5136
Experimentation is conducted to process polyethylene terephthalate bottles and packaging into filament that can then be used for additive manufacturing methods like fused filament fabrication , without the use of additives or modification to the polymer .
 process, polyethylene terephthalate, filament, be, additive manufacturing, fused filament fabrication, additives, polymer
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 process, polyethylene terephthalate, filament, be, additive manufacturing, fused filament fabrication, additives, polymer