A Review of Vegetable Oil-Based Polymers: Synthesis and Applications

The reviewed work addressed the shift in focus from conventional polymers to bio-based and renewable polymers. The environmental attributes of the renewable polymers make them preferred choice of matrix. The properties of the matrices from renewable origin could compete in high end applications. The composition of the fatty acids in plant seed oil was discussed and the determination of the level of unsaturation used the iodine value. This review also extensively discussed the values of various fatty acid components present in the oils. Areas of application of the thermosetting polymers obtained from plant seed oils were also discussed.

Bio-Based Polymers for Technical Applications: A Review — Part 2

Triglyceride oil of plant seed cannot be used on its own without further modification. The fatty acids must be suitably functionalized in order to add polymerisable functionalities which will help in the curing process. The purpose of these modifications is to reach a higher level of molecular weight and cross-link density, and also to incorporate chemical functionalities known to impart stiffness in a polymer network. The modification can go through various path ways which were described in this study.

Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.

In situ differential scanning calorimetry analysis of dissolution and precipitation kinetics in Mg-Y-RE alloy WE43

Further development of our differential scanning calorimetry(DSC)method for the analysis of solid-solid phase transformations now also allows for its application in the kinetic analysis of age hardening in Mg alloys.As a result,the state-of-the-art for DSC on Mg alloys has been improved with respect to the accessible temperature range,zero-level accuracy and dynamic range.DSC analysis was performed on the example of Mg wrought alloy WE43.Heating DSC experiments on the initial condition T4 and even direct continuous cooling DSC analysis on the kinetics of quench induced precipitation during cooling from solution treatment were possible,covering a dynamic range of 0.01-3 K/s.The DSC findings are discussed with respect to literature knowledge and scanning electron microscopy analysis of the defined heat treatment states.

Processing of Lyocell Fiber Mat: An Alternative Renewable Reinforcement in Composite Manufacturing

The carding of the Lyocell cellulose fiber was done with a cylindrical cross lap machine supplied by Cormatex Prato, Italy. Several mats were made by carding and needle punching in order to have a compact and well entangled mat suitable for reinforcement. The speed of the cross lap machine, the frequency of needle punching, the number of times the mat goes through needle punching, the feeding rate of the carded fiber and the depth of needle penetration determined the level of entanglement of the Lyocell fiber which ultimately increased the mechanical properties of the fiber. The good mechanical properties of the carded Lyocell fiber made it a renewable and environmentally friendly alternative as reinforcement in composite manufacturing. Compared with other jute fiber reinforced composites, the mechanical properties of the resulting Lyocell composites were found to be better. Regenerated cellulose fiber (Lyocell) composites were environmentally friendly and the mechanical properties were comparable to those of natural fibers.

Quasi-in vivo corrosion behavior of AZ31B Mg alloy with hybrid MWCNTs-PEO/PCL based coatings

This study investigated the effects of multi-walled carbon nanotubes(MWCNTs) and polycaprolactone(PCL) on the quasi-in vivo corrosion behavior of AZ31B Mg alloy treated by plasma electrolytic oxidation(PEO). Thin(~2 μm, PCTPCL4) and thick(~60 μm, PCTPCL6) PCL layers were applied only onto the MWCNTs-PEO coating(PCT) as it showed better corrosion performance. Findings reveal that incorporation of MWCNTs induced several structural and functional modifications in the PEO coating, such as increased roughness, a thicker inner barrier layer, and reduced hydrophilicity.Quasi-in vivo corrosion testing was carried out under controlled temperature, p H, and fluid flow in simulated body fluid(SBF) by electrochemical impedance spectroscopy(EIS) and hydrogen evolution experiments. EIS results revealed that, after 48 h immersion, a diffusion process controlled hydration of the ceramic coatings. Comparison of the collected hydrogen after 15 days of immersion in the quasi-in vivo environment revealed that the PEO and PCT ceramic coatings decreased hydrogen generation by up to 74% and 91%, respectively, compared to non-coated alloy.PCTPCL6 coating exhibited the lowest amount of collected hydrogen(0.2 m L/cm^(2)). The thick PCL layer delayed the onset of substrate corrosion for at least 120 h, reducing the corrosion rate by 85% compared with the PCT.

