Polyethylene Terephthalate (PET/PETG) - Revision history

Mtanjutco3 at 17:57, 9 November 2025

2025-11-09T17:57:03Z

← Older revision		Revision as of 13:57, 9 November 2025
Line 14:		Line 14:

	=== On the Atomic Level ===		=== On the Atomic Level ===
			At the molecular level, PET is a '''thermoplastic polyester''' composed of repeating '''ester linkages''' between '''aromatic terephthalate units''' and '''aliphatic ethylene glycol units'''. Its repeating structural unit is:

			[−O−CH2−CH2−O−CO−C6H4−CO−]n

			* The '''benzene ring (C₆H₄)''' in terephthalate provides rigidity and strength, while the '''ethylene (CH₂–CH₂)''' segment imparts flexibility.
			* The '''ester groups (–CO–O–)''' form strong dipole interactions, giving PET its high tensile strength and thermal stability.
			* '''Crystallinity''' plays a key role:
			** '''Amorphous PET''': transparent, flexible, lower barrier properties.
			** '''Semi-crystalline PET''': opaque, higher strength and resistance to deformation.
			* PET’s '''glass transition temperature''' is around 70 °C, and its '''melting point''' is approximately 250 °C.

			These atomic-scale characteristics make PET highly suitable for both '''structural''' and '''packaging''' applications.

			=== Production Process ===
			Polyethylene terephthalate (PET) is produced through a '''polycondensation reaction''' between '''ethylene glycol (EG)''' and '''terephthalic acid (PTA)''', or alternatively '''dimethyl terephthalate (DMT)'''. Two industrial routes are widely used:

			# '''Direct Esterification Route (PTA/EG Process):'''
			#* PTA and EG are combined at elevated temperatures (~250 °C) to form '''bis(2-hydroxyethyl) terephthalate (BHET)''' and water.
			#* The mixture then undergoes '''polycondensation''', releasing excess ethylene glycol and forming long PET polymer chains.
			#* Catalysts such as '''antimony trioxide''', '''titanium butoxide''', or '''germanium dioxide''' are used to accelerate polymerization.
			# '''Transesterification Route (DMT Process):'''
			#* DMT reacts with EG to form BHET and '''methanol''' as a by-product.
			#* The BHET is then polymerized under heat and vacuum to yield PET.

			The resulting polymer can be processed into '''amorphous''' (transparent) or '''semi-crystalline''' (opaque) forms depending on cooling rates and crystallization conditions. Rapid cooling prevents molecular alignment, while slower cooling promotes crystalline structure formation.

			=== Safety, Hazards, and Environmental Measures ===
			'''Occupational and consumer safety:'''

			* PET itself is '''chemically stable and non-toxic''', but '''catalyst residues''' (particularly '''antimony compounds''') can migrate in trace amounts from containers into food or beverages under high temperatures (e.g., prolonged sunlight exposure).
			* Workers in PET manufacturing must control exposure to '''ethylene glycol vapors''', '''antimony dust''', and high-temperature processing conditions, typically using '''ventilation systems''', '''PPE''', and '''temperature-controlled reactors'''.

			'''Environmental impacts:'''

			* PET is '''non-biodegradable under normal conditions''', contributing to long-term plastic waste accumulation and '''microplastic pollution''' through fiber shedding or fragmentation.
			* Recycling mitigates this impact. PET can be '''mechanically recycled''' into new bottles or '''chemically depolymerized''' back into its monomers (BHET, EG, PTA).
			* Certain microorganisms, such as ''Ideonella sakaiensis'', have shown the ability to '''enzymatically degrade PET''', offering future solutions for biorecycling.

			'''Safety and sustainability measures include:'''

			* Using '''food-grade catalysts''' (e.g., titanium-based alternatives to antimony).
			* Maintaining '''closed-loop recycling systems''' to recover and reuse PET materials.
			* Minimizing high-temperature storage of PET bottles to prevent antimony migration.

