Photopolymerization Process Quiz
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Questions and Answers

What type of radiation do most photopolymers react to?

  • X-rays
  • Microwave radiation
  • Infrared radiation
  • Ultraviolet (UV) range of wavelengths (correct)

    • In which industry are photopolymers widely applied?

  • Coating and printing industry (correct)
  • Textile industry
  • Automotive industry
  • Food processing industry

    • What is the primary material used in photopolymerization processes?

  • Radiation-curable resins or photopolymers (correct)
  • Metals
  • Plastics
  • Glass

    • What is the first vat photopolymerization process called?

    <p>Stereolithography</p> Signup and view all the answers

    What type of radiation do most photopolymers react to?

    <p>Ultraviolet (UV) radiation</p> Signup and view all the answers

    What is the primary material used in photopolymerization processes?

    <p>Liquid, radiation-curable resins</p> Signup and view all the answers

    In which industry are photopolymers widely applied?

    <p>Coating and printing industry</p> Signup and view all the answers

    What is used to seal the top surfaces of teeth and prevent cavities?

    <p>Photopolymers</p> Signup and view all the answers

    How are coatings cured in the application of sealing teeth surfaces?

    <p>By radiation that blankets the resin</p> Signup and view all the answers

    What changed with the introduction of stereolithography in sealing teeth surfaces?

    <p>The need for patterning either the material or the radiation</p> Signup and view all the answers

    What is the term that encompasses stereolithography (SL) and related processes?

    <p>Vat photopolymerization</p> Signup and view all the answers

    Which type of radiation is commonly used in VP systems for curing commercial photopolymers?

    <p>UV and visible light</p> Signup and view all the answers

    In which industry is visible light predominantly used for curing photopolymers?

    <p>Dentistry</p> Signup and view all the answers

    What was the company created to market SL machines as 'rapid prototyping' machines to the product development industry?

    <p>3D Systems</p> Signup and view all the answers

    Which configuration for photopolymerization processes in a vat has seen some research interest?

    <p>Two-photon approaches</p> Signup and view all the answers

    Which method of processing is not covered in the chapter on photopolymerization?

    <p>Line-wise processing</p> Signup and view all the answers

    What type of approach irradiates entire layers at one time in photopolymerization processes?

    <p>Mask projection, or layer-wise, approaches</p> Signup and view all the answers

    What distinguishes the mask projection approach from the vector scan and two-photon approaches?

    <p>It utilizes a large radiation beam patterned by a Digital Micromirror Device™</p> Signup and view all the answers

    What is unique about the photopolymerization process in the two-photon approach?

    <p>Photopolymerization occurs at the intersection of two scanning laser beams</p> Signup and view all the answers

    What is a distinguishing feature of the vector scan and mask projection approaches in comparison to the two-photon approach?

    <p>They require recoating or applying a new layer of resin</p> Signup and view all the answers

    What is the primary focus of the chapter on photopolymerization?

    <p>Introducing photopolymer materials and presenting different technologies and processes</p> Signup and view all the answers

    What is the main advantage of approaches that avoid recoating in photopolymerization?

    <p>Faster and less complicated processes</p> Signup and view all the answers

    What does the chapter contrast the mask projection approach with?

    <p>The vector scan approach</p> Signup and view all the answers

    What is the focus of the section on Vat Photopolymerization Materials?

    <p>Background of UV photopolymers</p> Signup and view all the answers

    From where is much of the material in the Vat Photopolymerization Materials section derived?

    <p>Jacobs book and a Master’s thesis</p> Signup and view all the answers

    What are the two subsections that conclude the Vat Photopolymerization Materials section about?

    <p>Reaction rates and characterization methods</p> Signup and view all the answers

    What type of radiation is predominantly used in commercial SL systems for curing photopolymers?

    <p>UV</p> Signup and view all the answers

    Which type of laser is used in the SLA-250 from 3D Systems for photopolymer curing?

    <p>Helium–cadmium (HeCd) laser</p> Signup and view all the answers

    What distinguishes thermoplastic polymers from VP photopolymers?

    <p>VP photopolymers exhibit much less creep and stress relaxation.</p> Signup and view all the answers

    In mask projection DMD-based systems, what types of radiation are used for curing photopolymers?

    <p>UV and visible light</p> Signup and view all the answers

    What is a disadvantage of epoxy resins in SL resins?

