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Rapid prototypes formed using stereolithography (SL) method have to undergo post‐curing to increase their strength and rigidity. This study attempts to reduce, if not eliminate, post‐cure distortion by characterising curing behaviours. Curing (both heat and UV initiated) characteristics of an acrylic‐based photopolymer under actual fabrication conditions were studied using Raman spectroscopy as well as differential scanning calorimetry (DSC) and differential scanning photo‐calorimetry (DSP). Specimens of single photopolymer lines were created using a SL machine. Raman spectroscopy was used to quantify the curing percentage at different areas on the cross‐section of these lines. Curing percentages before and after post‐curing were also obtained from the experiments. Difference in percentage of post‐curing gave an indication of the distortions faced. It was found that uncured and partially cured resins trapped within the photopolymer resulted in inhomogeneity of curing in the specimens causing shrinkage and distortion.

This study aims to explore the infrared imaging effect of fabrics coated with phase change material microcapsules (PCM-MCs), which are prepared by the initiation of ultraviolet (UV) light.

PCM-MCs were prepared by UV polymerization using paraffin (PA) as core material, polymethyl methacrylate as wall material and ferric chloride as photoinitiator. The effects of emulsifier dosage and emulsification temperature on the properties of PA emulsion were investigated. Scanning electron microscopy, particle size analysis, infrared spectroscopy, differential scanning calorimetry and infrared imaging test were used to characterize the properties of microcapsules.

The PCM-MCs with good morphology and particle size were prepared with 25 cm of the distance between light source and the liquid. The average particle size was 1.066 µm and the latent heat of phase transition was 19.96 J/g. After 100 accelerated thermal cycles, the latent heat only decreased by 1.8%. It had good heat storage stability and thermal stability. The fabric coated by the microcapsules exhibited a variable temperature hysteresis effect when placed in the sun, and presented a color close to the infrared images of the human palm under the external environment temperature close to the human body temperature.

The PCM-MCs prepared based on UV light initiation showed good thermal properties and its coated fabrics had an infrared decoy effect below the temperature of the human body.

This study explored the application of microcapsules in textiles.

The microcapsules had a certain application potential in infrared decoy effect.

The build characteristics of two liquid crystal (LC) reactive monomers were studied using a table‐top stereolithography apparatus (TTSLA). LC materials contain stiff, rod‐like mesogenic segments in their molecules, which can be aligned causing an anisotropy in properties. When cured in the aligned state the anisotropic structure is “locked in” resulting in materials with anisotropic physical and mechanical properties. By varying the alignment of layers, properties such as thermal expansion coefficient can be optimized. High heat distortion (or glass transition) temperatures are possible depending on the monomer chemical structure. Working curves for the LC resins were developed under various conditions. A permanent magnet placed outside the TTSLA vat was used to uniformly align the monomer in the nematic state. Photo‐initiator type and content; alignment of the nematic phase; and operating conditions affected the working curve parameters. Glass transition temperatures of post‐cured parts ranged from 75 to 1488C depending on the resin and processing conditions. Mechanical analysis data revealed a factor of two difference between glassy moduli measured in the molecular alignment versus the transverse alignment directions. Based on these initial studies, more advanced resins with higher glass transitions are being developed at the University of Dayton.

The purpose of this paper is to prepare poly(sodium‐p‐styrenesulphonate) (PSSNa) and investigate the effects of polymerisation conditions on the polymerisation rate of sodium styrenesulphonate (SSNa) and molecular weight of PSSNa.

SSNa polymers were prepared in both solution state and solid state by the γ‐ray radiation‐induced polymerisation. The molecular weight of polymer was measured with Ubbelohde viscosimeter and the molecular structure was characterised with IR and UV spectrophotometers.

