Search

Acrylic waterproofing materials are known for their excellent physical properties, waterproofing capabilities, and convenient construction, but their high cost and under-researched bonding strength pose challenges. To enhance adhesion and elucidate the imperviousness mechanism of engineering waterproofing materials while effectively controlling costs, this study proposed the compounding of acrylic ester polymer emulsion with low-cost styrene-acrylate copolymer emulsion for the preparation of waterproofing materials. By integrating theoretical analysis with experimental research, the physical and mechanical properties, as well as the imperviousness of the waterproofing materials, were investigated. The optimal mix-ratio design for the waterproofing materials was determined. Results demonstrate that, (1) The compounding of styrene-acrylic emulsion with pure-acrylic emulsion can achieve good performance while lowering costs. (2) The common silicate cement strength 42.5MPa (C42.5) had better comprehensive properties than the common silicate cements strength 32.5MPa (C32.5) and 52.5MPa (C52.5) and the rapid-hardening sulfate-aluminate cement. (3) In the imperviousness and bonding-strength tests of the coating, when the waterborne non-silicone defoamer was added at 0.3%, it was dense inside the coating with reduced microspaces, and the coating passed the imperviousness test after 30 min under a water pressure of 0.3 MPa. (4) The bonding strength with cement-based surfaces was 1.8 MPa. This study can serve as a good reference for research on high-bonding waterproofing coatings of acrylic acid for underground engineering applications and imperviousness-performance tests. [ABSTRACT FROM AUTHOR]

The exchange of small molecules between the cell and the environment happens through transporter proteins. Besides nutrients and native metabolic products, xenobiotic molecules are also transported, however it is not well understood which transporters are involved. In this study, by combining exometabolome screening in yeast with transporter characterization in Xenopus oocytes, we mapped the activity of 30 yeast transporters toward six small non-toxic substrates. Firstly, using LC--MS, we determined 385 compounds from a chemical library that were imported and exported by S. cerevisiae. Of the 385 compounds transported by yeast, we selected six compounds (viz. sn-glycero-3-phosphocholine, 2,5-furandicarboxylic acid, 2-methylpyrazine, cefadroxil, acrylic acid, 2-benzoxazolol) for characterization against 30 S. cerevisiae xenobiotic transport proteins expressed in Xenopus oocytes. The compounds were selected to represent a diverse set of chemicals with a broad interest in applied microbiology. Twenty transporters showed activity toward one or more of the compounds. The tested transporter proteins were mostly promiscuous in equilibrative transport (i.e., facilitated diffusion). The compounds 2,5-furandicarboxylic acid, 2-methylpyrazine, cefadroxil, and sn-glycero-3- phosphocholine were transported equilibratively by transporters that could transport up to three of the compounds. In contrast, the compounds acrylic acid and 2-benzoxazolol, were strictly transported by dedicated transporters. The prevalence of promiscuous equilibrative transporters of non-native substrates has significant implications for strain development in biotechnology and offers an explanation as to why transporter engineering has been a challenge in metabolic engineering. The method described here can be generally applied to study the transport of other small non-toxic molecules. The yeast transporter library is available at AddGene (ID 79999). [ABSTRACT FROM AUTHOR]

The 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers are mimetic to phospholipids, being widely used as biocompatible polymers. In our previous study, MPC polymer hydrogels proved more effective for optical tissue clearing compared to acrylamide (AAm) polymer hydrogels. In the present study, 2-acryloyloxyethyl phosphorylcholine (APC) was synthesized and employed to create hydrogels for a comparative analysis with methacrylic MPC-based hydrogels. APC, an acrylic monomer, was copolymerized with AAm in a similar reactivity. In contrast, MPC, as a methacrylic monomer, demonstrated higher copolymerization reactivity than AAm, leading to a spontaneously delayed two-step polymerization behavior. This suggests that the polymer sequences and network structures became heterogeneous when both methacrylic and acrylic monomers, as well as crosslinkers, were present in the copolymerization system. The molecular weight of the APC polymers was considerably smaller than that of the MPC polymers due to the formation of mid-chain radicals and subsequent β-scission during polymerization. The swelling ratios in water and strain sweep profiles of hydrogels prepared using acrylic and methacrylic compounds differed from those of hydrogels prepared using only acrylic compounds. This implies that copolymerization reactivity influences the polymer network structures and crosslinking density in addition to the copolymer composition. APC-based hydrogels are effective for the optical clearing of tumor tissues and are applicable to both passive and electrophoretic methods. [ABSTRACT FROM AUTHOR]

The widespread UbiD enzyme family utilises the prFMN cofactor to achieve reversible decarboxylation of acrylic and (hetero)aromatic compounds. The reaction with acrylic compounds based on reversible 1,3-dipolar cycloaddition between substrate and prFMN occurs within the confines of the active site. In contrast, during aromatic acid decarboxylation, substantial rearrangement of the substrate aromatic moiety associated with covalent catalysis presents a molecular dynamic challenge. Here we determine the crystal structures of the multi-subunit vanillic acid decarboxylase VdcCD. We demonstrate that the small VdcD subunit acts as an allosteric activator of the UbiD-like VdcC. Comparison of distinct VdcCD structures reveals domain motion of the prFMN-binding domain directly affects active site architecture. Docking of substrate and prFMN-adduct species reveals active site reorganisation coupled to domain motion supports rearrangement of the substrate aromatic moiety. Together with kinetic solvent viscosity effects, this establishes prFMN covalent catalysis of aromatic (de)carboxylation is afforded by UbiD dynamics. Understanding the structure and dynamics of enzymes is important for a number of applications. Here, the authors report on the crystal structure of vanillic acid decarboxylase, and show how the dynamics of the UbiD superfamily enzymes relate to the covalent catalysis of aromatic (de)carboxylation. [ABSTRACT FROM AUTHOR]

