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ref: -0 tags: polyimide polyamide basic reduction salt surface modification date: 02-27-2015 19:45 gmt revision:0 [head]

Kinetics of Alkaline Hydrolysis of a Polyimide Surface

  • The alkaline hydrolysis of a polyimide (PMDA-ODA) surface was studied as a function of time, temperature and hydroxide ion concentration.
  • Quantification of the number of carboxylic acid groups formed on the modified polyimide surface was accomplished by analysis of data from contact angle titration experiments.
  • Using a large excess of base, pseudo-first-order kinetics were found, yielding kobs ≈ 0.1−0.9 min-1 for conversion of polyimide to poly(amic acid) depending on [OH-].
  • From the dependence of kobs on [OH-], a rate equation is proposed.
  • Conversion of the polyimide surface to one of poly(amic acid) was found to reach a limiting value with a formation constant, K, in the range 2−10 L·mol-1.

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ref: car-0 tags: saab modifications convertible 900 SE date: 04-29-2013 18:09 gmt revision:12 [11] [10] [9] [8] [7] [6] [head]

So, a year and a half ago I bought a green 1995 900 SE convertible for $600. At that time, it didn't move or go in reverse. Since then, I've been fixing up random things here an there (or just straight modifying / breaking the car by other standards) and recently realized that I had better start keeping track of everything that's been done, in case my memory lapses or i need to know where some random part came from. I doubt this will be useful to anyone else - next time, pictures!

Things that I've done to the green convertible, in approximate chronological order:

  1. replaced the clutch cable. previous owner says that the clutch was relatively new; verified when i swapped the transmission.
  2. replaced the turbo transmission with one from a 900 S n/a; new transmission has slightly shorter final drive ratio, which is fun. Both transmissions have approximately the same number of miles on them (again, the original tranny had no reverse).
    1. The subframe brace bolts were seized on this car - it took several weeks off and on + heat + rust solvent to remove both large 18mm bolts. I recommend replacing them with new ones if possible (these look fine, they are very heavy bolts).
    2. In the process of doing this, I stripped one captive nut used for the transmission mount, and had to drill it out & replace it with a 3/8" grade 8 bolt & double nut affair from home cheapo. Be careful when threading these bolts in, or you'll have to do the same!
  3. replaced the rubber boots on the control-arm ball joints, and in turn repacked the ball joints with grease. This takes a lot of patience.
  4. installed a new gas filler hose from the plastic filler line to the gas tank. Previous one was held on with zip-ties. (yes, zip-ties: after i filled the damn thing up, i noticed that it was leaking excessively, and had to drive it around until the gas was burned through & unlikely to drip all over the ground once the car was parked.)
  5. removed turbo silencer prior intercooler.
  6. installed a new passenger side headlamp assembly.
  7. replaced the thermostat.
  8. replaced and gapped all 4 spark plugs.
  9. reflashed the ECU to stage 2.5 or so - 1.4 bar peak boost @ 3k rpm, 1.2 bar above 4k rpm, no boost limit in 2nd gear. This was done via Trionic5 suite, available from http://ecuproject.com/
  10. replaced both front struts & shocks with parts from a junkyard 1997 900 SE; previous ones had a loose / faulty wheel bearing. Very worthy upgrade.
  11. replaced all brake pads + front brake rotors to fit the struts/shocks/bearing hubs from the 97 900 SE. (the hubs are incompatible with 1995 disc rotors - different internal flange diameter.)
  12. replaced both front brake calipers. The previous 1995-version calipers did not mate well with '97 struts and '97 discs. Initially bought used calipers off of ebay, but the damn bleeder valve was sheared off at the nut, so I took the pads off them and installed remaned ones. Brake feel is much, much better now.
  13. added internal bracing / roll cage, though without the top hoop. removed most of the upholstery & seats in the back to fit this.
  14. oil and filter changed at 161k.
  15. adjusted some of the window seals - but they still need to be replaced eventually.
  16. removed condenser and AC compressor.
  17. replaced / changed the serpentine belt to a 71" / 1805mm 6-tooth duralast belt - aka AC delete belt ref. Water pump is only 25% engaged with the belt now, but seems to work just fine (and the internet verifies this.)
  18. repainted some rust spots on the trunk lid.
  19. installed plenty of grease on the upholstery -- oops :P
  20. Got two used tires from America's discount tires; rear tires still shady. Will get around to replacing them; have already gotten around to destroying the front ones with second-gear burnouts to 60 :)
  21. Resurfaced flywheel, replaced clutch disc with one from a Jeep Wagoneer (though not the pressure plate -- it looked fine, no signs of cracking).
  22. Replaced drivers side main crankcase seal.
  23. Replaced drivers side transaxle output bushing + drivers and passengers transaxle output seals
  24. Removed oil pan, cleaned pickup, and re-did oil pan seal.
  25. Welded a new stud on the turbo, applied with anti-seize this time! always use anti-seize on exhaust parts, they get hot!
  26. Removed head, had it ground to fix a minor valve leak and milled flat (increasing the compression ratio a bit). Cleaned the block top surface, intake manifold, fuel injectors, piston heads, and cylinders as best I could. Removed & replaced the broken stud underneath the power steering pump. In the course of having the head out, replaced the relevant seals:
    1. Valve stem seals
    2. Head gasket
    3. Intake gasket
    4. Exhaust gasket
  27. Replaced upper and lower radiator hoses.
  28. As of May 1 2012, I no longer own the car -- I'm off to California, and can't take it with me. May the new owner enjoy it as much as I have!

