Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use of peptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study of biological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries of existing disciplines. Many self-assembling systems are range from bi- and tri-block copolymers to DNA structures as well as simple and complex proteins and peptides. The ultimate goal is to harness molecular self-assembly such that design and control of bottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes of life and non-life science applications. Such aspirations can be achieved through understanding the fundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.
Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.
This study was conducted for the development of the green protection garments. For this purpose, laminate composite material was developed from Kevlar 29-ramie-unsaturated polyester resin. The aim of this study was to develop a solid body armour that meets the specific requirements of ballistic resistance. This composite is subjected to high impact loading. The target was shot using gas gun machine that is supported by camera hardware to capture the projectile speed. In order to achieve the goal of the research, several experiments were conducted with the aim to estimate the ballistic limit, maximum energy absorption, composite failure mode, life time rupture, target geometry, and environmental effect. The results of these experiments indicated that the maximum ballistic limit validated at impact speed is in the range of 250 m/s to 656.8 m/s for the second protection level. The targets are improved in term of the impact response with the increase in the relative humidity, i.e. the range of 50% ± 20%, whereas, reduction of resistance results in the increase of temperature. The range of temperatures was between 20oC and 70oC. A limited delamination was generated under multiple shots. Targets geometry plays a major role in increasing the impact response. Hence, the results present a high resistant impact for pairs from the panels with total thickness arrived to 15
mm ± 3 mm. This body armour is one of the most economical armour products, in which common materials are used in its production, particularly to reduce the amount of Kevlar, and this could further lead to a decrease in its production cost. On the other hand, this armour meets the ballistic threats under 623 m/s of 15 mm ± 3 mm target thickness and 837.5 m/s of 25 mm ± 2.mm. Thus, the armour is equivalent to the third level of protective ballistic limits in the National Institute of Justice (NIJ) standards.
Various palm oil (RBD Palm Olein) based urethane acrylate prepolymers (UPs) having different structures and molecular weights were synthesised from palm oil based polyols, diisocyanate compounds and hydroxyl terminated acrylate monomers by following established synthesis procedures described elsewhere. The products (UPs) were compared with each other in terms of their molecular weights (MW), viscosities and UV curing performances of pressure sensitive adhesives (PSA) UP based formulations. The molecular structure of diisocyanate compounds and hydroxyl acrylate monomers tend to determine the molecular weights and hence viscosities of the final products of urethane acrylate prepolymers (UP), whereas, the MW of the UP has no direct effects on the coatings and adhesive properties of UV curable UP based PSA.
Membrane technologies have received high interest in the separation gas mixture. The
ceramic inorganic membranes have possessed high permeability, excellent thermal,
chemical and mechanical stabilities compared to conventional polymer membranes.
This work presents the fabrication of silica ceramic membrane by sol dip-coating
method. The tubular support was dipped into the solution of tetrethylorthosilicate
(TEOS), distilled water and ethanol with the addition of nitric acid as a catalyst. The
fabricated silica membrane was then characterized by (Field Emission Scanning
Electron Microscope) FESEM and (Fourier transform infrared spectroscopy) FTIR to
determine structural and chemical properties at different dipping number. FESEM
images indicate that the silica has been deposited on the surface fabricated ceramic
membrane and penetrate into the pore walls. However, number of dipping did not
affect the intensity peak of FTIR analysis.
The main aim of this study was to evaluate the suitability of sulfonated alginate as a modifying agent to enhance the hemocompatibility of self-fabricated polyethersulfone (PES) hollow fiber membrane for blood detoxification. Sodium alginate was sulfonated with a degree of 0.6 and immobilized on the membrane via surface amination and using glutaraldehyde as cross-linking agent. Coating layer not only improved the membrane surface hydrophilicity, but also induced -39.2 mV negative charges on the surface. Water permeability of the modified membrane was enhanced from 67 to 95 L/m2·h·bar and flux recovery ratio increased more than 2-fold. Furthermore, the modified membrane presented higher platelet adhesion resistance (reduced by more than 90%) and prolonged coagulation time (35 s for APTT and 14 s for PT) in comparison with the pristine PES hollow fiber membrane, which verified the improved anti-thrombogenicity of the modified membrane. On the other hand, obtained membrane after 3 h coating could remove up-to 60% of the uremic toxins. According to the obtained data, sulfonated alginate can be a promising modifying agent for the future blood-contacting membrane and specially blood purification issues.