Ammonia is the most essential hydrogenated nitrogen composition that can cause problems when it enters the environment. One of the most important natural and synthetic adsorbents is hydrogels, which can reduce the economic costs of treating industrial effluents and minimize the concentration of ammonia in the drainage of sugarcane fields. In this study, carrageenan, which is a type of polysaccharide, and acrylic acid were used to prepare nanomagnetic hydrogels. Also, the effect of pH, concentration, and temperature on the amount of ammonia adsorption was analyzed by the spectrophotometer, and finally, the adsorption property of the hydrogel was analyzed by the scanning electron microscope (SEM). The results of scanning electron microscopy show that there are holes in the hydrogel surface that increase the rate of adsorption. Experimental data from the spectrophotometer show that the rate of ammonia adsorption increases by about 50% over 80 minutes as its concentration in the effluent increases. The inflation rate of these hydrogels was selected to be 991.52 (mg/g) under optimal conditions, and the nanomagnetic hydrogel adsorption capacity remained constant at a pH range of 4 to 9, while when the pH was below four or above 9, the capacity of adsorption shows a slight decrease. Adsorption by acrylic hydrogels is significant. There is an issue that by modifying the acrylic compounds in the production of the hydrogel, it is possible to absorb the heavy elements or colors in the best way and also to achieve high efficiency. Also, by increasing the amount of adsorbent nanomagnetic hydrogel up to 40 mg led to the adsorption of 89.16%, 32.50%, and 31.11% of ammonia in three pools of the test site, respectively. The results also show that the use of iron oxide nanoparticles in the hydrogel substrate has increased thermal stability by thermogravimetric analysis (TGA) which shows that at 650 degrees centigrade, kappa-carrageenan, hydrogels, and nanomagnetic hydrogels have a weight loss of 72.66%, 58.79%, and 52.39%, respectively. Studies have shown that the kappa-carrageenan-based hydrogel nanocomposite is more cost-effective, while it is more efficient at absorbing NH4+. Therefore, this adsorbent can be a promising material in terms of economic as well as its effectiveness in eliminating ammonia from sewage. Investigations were performed for ammonia desorption and the reusability of nanomagnetic hydrogels. Also, the rate of ammonia adsorption by nanomagnetic hydrogels after 6 cycles of recovery cycle using NaCl can be about 43% of the initial rate. All statistical studies were performed by Minitab software version 18 and considering p value = 0.05. [ABSTRACT FROM AUTHOR]

Objective. Infection control protocols in dentistry dictate that orthodontic acrylics have to be disinfected. No specific products for orthodontic acrylics are available. The objective of this study was to investigate the influence of chemical disinfectants on mechanical properties of orthodontic acrylics. Materials and Methods. 260 test specimens of two cold-curing orthodontic acrylics were manufactured. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, and Stammopur DR. Test specimens were stored in distilled water and divided into test groups. E-Modulus, flexural strength, macro hardness, micro hardness, average roughness, and colour change were measured. Results. Disinfection agents showed no significant influence on E-modulus. Values ranged from 1783.80 ± 163.80 MPa (Forestacryl colourless) to 2474.00 ± 135.00 MPa (Orthocryl green) after storage in distilled water. Disinfection agents performed no significant influence on flexural strength. Values ranged from 18.64±1.59 N/mm2 (Forestacryl colourless) to 25.64 ± 1.43 N/mm2 (Orthocryl green) after storage in distilled water. Orthocryl colourless showed a reduction of the macro hardness after disinfection (Stammopur DR (p≤0.001), D050 Instru-Gen (p≤0.037)). Disinfection of Orthocryl green with D050 Instru-Gen (p<0.001) and Forestacryl colourless with Impresept (p≤0.001) led to a reduction of macro hardness. Micro hardness of Orthocryl colourless altered significantly after disinfection with D050 Instru-Gen (p≤0.001). Micro hardness of Forestacryl colourless increased (Impresept (p≤0.039)) and decreased (Stammopur DR (p≤0.006) Instru-Gen (p≤0.001)) after disinfection. Average roughness did not change significantly (Orthocryl colourless). Forestacryl colourless performed a significant change after disinfection with Stammopur DR (p≤0.05). This is also true for the disinfection of Orthocryl green and Forestacryl pink with Instru-Gen (p≤0.05). Disinfection performed no significant influence on colour change. ΔE-values were in a range of 1 to 2. Conclusions. Some orthodontic acrylics disinfection caused significant changes of determined parameters. Changes were specific for the applied disinfectant and tested orthodontic acrylic. Further studies should verify the impact of long-term disinfection intervals. Thus, from manufacturers of orthodontic acrylics recommendations for appropriate disinfectants would be desirable. [ABSTRACT FROM AUTHOR]

Abstract Cancer vaccines targeting patient-specific tumor neoantigens have recently emerged as a promising component of the rapidly expanding immunotherapeutic armamentarium. However, neoantigenic peptides typically elicit weak CD8+ T cell responses, and so there is a need for universally applicable vaccine delivery strategies to enhance the immunogenicity of these peptides. Ideally, such vaccines could also be rapidly fabricated using chemically synthesized peptide antigens customized to an individual patient. Here, we describe a strategy for simple and rapid packaging of peptide antigens into pH-responsive nanoparticles with endosomal escape activity. Electrostatically-stabilized polyplex nanoparticles (nanoplexes) can be assembled instantaneously by mixing decalysine-modified antigenic peptides and poly(propylacrylic acid) (pPAA), a polyanion with pH-dependent, membrane destabilizing activity. These nanoplexes increase and prolong antigen uptake and presentation on MHC-I (major histocompatibility complex class I) molecules expressed by dendritic cells, resulting in enhanced activation of CD8+ T cells. Using an intranasal immunization route, nanoplex vaccines inhibit formation of lung metastases in a murine melanoma model. Additionally, nanoplex vaccines strongly synergize with the adjuvant α-galactosylceramide (α-GalCer) in stimulating robust CD8+ T cell responses, significantly increasing survival time in mice with established melanoma tumors. Collectively, these findings demonstrate that peptide/pPAA nanoplexes offer a facile and versatile platform for enhancing CD8+ T cell responses to peptide antigens, with potential to complement ongoing advancements in the development of neoantigen-targeted cancer vaccines. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Magneto-rheological elastomer (MRE) is a kind of smart material based on elastomer matrix and it is divided into isotropic (i-MRE) and anisotropic MRE (a-MRE) depending on the magnetic particle arrangement. In the i-MRE, carbonyl iron particles (CIP) are randomly dispersed, while they form a chain-like structure in the a-MRE. Two manufacturing procedures of a-MRE have been introduced. The a-MRE-1 was manufactured by one-step process involving application of magnetic field and curing of matrix simultaneously. On the other hand, a-MRE-2 was manufactured by two-step process in which the magnetic field was applied to induce CIP orientation and then the matrix was cured. The microstructure and mechanical properties of MRE were characterised by scanning electron microscope, universal testing machine and dynamic mechanical analysis. The results showed that the CIP content in MRE had no effect on the cure properties. A chain-like structure existed in a-MRE-1, whereas the orientation structure of CIP in the a-MRE-2 was not as clear as that in a-MRE-1. The tensile strength of a-MRE-1 was the lowest because no interfacial reaction occurred between the CIP and the rubber molecules chain, whereas i-MRE had the highest tensile strength. [ABSTRACT FROM AUTHOR]

