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Then , the proposed methodology is applied to the recycling study of polylactic acid ( PLA ) material addressed to the fused filament fabrication ( FFF ) technique , which is currently the most widely used .
 methodology, recycling, polylactic acid, PLA, material, fused filament fabrication, FFF
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:
 methodology, recycling, polylactic acid, PLA, material, fused filament fabrication, FFF