The volume of waste generated from surface coating industries is of global concern. The disposal of this waste in the form of effluent has put enormous pressure on land and also poses as a health hazard when it leaches into soil and underground water. The study aims to examine the utilization of vinyl acetate effluents from water based paint factories as an admixture in concrete. Concrete specimens containing 0%, 2.5%, 5% and 10% of vinyl acetate effluents by weight of cement were prepared. The specimens were tested for drying shrinkage for 28 days and porosity was tested using mercury intrusion porosimetry. Findings show that concrete containing various proportions of vinyl acetate effluents manifests higher shrinkage behaviour compared to the control item. An investigation of pore size distribution reveals that polymer effluents have particles size larger than 50 nm which are categorize as macroporous in accordance to IUPAC classification. It can be concluded that adding polymer vinyl acetate effluents affects concrete deformation due to the condition of its pore structures. The utilization of this material may provide beneficial effect in terms of the durability performance of concrete and minimize environmental pollution.
Solid polymer electrolyte based on methyl cellulose (MC)-lithium triflate (LiCF3SO3) plasticised with ethylene carbonate (EC) was prepared using solution cast technique. The X-ray diffraction (XRD) studies proved that the amorphous nature of the electrolyte systems was increases due to the addition of salt and plasticiser. The improved surface morphology of plasticised polymer system ensures it has good electrode-electrolyte contact during performance testing. The polymer electrolyte was found to have high thermal stability indicating that the electrolyte can be used at higher temperature. The ionic conductivity increased up to 1.24 x 10-4 S cm-1 at optimum amount of EC plasticiser associated to the effect of plasticiser that initially leads to the formation of Li+-EC complex. Consequently, it reduces the fraction of polymer-Li+ complex which contributes to the increase of the segmental chain flexibility in the plasticized system. Temperature dependent studies indicate ionic conductivity increase due to the temperature increase and is in line with Arrhenius behaviour pattern. An activation energy of 0.26 eV at highest conductivity sample was obtained. The addition of plasticiser lowers the activation energy thus increasing the ion mobility of the system and contributing to ionic conductivity increment. The plasticization method is a promising means to dealing with the solid polymer electrolyte problem and producing electrolytes that meet the needs of electrochemical devices.
Neat cellulose acetate (CA) and CA/polysulfone (PSf) blend ultrafiltration membranes in the presence of polyvinylpyrrolidone as a pore former were prepared via a phase inversion technique. The prepared membranes were characterized by Fourier transform infrared, scanning electron microscopy, mechanical strength, water content, porosity, permeate flux and heavy metals (Pb2+, Cd2+, Zn2+ and Ni2+) rejection to comprehend the impact of polymer blend composition and additive on the properties of the modified membranes. The water flux expanded by increasing of PSf content in the polymer composition. CA/PSf (60/40) had the highest flux among prepared membranes. Prepared blend membranes were able to remove heavy metals from water in the following order: Pb2+ > Cd2+ > Zn2+ > Ni2+. The CA/PSf (80/20) blend membrane had great performance among prepared membranes due to the high heavy metals removal and permeate flux.
The copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has proven to be a pivotal advance in chemical ligation strategies with applications ranging from polymer fabrication to bioconjugation. However, application in vivo has been limited by the inherent toxicity of the copper catalyst. Herein, we report the application of heterogeneous copper catalysts in azide-alkyne cycloaddition processes in biological systems ranging from cells to zebrafish, with reactions spanning from fluorophore activation to the first reported in situ generation of a triazole-containing anticancer agent from two benign components, opening up many new avenues of exploration for CuAAC chemistry.