This study characterizes the degree of cure c, of a two‐part epoxy/acrylic photopolymer used in stereolithography, SLA. The use of solid free form fabrication has added a whole new list of thermosets with a chemical reaction—curing reaction—targeted for these specific manufacturing processes. The studied thermosetting system exhibits a fast curing reaction triggered by a UV‐light source. An innovative stepwise method to quantify the degree of cure using Raman spectroscopy is reported. This method abates the Raman noise and compensates for the weak signal of fast measurements. The Raman data processing algorithm BEADS was implemented. The technique presented here was capable of following the degree of cure of the individual components of the photopolymer. Based on the epoxy/acrylic monomers concentration (75%/25%), the degree of cure for the whole system was quantified. The experimental results were modeled using a modified phenomenological kinetics equation. This model includes the dependency of the rate of cure on the light intensity, and cure state. Based on the analysis reported here, the proposed model accurately fits the initiation, propagation, and termination phases of the cure cycle. The technique and methods presented here can potentially be integrated to in situ process monitoring with instant parameter feedback, and numerical modeling of residual stresses in additive manufacturing of thermosets. POLYM. ENG. SCI., 58:228–237, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract: Flavor compounds have been shown to interact with packaging materials either by scalping, the movement of flavorings from the food product to the package, or by flavor release, movement of flavorings from the package to the food. Work has elucidated the parameters important for the scalping of flavor compounds to polyolefin packaging materials, but very little work has been conducted examining the scalping of flavor compounds by can lining materials. Can linings composed of three different polymers, polyolefin, acrylic, epoxy, were studied for binding of volatile flavor compounds (octanal, nonanal, decanal, eugenol, d‐limonene) at room temperature over a 2‐week period. Solid phase microextraction (SPME) was used with gas chromatography mass spectrometry to identify and quantify volatile compounds. Flavor compounds were studied at concentrations around 4–1,000 ppb. Fourier transform infrared spectroscopy was used to verify can lining polymer chemistry. Almost complete binding of all five of the volatile compounds studied was observed over 9–14 days at room temperature for each of the can lining chemistries. The number of time data points limited our ability to determine the order and rate constants of binding. This model system appears to be a valuable for investigating flavor binding of polymeric can lining materials. [ABSTRACT FROM AUTHOR]

Natural fibers have recently become attractive to researchers due to their low cost, fairly good mechanical properties, high specific strength, non-abrasive, eco-friendly, bio-degradability and biocompatibility characteristics, they are exploited as a replacement for the conventional fibers, such as glass, aramid and carbon. This study investigated the influence of fiber length and weight fraction of natural siwak fiber, with the selected length of (2, 6 and 12 mm) and weight fraction (3, 6 and 9 wt %), on some of mechanical and physical properties such as (tensile, impact and hardness), in addition to test the infrared spectroscopy FTIR of the prepared denture base resin and all of these tests were carried out at laboratory temperature. The properties of PMMA reinforced by natural fiber are mainly affected by the interfacial adhesion strength between the matrix and the fiber, and in order to improve interconnection between the siwak fiber and PMMA matrix, so the siwak fibers were treated with alkali (sodium hydroxide) solution prior to use as reinforcement materials. The results illustrated that the tensile strength, young modulus, fracture toughness and hardness tended to be improved with length and concentration ratios of siwak fiber, while the impact strength and elongation percentage at break decrease with fiber content in composite samples. [ABSTRACT FROM AUTHOR]

Background Acrylic monomers (acrylates), methacrylates and cyanoacrylates all cause asthma by respiratory sensitization. Occupational inhalation exposures occur across a variety of industries including health care and dental work, beauty, laboratory science, assembly and plastic moulding. Aims To examine notifications of occupational asthma caused by acrylic compounds from a UK-based regional surveillance scheme, in order to highlight prevalent exposures and trends in presentation. Methods Retrospective review of all cases reported to the SHIELD surveillance scheme for occupational asthma, West Midlands, UK between 1989 and 2014. Patient data were gathered on demographics, employment, asthma symptoms and diagnostic investigations including serum immunological testing, serial peak flow analysis and specific inhalation challenge tests. Descriptive statistics were used to illustrate worker characteristics and evidence for sensitization to acrylic compounds. Results There were 20 affected patients out of 1790 total cases of occupational asthma (1%); all cases were confirmed by OASYS (Occupational Asthma SYStem) analysis of serial peak flow measurements, with three additional positive specific inhalation challenge tests. Three out of 20 (15%) patients were current smokers and 11/20 (55%) were atopic. A variety of exposures and industries were implicated including: manufacturing, health care, beauty and printing and a novel presentation seen in teachers exposed to floor adhesives. Conclusions This is the largest reported series of occupational asthma caused by acrylic compounds, which remain an important aetiological factor in this disease. Exposure occurs in a variety of industries, particularly in manufacturing and is seen with other, perhaps better recognized sensitizing agents such as isocyanates and epoxy resins. [ABSTRACT FROM AUTHOR]

In this work, we report a facile and inexpensive approach which was demonstrated for the creation of hierarchical porous Al 2 O 3 /acrylic resin composites as durable, efficient and recyclable absorbents for oil/water separation. Using hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent, the lamellar γ-AlOOH with porous architectures was successfully prepared via a hydrothermal route. The hierarchical Al 2 O 3 clusters, as the inorganic phase of resin composites, retain the unique structure of lamellar γ-AlOOH by calcination treatment. In order to enhance the hydrophobic and oleophilic properties of Al 2 O 3 clusters, silane coupling agent (A151) was used to modify the surface of Al 2 O 3 clusters under microwave irradiation. The surface modified Al 2 O 3 clusters exhibit excellent hydrophobicity, oleophilicity and chemical stability, owing to the tight binding of the hydrophobic functional groups on the inorganic Al 2 O 3 clusters and the inherent stability of the grafted hydrophobic molecule chains. The porous Al 2 O 3 /acrylic resin composites were synthesized by suspension polymerization of butyl acrylate (BA) and methacrylic acid butyl ester (MBA) on the surface modified Al 2 O 3 clusters under microwave irradiation in the presence of coupling agents. The porous Al 2 O 3 /acrylic resin composites can effectively separate oils and organic solvents with high oil absorption rate and high oil retention capacity. Moreover, the obtained resin composites have high oil uptake capacities due to the synergy absorption of porous Al 2 O 3 clusters and acrylic resin. These excellent performances, such as excellent oil recoverability, excellent recyclability and high oil retention capacities, endow the material to be an ideal candidate to separate a variety of organic liquids from water. [ABSTRACT FROM AUTHOR]

