Thermal Behavior of Nanoclay Reinforced Ultraviolet Curable Epoxy Acrylate

This study related to preparation of UV curable epoxy nanoclay nanocomposite and investigation on mechanical and thermal properties of their thin films. For achieving this UV-curable epoxy dimethacrylate was synthesized by epoxy resin (EPIKOTE 828), methacrylic acid, triphenylphosphine (PPh3) as catalyst and para-methoxy phenol (PMP) as inhibitor at 80 ºC for 2 hours (yield 99%). Formulation of UV curable resin was achieved by 5% w/w benzophenone and N, N dimethylaminoethyl methacrylate. The resin was reinforced by using 1-5% w/w modified nanoclay in total formulation. Synthesized resin was characterized by FTIR spectroscopy and thermal behaviors of nanocomposites were evaluated by TGA and DSC analysis. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521

Freeform Fabrication of Biological Scaffolds by Projection Photopolymerization

This article presents a micro-manufacturing method for direct, projection printing of 3- dimensional (3D) scaffolds for applications in the field of tissue engineering by using a digital micro-mirror-array device (DMD) in a layer-by-layer process. Multi-layered scaffolds are microfabricated using curable materials through an ultraviolet (UV) photopolymerization process. The pre-patterned UV light is projected onto the photocurable polymer solution by creating the “photomask” design with graphic software. Poly (ethylene glycol) diacrylate (PEGDA), is mixed with a small amount of dye (0.3 wt %) to enhance the fabrication resolution of the scaffold. The DMD fabrication system is equipped with a purging mechanism to prevent the accumulation of oligomer, which could interfere with the feature resolution of previously polymerized layers. The surfaces of the pre-designed, multi-layered scaffold are covalently conjugated with fibronectin for efficient cellular attachment. Our results show that murine marrow-derived progenitor cells successfully attached to fibronectin-modified scaffolds.Mechanical Engineerin

Synthesis and characterization of ultra violet curable renewable polymer graphite composites

This thesis aims is to evaluate the synthesis and characterization of ultra violet (UV) curable renewable polymer graphite (RPG) composites. Accordingly, the renewable polymeric composites were prepared through a film slip casting method at room temperature wherein graphite particles of various weight loadings were mixed with mass proportion 2:1 of renewable monomer and Methylene Diphenyl Diisocyanate, MDI respectively. The main concerned was given to renewable monomer based vegetable cooking oil produced at the SPEN-AMMC UTHM. The morphology-structural relation of the RPG composites confirmed that the graphite particles contain functional groups such as hydroxyl and carboxylic groups are randomly distributed and attributed to formation of interconnected interface within the polymeric composites. Furthermore, as the graphite particle loading increased, the thermal degradation temperature at three distinct decomposition stages shifted and to some extent, resulting in much higher crystallinity. As expected, the mechanical properties of the composites were also enhanced with the modulus and tensile strength increment up to ~440% and ~100% respectively. Significantly, all of these results correlate with viscoelastic properties in which the composites achieved percolation threshold at RPG20 composites. Moreover, the decreased in optical energy band gap (Eg) which afterwards took the leads to electrical conductivity (σ). Aptly, the composites (RPG20, RPG25 and RPG30) were found to possess favorable electrical conductivity range of 10-5 – 10-4 S/m, while all other samples were deemed to be not conductive due to improper dispersion of graphite particulates. On the contrary, UV curable composites did not show any significant enhancement and graphite particle acted as UV stabilizer in this manner. Therefore, the stability of the conductive renewable polymer graphite composite is suitable to be used in various composites applications

A new UV-curable PU resin obtained through a nonisocyanate process and used as a hydrophilic textile treatment

[[abstract]]A new UV-curable hydrophilic PU resin was obtained through a green, nonisocyanate, three-reaction process: (1) a bis(cyclic carbonate) (BCC) compound is prepared by inserting carbon dioxide into an epoxy resin (DGEBA) at atmospheric pressure; (2) an amino-terminated hydrophilic PU (NH2-PU) oligomer is obtained through the ring-opening polymerization of BCC utilizing a difunctional amino hydrophilic (polyether) compound such as Jeffamine D-2000; (3) the UV-curable acrylate-PU (UV-PU) prepolymer is obtained as an adduct from the Michael addition of NH2-PU to a diacrylate-terminated compound, 3-acryloyloxy-2-hydroxypropyl methacrylate (AHM). A polyester (PET) textile was treated with this hydrophilic UV-PU prepolymer and then cured by irradiation with UV light. The UV-PU resin was found to crosslink and anchor to the textile fibers after UV irradiation, resulting in a long-lasting hydrophilic surface for the treated textile. The performance properties of the new PU resin on the treated textile were investigated.[[incitationindex]]SCI[[booktype]]紙

lOptical coupling structure made by imprinting between single-mode polymer waveguide and embedded VCSEL

Polymer-based integrated optics is attractive for inter-chip optical interconnection applications, for instance, for coupling photonic devices to fibers in high density packaging. In such a hybrid integration scheme, a key challenge is to achieve efficient optical coupling between the photonic chips and waveguides. With the single-mode polymer waveguides, the alignment tolerances become especially critical as compared to the typical accuracies of the patterning processes. We study novel techniques for such coupling requirements. In this paper, we present a waveguide-embedded micro-mirror structure, which can be aligned with high precision, even active alignment method is possible. The structure enables 90 degree bend coupling between a single-mode waveguide and a vertical-emitting/detecting chip, such as, a VCSEL or photodiode, which is embedded under the waveguide layer. Both the mirror structure and low-loss polymer waveguides are fabricated in a process based mainly on the direct-pattern UV nanoimprinting technology and on the use of UV-curable polymeric materials. Fabrication results of the coupling structure with waveguides are presented, and the critical alignment tolerances and manufacturability issues are discussed