	=== Prints ===		=== Prints ===

Mtanjutco3 at 18:21, 26 October 2025

2025-10-26T18:21:38Z

← Older revision		Revision as of 14:21, 26 October 2025
Line 1:		Line 1:
	[[File:PROseriesPETG (2).png\|thumb\|600x600px\|The relative property levels of PETG.]]		[[File:PROseriesPETG (2).png\|thumb\|600x600px\|The relative property levels of PETG.]]
	PETG (Polyethylene Terephthalate) is a commonly use filament FDM 3D printing. It is a more durable version than PLA so can be used in higher ~~stress~~ related prototypes. Notably, PETG is used commonly in the Take-a-T Make-a-T project at the MILL.		PETG (Polyethylene Terephthalate) is a commonly use filament FDM 3D printing. It is a more durable version than PLA so can be used in higher impact strength related prototypes. Notably, PETG is used commonly in the Take-a-T Make-a-T project at the MILL.
	[[File:Screenshot 2025-10-26 133956.jpg\|thumb\|382x382px\|The atomic structure of PETG.]]		[[File:Screenshot 2025-10-26 133956.jpg\|thumb\|382x382px\|The atomic structure of PETG.]]

Mtanjutco3 at 18:08, 26 October 2025

2025-10-26T18:08:05Z

← Older revision		Revision as of 14:08, 26 October 2025
Line 1:		Line 1:
	[[File:PROseriesPETG (1).~~webp~~\|thumb\|~~597x597px~~\|The relative property levels of PETG.]]		[[File:PROseriesPETG (2).png\|thumb\|600x600px\|The relative property levels of PETG.]]
	PETG (Polyethylene Terephthalate) is a commonly use filament FDM 3D printing. It is a more durable version than PLA so can be used in higher stress related prototypes. Notably, PETG is used commonly in the Take-a-T Make-a-T project at the MILL.		PETG (Polyethylene Terephthalate) is a commonly use filament FDM 3D printing. It is a more durable version than PLA so can be used in higher stress related prototypes. Notably, PETG is used commonly in the Take-a-T Make-a-T project at the MILL.
	[[File:Screenshot 2025-10-26 133956.jpg\|thumb\|382x382px\|The atomic structure of PETG.]]		[[File:Screenshot 2025-10-26 133956.jpg\|thumb\|382x382px\|The atomic structure of PETG.]]
Line 11:		Line 11:
	* Bending Strength (MPa): 67.5 ± 2.5		* Bending Strength (MPa): 67.5 ± 2.5

	[[~~index~~.php?title=File:~~PLA_Atomic~~.png\|link=https://millwiki.mse.gatech.edu/File:PLA_Atomic.png\|thumb]]		[[Index.php?title=File:PLA Atomic.png\|link=https://millwiki.mse.gatech.edu/File:PLA_Atomic.png\|thumb]]

	=== On the Atomic Level ===		=== On the Atomic Level ===

	=== Prints ===		=== Prints ===

Mtanjutco3: Images/template

2025-10-26T17:54:19Z

Images/template

New page

[[File:PROseriesPETG (1).webp|thumb|597x597px|The relative property levels of PETG.]]
PETG (Polyethylene Terephthalate) is a commonly use filament FDM 3D printing. It is a more durable version than PLA so can be used in higher stress related prototypes. Notably, PETG is used commonly in the Take-a-T Make-a-T project at the MILL.
[[File:Screenshot 2025-10-26 133956.jpg|thumb|382x382px|The atomic structure of PETG.]]

=== Specific Properties ===

* Printing Temperature (oC): 220 - 250
* Hot bed Temperature (oC): 70 - 90
* Printing Speed (mm/s): 40 - 80
* Density (g/cm3): 1.28
* Bending Strength (MPa): 67.5 ± 2.5

[[index.php?title=File:PLA_Atomic.png|link=https://millwiki.mse.gatech.edu/File:PLA_Atomic.png|thumb]]

=== On the Atomic Level ===

=== Prints ===