Limited studies investigated the effect of recycled polymers obtained from the paint industry on concrete bond stress-slip with embedded steel bars, including whether such behavior would be similar to that imparted by virgin polymeric latexes. Around 50 concrete mixtures containing different vinyl acrylic-based polymer concentrations are tested by direct bond and beam-end methods. Test results have shown that the concrete-bar interfacial bond stresses occurring in the elastic region substantially improved with recycled and virgin polymers. At a similar polymer-to-cement ratio, concrete incorporating recycled polymers exhibited improved bond properties than mixtures prepared with virgin ones. This was indirectly related to the pigment and extender powders in the waste latex paints, thus reducing porosity and improving denseness of cement paste that strengthen the transition zone adjacent to reinforcing bars. The effect of reducing the water- to-cement ratio while adding superplasticizer to compensate the loss in workability and compressive strength was found efficient to increase the ultimate bond strength. [ABSTRACT FROM AUTHOR]

3D printing has potential to provide various solid insulating material such as a functionally graded material. It has not been clarified if the polymer-ceramic composite, the basic structure for the solid insulating material, can be 3D-printed even when the large amount of insulating ceramics fillers are introduced. This paper investigated the feasibility of the stereolithographic 3D printing of an insulating component using a UV-cured acrylic composite with a micorometric alumina fillers (alumina/UV-cured acrylic composite). Since scattering and absorption of UV light by alumina fillers were potential obstacle to UV curing, the UV light transmission characteristics of the alumina/UV-cured acrylic composite were obtained. The result provides the evidence that UV light reaches the back side of the layer of the composite and the resin is cured. As basic dielectric properties, permittivity and loss tangent of the alumina/UV-cured acrylic composites were obtained. It was confirmed that the permittivity of the composites was in accordance with the formulas for permittivity of two-component composite. By using the composite material, a 3D model of the conical insulating spacer was designed with physics simulation software and the data was printed out. [ABSTRACT FROM PUBLISHER]

The use of innovative lightweight materials for structural design in the automotive industry is no longer a novelty. When joining different parts made of these new materials it is clear that adhesives are one of the best solutions. However, the selection of a suitable adhesive for this application and the performance of the joint under real car conditions need to be intensively investigated. In this paper, an extremely ductile acrylic adhesive was selected to bond a commonly used unidirectional carbon fibre reinforced polymer with an environmentally friendly biopolymer in a single lap joint. The strength of the joint was characterised under quasi-static and impact loading at −30, +23 and +80 °C. It was found that the effect of the strain rate on the maximum failure load increased with temperature. A numerical study was also conducted to predict failure at room temperature. While the quasi-static model predicted accurately the joint behaviour, the impact model overestimated the joint strength as a consequence of the bad adhesion found experimentally. [ABSTRACT FROM AUTHOR]

This work aims at developing versatile low-biofouling polymeric coatings by using acrylic terpolymers (DOFs) that bear pendant catechol (D), oligo(ethylene glycol) (O), and perfluoroalkyl (F) groups in varying ratios. The polymers were endowed with the ability to form firmly coatings on virtually any surfaces and undergo surface microphase separation and self-assembly, as revealed by the surface enrichment of F pendants and the morphology variation from irregular solid domains to discrete crater-type aggregates of different size. The effect on protein adsorption was investigated using bovine serum albumin (BSA) and adhesive fibrinogen (Fib) as model proteins. The coating of DOF164 (low F content), which has morphology of discrete crater-type aggregates of ∼400 nm in size, adsorbed a least amount of protein but with a highest protein unit activity as determined by SPR and immunosorbent assay; whereas the coating of DOF1612 (high F content) showed a 12.3-fold higher adsorption capacity toward Fib. Interestingly, a 2.2-fold lower adsorption amount but with a 1.8-fold higher unit activity was found for Fib adsorbed on the DOF164 surface than on DOF250 (without F fraction), whose OEG segments being a widely recognized protein compatible material. The features of the DOF164 terpolymer presenting a robust coating ability and a minimal protein adsorption capacity while with a high protein unit activity suggest its potential application as a non-fouling surface-modifier for medical antifouling coatings and as a matrix material for selective protein immobilization and activity preservation in biosensor construction. [ABSTRACT FROM AUTHOR]

Amorphous cellulose and poly(methyl methacrylate) (PMMA) blends in the form of free standing transparent hybrid films were prepared by dissolving both polymers in trifluoroacetic acid (TFA). Ultraviolet–visible (UV–vis) measurements indicated that the transparency of the films was always maintained regardless of cellulose-PMMA proportions. In addition, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements were carried out in order to characterize the chemical composition, intermolecular interactions and the crystallinity of the hybrid films. Thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC) and tensile test measurements demonstrated that amorphous cellulose improved the thermal and mechanical properties of PMMA considerably. Scanning electron microscope (SEM) and atomic force microscopy (AFM) measurements showed that hybrid films had no micron scale phase separation or segregation, resulting in highly uniform and homogenous miscibility between amorphous cellulose and PMMA. The wetting characteristics of the hybrid films were also studied by water contact angle measurements. Hybrid films showed better water barrier properties in comparison to commercial paper packaging. Furthermore, the hybrid films exhibited relative high dissolution resistance to common organic solvents, which dissolve PMMA completely. Considering the recent interest in polymer blends based on natural and synthetic macromolecules, these new transparent hybrids can have various potential applications particularly in general packaging and biomedical technologies. [ABSTRACT FROM AUTHOR]

Gelcasting is a good method for obtaining ceramic components with a pre-defined shape. From the point of view of the course of the ceramic casting process, a very important issue is the so-called idle time or gelation time whose measurement is usually based on determining changes in ceramic slurry viscosity by means of rheometers. However, searches are being continued to find methods which would have the least impact on the interactions between ceramic powder particles and the forming polymeric structure and would allow more time range to observe changes in gelcasting process compared to classic measurements of viscosity. In the article, based on measurements on Al 2 O 3 , ZrO 2 and SiC-based gelcasting systems with various water-soluble acrylic monomers, it has been demonstrated that such requirements may be fulfilled by IET (Impulse Excitation Technique). [ABSTRACT FROM AUTHOR]