    <p>Slow photospeed and brittleness of the cured parts</p> Signup and view all the answers

    What is a benefit of adding acrylate to epoxy resins in SL resins?

    <p>Rapidly building part strength and reducing brittleness</p> Signup and view all the answers

    What is a characteristic of the polymerization of epoxy compositions in SL resins?

    <p>Leads to a shrinkage of 1–2 %</p> Signup and view all the answers

    Why are most commercially available SL resins today epoxides with some acrylate content?

    <p>To combine the advantages of both curing types</p> Signup and view all the answers

    What is a disadvantage of acrylate-based resins in SL resins?

    <p>'High reactivity but typically produced weak parts due to inaccuracy caused by shrinkage and curling'</p> Signup and view all the answers

    'When a fresh coating was put on the exposed layer, some radiation went through the new coating and initiated new photochemical reactions in the layer that was already partially cured.' This statement refers to which type of resin in SL resins?

    <p>'Acrylate-based resins'</p> Signup and view all the answers

    What is a consequence of additional cross-linking on a layer in SL resins?

    <p>Extra shrinkage, increased stresses, and curling observed during or after part fabrication process</p> Signup and view all the answers

    Why are acrylates useful in epoxy resins for SL processes?

    <p>To rapidly build part strength and reduce brittleness</p> Signup and view all the answers

    What is the term used to describe the process of linking small molecules into larger molecules in photopolymer chemistry?

    <p>Polymerization</p> Signup and view all the answers

    Which type of photopolymerization involves the creation of strong covalent bonds between polymer chains?

    <p>Free-radical photopolymerization</p> Signup and view all the answers

    What undergoes a chemical transformation when UV radiation impinges on VP resin in photopolymer chemistry?

    <p>Photoinitiators</p> Signup and view all the answers

    What does the symbol R denote in the molecular structures of photopolymers?

    <p>Molecular group with one or more vinyl groups</p> Signup and view all the answers

    What is the primary disadvantage of acrylate photopolymers in SL resins?

    <p>Significant shrinkage and tendency to warp and curl</p> Signup and view all the answers

    What is the most common type of cationic photopolymer used?

    <p>Epoxies</p> Signup and view all the answers

    What happens when epoxy monomers react in photopolymerization?

    <p>Rings open, resulting in sites for other chemical bonds</p> Signup and view all the answers

    What is necessary to initiate the polymerization of VP monomers?

    <p>A catalyst</p> Signup and view all the answers

    What is the term used to describe the process when two polymer chains merge by joining two radicals?

    <p>Recombination</p> Signup and view all the answers

    What does occlusion refer to in polymerization termination?

    <p>Trapped free radicals within a solidified polymer</p> Signup and view all the answers

    What does the P–I term indicate in Fig. 4.4 in relation to photopolymerization?

    <p>Photoinitiator</p> Signup and view all the answers

    What is the primary purpose of a photoinitiator in the polymerization process?

    <p>Initiate radical formation for polymerization</p> Signup and view all the answers

    What is the main consequence of longer polymer molecules being preferred in photopolymerization?

    <p>More complete reaction and higher molecular weights</p> Signup and view all the answers

    What is the term used to describe the process where free radicals become 'trapped' within a solidified polymer?

    <p>Occlusion</p> Signup and view all the answers

    What are the intermediate steps of the process called where one radical can lead to the polymerization of over 1,000 monomers?

    <p>Propagation steps</p> Signup and view all the answers

    What type of catalyst is typically used for cationic polymerization?

    <p>Lewis Acid</p> Signup and view all the answers

    What initiates the cationic photopolymerization process?

    <p>Photoinitiator generating a cation</p> Signup and view all the answers

    What has led to increased attention to cationic photopolymerization in the 1990s?

    <p>Advances in the microelectronics industry</p> Signup and view all the answers

    What are the main chemical families of oligomers used for radiation curing?

    <p>Polyester acrylate (PEA), epoxy acrylates (EA), urethane acrylates (UA)</p> Signup and view all the answers

    What is added to photoinitiators to shift the absorption towards longer wavelengths?

    <p>Photosensitizers</p> Signup and view all the answers

    What do resin suppliers mix with oligomers and monomers to create ready-to-use formulations?

    <p>Photoinitiator and other materials affecting reaction rates and part properties</p> Signup and view all the answers

    What is often used in combination with the photoinitiator in photoinitiating systems?