Things that need to be done to the 'vert:

  1. There is still a click in the rear drivers-side brake, should inspect it; likely brake pads.
  2. New rear tires (!!).
  3. hood gas springs are shot. Meh.

Now, wonders of wonders, I have another of these cars - though a sedan, not a convertible. It cost much more (about 8x as much), and is hence in much better shape. That said, I've had to do the following:

  1. Replaced the rear drivers side brake caliper. In the rain; should have waited for a sunny day, as this took longer than expected. (Everything does.)
  2. New front disc rotors & pads Dec 2008. As of July 2010, they should be replaced soon.
  3. Replaced the clutch + throwout bearing. The latter was making terrible noises back when I drove to Atlanta fall 2008; I nearly didn't make it back.
  4. Removed a "Saab saver" steering rack brace installed by a previous owner. To install this brace, you need to drill through the wheel well, which allows (possibly salty) water to touch the bare metal. As a result of this + stress upon metal that was not engineered to bear it, the wheel well cracked almost to the point where the shock mount was about to go through the hood! I'm glad I caught this while the car was parked, and not while i was going 70!
  5. welded the wheel well back together with 2x1/4" steel strap. I tried to weld to the major braces of the unibody, and later covered everything with plenty of paint and spray-on rubber soundproofing compound. Still, I worry about the opposite side of the metal, where the heat from the welding undoubtably removed rust-preventing paint. Seems reliable so far.
  6. replaced drivers side inner CV joint boot & of course repacked the CV joint grease. You need to take the CV joint completely apart to fit the thing - it won't stretch!
  7. Built a tool for removing the differential output bushing from the transmission. As the output of the differential is only a bushing, and it's put under a lot of stress during hard acceleration (especially peel outs - one wheel spinning much faster than the other = lots of strain on diff), the bushing wears out quickly. It is a pressure fit sleeve, so I reasoned that it could be removed by pressure - not quite. It must be cut out, very tediously, using a single-ended hacksaw. To keep metal debris out of the diff housing, insert a rag into where the CV axle was, and flush the tranny throughly after installing a new bushing.
    1. This is all rather difficult, so don't peel out!
    2. The passengers side half-axle is supported by a bearing by the alternator, so it does not have the same levels of stress & does not wear as quickly.
  8. Four new tires. $560 - beh.
  9. Replaced front brake discs Nov 2010
  10. New front strut inserts + reground front brakes May 2012 -- in Albuquerque.
  11. Flushed transmission oil in the desert outside of Lake Powell; the heat of Phoenix did it in & shifting was starting to be very sticky. Also adjusted the clutch cable, which later snapped while driving in SF. (Fortunately, was able to first gear it to a parking garage, where I fixed it on the spot).
  12. Fan control relay went out in the desert of Utah; ended up shorting it closed with a bit of wire. Said wire must be removed after turning off the car, otherwise the fan will run indefinitely!
  13. Sold car February 2013. May the next owner enjoy her well!