In this study, an efficient method has been presented for preparation of uniform dispersion of modified multiwall carbon nanotubes (G-MWNTs) in poly (methyl methacrylate-co-butyl acrylate) via ultrasonically-assisted emulsion polymerization. Two steps were exploited for this reason: first, MWNTs were modified via Friedel–Crafts acylation and polymerizable functional groups were incorporated to their surfaces and second, an optimized ultrasonically-assisted emulsion polymerization was applied to reach to the desired nanocomposites. The progress of modification reaction was followed by FT-IR and TGA analyses and morphology of the obtained latexes were observed by TEM. Studies on the final properties revealed that the inclusion of G-MWNTs in the acrylic copolymer has significant enhancement in thermo-mechanical properties of the resulting films. Thermal conductivity of the samples increased remarkably as a function of MWNTs content. It was found that at 3 wt% of G-MWNTs, thermal stability increased more than 29% and tensile strength and Young modulus of the resulting films were improved up to 70% and 75%, respectively. To elucidate the importance of this technique, similar nanocomposite latexes were prepared by simple mixing and compared with the above obtained results. [ABSTRACT FROM AUTHOR]

High temperature proton exchange membranes were synthesized via electron beam treatment of commercial poly(ethylene-alt-tetraflouroethylene) (ETFE) films and subsequent graft radical copolymerizations with 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl acrylate (HEA). The maximum degree of grafting achieved was 193%. Both grafted monomers are hydrophilic and lead to high membrane affinity to phosphoric acid. Doping with phosphoric acid resulted in a maximum doping level of 310%. The grafted membranes combine stable ETFE backbone polymer with hydrophilic side chains. As indicated by stress–strain curves the graft copolymer membranes show good mechanical stability. In addition, the polymer–acid-composites are thermally stable up to around 210 °C. The polymer–acid-composite materials were tested in H 2 /O 2 fuel cells at 120 °C. Power densities of up to 108 mW cm ‒2 were obtained at a current density of 200 mA cm ‒2 . It is shown that the alternate concept of polymer–acid composites without any basic units is also suitable for the application in high temperature fuel cells. [ABSTRACT FROM AUTHOR]

PURPOSE. Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens. MATERIALS AND METHODS. Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at 37°C. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using ×40 magnification under a light microscope and data were analysed. RESULTS. Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05). CONCLUSION. In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia. [ABSTRACT FROM AUTHOR]

PURPOSE. The aim of this study was to appraise the some mechanical properties of polymethyl methacrylate based denture base resin polymerized by copolymerization mechanism, and to investigate the cytotoxic effect of these copolymer resins. MATERIALS AND METHODS. 2-hydroxyethyl methacrylate (HEMA) and isobutyl methacrylate (IBMA) were added to monomers of conventional heat polymerized and injection-molded poly methyl methacrylate (PMMA) resin contents of 2%, 3%, and 5% by volume and polymerization was carried out. Three-point bending test was performed to detect flexural strength and the elasticity modulus of the resins. To determine the statistical differences between the study groups, the Kruskall-Wallis test was performed. Then pairwise comparisons were performed between significant groups by Mann-Whitney U test. Agar-overlay test was performed to determine cytotoxic effect of copolymer resins. Chemical analysis was determined by FTIR spectrum. RESULTS. Synthesis of the copolymer was approved by FTIR spectroscopy. Within the conventional heat-polymerized group maximum transverse strength had been seen in the HEMA 2% concentration; however, when the concentration ratio increased, the strength decreased. In the injection-molded group, maximum transverse strength had been seen in the IBMA 2% concentration; also as the concentration ratio increased, the strength decreased. Only IBMA showed no cytotoxic effect at low concentrations when both two polymerization methods applied while HEMA showed cytotoxic effect in the injection-molded resins. CONCLUSION. Within the limitations of this study, it may be concluded that IBMA and HEMA may be used in low concentration and at high temperature to obtain non-cytotoxic and durable copolymer structure. [ABSTRACT FROM AUTHOR]

Objective: To evaluate if there is any interference when adding coffee or chocolate to cow milk in the enamel des-remineralization process (orange juice/saliva). Material and Methods: 48 specimens of human enamel (4x4 mm) were included in acrylic resin, ground flat, polished and randomly divided into the following experimental groups (n = 8): G1-saliva, G2-orange juice, G3 orange juice / milk; G4-Orange Juice / Chocolate, G5- Orange Juice / Coffee + milk and G6- milk. Each group was immersed for 60 seconds on each solution proposed and then immersed for 30 minutes in saliva. This cycle was repeated 4 times. Prior to these cycles, the Knoop microhardness average of each specimen was obtained. After the challenges proposed, the final microhardness average was calculated. The values obtained from the difference between the initial and final microhardness were subjected to ANOVA followed by Tukey test (p <0,05). Results: The orange juice had the highest change in microhardness and statistically different from all other groups. The microhardness change was statistically similar in the groups submitted to orange juice followed by immersion in milk, in chocolate and in the mixture milk + coffee. The pure milk and saliva caused no change in surface hardness of enamel. Conclusion: Milk or the addition of chocolate and coffee to milk was able to produce a protective effect of the enamel surface against an erosive challenge. [ABSTRACT FROM AUTHOR]

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed on implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LECs) undergoing Epithelial Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including the patient's age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs have shown that the former has more severe PCO. On the other hand, we have previously demonstrated that the adhesion of LECs is favored on hydrophobic compared to hydrophilic materials. By combining these two facts and contemporary knowledge in PCO development via the EMT pathway, we propose a biomimetically inspired strategy to promote LEC adhesion without de-differentiation to reduce the risk of PCO development. By surface grafting of a cell adhesion molecule (RGD peptide) onto the conventional hydrophilic acrylic IOL material, the surface-functionalized IOL can be used to reconstitute a capsule-LEC-IOL sandwich structure, which has been considered to prevent PCO formation in literature. Our results show that the innovative biomaterial improves LEC adhesion, while also exhibiting similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties compared to the starting material. In addition, compared to the hydrophobic IOL material, our bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression, which is the crucial pathway to induce PCO. The in vitro assays suggest that this biomaterial has the potential to reduce the risk factor of PCO development. [ABSTRACT FROM AUTHOR]

