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Carbon fibers were placed between layers of 3D printed polymer to improve strength and fatigue life , while thermal treatment was performed to further increase the mechanical properties .
 material: Carbon fibers; manufacturing process: 3D printed; machanical property: strength; machanical property: fatigue life; manufacturing process: thermal treatment; concept or principle: mechanical properties
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: 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:
 material: Carbon fibers; manufacturing process: 3D printed; machanical property: strength; machanical property: fatigue life; manufacturing process: thermal treatment; concept or principle: mechanical properties