Photopolymer Composition Research Articles

Current state of research in the field of 3D printing device designs using photopolymer composites (review)

Current state of research in the field of 3D printing device designs using photopolymer composites (review)

Elasticity study of SLA Additively Manufactured Composites

This study investigates the mechanical properties of ceramic and photopolymer composites created using stereolithography (SLA) 3D printing. It aims to evaluate and compare the performance of two SLA materials: Liqcreate Composite-X and Phrozen's Water-Washable Resin, using dynamic flexural vibration tests to determine Young's modulus. Liqcreate Composite-X, a photopolymer resin with excellent mechanical properties, including high tensile and flexural strength, showed a first resonance frequency of 318 Hz and a Young's modulus of 0.93 x 1010 Pa. Phrozen's Water-Washable Resin, designed for easy post-processing, had a first resonance frequency of 210 Hz and a Young's modulus of 0.30 x 1010 Pa. In conclusion, Liqcreate Composite-X demonstrates superior mechanical performance, making it suitable for high-strength applications, while Phrozen's Water-Washable Resin, with lower mechanical properties, is more suited for less demanding uses. This study enhances the understanding and application of SLA-based ceramic composites in various engineering domains.

Typ‐I‐Photoinitiator auf der Basis nachhaltiger Kohlenstoffpunkte

AbstractNachhaltige Kohlenstoffpunkte, die an der Oberfläche Oximestergruppen enthalten, welche einer homolytischen Bindungsspaltung folgen, zeigen ein Potential als Photoinitiatoren für die traditionelle freie radikalische Photopolymerisation. Die Kohlenstoffpunkte wurden nach einem solvothermalen Verfahren aus nachhaltigem Furfural, welches über Lignocellulose erhältlich ist, hergestellt. Aldehydgruppen der Oberfläche reagierten mit Hydroxylamin zu dem entsprechendem Oxim, während die Reaktion mit Benzoylchlorid zu einem bio‐basierten Typ I Photoinitiator (CD‐PI) führte, welcher nachhaltige Kohlenstoffpunkte enthält. Die Fähigkeit zur Photoinitiierung wurde unter UV‐Bestrahlung bei 365 nm mit dem traditionellen Photoinitiator (PI) Ethyl (2,4,6‐trimethyl benzoyl) phenyl phosphinat (TPO‐L) mittels Echtteit FTIR Spektroskopie verglichen. Die auf einem Gemisch von Urethandimethacrylat (UDMA) und Tripropylenglykoldiacrylat (TPGDA) basierte Photopolymerzusammensetzung führte unter Verwendung von CD‐PI oder TPO‐L zu einem ähnlichen Endumsatz von etwa 70 %. Dennoch erschien das vernetzte Material im Fall der Zusammensetzungen, die mit CD‐PI verarbeitet wurden, homogen, während jene, die mit TPO‐L hergestellt wurden, heterogen waren, was durch die beiden Glasübergangstemperaturen gezeigt wurde. Außerdem war die Migrationsgeschwindigkeit von CD‐PI in den gehärteten Proben geringer im Vergleich zu jenen Proben für die TPO‐L als PI eingesetzt wurde.

Type I Photoinitiator Based on Sustainable Carbon Dots.

Sustainable carbon dots comprising surficial oxime ester groups following homolytic bond cleavage exhibit potential as photoinitiators for traditional free radical photopolymerization. Carbon dots were made following a solvothermal procedure from sustainable furfural available from lignocellulose. Surficial aldehyde moieties reacted with hydroxylamine to the respective oxime while reaction with benzoyl chloride resulted in a biobased Type I photoinitiator comprising sustainable carbon dot (CD-PI). Photoinitiating ability was compared with the traditional photoinitiator (PI) ethyl (2,4,6-trimethyl benzoyl) phenyl phosphinate (TPO-L) by real-time FTIR with UV exposure at 365 nm. Photopolymer composition based on a mixture of urethane dimethacrylate (UDMA) and tripropylene glycol diacrylate (TPGDA) resulted in a similar final conversion of about 70 % using either CD-PI or TPO-L. Nevertheless, it appeared homogeneous in the case of compositions processed with CD-PI, while those made with TPO-L were heterogeneous as shown by two glass transition temperatures. Moreover, the migration rate of CD-PI in the cured samples was lower in comparison with those samples using TPO-L as PI.