In the radiation‐induced polymerisation of SSNa, factors such as irradiation dose rate, total dose, irradiation temperature, additives, etc. have impacts on the polymerisation rate, polymer yield and molecular weight of polymer. In aqueous solution, the reacted monomer number of SSNa and the total activation energy (Ea) of polymerisation were found to be 1.28×10⁴mol/100 eV and 12.98 kJ/mol, respectively. In the solid state, the SSNa was polymerised too, although the irradiation dose needed for the polymerisation was much higher comparing with that in the liquid state.

There are few reports on polymerisation process for the preparation of PSSNa via radiation techniques.

PSSNa has been widely used in many fields. Polymers prepared by radiation‐induced polymerisation could be used in special aspects such as biomedical application which requires products of higher purity.

The paper provides a way for the preparation of higher purity PSSNa without the use of polymerisation initiator.

UV‐radiation curing has become a well accepted technology which has found its main applications in the coating industry, the graphic arts and microelectronics. The liquid to solid phase change proceeds within a fraction of a second on intense illumination at ambient temperature. The kinetics of such ultrafast polymerization have been followed in situ by real‐time infrared spectroscopy. This technique proved well suited to assess the performance of the various constituents of a UV‐curable formulation (photoinitiator, monomer, functionalized oligomer) from measurements of the actual polymerization rate and of the final cure extent. The photopolymerization of both radical‐type (acrylates) and cationic type (epoxides, vinyl ethers) monomers has been examined, as well as that of monomer blends. Interpenetrating polymer networks have been synthetized by photocrosslinking of a hybrid acrylate/epoxide system which generates a hard and scratch‐resistant polymer material.

The purpose of this paper is to use alternative polymerisation methods, i.e. UV irradiation to synthesise poly(acrylamide)/montmorillonite nanocomposite and characterise the composite.

Polymer/montmorillonite nanocomposite was synthesised by the polymerisation, induced by UV radiation and the structure of the composite was studied by means of FTIR, NMR(¹³ C, ²⁷Al and ²⁹Si) and X‐ray diffraction.

The poly(acrylamide)/montmorillonite nanocomposite was synthesised by UV irradiation, and its structures showed that the acrylamide was intercalated in the lamina of montmorillonite in bimolecular layers. FTIR and NMR analyses showed that there was no major chemical change of the polymer chain associated with the intercalation. The interaction between montmorillonite and polymer was mainly related with the van der Waals forces and hydrogen bonding, not with the bonding involved with the carbon atoms.

There are few reports on the synthesis and characterisation of polymer/montmorillonite composite prepared with UV radiation.

The alternative synthesis method using UV irradiation can provide a new way for the preparation of montmorillonite/acrylamide nanocomposite for the application in moisture and organic solvent vapour sensors, etc.

This provides a way for the synthesis of polymer/montmorillonite nanocomposite using polymerisation induced by UV radiation, which can be used in the thin membrane preparation for sensor and special application. Characterisation of the material revealed the structure of the nanocomposite, which would be helpful for the study of structure design and property improvement.

The purpose of this paper is to provide a critical and in‐depth review of the present status and recent developments in synthetic methodologies, reaction engineering, process design and quality control aspects associated with the manufacture of mono and multifunctional acrylate monomers.

This paper reviews commercially important UV cure mono and multifunctional acrylate monomers. It covers their synthesis, catalyst, and appropriate solvents for azeotropic removal of byproducts. The detail discussion on catalysis, basis of design of reactors and commercial plant and the process engineering associated with the manufacture has been supported through citation of synthesis of various acrylate monomers. The methodologies adopted for determination of physical, chemical and compositional characterisation of acrylate monomers have been presented. In addition, the guidelines regarding the bulk storage and commercial handling of acrylates have been reviewed.

The reaction engineering of esterification reaction between acrylic acid and polyol has been worked out to provide the basis for selection of reactors. The reaction has been modeled as a series – parallel complex reaction for providing explanation for generation of various byproducts/adducts and multiple esters.

The detailed discussion on formation, characterisation and treatment of Michael adducts and purification of acrylate monomers will be relevant for new researchers for further development. A review of guidelines on selection of homogenous and heterogeneous catalysts for synthesis of acrylate monomers has been presented.

