Polymers and elastomers · Banned
PVC, nylon, acrylic
PVCvalues describe: PVC
Why it's out
Plasticizers, water, monomers.
Where it hides
Cable jackets and quick brackets that never got reviewed.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated. Provisional provenance: NASA outgassing database; O'Hanlon, A User's Guide to Vacuum Technology.
Wet cleaning
| Recipe | not applicable |
|---|---|
| Forbidden | nylon in particular: it comes out of the bath heavier than it went in |
| Limit | water absorption |
Vacuum and outgassing
| Outgassing, unbaked (10 h) | 1e-5 to 1e-6 mbar·L/s/cm² |
|---|---|
| Vapour pressure | PVC plasticiser is continuous; nylon holds several percent water by mass |
Temperature
| Bake, assembled | 60 °C |
|---|---|
| Metallurgical limit | THE CONDEMNING MECHANISM: plasticiser for PVC, water absorption for nylon, and PVC releases chloride that attacks stainless |
Thermal
| CTE | 70 ppm/K |
|---|---|
| Thermal conductivity | 0.19 W/m·K |
| Specific heat | 1000 J/kg·K |
| Emissivity | 0.9 |
Mechanical
| Strength | 50 tens MPa |
|---|---|
| Tensile | 50 MPa |
| Young's modulus | 3 GPa |
| Density | 1.4 g/cm3 |
Electrical and magnetic
| Relative permeability | 1.0 |
|---|
Engineering
| Availability and cost | commodity |
|---|
Outgassing
9 sourced measurements for this card. A rate means nothing without the pumping time it was read at, so each one states it or declares it missing. The whole base, filters included, is at /tools/outgassing/.
Signature: 1e-5 unbaked to 1e-8 baked, a drop of 3.0 decades.
| Material as published | Species | State | Pumping time | Rate |
|---|---|---|---|---|
| Methyl methacrylate | total | unbaked | the abscissa of the curve below | 5.60e-6 at 1 h to 1.87e-6 at 10 h |
| Nylon | total | unbaked | the abscissa of the curve below | 1.60e-5 at 1 h to 8.00e-6 at 10 h |
| Plexiglas | total | unbaked | the abscissa of the curve below | 9.60e-7 at 1 h to 3.60e-7 at 10 h |
| Plexiglas | total | unbaked | the abscissa of the curve below | 4.13e-6 at 1 h to 2.40e-6 at 10 h |
| Polyamid | total | unbaked | the abscissa of the curve below | 6.13e-6 at 1 h to 3.07e-6 at 10 h |
| PVC (24 h at 95 percent RH) | total | unbaked | the abscissa of the curve below | 1.13e-6 at 1 h to 2.67e-8 at 10 h |
| Ultrahigh molecular weight polymethylmethacrylate, sample number 2, obtained by frontal polymerization at 60 C for 5 days, molecular weight about 1e7 g per mole | total | baked | the abscissa of the curve below | 1.04e-6 at 24 h to 1.60e-7 at 264 h |
| Ultrahigh molecular weight polymethylmethacrylate, sample number 2, obtained by frontal polymerization at 60 C for 5 days, molecular weight about 1e7 g per mole | total | baked | the abscissa of the curve below | 2.13e-8 at 24 h to 1.79e-8 at 72 h |
| Ultrahigh molecular weight polymethylmethacrylate, sample number 2, obtained by frontal polymerization at 60 C for 5 days, molecular weight about 1e7 g per mole | total | unbaked | the abscissa of the curve below | 1.56e-7 at 24 h to 3.67e-8 at 96 h |
Sources: S-ELSEY-1975-II, S-SEMENOV-IPAC2021. Full citations and conditions at the base and in /data/outgassing.json.