Photopolymer Materials in the Practice of Restoration and Conservation Works on Objects of Historical and Cultural Value

The evolution is analyzed and modern approaches to carrying out restoration, conservation and reconstruction works at objects of historical and cultural value are presented from the standpoint of the limits of the permissibility of using non-authentic materials. The principles of choosing materials for restoration and conservation work are considered. An analysis of the experience of using photopolymer materials in the creation of protective, decorative or reconstructive layers and coatings in order to preserve or recreate objects of historical and cultural significance is presented. The results of studies on the use of liquid photopolymer compositions based on acrylates in restoration and conservation work are presented. The prospects of using photopolymer materials in the practice of restoration and reconstruction are shown, and directions for further research are formulated.

Tailoring the shape memory properties of silica nanoparticle infused photopolymer composites for 4D printing applications: A Taguchi analysis

The study aims to optimize the shape change response of the Shape Memory Photopolymer Composites (SMPPCs) through the use of the Taguchi method. The SMPPCs were created by blending of Soft Photopolymer Resin (SPPR) with Hard Photopolymer Resin (HPPR) in various weight fractions and reinforcing with Silica Nanoparticles (SNPs) at different weight percentages using a Masked Stereolithography (MSLA). The researchers measured the ability of the material to change its shape by determining its shape recovery time (T), fixity ratio (Rf), recovery ratio (Rr), and recovery rate (Vr). The results indicated that the fastest T was observed in unreinforced Blended Photopolymer Resin (BPPR) with 75 wt% SPPR and 25 wt% HPPR. However, when the BPPR was reinforced with 0.3 wt% SNPs, the T was slower. The use of SNPs as reinforcement resulted in excellent Rf, whereas higher weight percentages of SPPR led to better Rr. The weight percentage of SPPR was found to be the primary contributor to T, Rr, and Vr, while the weight percentage of SNPs played a significant role in Rf. The optimum parameters for T and Vr were A1/B3/C1, for Rf were A3/B1/C1, and for Rr were A2/B2/C1. The research findings indicate that reinforced BPPR has outstanding fixity ratios and it is more appropriate for applications that necessitate lengthier recovery and slower recovery rate. The inclusion of SNPs in BPPR increases the T and prolongs the temporary shape retention of the specimen. The generated regression models were validated through confirmation experiments, which yielded strong agreement.

Biomimetic tissue phantoms for neurosurgical near-infrared fluorescence imaging.

Neurosurgical fluorescence imaging is a well-established clinical approach with a growing range of indications for use. However, this technology lacks effective phantom-based tools for development, performance testing, and clinician training. Our primary aim was to develop and evaluate 3D-printed phantoms capable of optically and morphologically simulating neurovasculature under fluorescence angiography. Volumetric digital maps of the circle of Willis with basilar and posterior communicator artery aneurysms, along with surrounding cerebral tissue, were generated. Phantoms were fabricated with a stereolithography printer using custom photopolymer composites, then visualized under white light and near-infrared fluorescence imaging. Feature sizes of printed components were found to be within 13% of digital models. Phantoms exhibited realistic optical properties and convincingly recapitulated fluorescence angiography scenes. Methods identified in this study can facilitate the development of realistic phantoms as powerful new tools for fluorescence imaging.

Synthesis and optimization for shape memory behaviour of 4D printed GNPs reinforced shape memory photopolymer composite

PurposeShape memory materials are functional materials having a good number of applications due to their unique features of programmable material technology such as self-stretching, self-assembly and self-tightening. Advancements in today’s technology led to the easy fabrication of such novel materials using 3D printing techniques. When an external stimulus causes a 3D printed specimen to change shape on its own, this process is known as 4D printing. This study aims to investigate the effect of graphene nano platelet (GNPs) on the shape memory behaviour of shape memory photo polymer composites (SMPPCs) and to optimize the shape-changing response by using the Taguchi method.Design/methodology/approachSMPPCs are synthesized by blending different weight fractions (Wt.%) of flexible or soft photopolymer (FPP) resin with hard photopolymer (HPP) resin, then reinforced with GNPs at various Wt.% to the blended PP resin, and then fabricated using masked stereolithography (MSLA) apparatus. The shape memory test is conducted to assess the shape recovery time (T), shape fixity ratio (Rf), shape recovery ratio (Rr) and shape recovery rate (Vr) using Taguchi analysis by constructing an L9 orthogonal array with parameters such as Wt.% of a blend of FPP and HPP resin, Wt.% of GNPs and holding time.FindingsSMPPCs with A3, B3 and C2 result in a faster T with 2 s, whereas SMPPCs with A1, B1 and C3 result in a longer T with 21 s. The factors A and B are ranked as the most significant in the Pareto charts that were obtained, whereas C is not significant. It can be seen from the heatmap plot that when factors A and B increase, T is decreasing and Vr is increasing. The optimum parameters for T and Vr are A3, B3 and C2 at the same time for Rf and Rr are A1, B3 and C1.Research limitations/implicationsFaster shape recovery results from a higher Wt.% of FPP resin in a blend than over a true HPP resin. This is because the flexible polymer links in FPP resin activate more quickly over time. However, a minimum amount of HPP resin also needs to be maintained because it plays a role in producing higher Rf and Vr. The use of GNPs as reinforcement accelerates the T because nanographene conducts heat more quickly, releasing the temporary shape of the specimen more quickly.Originality/valueThe use of FPP and HPP resin blends, fabricating the 4D-printed SMPPCs specimens with MSLA technology, investigating the effect of GNPs and optimizing the process parameters using Taguchi and the work was validated using confirmation tests and regression analysis, which increases the originality and novelty.

