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Lactide: Lactic Acid Condensed and Cracked under Vacuum, Recrystallised
Charlie

Imeundwa na

Charlie

19. Oktoba 2026DE
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Lactide: Lactic Acid Condensed and Cracked under Vacuum, Recrystallised

Lactide is the ring-shaped double molecule of lactic acid, the monomer from which PLA is made. Schneider's du Pont patent (US 2,703,316, 1955) drives the water out of lactic acid, condenses it under vacuum to a syrupy low polymer, then heats that to 200–250 °C at 8–10 mm so that lactide distils off. For a tough plastic it must be very pure: recrystallise it from ethyl acetate until it melts at 120 °C or higher (best 123–125 °C). The picture: our diagram.
Juu
1–2 days

Maagizo

1

Drive off the water

Distil the lactic acid at atmospheric pressure at 120–130 °C until nearly all the water of dilution has gone.

Vifaa kwa hatua hii:

Asidi ya Laktiki (ya kiufundi)Asidi ya Laktiki (ya kiufundi)1 kipande

Zana zinazohitajika:

Chupa yenye chini cha mviringoChupa yenye chini cha mviringo
Koili ya kifidishajiKoili ya kifidishaji
Sahani ya Kupasha JotoSahani ya Kupasha Joto
Bafu la MafutaBafu la Mafuta
Kipimajoto cha maabaraKipimajoto cha maabara
2

Condense under vacuum

Continue distilling under 17–35 mm of mercury. Water of esterification comes off and the acid becomes a syrupy low polymer (polylactic acid).

Zana zinazohitajika:

Pampu ya utupuPampu ya utupu
Kipima utupuKipima utupu
Mtego baridiMtego baridi
Bafu la MafutaBafu la Mafuta
Kipimajoto cha maabaraKipimajoto cha maabara
3

Crack to lactide

Lower the pressure to 8–10 mm and raise the temperature to 200–250 °C. Lactide distils at 130–140 °C (10–13 mm) and sets to a soft crystalline solid.

Zana zinazohitajika:

Pampu ya utupuPampu ya utupu
Kipima utupuKipima utupu
Koili ya kifidishajiKoili ya kifidishaji
Bafu la MafutaBafu la Mafuta
Kipimajoto cha maabaraKipimajoto cha maabara
Glavu Zinazostahimili JotoGlavu Zinazostahimili Joto
4

Recrystallise from ethyl acetate

Recrystallise the crude lactide from ethyl acetate, filter and dry. Repeat: in the patent the melting point rose from 114–115 °C after the first crystallisation to 118, 123–124 and 124–125 °C after the fourth.

Zana zinazohitajika:

Ethyl AsetatiEthyl Asetati
Bikari ya kioo inayostahimili jotoBikari ya kioo inayostahimili joto
Sahani ya Kupasha JotoSahani ya Kupasha Joto
Kifaneli cha Büchner (kauri)Kifaneli cha Büchner (kauri)
Karatasi ya KuchujaKaratasi ya Kuchuja
Miwani ya kinga dhidi ya kemikaliMiwani ya kinga dhidi ya kemikali
5

Check the melting point

Put a few crystals in a capillary tube and warm slowly. Lactide melting at 120 °C or above is fit for making PLA; below 120 °C it gives a brittle polymer.

Zana zinazohitajika:

Mrija mwembamba wa kiooMrija mwembamba wa kioo
Kipimajoto cha maabaraKipimajoto cha maabara
Bafu la MafutaBafu la Mafuta

Vifaa

1

Zana Zinazohitajika

15

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Laktaidi

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Blueprint zinazohusiana

Blueprint hizi zinashiriki maarifa — mbinu, vifaa au kanuni

Lactic Acid: Glucose Fermented over Chalk, Freed with Sulphuric Acid
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Lactic Acid: Glucose Fermented over Chalk, Freed with Sulphuric Acid

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Ethyl Acetate: Alcohol, Sulphuric Acid and Sodium Acetate Distilled
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Ethyl Acetate: Alcohol, Sulphuric Acid and Sodium Acetate Distilled

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