Background: Vancomycin is the antibiotic of choice in therapy of orthopaedic implant infections caused by methicillin-resistant bacteria but its use poses a risk of toxicity, especially in patients with renal insufficiency. Addition of vancomycin to acrylic cement may cause systemic exposition to this drug eluting from cement to serum, which may require high-flux hemodialysis. Methods: A patient hemodialysed twice a week underwent implantation of a spacer due to methicillin-resistant S. epidermidis infection of knee prosthesis. The spacer was made of acrylic cement loaded with 0,55 g of gentamicin per 40 g of cement and 6 g of vancomycin into totally 120 g of cement. The measurements of vancomycin concentration in serum within 9 days and in intraarticular fluid within 2 days were performed. Results: Maximal intraarticular vancomycin concentration was reached 7 hours after surgery ( 120 μg/ mL) and was over Minimal Inhibitory Concentration for 47 hours. The serum concentration reached maximal value (2,6 μg/mL) 13 hours after implantation of spacer and was 2,3 μg/mL on 9-th postoperative day. Conclusion: This composition of acrylic cement spacer containing gentamicin and vancomycin was found therapeutically effective and not necessitating high-flux hemodialysis in a hemodialysed patient with chronic renal failure. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 35-year-old woman who experiences discoloration in thumbnail and slight pain in thumb. She was subjected to clinical examination and was diagnosed with dyschromia and onycholysis. Dermatoscopy reveals yellowish discoloration in her nail. Moreover, the article discusses onycholysis, a nail disease in which the nail detaches from the nail bed and is triggered by physical trauma and utilization of acrylic nails.

Abstract: Volatile organic compounds (VOCs) in model aqueous solutions and in acrylic latex binder used for formulating latex paint can be stripped without foaming by using a nanoporous hydrophobic polypropylene membrane. The stripping gas employed was dry, room temperature nitrogen or 50°C water-saturated air. For the dry nitrogen stripping gas, fouling was minimal for the hydrophobic polypropylene over several days, in sharp contrast to experiments with hydrophilic membranes. No fouling of the polypropylene membrane was observed for experiments with the water-saturated strip gas. The rate of VOC removal in these experiments depends on mass transfer in the aqueous latex and in the membrane. These results allow estimates of the membrane area to strip VOCs from commercially relevant quantities of acrylic latex paint. [Copyright &y& Elsevier]

Highlights: [•] Thermal behavior study of 134 urban materials (tiles, pavements and claddings). [•] Materials were categorized according to their solar reflectance index. [•] Materials used in facades offer more possibilities for manage their thermal behavior. [•] In tiles the better thermal behavior is linked to the effect of composition and color. [•] The acrylic claddings show better cooling potential than concrete claddings. [ABSTRACT FROM AUTHOR]

Highlights: [•] Method of incorporation of preformed gold nanoparticles (AuNPs) into the acrylic polymer (AP) matrices was developed. [•] Optical and TEM characterization of AuNP/AP bulk and film composite was done. [•] It was shown that incorporation of dodecanethiol-covered AuNP can be enhanced in the presence of SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Nanocomposites of encapsulated silica nanoparticles were prepared by in situ emulsion polymerization of acrylate monomers. The synthesized material showed good uniformity and dispersion of the inorganic components in the base polymer, which enhances the properties of the nanocomposite material. A nonionic surfactant with lower critical solution temperature (LCST) was used to encapsulate the silica nanoparticles in the acrylic copolymer matrix. This in situ method combined the surface modification and the encapsulation in a single pot, which greatly simplified the process compared with other conventional methods requiring separate processing steps. The morphology of the encapsulated nanosilica particles was investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM), which confirmed the uniform distribution of the nanoparticles without any agglomerations. A neat copolymer was also prepared as a control sample. Both the neat copolymer and the prepared nanocomposite were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analyses (TGA), dynamic mechanical thermal analysis (DMTA) and the flame resistance test. Due to the uniform dispersion of the non-agglomerated nanoparticles in the matrix of the polymer, TGA and flame resistance test results showed remarkably improved thermal stability. Furthermore, DMTA results demonstrated an enhanced storage modulus of the nanocomposite samples compared with that of the neat copolymer, indicating its superior mechanical properties. [ABSTRACT FROM AUTHOR]

Acrylic pressure sensitive adhesives (PSAs) have a range of applications in industry, such as medical products, aircraft, space shuttles, electrical devices, optical products, and automobiles, etc. In this study, acrylic PSAs with fluorinated groups were synthesized using 2,2,2-trifluoroethyl methacrylate (TFMA) under UV radiation. The surface properties and adhesion strength were measured. The results showed that the addition of TFMA reduced the surface energy of the PSAs and improved the adhesion strength. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article focuses on the art of science celebrated by the Micrograph Project of the Minerals, Metals & Materials Society (TMS). It cites the micrography contest conducted by the TMS in which winning pieces will be displayed at TMS headquarters, reflecting the society's physical metallurgy roots. It also features the winning micrographs imprinted on acrylic panes and created by members including MariAnne Sullivan, Raymond Thompson, and Amit Shyam.

Highlights: [•] Cationic ultra-fine pigment was prepared with cationic dispersant agent. [•] The dyed acrylic yarns presented a maximum K/S value when pigment dosage was 2%. [•] The levelling properties and the light fastness were improved. [Copyright &y& Elsevier]

Purpose: To investigate the effect of superstructure materials and cuspal angle in an implantsupported fixed partial denture. Materials and Methods: This finite element analysis study was carried out with varying cuspal angulations of 0°, 20° and 33° and superstructure materials. The simulated models were loaded with 300N forces under different axial and non-axial angulations. The graphical and numerical stresses were investigated. Results: The results demonstrated that the maximum stress occurred in the metal framework in all the materials except acrylic, for which it occurred in the coronal part of the implant. In the acrylic, the maximum stress recorded was 78 MPa with the 20° angulation. Ni Cr recorded a maximum stress of 111 MPa with the 33° angulation. Conclusion: The cuspal morphology and type of superstructure material plays a pivotal role in controlling the stress transferred to the implant and the supporting bone. [ABSTRACT FROM AUTHOR]