Effect of GNPs and resin blend on tear resistance of 4D printed shape memory photopolymer composite

PurposeThe tear strength (Ts) is a significant property for any kind of soft polymeric material such as rubber, elastomer, viscoelastic material and its composites, to quantify the suitability of a material for any shape memory applications. Many times, the soft elastomeric polymer material has to be capable enough to deform to a maximum extent of displacement but at the same time, it has to withstand the maximum load without fail. Along with shape recovery properties (i.e. the ability to recover its shape from programmed to the original), the success of the shape memory cycle is mainly depending on its stiffness and strength. It has to resist tear during stretching (i.e. programming stage) as repeatedly subjected to deformation, and, hence, it is important to study the tear behaviour for shape memory polymers (SMPs) and their composites. The purpose of the work is to investigate the effect of parameters on Ts of 4D printed specimen using Taguchi method.Design/methodology/approachThe objective of the work is to tailor the Ts of SMPs by reinforcing the graphene nano particles (GNPs) in a blended photopolymer (PP) resin with flexible PP and hard PP resin. In this study, a total of nine experiments were designed based on the L9 orthogonal array (OA) using the design of experiments (DOEs). All the shape memory photopolymer composite’s (SMPPCs) specimens are fabricated using masked stereolithography (MSLA), also known as resin three-dimensional printing (R3DP) technique.FindingsSpecimens are tested using universal testing machine (UTM) for maximum tear force (Fmax) and displacement (δ) caused by tearing the specimen to evaluate the strength against the tear. The results showed that the Wt.% of resin blend highly influenced both Fmax and δ, while GNPs also had an impact on δ. The specimens are offering more tear resistance for those specimens blended with less Wt.% of flexible PP at the same time the specimens enable more δ for those specimens reinforced with 0.3 Wt.% GNPs at 10-s exposure time. The optimum combinations are A1, B1 and C3 for the Fmax and Ts and at the same time A1, B3 and C3 for δ.Research limitations/implicationsTo customise the tear resistance of SMPPCs using MSLA 3 D printing, this study suggested a blend of PP resins reinforced with GNPs. This opens up a new path for creating novel, inexpensive multi-functional 4-dimensional (4D) printed parts.Originality/valueThe use of flexible PP and hard PP resin blends, fabricating the SMPPCs specimens using 3 D printed MSLA technology, investigating the effect of GNPs, resin blend and exposure time, optimizing the process parameters using Taguchi and the work were all validated using confirmation tests and regression analysis using test train method, which increases the originality and novelty.

Transmission functions of transmissive multilayer inhomogeneous holographic photopolymer liquid crystal diffraction structures

A new analytical model of diffraction of quasimonochromatic light beams on spatially inhomogeneous multilayer diffraction structures formed in photopolymer material with nematic liquid crystals having smooth optical inhomogeneity in the thickness of layers is presented. It is shown that when an applied electric field isapplied to diffraction layers containing a photopolymer composition with a high proportion of liquid crystalline component, a transformation of the selective response with a significant shift in angular selectivity occurs

Ethylene-Vinyl Acetate Copolymers as Potential Thermoplastic Modifiers of Photopolymer Compositions.