The development of molecularly imprinted polymer nanoparticles (MIP-NPs), which specifically bind biomolecules, is of great interest in the area of biosensors, sample purification, therapeutic agents and biotechnology. Polymerisation techniques such as precipitation polymerisation, solid phase synthesis and core shell surface imprinting have allowed for significant improvements to be made in developing MIP-NPs which specifically recognise proteins. However, the development of MIP-NPs for protein templates (targets) still require lengthy optimisation and characterisation using different ratios of monomers in order to control their size, binding affinity and specificity. In this work we successfully demonstrated that differential scanning fluorimetry (DSF) can be used to rapidly determine the optimum imprinting conditions and monomer composition required for MIP-NP design and polymerisation. This is based on the stability of the protein template and shift in apparent melting points (Tm) upon interaction with different functional acrylic monomers. The method allows for the characterisation of molecularly imprinted nanoparticles (MIP-NPs) due to the observed differences in melting point profiles between, protein-MIP-NPs complexes, pre-polymerisation mixtures and non-imprinted nanoparticles (NIP-NPs) without the need for prior purification. The technique is simple, rapid and can be carried out on most quantitative polymerase chain reaction (qPCR) thermal cyclers which have the required filters for SYPRO
Several blends of cellulose derived from bast part of kenaf (Hibiscus cannabinus L.) plant, with different thermoplastics, low density polyethylene (LDPE) and high density polyethylene (HDPE), were prepared by a melt blending machine. Polyethylene glycol (PEG) was used as plasticizer. Biodegradability of these blends was measured using soil burial test in order to study the rates of biodegradation of these polymer blends. It was found that the cellulose/LDPE and cellulose/HDPE blends were biodegradable in a considerable rate. The bio-composites with high content of cellulose had higher degradation rate. In addition, biodegradability of the bio-composites made up using PEG was superior to those of the bio-composites fabricated without PEG, due to the improved wetting of the plasticizer in the matrix polymer. The results were also supported by the scanning electron microscopy (SEM).
In this study, low-bandgap polymer poly{[4,4-bis(2-ethylhexyl)-cyclopenta-(2,1-b;3,4-b')dithiophen]-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl} (PCPDTBT) nanostructures have been synthesized via a hard nanoporous alumina template of centrifugal process. Centrifuge has been used to infiltrate the PCPDTBT solution into the nanoporous alumina by varying the rotational speeds. The rotational speed of centrifuge is directly proportional to the infiltration force that penetrates into the nanochannels of the template. By varying the rotational speed of centrifuge, different types of PCPDTBT nanostructures are procured. Infiltration force created during the centrifugal process has been found a dominant factor in tuning the morphological, optical, and structural properties of PCPDTBT nanostructures. The field emission scanning electron microscopy (FESEM) images proved the formation of nanotubes and nanowires. The energy-dispersive X-ray spectroscope (EDX) analysis showed that the nanostructures were composed of PCPDTBT with complete dissolution of the template.
This paper discusses sputtered silicon encapsulation as a wafer level packaging approach for isolatable MEMS devices. Devices such as accelerometers, RF switches, inductors, and filters that do not require interaction with the surroundings to function, could thus be fully encapsulated at the wafer level after fabrication. A MEMSTech 50g capacitive accelerometer was used to demonstrate a sputtered encapsulation technique. Encapsulation with a very uniform surface profile was achieved using spin-on glass (SOG) as a sacrificial layer, SU-8 as base layer, RF sputtered silicon as main structural layer, eutectic gold-silicon as seal layer, and liquid crystal polymer (LCP) as outer encapsulant layer. SEM inspection and capacitance test indicated that the movable elements were released after encapsulation. Nanoindentation test confirmed that the encapsulated device is sufficiently robust to withstand a transfer molding process. Thus, an encapsulation technique that is robust, CMOS compatible, and economical has been successfully developed for packaging isolatable MEMS devices at the wafer level.
