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Polycarbonate
In 1953 Hermann Schnell at Bayer joined bisphenol A into long chains through carbonate links and got a clear plastic of remarkable toughness. Daniel Fox at General Electric reached the same material independently the same year, and both companies were selling it by around 1960.
**US 3,028,365**, "Thermoplastic aromatic polycarbonates and their manufacture", Schnell, Bottenbruch and Krimm, assigned to Bayer, filed 12. October 1954, granted 3. April 1962, claims "a high molecular weight, thermoplastic polycarbonate having a melting point of at least about 135°C", made from bisphenol A among a wider family.
**The classic route uses phosgene, a war gas.** You build a drop-weight rig and find the energy that cracks acrylic - then drop the same on polycarbonate.
Oqalayo
2 hours
Imiyalelo
1
1
The specimen table
The specimen table
Cut a 300 x 300 mm plywood board and bore a 100 mm hole in its centre with the hole saw. Rest it on two blocks so the hole is open underneath.
Izinto zokwakha zalesi sinyathelo:
Ishidi le-plywood1 ucezuAmathuluzi adingekayo:
Isaha Sesandla
Isethi yamasaha ezimbobo
Ibhola Elingenantambo2
2
The drop tube
The drop tube
Take 2 m of 32 mm PVC pipe. Mark heights from the bottom every 100 mm and drill a 3 mm hole straight through at each mark. A nail through a hole holds the ball; pulling it drops the ball from that height.
Izinto zokwakha zalesi sinyathelo:
Ipayipi Le-PVC2 amamitha
Izipikili1 ucezuAmathuluzi adingekayo:
Ithephu Lokulinganisa
Isethi yamamaka kapendeIbhola Elingenantambo
Isethi yamabhola okubhoboza ebhokisini3
3
Stand it plumb
Stand it plumb
Clamp the tube to a post or bench leg with pipe clamps, its bottom 10 mm above the hole's centre. Check it with the plumb bob in two directions.
Amathuluzi adingekayo:
Isibambi somshini
Umucu wesisindo (i-plumb bob)4
4
Clamp a sheet
Clamp a sheet
Cut 150 x 150 mm squares of 3 mm acrylic and 3 mm polycarbonate. Leave the protective film on. Clamp one over the hole at all four corners.
Izinto zokwakha zalesi sinyathelo:
Ipuleti Le-akhriliki1 ucezu
Ipuleti le-polycarbonate (elicwebile)1 ucezuAmathuluzi adingekayo:
Isibambo esiyi-C
Izibuko Zokuphepha Ezicwathile5
5
Climb the ladder
Climb the ladder
Glasses on. Weigh the 25 mm ball. Drop it from 100 mm, then 200 mm, and so on, on a fresh spot each time, until the acrylic cracks. Record that height. If it survives the top hole, repeat with the 1 kg weight as in the next step.
Amathuluzi adingekayo:
I-bearing yamabhola ensimbi
Isikali Sedijithali EsinembileIzibuko Zokuphepha Ezicwathile6
6
Same on polycarbonate
Same on polycarbonate
Repeat the whole ladder on polycarbonate. If it survives the top hole, tape the 1 kg weight to a rounded bolt head and drop that from 1.8 m outside the tube, hands clear.
Amathuluzi adingekayo:
IsisindoIzibuko Zokuphepha Ezicwathile7
7
Energy at failure
Energy at failure
Ilayisha incwadi ye-Jupyter…
8
8
History & Context
History & Context
**What the patent specifies:** high-molecular aromatic polycarbonates from dihydroxy compounds such as bisphenol A, melting at 135 °C or more. **Modern build (derived):** extruded clear polycarbonate sheet.
It went into safety glasses, riot shields, machine guards, bottles and later CDs. Its limits: it scratches easily, yellows in sunlight without a UV coat, is attacked by some solvents, and bisphenol A leaching from food containers made many makers switch those to other plastics.
Izinto
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Amathuluzi Adingekayo
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