The possibility of using thermoplastic polymers in photopolymer compositions for SLA and DLP is discussed in this article. The diffusion and mutual solubility of uncured systems based on tert-butyl acrylate (tBA) and ethylene-vinyl acetate copolymers (EVA) or low-density polyethylene (LDPE) were studied. The solubility and diffusion of tBA with EVA containing 7, 20, and 40 wt.% vinyl acetate (VA) and with LDPE in the temperature range 20-75 °C were studied by optical micro-interferometry method. Phase diagrams of LDPE-tBA, EVA-7-tBA, and EVA-20-tBA systems were obtained. It is shown that the compositions are characterized by the phase-state diagrams of amorphous separation with the upper critical solution temperature (UCST). The concentration dependences of the interdiffusion coefficients as well as dependences of the self-diffusion coefficients on VA content and on temperature were plotted. The activation energy of self-diffusion of EVA and LDPE was calculated. It was shown that the most promising tBA modifier is EVA-40, which is completely soluble at all studied temperature ranges. The obtained data on the mixing of the initial components is valuable for further studies of the processes of structure formation during photocuring of compositions, regulation of the phase structure and, as a consequence, the performance characteristics of the 3D printable materials.

Nanostructured Luminescent Gratings for Sensorics.

Two-dimensional holographic structures based on photopolymer compositions with luminescent nanoparticles, such as quantum dots, are promising candidates for multiresponsive luminescence sensors. However, their applicability may suffer from the incompatibility of the components, and hence aggregation of the nanoparticles. We showed that the replacement of an organic shell at the CdSe/ZnS quantum dots' surface with monomer molecules of the photopolymerizable medium achieved full compatibility with the surrounding medium. The effect was demonstrated by luminescence spectroscopy, and steady-state and time-resolved luminescent laser scanning microscopy. We observed the complete spectral independence of local photoluminescence decay, thus proving the absence of even nanoscale aggregation, either in the liquid composition or in the nodes and antinodes of the grating. Therefore, nanostructured luminescent photopolymer gratings with monomer-covered quantum dots can act as hybrid diffractive-luminescent sensor elements.

Water-Soluble Holographic Photopolymers for a Sustainable Future—A Review

Holographic photopolymers are subject to extensive studies in recent years because they are low-cost, easy-to-handle, self-processing materials, which have a number of advantages over more traditional holographic materials. The development of low-toxicity photopolymers that are environmentally friendly is highly desirable. The availability of low-toxicity photopolymers will permit the mass production of commercial holograms without harm to the environment. This paper reviews recent developments in low-toxicity water-soluble holographic photopolymers. A novel composition for a water-soluble, low-toxicity photopolymer is described. This new holographic photopolymer has 90% diffraction efficiency in the transmission mode of recording and 50% diffraction efficiency in the reflection mode of recording. This photopolymer has all the necessary holographic characteristics to make it very attractive for commercialisation. The optimised chemical composition of the holographic photopolymer for the production of pressure sensors is addressed. A novel and unique feature of this new material is its high sensitivity to pressure, which can be controlled by changing its composition. Several promising environmentally friendly optical materials are being developed for future holographic applications. The presented review of low-toxicity, water-soluble, holographic photopolymers is the first of its kind. Thus, the importance of the review is twofold—it helps contribute to the development of low-toxicity holographic photopolymers, and it provides insight and new ideas for the development of water-soluble photopolymers for other applications.

Spin Transition of the Iron(II) Clathrochelate in the Photopolymer Composition for 3D Printing from Optical Spectroscopy Data

Spin Transition of the Iron(II) Clathrochelate in the Photopolymer Composition for 3D Printing from Optical Spectroscopy Data

3D Printing of Soft Magnetoactive Devices with Thiol‐Click Photopolymer Composites

Magnetoresponsive polymers have gained increased attention in the design of soft actuators as they can be spatially as well as temporally activated and enable an external noninvasive control of movement. By introducing the magnetoresponsive properties in photocurable resins, one can fabricate personalized and complex structures (via vat photopolymerization 3D printing), whose movement can be conveniently controlled by an external magnetic field. Advancing from acrylate‐based photopolymers, which often suffer from shrinkage stress, low monomer conversion, and oxygen inhibition, the fabrication of magnetoresponsive thiol‐click photopolymers containing Fe3O4 nanoparticles as magnetic fillers is highlighted. The addition of the thiol crosslinker yields soft and flexible polymer composites, whose cure kinetics, viscosity, thermal, and mechanical properties are studied as a function of the thiol and filler content. Although cure rate and final monomer conversion decrease with rising filler concentration, the cure kinetics is reasonably fast at 6 wt%. The short pot life, a result of thiol‐Michael reactions induced by Fe3O4 nanoparticles, and a high thiol content, are overcome by the addition of an appropriate stabilizer. As proof of concept, 3D structures are fabricated by digital light processing (DLP) 3D printing and their magnetically driven movement is demonstrated.