This review paper briefly explains the meaning and characteristics of endocrine disrupting compounds (EDCs). EDCs comprise various types of natural and synthetic chemical compounds that can impede the reproductive action of the endocrine system in animals and humans. Further discussion is on bisphenol A (BPA), one of the examples of EDCs that is extensively used in industries nowadays. It acts as a monomer, which is desired in the production of polycarbonate plastics and epoxy resins. BPA later ends up in environmental compartments (air, water, sediment). In spite of this, BPA is not categorized as a persistent compound and it will be degraded either by photolysis or bacteria. It can only exist between three and five days in the environment. The concentration of BPA varies in different locations depending on the temperature, pH, source and time of sampling. BPA has been frequently debated due to its toxicity and carcinogenicity towards animals and humans. This paper also explains several extraction procedures and analytical methods concerning how to identify BPA in either aqueous or solid samples. However, an additional review is needed in respect of how to handle, reduce the level of BPA in the environment and understand the details concerning the existence of BPA.
Aesthetic value of the automotive car seat has been one of the selling points of each car besides
providing functions such as being safe, supportive as well provides comfort to the occupants. Other
criteria considered besides the aesthetic element are cushion foam and self-adjustment factor.
Ergonomics is not a new issue because most of the existing seat design today have already practiced it.
Existing car seat manufacturers have considered anthropometry data. The average upon 95th percentile of
human measurement had been deliberated. However, issues such as time spent driving and seat design
issue have arisen upon the search of comfort and rising of musculoskeletal disease such as back pain. As a
solution, this study would propose an automotive car seat design of ergonomic evolution, which would
create comfort by manipulating the seat cushion foams. The proposed seat cushion foam would be use to
replace the existing polymers with beanbag foam. This is inspire by the nature of beanbag, fitting up and
providing comfort to the occupants of various body sizes and shapes. Malaysian anthropometry
measurements are required for design of car seat, which later compared with the existing seats of
commercial vehicle. The literature review showed the pressure mapping technique of respondent seating
on the existing car seat. The most sensitive compartments where discomfort are experienced studied and
placed with sachets filed with beanbag beads. This experiment conducted many times over a few
respondents by using the pressure mat to find out, if there are any changes in terms of comfort. This
design of new car seat with a manipulation cushion foam replaced with beanbag foam could be a niche to
eliminate discomfort to all range body sizes and shapes.
Phenol Formaldehyde (PF) resin has been extensively used in the manufacturing industry as a binding agent, especially in the production of wood-based panels because of its ability to provide good moisture resistance, exterior strength and durability as well as excellent temperature stability. However, due to the use of limited petroleum-based phenol in its formulation, there is a strong interest in exploring renewable biomass material to partially substitute the petroleum-based phenol. In this study, the slow pyrolysis of biomass decomposition process was used to convert two types of biomass, namely, oil palm frond and Rhizophora hardwood, into bio-oil. The phenol-rich fraction of the bio-oil was separated and added into the formulation of PF resin to produce an environmentally-friendly type of PF resin, known as bio-oilphenol-formaldehyde (BPF) resin. This BPF resin was observed to have comparable viscosity, better alkalinity, improved non-volatile content and faster curing temperature than conventional PF resin. Moreover, the particleboard bonded with this BPF resin was observed to have just as excellent bonding strength as the one bonded using conventional PF resin. However, the BPF resin exhibited an increased level of free formaldehyde and less thermal stability than the conventional PF resin, probably due to the addition of the less reactive bio-oil.