    <p>Photosensitizers</p> Signup and view all the answers

    Which of the following is not a category of 3D printing processes?

    <p>Solid-state fusion</p> Signup and view all the answers

    What are some factors associated with different 3D printing processes and equipment?

    <p>Speed, costs, versatility, geometrical limitations, and mechanical and appearance properties</p> Signup and view all the answers

    What term is preferred for 3D printing processes used in industry?

    <p>Additive manufacturing</p> Signup and view all the answers

    What distinguishes 3D printing processes used by amateurs from those used by professionals?

    <p>The type of physical transformations involved</p> Signup and view all the answers

    What is the trademarked term for fused filament fabrication (FFF)?

    <p>Fused Deposition Modeling (FDM)</p> Signup and view all the answers

    What material is fed into an extrusion nozzle head in fused deposition modeling?

    <p>Filament of thermoplastic or other low melting point material</p> Signup and view all the answers

    What type of motors are usually employed to move the extrusion head and adjust the flow in a 3D printer?

    <p>Stepper motors or servo motors</p> Signup and view all the answers

    What is typically used as the most common material for fused deposition modeling?

    <p>$Plastic$</p> Signup and view all the answers

    What type of material has been developed as an alternative to filament in fused deposition modeling?

    <p>$Pellets or particles of plastic$</p> Signup and view all the answers

    What software package is used to generate the G-Code that controls the motors in a 3D printer?

    <p>$Computer-aided manufacturing (CAM)$ software package</p> Signup and view all the answers

    Which of the following is an example of material jetting technology?

    <p>Drop-on-demand (DOD) inkjets</p> Signup and view all the answers

    What is a key feature of the Pixelmaster developed by Howtek?

    <p>High-temperature hot-melt inks</p> Signup and view all the answers

    What has significantly impacted the additive manufacturing industry according to the text?

    <p>Inkjet technology</p> Signup and view all the answers

    Which technology has evolved from Teletype's inktronic teleprinter to modern material jetting printers?

    <p>Inkjet technology</p> Signup and view all the answers

    What is the primary focus of material jetting technologies?

    <p>Expanding possibilities for 3D printing</p> Signup and view all the answers

    Which company pioneered the development of inkjet technology?

    <p>Howtek, Inc.</p> Signup and view all the answers

    What is a distinguishing feature of material jetting technology?

    <p>High-temperature hot-melt inks</p> Signup and view all the answers

    What is a key advantage of material jetting technologies?

    <p>High precision printing capabilities</p> Signup and view all the answers

    What are the main differences in 3D printing processes according to the text?

    <p>Layer deposition methods and materials utilized</p> Signup and view all the answers

    What did Howtek's Pixelmaster feature that contributed to high precision printing?

    <p>32 inkjet single nozzles per printhead</p> Signup and view all the answers

    What is an example of a 3D printing process according to the text?

    <p>Layer deposition methods and materials utilized</p> Signup and view all the answers

    Study Notes

    3D Printing Processes and Material Jetting

    • Additive manufacturing technologies range from large-scale building fabrication to micro and nanoscale object production
    • Various 3D printing processes have been developed since the late 1970s, expanding capabilities and materials used
    • Differences in 3D printing processes lie in layer deposition methods and materials utilized
    • Processes include selective laser melting (SLM), direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), and more
    • Material jetting involves the use of nozzles to manipulate liquid materials, with inkjet technology being a key example
    • Inkjet technology has evolved from Teletype's inktronic teleprinter in 1966 to modern material jetting printers
    • Drop-on-demand (DOD) inkjets were invented in 1972, initially using water-based inks and experimentation with nozzle designs
    • Howtek, Inc. pioneered the development of inkjet technology, refining the process to produce precise, high-temperature, hot-melt inks
    • The Pixelmaster, developed by Howtek, featured 32 inkjet single nozzles per printhead, capable of printing CMYK colors with high precision
    • Material jetting technologies have been instrumental in advancing additive manufacturing and 3D printing capabilities
    • The evolution of inkjet technology from its early beginnings to modern material jetting has significantly impacted the additive manufacturing industry
    • Advancements in material jetting have expanded the possibilities for 3D printing, offering precise and versatile production capabilities

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    Description

    Test your knowledge about the photopolymerization process, which utilizes liquid, radiation-curable resins or photopolymers that react to UV or visible light to become solid. Learn about the chemical reaction involved in photopolymerization and its development since the late 1960s.

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