Studying the process of holographic formation of multilayer inhomogeneous PPM-LC diffraction structures

The article describes a theoretical model for the formation of a multilayer diffractive holographic structure (MIHDS) based on a photopolymer composition including liquid crystals (LC). We presented mathematical modeling of spatial profiles kinetics of the refractive index of the first harmonic of MIHDS considering the photoinduced light absorption (PLA) of the non-optimized and optimized composition. Numerical modeling has shown that optimization of the composition of MIHDS at different thicknesses of the diffraction layer requires a difference in the concentration of the dye-sensitizer for subsequent layers.

Mechanical evaluation of dental trauma splints fabricated using recently-developed photo-polymerizable composites.

This study aimed to determine functionality and mechanical properties of dental splints. Five splints were tested: a control splint Filtek Z350XT (ZF), two splints with G-Fix (GF) and Light Fix (LF), and two wire-composite splints with ZF (ZW) and Ortho Connect Flow (CW). Periotest values, elastic modulus, flexural, compressive, and diametral tensile strength were measured. ZW and CW showed no significant differences in flexibility in labial or occlusal pressure of upper central incisors. LF, GF, and ZF did not differ in labial or palatal pressure. ZW and CW had higher flexibility than LF, GF, and ZF. LF had the lowest flexural and compressive strength but the highest diametral tensile strength. This study showed that ZW and CW might be options for flexible splints, whereas LF and GF would be options for rigid splints. Additionally, CW and LF/GF might be simpler alternatives to ZW and ZF, respectively.

Регенерація розчину для вимивання фотополімерних друкарських форм як вирішення екологічної проблеми

Much attention from the point of view of environmental protection is paid to the process of manufacturing photopolymer flexographic printing plates, where the waste is saturated with washout photopolymer components solutions that pose a potential hazard to the environment and require the introduction of additional measures for disposal or regeneration. Washout solutions are mixtures of organic solvents with washout photopolymer composition, which can be regenerated for reuse. Distillation was performed in a glass reactor on an oil bath with electric heating. The vapors were condensed in a direct-flow water-cooled reflux condenser. The quality of the regenerated mixed solvents was controlled by the refractive index. The refractive index was determined on a refractometer RL-2. The following temperature regime of regeneration of the spent washout solution was established: the beginning of distillation (at 760 mm Hg) — 130°°C, distillation of the main fractions — 135…170°°C. After regeneration, 90…95°% of the distillation and up to 10°% of the photopolymer composition residue were obtained after distillation by the composition of solvents according to the values of the refractive index, for which a linear correlation was established. The studies have shown the possibility of regeneration of the solution for washout the relief image of photopolymer printing plates by distillation. In this case, preference should be given to a mixture of solvent-isopentanol in proportions of 10:2 or 10:3, as such proportions allow to intensify the distillation process. The experimental results indicate the possibility of adjusting the composition of the solution after distillation according to the refractive index values, according to the obtained linear correlation.

ТЕХНОЛОГИЯ УФ-ОТВЕРЖДЕНИЯ. ТЕОРИЯ И ПРАКТИКА

The article provides a justification for the use of UV-curing technology in the modern practice of creating films and coatings for various purposes with a given specificity of properties. The key provisions of formulation compounding of photopolymer compositions are considered, specific examples of formulations developed by members of the scientific school «Technologies of functional composite Materials» (head: Professor, Doctor of Technical Sciences Babkin O.E.) are given.

PHOTOPOLYMERIZED COMPOSITIONS AND LIGHT SOURCES FOR DENTAL PRACTICE (REVIEW)

The review presents an analysis of articles published for the period 2005-2021. in top-rated publications devoted to the research results in the field of creating light-curing (photopolymerizable) compositions for use in dental practice. The information concerning the main ingredients of the compositions: di (meth) acrylate monomers, fillers, pigments, and photoinitiators is summarized. A comparative assessment of light sources, which determine the curing efficiency of materials of such a functional purpose, is presented. The results of a patent search, in the PatentScope database, are presented. For the period 2000-2021. have been identified 692 patents, which are related to the creation of dental photopolymer composites.