On 1/22/2016 12:05 PM, lists wrote:
> remember, hydrolysis is a bi-directional chemical reaction. Not only is
> there a threshold at which hydrolysis will occur, there is also a threshold
> at which hydrolysis will run in the other direction and the oligomers will
> cross-link back into polymers.
That was definitely Bertram and Cuddihy's conjecture, but in the work
that Ric Bradshaw did at IBM, he has seen evidence that this is not the
case. As I understand it, he draws the following distinction:
In basic chemical theory, the reaction is bidirectional, but in the
filled matrix that is the recording tape binder, there is little
likelihood that the ends of the severed long chain molecules will find
receptive "landing sites" [RLH's phrase, not RWB's] and even less
likelihood that they will find the original points from which they were
So, while there may be some random cross linking, the physical presence
of the magnetic particles, lubricants, and other components of the mag
coat matrix interferes with the reversing of the process. I believe I
can state Bradshaw's conjecture as: yes, there may be some re-linking,
but it never will come close to the original condition on day of
manufacture. In other words, once it goes down this path, it's never
coming all the way back.
Thank you for the clarification of Richardson's hypothesis. I don't
think I ever got that out of what I've read of his, but I have not read
all of the material he sent as some was sent under non-disclosure and I
do not recall opening it. I felt if I read it and integrated it into my
understanding, I might inadvertently disclose something. At one point in
my past life, I commented, "I have signed so many NDAs that I can't even
talk to myself!"
Also, thanks for confirming the existence of a threshold in the onset of
hydrolysis. That makes sense.
One other question. One of your recent posts seems to suggest that the
hydrophilic nature of the carbon black or other back-coating materials
was part of the plan. Was it? Or was carbon black chosen to be
conductive to dissipate the static charge which, under certain
conditions can spark over and print a "tick" to the tape? Perhaps the
hydrophilic nature of carbon black was either ignored or not known by
the designers--or they thought that it wouldn't be an issue. It would be
much more expensive to deposit a copper or silver (and probably even
aluminum) thin film on the back side of the base film to provide that
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
Quality tape transfers -- even from hard-to-play tapes.