Ultrafiltration has been proven to be very effective in the treatment of oil-in-water emulsions, since no chemical additives are required. However, ultrafiltration has its limitations, the main limits are concentration polarization resulting to permeate flux decline with time. Adsorption, accumulation of oil and particles on the membrane surface which causes fouling of the membrane. Studies have shown that the ultrasonic is effective in cleaning of fouled membrane and enhancing membrane filtration performance. But the effectiveness also, depends on the selection of appropriate membrane material, membrane geometry, ultrasonic module design, operational and processing condition. In this study, a hollow and flat-sheet polyurethane (PU) membranes synthesized with different additives and solvent were used and their performance evaluated with oil-in-water emulsion. The steady-state permeate flux and the rejection of oil in percentage (%) at two different modes were determined. A dry/wet spinning technique was used to fabricate the flat-sheet and hollow fibre membrane (HFMs) using Polyethersulfone (PES) polymer base, Polyvinylpyrrolidone (PVP) additive and N, N-Dimethylacetamide (DMAc) solvent. Ultrasonic assisted cross-flow ultrafiltration module was built to avoid loss of ultrasonic to the surrounding. The polyurethane (PU) was synthesized by polymerization and sulphonation to have an anionic group (-OH; -COOH; and -SO3H) on the membrane surface. Changes in morphological properties of the membrane had a significant effect on the permeate flow rate and oil removal. Generation of cavitation and Brownian motion by the ultrasonic were the dominant mechanisms responsible for ultrafiltration by cracking the cake layers and reducing concentration polarization at the membrane surface. The percentage of oil after ultrafiltration process with ultrasonic is about 90% compared to 49% without ultrasonic. Ultrasonic is effective in enhancing the membrane permeate flux and controlling membrane fouling.
Glycerol is a by-product produced from biodiesel, fatty acid, soap and bioethanol industries. Today, the value of glycerol is decreasing in the global market due to glycerol surplus, which primarily resulted from the speedy expansion of biodiesel producers around the world. Numerous studies have proposed ways of managing and treating glycerol, as well as converting it into value-added compounds. The electrochemical conversion method is preferred for this transformation due to its simplicity and hence, it is discussed in detail. Additionally, the factors that could affect the process mechanisms and products distribution in the electrochemical process, including electrodes materials, pH of electrolyte, applied potential, current density, temperature and additives are also thoroughly explained. Value-added compounds that can be produced from the electrochemical conversion of glycerol include glyceraldehyde, dihydroxyacetone, glycolic acid, glyceric acid, lactic acid, 1,2-propanediol, 1,3-propanediol, tartronic acid and mesoxalic acid. These compounds are found to have broad applications in cosmetics, pharmaceutical, food and polymer industries are also described. This review will be devoted to a comprehensive overview of the current scenario in the glycerol electrochemical conversion, the factors affecting the mechanism pathways, reaction rates, product selectivity and yield. Possible outcomes obtained from the process and their benefits to the industries are discussed. The utilization of solid acid catalysts as additives for future studies is also suggested.
In the current paper, ion transport parameters in poly (vinyl alcohol) (PVA) based solid polymer electrolyte were examined using Trukhan model successfully. The desired amount of lithium trifluoromethanesulfonate (LiCF3SO3) was dissolved in PVA host polymer to synthesis of solid polymer electrolytes (SPEs). Ion transport parameters such as mobility (μ), diffusion coefficient (D), and charge carrier number density (n) are investigated in detail using impedance spectroscopy. The data results from impedance plots illustrated a decrement of bulk resistance with an increase in temperature. Using electrical equivalent circuits (EEC), electrical impedance plots (ZivsZr) are fitted at various temperatures. The results of impedance study demonstrated that the resistivity of the sample decreases with increasing temperature. The decrease of resistance or impedance with increasing temperature distinguished from Bode plots. The dielectric constant and dielectric loss values increased with an increase in temperature. The loss tangent peaks shifted to higher frequency region and the intensity increased with an increase in temperature. In this contribution, ion transport as a complicated subject in polymer physics is studied. The conductivity versus reciprocal of temperature was found to obey Arrhenius behavior type. The ion transport mechanism is discussed from the tanδ spectra. The ion transport parameters at ambient temperature are found to be 9 × 10-8 cm2/s, 0.8 × 1017 cm-3, and 3 × 10-6 cm2/Vs for D, n, andμ respectively. All these parameters have shown increasing as temperature increased. The electric modulus parameters are studied in an attempt to understand the relaxation dynamics and to clarify the relaxation process and ion dynamics relationship.