Since the related literature on acrylate monomers is scarce, scattered and proprietary, the consolidated coverage in one paper will be useful.

The conventional curing of oxirane containing molecules such as cycloaliphatic epoxies with organic acid anhydrides, organic acids, Lewis acids and blocked Lewis acids is widely practised in the industry and the reaction mechanisms are well documented and described in epoxy resin related books

Photoresist imaging traditionally uses silver halide or diazo based phototools for contact exposure to an actinic UV light source. By contrast, laser direct imaging uses digital imaging data to control a laser beam scanner to write directly on to the photoresist, therefore eliminating the need for phototools. In the past, even though the benefit of a UV system was recognised, laser direct imaging was mainly limited to the use of a visible laser as early UV lasers were low in power, unreliable and expensive. So far, no visible systems have gained commercial recognition because of the inherent deficiencies of the visible system. Recent advantages in UV laser equipment and UV sensitive photoresist have now made UV laser direct imaging a viable alternative to traditional contact imaging. As new UV laser imaging systems start to emerge, interest and attention are also growing among printed circuit board manufacturers. This paper discusses various attributes of a UV laser direct imaging system and fundamental differences in photophysics between laser direct imaging and conventional UV imaging.

Over the last several years, the range of applications for the photopolymerisation process has been steadily increasing, especially in such areas as rapid prototyping, UV inks, UV coats and orthodontic applications. In spite of this increase, there are still several challenges to be overcome when the application concerns materials formulation and their mechanical properties. In this context, the main aim of this work is to outline the contribution of the formulation components for the parameters of the photopolymerisation process and the resultant mechanical properties of the material.

For this research, the authors have applied multivariable analysis methods, which allow the identification of principal conclusions based on experimental results. For the experimental analysis, the authors applied design of experiment, while the material formulation was based on methyl methacrylate as a monomer, Omnrad 2500 as a photoinitiator and trimethylolpropane triacrylate as an oligomer. The authors analysed the photopolymerisation rate, viscosity, mechanical tensile strength, flexural stiffness and softening. These results comprise a multiobjective optimisation study to identify the ideal material formulation for additive manufacturing applications. The values chosen for the materials were the following: the initiator concentration was 2 and 5% wt., the monomer volume was 5 and 10 ml and the oligomer volume was 3 and 5 ml. To analyse the system kinetics and the photopolymerisation rate, the authors identified the polymer conversion rate through a photometric-cum-gravimetric method with a wavelength of 390 nm at the peak intensity. For the softening test, the authors identified the stiffness of the material as a function of temperature, characterising the thermal-mechanical behaviour of the material and determining its degree of crystallinity (cross-linking). Additionally, the authors performed an optimisation to maximise the mechanical tensile strength, flexural stiffness, softening temperature and photopolymerisation rate while minimising the viscosity.

Based on these studies, it was possible to identify the influence of the monomer/oligomer ratio and the initiator concentration as function of polymerisation rate, viscosity, mechanical tensile strength, stiffness and softening of the material. It was also possible to determine the photopolymerisation rate in addition to the constants of propagation and termination. As a result of these studies, the authors identified a material formulation that resulted in a softening temperature greater than 70°C, while the viscosity of material remained lower than 3 cP. The mechanical ultimate tensile strength was between 10 and 50 MPa, and the stiffness was between 1.6 and 5.8 GPa. The effect of cross-linking on the process highlighted the interaction between the monomer/oligomer ratio and the initiator. The contribution of the initiator and the inhibitor to the polymerisation rate was identified via a numerical model, which allows the prediction of the material's behaviour in different process conditions, as such curing time and penetration depth.

The main value of this work is to show the possibility of optimized photopolymerizable systems through an experimental approach as a function of the mechanical properties of material. In addition, it emphasised the possibility of predicting the material behaviour in front of different situations.