Surface Treatments of Natural Fibres—A Review: Part 1

This review is based on the surface treatment of natural fibres which can be used in technical applications. Natural fibres on their own have some draw backs regarding moisture uptake, quality variations, low thermal stability, and poor wettability. Insufficient adhesion between polymer matrix and fibre leads in time to debonding. Overcoming the weaknesses of these natural fibres gave the motivation for this study where physical and chemical methods of modification were considered. Physical methods such as electric discharge and mercerization were reported as well as the chemical methods such as graft copolymerization and treatment with isocyanates, and the results due to these modifications were discussed. This study reveals that natural fibres are good candidates for reinforcement but they have to be suitably treated to improve their properties if they are to be used in technical applications. The various fibre surface treatments actually improve the interfacial adhesion between the fibre surface and the matrix, thereby giving good mechanical properties to the resulted polymer composites.

Application of Artificial Intelligence (AI) Modeling in Kinetics of Methane Hydrate Growth

Determining thermodynamic and kinetic conditions for natural gas hydrate formation is an interesting subject for many researches. At the present, suitable information including experimental data and the thermodynamic models of hydrate formation are available which predict the thermodynamic conditions of hydrate formation. Conversely, there is no sufficient study about the kinetics of natural gas hydrate and most of experimental data and kinetic models in the literature are incomplete. Artificial Intelligence (AI) having sub-branches such as artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS) has been proved as a novel tool with acceptable accuracy for modeling of engineering systems. Therefore, this paper aims to investigate the kinetics of hydrate formation by predicting the relationship of growth rate of methane hydrate with temperature and pressure using ANN and ANFIS. This goal can also be achieved by solving complicated governing equations while artificial intelligence provides an easier way to accomplish this goal. The result has shown that ANIFS is a more potential tool in predication relationship of kinetics of hydrate formation with temperature and pressure in comparison of ANN in present work.

Chemical and Morphological Surface Modification of Epoxy Based Thermosets

Recently developed low fluorine containing polymers are advanced materials which confer advantageous properties to surfaces at a lower cost than conventional fluoropolymers (like PTFE), and are also more easily processable. Fluoropolymer surfaces are characterized by a low surface energy, high oleo and hydrophobicity, low coefficients of friction, among many other properties. This makes them desired materials in microelectronics, antifogging, antifouling and medical applications, to name a few. Fluorinated compounds are not easily coupled with macromolecules or common organic systems, and great efforts are made to compatibilize fluorinated species with hydrocarbon polymers. In this work, two chemical routes were explored in order to incorporate perfluorinated alkyl chains in an epoxy-amine based thermoset. On one side, a perfluoroalkyl thiolated molecule was used as a stabilizing ligand for silver nanoparticles, which were incorporated in the matrix polymer. On the other hand, fluorinated chains containing epoxy functionalities, were used as the matrix modifier. In the first case, fluorinated chains covering the nanoparticles, were mixed with the matrix, while in the second case, the fluoroalkyl chains were chemically linked to the network. Fluorine migration to the air—polymer interface was confirmed by X-Ray photoelectron spectroscopy (XPS). The materials hydrophobicity was then studied in terms of their contact angle with water (CA), as a function of the surface composition and the topography. Scanning electron microscopy (SEM) and atomic force microscopy (AFM), operated in moderate and light tapping modes, were used to morphologically describe the surfaces. An exhaustive surface analysis was made in order to explain the different hydrophobicity grades found.

SYNTHESIS, CHARACTERIZATION AND SPECTROSCOPIC INVESTIGATION OF PYRAZINOPORPHYRAZINE NETWORK POLYMER-SUPPORTED METAL (Ⅱ)-BASED CATALYSTS

Chloranil through condensation reaction with vicinal diamine such as diaminomaleonitrile produced heterocyclic monomer, p-benzoquinonebis[2,3-b; 2＇,3＇-b＇]pyrazine-5,6-dinitrile. The tetranitrile monomer was cyclo-tetramerised using lithium/pentanol and acetic acid affording the corresponding tetrap-benzoquinone bis[2,3-b; 2＇,3＇-b＇]pyrazinoporphyrazine）]- based network polymer （2H-Pz）. The tetranitril monomer was cyclo-tetramerised using metal salt and quinoline affording the corresponding porphyrazinato-metal II-based network polymers （M-Pz）, M = Co, Ni or Cu. Elemental analytical results, IR and NMR spectral data of the prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The prepared pyrazinoporphyrazines were used as efficient catalysts for the oxidation of thiophenol and benzylthiol to their disulfides in the presence of air atmosphere. The results of oxidation of thiophenol and benzylthiol show that after 15 min the maximum yield of the corresponding disulfides reached 95%, 91%, respectively.

