discovered facts]

posted 09-26-2003 20:37               

This flaw in NIJ testing protocol provides yet another loophole that the manufacturers are desperately trying to use to argue that it is not "fair" to call penetrations FAILURES if the rated rounds hit "unrated" areas of the vest.

Take your vest, and draw a line around the perimeter of it, three inches from the edges. The interior of this line would define the manufacturer's concept of the "fair hit" area of the vest.
They would argue that any penetration from that line to the edge is technically NOT a vest failure.

Tell that to the officers with bullet holes in their bodies.

posted 02-29-2004 08:49            

I spent about 9 hours yesterday following the various links on this topic here in TF, and following up using other search engines. To say yesterday was a rude awakening for me is a huge understatement.

I undertook this reading as a direct result of your surprisingly rude comments posted last Friday on the TE forum. Since I have generally agreed with your positions on most issues, and your posts are generally well-written and polite, I was stunned at your reaction. Not knowing that TF is your personal sandbox, and not realizing you were a leading advocate in this ongoing conflict, I had no idea I was treading on your toes. I guess now I know better.

Having done the research to get up to speed on the Zylon debacle, however, I now canunderstand your anger. I recently lost a brother officer and good friend due to vest failure (Kevlar IIIa, 7.62x39 round), so I know where the anger comes from and what it can do to you.

Zylon isn't very popular up here in WI, as we don't have the heat/humidity to deal with. That is part of why I had no real knowledge of this issue. Another reason is that I have been heavily occupied in researching another topic related to officer survival, and frankly haven't had the time to keep up with every other area and field in law enforcement. I'm not offering that as an excuse, just by way of explanation.

At this point, I can only say that I appreciate the summary you've provided here. It lines up pretty well with what I have read here and elsewhere. I have copied your summary to contacts at several PD's I deal with regularly.

posted 02-29-2004 11:14            

Your comments are those of a true gentleman--my hat is off to you.

------------------

posted 02-29-2004 13:24            

It is to blush. I deserve no credit. My hat is off to Mr McClung.

posted 02-29-2004 15:01               

Sir, I applaud your diligence in acquiring an understanding of the situation at hand.
Even, so, all we have really been able to expose is the tip of the iceburg.

Having been deeply immersed at the epicenter of this for as long as I have, I sometimes lose sight of the inability of newcomers to distinguish body armor propaganda and myth from harsh reality. Cherished illusions die hardest.
Working as close to the LE community as I do, this issue affects both my immediate and my extended family.
Nearly all of my best friends are LE and military folks, and all of them are at hazard for no good reason.

I trust that you now understand the underlying emotional content of my previous posts. I would like to take this opportunity to apologize for the abrupt manner in which I approached you. I will endeavor in the future to maintain a more detached presence on the topic.

I hope that the rest of the data presented at TF is of some assistance to you and yours.

Stay Sharp,
Mad Dog

posted 02-29-2004 16:53            

Detachment is a good thing to strive for in these things, but often difficult to maintain. And sometimes a little old-fashioned passion is necessary to get things moving.

Thanks again for giving me an opportunity to learn something very, very important. I will continue to support your work here in TF and in the Zylon Wars. You have my email address if there's anything I can do to help that you don't want to post in public.

Best,

posted 02-29-2004 19:30               

--why aren't the threads of the polymer fibers encased in a "sleeve" of a substance that isn't vulnerable to "forms of degradation under certain conditions"?

posted 02-29-2004 19:44               

Aside from the basic idea of Zylon being to deliver a stronger and less bulky fiber thereby rendering a more flexible, thinner and lighter vest being defeated entirely by adding relatively bulky insulators to the fiber, there is one other main reason.

Cost.

The fiber would have to be encapsulated soon enough after manufacture to prevent any and all exposure to light, heat and humidity, so that would necessitate the process being done at the Toyobo plant.

For some obscure reason, Toyobo prefers to sell the raw fiber in an unprotected state. It is shipped wrapped in black plastic, but otherwise unprotected.

Toyobo leaves it up to the individual users to determine what constitutes appropriate handling during manufacturing procedures and in the end products. Despite ample warnings from Toyobo, it seems that none of the armor manufacturers are taking suitable precautions to keep the Zylon from degrading.