ART
BEAUTY & WELLNESS
CRAFT
CULTURE & HISTORY
ENTERTAINMENT
ENVIRONMENT
FOOD & DRINKS
REVERSE ENGINEERING
SCIENCES
SPORTS
TECHNOLOGY
WEARABLES
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.
Advanced
1–2 days
Instructions
1
1
Drive off the water
Drive off the water
Distil the lactic acid at atmospheric pressure at 120–130 °C until nearly all the water of dilution has gone.
Materials for this step:
Lactic Acid (technical)1 pieceTools needed:
Round-Bottom Flask
Condenser Coil
Hot Plate
Oil Bath
Thermometer - Lab2
2
Condense under vacuum
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).
Tools needed:
Vacuum Pump
Vacuum Gauge
Cold TrapOil BathThermometer - Lab3
3
Crack to lactide
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.
Tools needed:
Vacuum PumpVacuum GaugeCondenser CoilOil BathThermometer - Lab
Heat-Resistant Gloves4
4
Recrystallise from ethyl acetate
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.
Tools needed:
Ethyl Acetate
Heat-Resistant Glass BeakerHot Plate
Buchner Funnel (Porcelain)
Filter Paper
Chemical Splash Goggles5
5
Check the melting point
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.
Tools needed:
Capillary Glass TubeThermometer - LabOil BathMaterials
1- 1 piecePlaceholder
Tools Required
15- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- 1 vendor sell this, none ship to you yetPlaceholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
- Placeholder
This blueprint makes
Related Blueprints
These blueprints share knowledge with this one — techniques, materials, or principles that connect them in the learning graph.
CC0 Public Domain
This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.
Support the Maker by purchasing products through their Blueprint where they earn a Maker Commission set by Vendors, or create a new iteration of this Blueprint and include it as a connection in your own Blueprint to share revenue.