Multibranched-Based Fluorinated Materials:Tailor-Made Design of ^(19)F‑MRI Probes

CONSPECTUS: Future medicine is primarily aiming at the development of novel approachesfor an early diagnosis of diseases and a personalized therapy for patients. For achieving theseobjectives, a key role is played by medical imaging. Among available noninvasive imagingtechniques, Fluorine-19 (^(19)F) Magnetic Resonance Imaging (MRI) is emerging as a powerfulquantitative detection modality for clinical use both for molecular imaging and for cell tracking.The strength of using ^(19)F-MRI is mainly related to the lack of endogenous organic fluorine intissues, with no background, enabling the visualization of fluorinated tracers as hot-spot images,adding secondary independent information to the anatomical features provided by thegrayscale ^(1)H-MRI. The main challenge for ^(19)F-MRI clinical application is the intrinsic reducedsensitivity of MRI. To improve sensitivity, undoubtedly the use of a high field MRI scanner andcryogenic radiofrequency probes is advantageous, but there is a clear need of developingincreasingly effective fluorinated tracers.The ideal tracer should bear as many as possible magnetically equivalent fluorine atoms andshow optimal magnetic resonance relaxivity properties (i.e., T_(1) and T_(2)), which enable reduced acquisition time with the possibility toapply fast imaging methods. Moreover, it should be biocompatible with reduced tendency to bioaccumulate in tissues, which is oneof the main drawbacks in using perfluorocarbons (PFCs), together with their difficulty to be chemically modified with functionalgroups. In fact, PFCs such as perfluorooctyl bromide (PFOB), perfluoro-15-crown-5-ether (PFCE), and linear perfluoropolyethers(PFPE) are currently the most used tracers in ^(19)F-MRI preclinical and clinical studies, with the above-mentioned limitations. In thisregard, molecules bearing short branched fluorinated chains gained a lot of attention for their high number of equivalent fluorinesand expected capability of reducing bioaccumulation concerns. A valuable building block for branched fluorinated tracers isperfluoro-tert-butanol (PFTB), with nine magnetically equivalent fluorines and easy availability and modification.In this Account we will discuss the main challenges that ^(19)F-MRI has to overcome for increasing its clinical use, highlighting on onehand the need of developing customized fluorinated materials for increasing sensitivity and enabling multimodal properties, and onthe other hand, the importance of the ultrastructure of the final formulation for the final biological response (i.e., clearance). In thiscontext, our group has been focusing on the synthesis and development of branched fluorinated tracers, for which the originator is amolecule called PERFECTA (from suPERFluorinatEdContrasT Agent), bearing 36 equiv ^(19)F atoms, which showed not only optimalrelaxometry properties but also a very specific and intense Raman signal. Thus, PERFECTA and its derivatives represent a newfamily of multimodal tracers enabling multiscale analysis, from whole body imaging (^(19)F-MRI) to microscopic detection at thecellular/tissue level (Raman microscopy). We believe that our proposed PFTB strategy can strongly promote the production ofincreasingly effective ^(19)F-MRI materials with additional functionalities, facilitating the clinical translation of this imaging modality.

DEHYDRATION KINETICS OF POLYVINYL ALCOHOL HYDROGEL WOUND DRESSINGS DURING WOUND HEALING PROCESS

The hydrogel wound dressing based on polyvinyl alcohol （PVA） was prepared by the freezing-thawing cyclic method. The dehydration kinetics of prepared hydrogels was determined using the experimental method and mathematical modeling based on diffusion mechanism. The results show that the dehydration rate of PVA hydrogel wound dressing inversely depends on the hydrogel thickness as well as water content of the wound. On the other hand, the initial water content of hydrogel and the atmospheric humidity have little direct effect on the dehydration rate. The good agreement between experimental and mathematical modeling results in early stages of dehydration process shows that the predominate factor determining the dehydration of these wound dressings is diffusion.

Dispersion of particles in the coatings characterized by laser scanning confocal micrscopy(LSCM) I:Vertical dispersion of particles in the coatings and the weathering property studied by orthogonal analysis method of LSCM

Two kinds of TiO_2 filled epoxy coatings were designed and prepared to obtain pigments with different dispersion degrees of TiO_2 particles.Laser scanning confocal microscope(LSCM)was used to investigate both the horizontal and vertical distributions of TiO_2 particles in the coatings.The results indicated that TiO_2 in the two samples shared considerable similarity in horizental dispersion,but exhibited great difference in vertical dispersion.TiO_2 showed uniform vertical distribution in disp coating,wheras a gap about 1.1μm was found in the non-disp coating,which significantly influenced the surface optical properties of the coatings during weathering.Based on the confocal data,the model of dispersion of pigments in the coatings was proposed and the change of surface properties during weathering was predicted:the surface optical properties showed an initial decrease followed by a subsequent increase,which was in good agreement with the weathering data.