Novel Bonding technologies for wafer-level transparent packaging of MOEMS

Depending on the type of Micro-Electro-Mechanical System (MEMS), packaging costs are contributing up to 80% of the total device cost. Each MEMS device category, its function and operational environment will individually dictate the packaging requirement. Due to the lack of standardized testing procedures, the reliability of those MEMS packages sometimes can only be proven by taking into consideration its functionality over lifetime. Innovation with regards to cost reduction and standardization in the field of packaging is therefore of utmost importance to the speed of commercialisation of MEMS devices. Nowadays heavily driven by consumer applications the MEMS device market is forecasted to enjoy a compound annual growth rate (CAGR) above 13%, which is when compared to the IC device market, an outstanding growth rate. Nevertheless this forecasted value can drift upwards or downwards depending on the rate of innovation in the field of packaging. MEMS devices typically require a specific fabrication process where the device wafer is bonded to a second wafer which effectively encapsulates the MEMS structure. This method leaves the device free to move within a vacuum or an inert gas atmosphere.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

Embedding of fibre optic sensors within flexible host

This work deals with the establishment of a UV polymerisation procedure combined with moulding technology towards the development of a mass production technology for the fabrication of flexible polymers with optical fibres embedded. The concept is to provide an artificial sensing skin based on fibre optic sensors which can be applied to irregular or moveable surfaces for distributed pressure applications, as for instance in structural monitoring or rehabilitation. The selected polymers for such an application are here reviewed and their composition adjusted in order to accommodate the required flexibility. As compared to other techniques, UV polymerisation advantages are pointed out when moving towards industrial applications and large scale productions. Meanwhile, curing tests to embed optical fibres in the developed polymers are carried out with an in house developed glass mould set-up and the results are presented. Laser ablation of polymers is also discussed in order to reply the demand of complex fibre layout as for example meandering or curved shape patterns

New technology to expose core from fiber for optical sensing application

For the future optical sensing application, a simple, fast and cost-effective method to achieve exposed core is required for a good mass production and commercialization. Hence, this paper proposes sensing application with exposed core technology using Self-Written Waveguide (SWW) method. The SWW method uses a UV-curable resin and enables fabrication of an optical channel waveguide. SWW is known as an attractive and useful technique in optical interconnection. This SWW is passively aligned between two fibers from the end of the optical fiber under irradiation UV light. This makes the technology is a reliable exposed core technology for sensing application. A SWW with length of 800 micrometers is fabricated from the end face of the multi-mode optical fiber under irradiation with UV light. Experiment is done under several testing materials with different refractive index. The output optical power is decreasing as the refractive indexes of testing materials are increasing. Simulation is also done using ray-tracing method. From these results, it seems possible to apply this SWW using UV-curable resin in sensing application

Ultraviolet-curable Silicone/Urethane Elastomer and Its Selective Modulus Enhancement

Department of Chemical EngineeringThermosets usually have brittle structure, but thermosetting polyurethane (PU) is classified as elastomer due to its urethane linkage in the backbone. Polyurethanes are used in many areas in a form of foam, adhesive and especially as an elastomer. To utilize elastomers in various applications without being fractured, various methods to control the mechanical properties of elastomers have been investigated such as incorporating fillers and additives or creating multiple networks. In this study, ultraviolet-curable silicone containing polyurethane acrylate was synthesized from poly(tetrahydrofuran) (PTH), hydroxy-terminated poly(dimethyl siloxane) (PDMS) and isophorone diisocyanate. The polyurethane chain was terminated with acrylate to fabricate modulus tunable and rapidly crosslinkable silicone/urethane composite elastomer. By adding 3-(trimethoxysilyl)propyl acrylate to the silicone/urethane elastomer network, the mechanical properties of silicone/urethane elastomer can be enhanced by creating additional covalent bonds at elevated temperature. The mechanical properties of the silicone-contained PUA elastomer can be enhanced even after complete photopolymerization, and local modulus enhancement is also possible by heating only desired area of the elastomer. We believe that the silicone/urethane elastomer can be used to fabricate flexible devices, force sensor, etc.clos

A New Microtensile Tester for the Study of MEMS Materials with the Aid of Atomic Force Microscopy

An apparatus has been designed and implemented to measure the elastic tensile properties (Young's modulus and tensile strength) of surface micromachined polysilicon specimens. The tensile specimens are "dog-bone" shaped ending in a large "paddle" for convenient electrostatic or, in the improved apparatus, ultraviolet (UV) light curable adhesive gripping deposited with electrostatically controlled manipulation. The typical test section of the specimens is 400 µm long with 2 µm x 50 µm cross section. The new device supports a nanomechanics method developed in our laboratory to acquire surface topologies of deforming specimens by means of Atomic Force Microscopy (AFM) to determine (fields of) strains via Digital Image Correlation (DIC). With this tool, high strength or non-linearly behaving materials can be tested under different environmental conditions by measuring the strains directly on the surface of the film with nanometer resolution