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Questions and Answers
What is the primary material used in photopolymerization processes?
What is the primary material used in photopolymerization processes?
Which range of wavelengths do most photopolymers react to?
Which range of wavelengths do most photopolymers react to?
In which industry are photopolymers widely applied?
In which industry are photopolymers widely applied?
What is the name of the first vat photopolymerization process?
What is the name of the first vat photopolymerization process?
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What role does the photoinitiator play in Vat Photopolymerization (VP)?
What role does the photoinitiator play in Vat Photopolymerization (VP)?
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Which family of radical photoinitiators is commonly used in VP?
Which family of radical photoinitiators is commonly used in VP?
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What are the basic raw materials used for radiation curing?
What are the basic raw materials used for radiation curing?
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What does occlusion refer to in the context of polymerization?
What does occlusion refer to in the context of polymerization?
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How does longer polymer molecules affect molecular weights in VP?
How does longer polymer molecules affect molecular weights in VP?
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What are included in resin formulations for VP?
What are included in resin formulations for VP?
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What process terminates polymerization in VP?
What process terminates polymerization in VP?
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What do photosensitizers do in VP?
What do photosensitizers do in VP?
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In cationic photopolymerization, what does the photoinitiator generate?
In cationic photopolymerization, what does the photoinitiator generate?
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What happens in photoinduced cationic polymerizations?
What happens in photoinduced cationic polymerizations?
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What does the P–I term in Fig. 4.4 indicate?
What does the P–I term in Fig. 4.4 indicate?
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What are often used with photoinitiators to achieve optimal performance?
What are often used with photoinitiators to achieve optimal performance?
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Which technology allows the production of solid 3D parts by curing one layer over a previous layer using UV-curable materials and a scanning laser?
Which technology allows the production of solid 3D parts by curing one layer over a previous layer using UV-curable materials and a scanning laser?
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What type of radiation is predominantly used in the microelectronics industry for photomask materials?
What type of radiation is predominantly used in the microelectronics industry for photomask materials?
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Which approach fabricates parts below the resin surface without the need for recoating in vat photopolymerization processes?
Which approach fabricates parts below the resin surface without the need for recoating in vat photopolymerization processes?
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What is 3D Systems primarily marketing SL machines as to the product development industry?
What is 3D Systems primarily marketing SL machines as to the product development industry?
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In which industries are photopolymers widely used for various applications including photoresists?
In which industries are photopolymers widely used for various applications including photoresists?
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Which type of radiation is predominantly used in dentistry for curing photopolymers?
Which type of radiation is predominantly used in dentistry for curing photopolymers?
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What types of radiation can be used to cure commercial photopolymers, with UV and visible light being predominantly used in commercial systems?
What types of radiation can be used to cure commercial photopolymers, with UV and visible light being predominantly used in commercial systems?
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What is the primary method for fabricating parts in mask projection approaches?
What is the primary method for fabricating parts in mask projection approaches?
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What is predominantly used exclusively in SL systems as a radiation source?
What is predominantly used exclusively in SL systems as a radiation source?
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Which company was created to market SL machines as 'rapid prototyping' machines to the product development industry?
Which company was created to market SL machines as 'rapid prototyping' machines to the product development industry?
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What do UV-curable photopolymers have critical requirements on when used as photoresists in the microelectronics industry?
What do UV-curable photopolymers have critical requirements on when used as photoresists in the microelectronics industry?
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Which type of radiation is predominantly used in mask projection DMD-based systems?
Which type of radiation is predominantly used in mask projection DMD-based systems?
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Which type of polymers are typically injection molded with a linear or branched molecular structure?
Which type of polymers are typically injection molded with a linear or branched molecular structure?
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What is a disadvantage of acrylate-based resins when exposed to the laser?
What is a disadvantage of acrylate-based resins when exposed to the laser?
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What is a characteristic of epoxy SL resins due to ring-opening polymerization?
What is a characteristic of epoxy SL resins due to ring-opening polymerization?
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What are the main components of VP photopolymers?
What are the main components of VP photopolymers?
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Which type of photopolymer chemistry exhibits high photospeed but significant shrinkage and a tendency to warp and curl?
Which type of photopolymer chemistry exhibits high photospeed but significant shrinkage and a tendency to warp and curl?
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What is the primary reason for adding acrylate to epoxy resins?
What is the primary reason for adding acrylate to epoxy resins?
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What is the characteristic of cationic photopolymerization (epoxy and vinylether)?
What is the characteristic of cationic photopolymerization (epoxy and vinylether)?
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What is a characteristic of free radical-initiated polymerization process?
What is a characteristic of free radical-initiated polymerization process?
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What is a disadvantage of epoxy resins?
What is a disadvantage of epoxy resins?
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What is the main reason for combining epoxies with acrylate in commercially available SL resins?
What is the main reason for combining epoxies with acrylate in commercially available SL resins?
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Study Notes
Vat Photopolymerization Processes and Materials Overview
- Thermoplastic polymers are typically injection molded with a linear or branched molecular structure, while VP photopolymers are cross-linked and do not melt, exhibiting less creep and stress relaxation.
- The first US patents for SL resins were published in 1989 and 1990, prepared from acrylates, which produced weak parts due to shrinkage and curling.
- Acrylate-based resins typically could only be cured to 46% completion when exposed to the laser, leading to accuracy issues and curling during or after part fabrication.
- Patents for epoxide composition for SL resins appeared in 1988 (Japanese), producing more accurate, harder, and stronger parts with lower shrinkage and reduced susceptibility to oxygen inhibition.
- Epoxy resins have disadvantages of slow photospeed and brittleness, requiring the addition of acrylate to rapidly build part strength and reduce brittleness.
- Most commercially available SL resins today are epoxides with some acrylate content to combine the advantages of both curing types and improve accuracy.
- VP photopolymers consist of photoinitiators, reactive diluents, flexibilizers, stabilizers, and liquid monomers, reacting with UV radiation to start polymer chains and cross-link.
- Two main types of photopolymer chemistry are evident: free-radical photopolymerization (acrylate) and cationic photopolymerization (epoxy and vinylether).
- Acrylate photopolymers exhibit high photospeed but significant shrinkage and a tendency to warp and curl, thus rarely used without epoxy or other elements.
- Epoxy SL resins typically have much smaller shrinkages and less tendency to warp and curl due to ring-opening polymerization, resulting in minimal volume change.
- Almost all commercially available SL resins have significant amounts of epoxies, with polymerization being an exothermic reaction requiring a catalyst.
- The free radical-initiated polymerization process involves the production of radicals from photons, which can lead to the polymerization of over 1,000 monomers.
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Description
Test your knowledge of polymer structures and properties with this quiz. Explore topics such as thermoplastic polymers, molecular structures, injection molding, cross-linking, stress relaxation, and more.