Abstract: It is shown that when short multi-walled carbon nanotube (MWCNT) dispersed methanol–toluene mixtures including the azeotrope are mixed with an aqueous fluoroacrylic copolymer latex dispersion (Capstone ST-100), stable and surfactant free MWCNT suspended polymer emulsions can be prepared. These emulsions are sprayed on various surfaces such as glass, paper and metals to form electrically conductive polymer nanocomposite coatings. Thermal curing of the spray-cast films slightly above the melting point of the fluorinated acrylic latex, transforms them into superhydrophobic films with static water contact angles exceeding 150°. Alternatively, thermal treatment by impinging flame heating by small diffusion flames for a few seconds, also transforms the films into superhydrophobic state with very high static water contact angles exceeding 165° and very low droplet roll-off angles less than 5°. During this process, amorphous carbon nanobeads are deposited on the nanocomposite surfaces changing their surface topology. Superhydrophobicity of the flame treated nanocomposites can even withstand water hammering from impacting liquid streams with impact speeds close to 7m/s. The nanocomposites remain electrically conductive at all times even after conversion into superhydrophobic state either by thermal curing or by flame treatment with an electrical conductivity of 25S/m. The ohmic conductivity shows superior resistance against long delay times during repeated bias sweeps. The ease of preparation and stable ohmic electrical properties of these coatings can make them very suitable for applications such as corrosion protection for metal surfaces, conductive electrode materials for electrochemical energy conversion devices and lab-on-a-chip systems. [Copyright &y& Elsevier]

Aim: To evaluate the color stability and flexural strength of poly (methyl methacrylate) (PMMA) and bis-acrylic composite based provisional crown and bridge auto-polymerizing resins exposed to tea, coffee, cola, and food dye. Materials and Methods: Two provisional crown and bridge resins, one DPI self-cure tooth molding powder (PMMA) (Group A), and one Protemp 4 Temporization Material (bis-acrylic composite) (Group B) were used. Disk-shaped specimens for color stability testing (n = 30 for each material) and bar-shaped specimens for flexural strength testing (n = 30 for each material) were fabricated using a metal mold. The specimens were immersed in artificial saliva, artificial saliva + tea, artificial saliva + coffee, artificial saliva + cola, and artificial saliva + food dye solutions and stored in an incubator at 37°C. Color measurements were taken before immersion, and then after 3 and 7 days of immersion. Flexural strength was evaluated after 7 days of immersion. Results: Group A showed significantly higher color stability as compared to Group B, and artificial saliva + coffee solution had the most staining capacity for the resins. Test solutions had no effect on the flexural strength of Group A, but Group B specimens immersed in artificial saliva + cola showed significantly lower flexural strength values as compared to the control group. Conclusion: The findings of the study showed that for materials used in the study, PMMA was more color stable than bis-acrylic composite based resin. Also, material based on PMMA was more resistant to damage from dietary beverages as compared to bis-acrylic composite based provisional crown and bridge resin. [ABSTRACT FROM AUTHOR]

This work reports the formulation of water-based graphene oxide/acrylic nanocomposite inks, and the structural and electrical characterization of test patterns obtained by inkjet direct printing through a commercial piezoelectric micro-fabrication device. Due to the presence of heavily oxygenated functional groups, graphene oxide is strongly hydrophilic and can be readily dispersed in water. Through a process driven by UV irradiation, graphene oxide contained in the inks was reduced to graphene during photo-curing of the polymeric matrix. Printed samples of the nanocomposite material showed a decrease of resistivity with respect to the polymeric matrix. The analysis of the influence of printed layer thickness on resistivity showed that thin layers were less resistive than thick layers. This was explained by the reduced UV penetration depth in thick layers due to shielding effect, resulting in a less effective photo-reduction of graphene oxide. [ABSTRACT FROM AUTHOR]

Abstract: Electronic structures and absorption spectra of mono-branched and di-branched di-anchoring triphenylamine cyanoacrylic dyes were calculated by density functional theory. Our result suggested that one can develop organic dyes focusing on the preferred higher absorptivity or the wider absorption range, based on the symmetric or asymmetric di-branched architectures, respectively. The calculated absorption spectra for mono-branched dyes are in good agreement with the experiment. Different types of aromatic rings in the π-conjugated backbone of mono-branched dyes have varying effect on the absorption wavelength in the order of pyrrole

Abstract: Films from multi-crosslinked polyurethane with different contents of guar gum (1–10wt%) were prepared through a solution-casting method, followed by a thermal treatment or natural light exposure crosslinking procedure. Acrylic terminated prepolymers were prepared by capping the NCO groups of polyurethane prepolymers with pentaerythritol triacrylate. The effect of the guar gum content on the miscibility, morphology and physical properties of the blend films was investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, surface properties and tensile tests. The results reveal that small guar gum content is well embedded in the crosslinked polyurethane network and forms films with good mechanical properties, thermal behavior and hydrophilic properties. These results prove guar gum to be eco-friendly filler for multi-crosslinked polyurethane network. In the case of polyether urethanes, incorporating up to 3wt% guar gum leads to a slight enhancement of the elongation at break, while for polyester urethanes incorporation up to 3wt% guar gum slight increases stress at break values. Incorporating guar gum into the polyurethane networks leads to an increase in the hydrophilic nature of the polymer blends and improved surface structure. The properties of guar gum – which can be abundantly found in nature – make it desirable for polymer blends for biomedical applications. [Copyright &y& Elsevier]

The aim of the study was to investigate and compare the effect of different joint surface contours and repair materials on transverse strength of repair acrylic resin with or without chemical treatment with ethyl acetate. A total of 60 rectangular heat cure acrylic specimens were fabricated and cut in the centre. The cut specimens were repaired by using heart cure acrylic resin, heart cure acrylic resin with chemical treatment self cure resin, self cure acrylic resin with chemical treatment, self cure acrylic resin with rounded joint surface contour, self cure acrylic with 45 degree bevel joint surface contour. The repaired specimens were tested for transverse strength in an Instron Universal Testing Machine and data thus collected was subjected to statistical analysis. One way ANOVA TEST (p?0.05) was used to determine the differences between the individual groups. The results showed that specimens repaired with heat cure acrylic resin with chemical treatment exhibited the highest transverse strength. Also rounded and 45 degree beveled joint surface enhanced the bond strength of repair material. Thus choice of material and method of repair have significant effect on strength of repaired denture. [ABSTRACT FROM AUTHOR]