And now the blue 1998 saab 900, sold to Adam:

  1. Replaced front oxygen sensor
  2. Replaced rear transmission mount (had to take off the subframe for this, yuck)
  3. Fixed front passengers side window regulator (ish).
  4. Adjusted clutch master cylinder. The linkage between the pedal and the master cylinder was plastic and badly worn, which was causing the clutch to never fully disengage, in turn gradually leading to third gear synchro wearing out. Adjusted the stop on the pedal to compensate for this; it should ultimately be replaced, though works fine now.
  5. Replaced front drivers side headlight.

Next, the saab 9000 aero:

  1. Swapped wastegate / APC control valve with one from my 900 to remedy overboost issues.
  2. Replaced alternator brushes. Thing was a bear to remove -- had to jack up the engine a bit to get it out!
  3. Re-soldered alternater to battery charging and starting wire
  4. Re-soldered engine-to-chassis grounding wire; transmission to battery wire seemed fine.
  5. Replaced tubing from blow-off valve, PCV, and fuel pressure regulator to intake manifold with aftermarket silicone tubing.
  6. Installed new radio.
  7. Replaced headlight relay.
  8. Replaced turn signal relay.
  9. Replaced thermostat.
  10. Replaced rear lower panhard rod bushing; was falling out and rubbing against the rear axle.
    1. All of the other rear-end suspension bushings looked fine!
  11. Gapped all 4 spark plugs.
  12. New tires @ 120k miles; will need to rotate them.
  13. Cut wire from glass break sensor to security / immobilizer module, as passing buses were setting off the car alarm.
  14. Bought new IAC valve off ebay, put it in (difficult compared to a NG900!), but it idled too high (perhaps I needed to reset the ECU?). Therefore I took the new one out, cleaned and lubricated the old one, and re-installed it. The car still idles high for ~10 seconds when put in neutral, but it comes down, and I suppose I'll live with that for now.
  15. Blocked off the evap & PCV & instrument boost gauge intake manifold barbs in the process of debugging the high idle (figured that there were vacuum leaks).
  16. Replaced central lock relay with a used one from ePartsLand.
  17. Installed new drivers-side wheel bearing. Note you need to take the axle out to get access to the hex-head bolts which hold the hub in. Thankfully, it's not hard once this is done.
  18. New front/rear brakes/rotors.
    1. Front brakes were easy; rear brakes have a hidden retraction allen key.
      1. Follow the directions here. To fit a new rotor and pads, the whole brake caliper needs to be taken apart!
  19. Removed A/C and installed a short belt 2325 mm length.
    1. Note: tensioner pully is threaded backwards to prevent pulley rotation from loosening it.
    2. Note: to disengage the tensioner, you don't need a special tool - just put a breaker bar on a 19mm socket & use that as a lever.
  20. Rear shocks were replaced with Bilstein HD types from thesaabsite.com
  21. Installed new heater core, and all but one of the hoses leading to it.
  22. New fuel filter 121k
  23. Headgasket job April 21-25:
    1. New headgasket + new headbolts. One of them did not torque up to the right 'feel' following the saab-specificed procedure (33ft-lbs, 44ft-lbs, 90deg torque-to-yield. I'm going to replace that one with a M12 12.9 grade bolt from Mcmaster; have ordered 110, 120, and 130mm length & will see which fits best. Original stretch bolts are grade 10.9.
    2. New radiator
    3. New idler pulley
    4. New head gasket + head bolts; only cleaned the block and head, did not have them ground. Seems OK so far!
    5. Flushed oil, though it still took a few hours at temperature to boil off the remaining antifreeze that had leaked into the engine oil.
    6. Kept the timing chain + guides, though it's stretched near the limit; will have to replace next time I have the thing disassembled.
    7. New exhaust manifold. Pain to install, as I didn't remove the turbo when removing the head. Still quite possible.
    8. New urethane engine torque mount. Just cut out the old rubber inserts with a hacksaw -- not too hard. Be careful which way you put in the new blue inserts -- they are asymmetrical.
    9. One new hood gas strut = enough.
    10. New plugs. Old ones were filthy.
  24. Todo
    1. Windshield & Por-15 the frame around it; I bet the previous installer scratched the paint.
    2. Camber bolts to help the tires last longer.