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dc.rights.licenseRestricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.
dc.contributorRyu, Chang Yeol
dc.contributorBae, Chulsung
dc.contributorShelley, Jacob T., 1984-
dc.contributorPalermo, Edmund
dc.contributor.authorSmallwood, Anna M. C.
dc.date.accessioned2021-11-03T09:23:51Z
dc.date.available2021-11-03T09:23:51Z
dc.date.created2021-07-07T16:12:57Z
dc.date.issued2020-12
dc.identifier.urihttps://hdl.handle.net/20.500.13015/2660
dc.descriptionDecember 2020
dc.descriptionSchool of Science
dc.description.abstractIn Chapter 3, the effect of type and concentration of resin additive on photopolymerization kinetics is examined via RT-FTIR ATR. Factors such as network conversion and relative concentration of remaining double bonds following UV irradiation were found to translate to the overall bulk mechanical properties of the SLA 3D printed object. Additionally, concentration of additive – photoinitiator, photosensitizer, or inhibitor – was found to have a significant impact on resin reactivity and overall SLA 3D printability.
dc.description.abstractIn Chapter 2, the depth of cure dependent structure-property relationships of SLA photopolymer resins and their resulting 3D printed specimens are investigated. The mechanical, thermomechanical, and structural properties of a model SLA photopolymer resin are examined and rationalized via RT-FTIR ATR depth analysis. The presence of a depth effect on network conversion was found via RT-FTIR ATR which affected the onset of the photopolymerization reaction, as well as the rate of polymerization. However, with the addition of common resin additives such as photoinitiator, photosensitizer, or radical inhibitor, it was found that depth effect was reduced or exacerbated, effectively changing the kinetic parameters of a confined resin sample depth during UV irradiation. Both functionality and viscosity of acrylate functional monomers commonly employed in SLA photopolymer resins were found to have a significant effect on depth of cure, especially in the context of the rate of polymerization. Lastly, the method of RT-FTIR data analysis was critiqued by comparing peak area vs. peak height analysis in the context of photopolymer resin characterization.
dc.description.abstractOne feature of SLA that has generally been overlooked in the literature is the effect of UV penetration depth on print layer formation. In the past, depth of cure has been studied in photopolymer coatings and adhesives, and especially thoroughly in restorative dental materials. These studies have found a presence of a network crosslinking gradient throughout the sample depth due to UV light attenuation and other factors that may affect the integrity of the resulting polymer network. However, information on depth of cure in the context of SLA 3D printing remains limited in the literature. Due to the layer-by-layer nature of the SLA print process, studying the depth of UV penetration, corresponding photopolymerization kinetics, and their effects on the polymer network’s bulk mechanical properties presents not only an opportunity to better understand the structure-property relationships of SLA 3D printed objects, but also to induce desired mechanical, thermomechanical, structural, and morphological properties for specific applications.
dc.description.abstract3D printing and additive manufacturing of polymer materials allows for conversion of virtual models into physical objects with complex shapes. Due to its customizable nature, production of 3D printed polymer parts offers the advantage of on-demand manufacturing and design flexibility unlike injection molding, where mold design is difficult to modify or tailor for specific customized applications. One method of 3D printing polymer materials which utilizes vat photopolymerization is stereolithography (SLA). SLA is known to be one of the highest resolution 3D printing methods and is therefore applicable to a wide range of applications requiring high spatial accuracy, including biomedical engineering and the fabrication of specialized microparts. The SLA process employs repeated layer-by-layer photopolymerization of photocurable multicomponent liquid resins, resulting in a layered morphology on the microscale.
dc.description.abstractIn Chapter 4, the kinetic competition between photopolymerization and phase separation between the network and PEG or methacrylated PEG in confined photopolymer resin films is investigated. It was found that factors such as PEG molecular weight, UV intensity, and PEG-surfactant weight fraction ratios could be adjusted to induce morphology changes throughout the depth of a confined resin film, analogous to a discrete print layer during SLA 3D printing.
dc.description.abstractLastly, Chapter 5 offers conclusionary statements about each chapter and their overarching contribution to knowledge in the context of SLA 3D printing and photopolymer characterization. Overall, these studies offer insight into the complexities affecting depth of cure effects in multicomponent SLA photopolymer resins including additive type/concentration, monomer formulation and functionality, UV intensity, and induced-morphology phase separation effects. Furthermore, structure-property relationships between these parameters and resulting bulk properties of the SLA 3D printed object are demonstrated. These studies suggest that an understanding of UV penetration depth and the corresponding depth of cure effects in SLA photopolymer resins are of importance for the successful development of novel and robust SLA 3D printable materials with diverse and desirable mechanical and morphological properties.
dc.description.abstractIn Chapter 1, an introduction to 3D printing and SLA is provided. Applications and limitations of SLA are discussed. A brief literature review is provided, in which the limited number of studies pertaining to depth of cure and structure-property relationships of SLA photopolymer materials are presented and discussed in the context of the following chapters.
dc.language.isoENG
dc.publisherRensselaer Polytechnic Institute, Troy, NY
dc.relation.ispartofRensselaer Theses and Dissertations Online Collection
dc.subjectChemistry
dc.titleDepth of cure effects on structure-property relationships of 3d printed polymer materials using stereolithography
dc.typeElectronic thesis
dc.typeThesis
dc.digitool.pid180476
dc.digitool.pid180477
dc.digitool.pid180478
dc.rights.holderThis electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
dc.description.degreePhD
dc.relation.departmentDept. of Chemistry and Chemical Biology


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