This paper studied the adsorption of cations, anions, nanometric metal-organocomplexes from the individual and binary solutions by acrylic hydrogels. We establish that the efficiency of sorption and strength of retention of metal compounds as cations is higher than of anions. Thus the number of bioelements adsorbed by acrylic hydrogels decreases in the row: Fe3+ > Cu2+ > Mn2+ > MnO4- > (Cu-Humate)- > (Fe-Humate)- > H2PO4-, while their desorption obeys an inverse relationship. Adsorption of bioelements is synchronous with swelling of hydrogels, desorption (in acidic medium at pH 4) -- with their collapse. By efficiency criiteria of bioelements sorption and slow desorption into the environment the hydrogel based on acrylamide-acrylonitrile has optimal parameters and can be used as an active component of the artificial soil or in mixture with a neutral filler (sand). Hydrogel matrix is brought into equilibrium with solutions of bioelements with final treatment by sulphate- and phosphate-containing solutions to form soluble nanocomposites of bioelements in the hydrogel pores which can diffuse into the external solution under the action of organic acids of plant origin. Such system of artificial soil provides accelerated growth and increased plants' productivity. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of new urethane dimethacrylate oligomers based on polytetrahydrofuran (PTHF)/poly(butylene adipate) (PBA): trimethyl-1,6-diisocyanatohexane (TMDI): 2-hydroxyethyl methacrylate (HEMA) (molar ratio 1:2:2) is presented. Organic–inorganic hybrid composites comprising urethane methacrylic macromers and 3-(trimethoxysilyl)propyl methacrylate (MPTS) taken in various gravimetric ratios were prepared by one-pot process through the UV-curing of photopolymerizable mixtures in the presence of 1wt.% Irgacure 819 photoinitiator, followed by the sol–gel reactions (hydrolysis and condensation) at ambient temperature. Additionally, in some formulations prior obtained silver nanoparticles (AgNPs) were incorporated before photopolymerization. Infrared spectroscopy monitored the microstructural evolution of the silica phase as well as the progress of double bond conversion during photopolymerization, while photo-differential scanning calorimetry (photo-DSC) gave us information on polymerization rate and conversion. The photopolymerization results show that the photopolymerization rates of the hybrid formulations are in the range of 0.084–0.158s−1, whereas the conversion degree after 5min of UV irradiation is over 70%. The thermal stability, Young’s modulus and tensile strength of the hybrid films are enhanced with the increase in alkoxysilane content, indicating significant reinforcement of the matrix in the presence of Sih name="sbnd" />Si linkages. The existence and homogeneous dispersion of nanosilver into the polymer matrix has been supported by EDX and TEM analysis, the last allowing a visualization of the formation of silver nanoparticles with size between 2 and 13nm (mean diameter 6.3nm). The four diffraction peaks appeared in the wide angle X-ray scattering spectrum can be assigned to the face-centered cubic silver phase, indicating the formation of metallic silver. The water/ethanol resistance for the hybrid coatings is augmented by the increase of inorganic content. [Copyright &y& Elsevier]

Abstract: Polymethyl-methacrylate (PMMA) is thermosetting plastic and called acrylic glass. PMMA sheet used in the industry to make aircraft and aquariums windows, and flat cut out letters. This research was to investigate tool wear, which was vertical milling of Polymethyl- methacrylate (PMMA). The experiment was done with HSS four flute end-milling cutter. The experiment was applied on two factors were consisted of three levels of cutting speed and feed rate. The tool wear was measured by the nose wear of end milling cutter. The results revealed that main factor affected on tool wear was feed rate. On the other hand, cutting speed was not main affected factor. Higher feed would cause of high tool wear than lower feed rate. High cutting speed that applied with high feed rate can be rapidly increase tool wear. Lower feed is better parameter for tool life of HSS end milling cutter. To keep long tool life, the low feed rate together with high cutting speed was recommended to milling PMMA sheets. [Copyright &y& Elsevier]

Abstract: VHB 4910 is an important polymeric material that has potential use as electro-active polymer in producing actuators. Such polymer, a member of the acrylic polymer group, is a very soft viscoelastic material. In this contribution, a comprehensive mechanical characterization of this important viscoelastic material has been carried out using different standard experiments such as single-step relaxation tests, multi-step relaxation tests and loading–unloading cyclic tests. In modelling the mechanical behaviour, a modified version of the micro-mechanically motivated Bergström–Boyce viscoelastic model has been used along with a finite linear evolution law. The model validation shows its excellent capability to predict the experimental results. [Copyright &y& Elsevier]

Mechanical failure of monodisperse Ni/Au coated acrylic particles has been investigated by individual compression tests using nanoindentation-based technique equipped with a flat diamond punch. We have found that both fracture property and morphology of particles depend on the compression loading rate. The breaking strain of the metal coating decreases with increasing loading rate, while the breaking stress increases. Two obvious fracture patterns with cracking in meridian or latitude direction are identified according to the loading rate, and attributed respectively to tension- or bendingdominated deformation of the coating. The findings reported here give a significant guiding to the manufacture design of metal coated polymer particles for Anisotropic Conductive Adhesive (ACA) packaging. [ABSTRACT FROM AUTHOR]

The distributions of three sodium alkyl sulfate surfactants in dry adhesive films cast from water-based latexes were characterized using confocal Raman microscopy (CRM) and contact angle (CA) and tack measurements. Sodium dodecyl sulfate (SDS), sodium tetradecyl sulfate (STS), and sodium octadecyl sulfate (SODS) were added to dialyzed commercial adhesive latex at various concentrations. Uneven distributions were found for all three surfactants along with a tendency to enrich film–air interfaces and, to a much lesser extent, film–glass interfaces. SDS demonstrated the greatest tendency to concentrate near film surfaces followed by STS and SODS. For all three surfactants, water CA values for dried films decreased sharply with increasing concentrations in the latex, but significant differences were observed, with SDS again having the greatest impact followed by STS and SODS. Tack of dried polymer films was also found to decrease with increasing latex surfactant levels, with SDS producing the sharpest drop as well as the lowest plateau values. Results indicate that interfacial enrichment by surfactants is detectable via both CRM and CA measurements, and this enrichment can significantly affect the performance of films. Finally, surface enrichment levels are qualitatively related to measures of the surfactants’ affinity for aqueous solutions, as characterized by the logarithm of their 1-octanol–water distribution coefficients (Kow). [ABSTRACT FROM AUTHOR]

An improvement in the rates of Morita-Baylis-Hillman reactions between isatin derivatives and acrylic esters or acrylonitrile under solvent-free conditions is presented. The reactions proceeded expediently at 0 °C under catalysis by 1,4-diazabicyclo[2,2,2]octane (DABCO) to afford the desired adducts. The optimized conditions are indicative of the presence of the more ordered transition states involved in these reactions, supporting the previously suggested mechanism for similar reactions. [ABSTRACT FROM AUTHOR]