Materiale Plastice Vol 57, Issue 3

Volume 57, Issue 3

Published: September 2020 Articles: 25 Pages: 1 – 278
Research Articles
1 – 18
Formulation of Polymeric Nanoparticles of Lercanidipine by Two Bottom Down Techniques Optimized by Design of Experiment
ALICIA MENEZES, SHANTHI LYSETTY, ANUP NAHA
Open Access DOI: 10.37358/MP.20.3.5375
HTML PDF
Abstract: Lercanidipine has found to be effective in lowering blood pressure among the potent calcium channel blockers, through its action on L- type calcium channels. However, the major disadvantage associated with Lercanidipine is, it is a BCS class II drug having low solubility bioavailability is around 10% through oral route due of extensive first pass metabolism. The present study is aimed to prepare and evaluate polymeric nanoparticles of Lercanidipine using a combination of two bottom down techniques, High speed homogenizer and Probe sonication. Preformulation studies like, DSC, FTIR using surfactants such as Tween 80, Sodium Lauryl sulphate, Polyvinyl Alcohol, singely and in combination were used. A full factorial method was utilized to study the effect of various factors such as surfactant concentration, homogenization speed, sonication amplitude and sonication time on Lercanidipine nanoparticles in two levels. Optimized nanoparticles (with PVA as surfactant) showed an average particle size of 141 nm, PDI 0.248 and zeta potential +6.46. Formulation was further optimized using Design Expert 10 software. Optimized formulation was found to be stable during 3 months stability studies as per ICH guidelines.
19 – 27
Surface Wettability and Morphology Implications on Interfacial Interactions of Chitosan with Certain Biological Media
ANDREEA IRINA BARZIC, RALUCA MARINICA ALBU, IULIANA STOICA, BOGDAN OPRISAN
Open Access DOI: 10.37358/MP.20.3.5376
HTML PDF
Abstract: Plastic materials based on biopolymers are of great importance in biomedical field. In this article, chitosan was investigated to elucidate the impact of the surface topography parameters and wettability on its interaction ability with certain biological molecules. The physicochemical properties of chitosan in acetic acid environment are analyzed by molecular modeling to predict some of the films properties. Morphology images show a hill–valley-structured surface of nanoscale level, with low surface bearing properties and valley fluid retention. Wetting features were determined for evaluation of the balance between the adhesion and cohesion forces acting at the biointerface. wetting or dewetting behavior of chitosan with several biological media.
28 – 40
Insight into the Role of a Isophthalic Dihydrazide Derivative Containing Piperonylic Acid in Poly(L-lactide) Nucleation: Thermal Performances and Mechanical Properties
HAO HUANG, YAN-HUA ZHANG, LI-SHA ZHAO, GUANG-MING LUO, YAN-HUA CAI
Open Access DOI: 10.37358/MP.20.3.5377
HTML PDF
Abstract: This work was aimed at synthesizing the N, N`-isophthalic bis(piperonylic acid) dihydrazide (PAID) to be as a new crystallization accelerator for poly(L-lactide) (PLLA), and a detailed investigations of the non-isothermal crystallization, melting behavior, thermal decomposition behavior and mechanical properties of PLLA nucleated by PAID were performed applying differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electronic tensile tester. The melt-crystallization proved that the PAID could act as a heterogeneous nucleating agent to significantly promote the crystallization in cooling, even the crystallization was still able to be accelerated upon the fast cooling at 50 oC/min. The final melt temperature was another crucial factor for PLLA’s melt crystallization, and when the final melt temperature was 170 oC, the onset crystallization temperature and melt-crystallization enthalpy was almost up to 150 oC and 56.8 J/g upon cooling of 1 oC/min, respectively. Furthermore, the chemical nucleation was proposed to be the nucleation mechanism of PAID for PLLA via the preliminary theoretical calculation. For the cold-crystallization, the addition of PAID exhibited an inhibition for the crystallization of PLLA, but the total crystallization process depended on the heating rate and PAID concentration. The single melting peak after cooling of 1 oC/min indicated that the crystallization had been thoroughly completed in cooling. Additionally, the single melting peak with different locations after full crystallization resulted from the different crystallization temperatures. A comparison in the onset decomposition temperature implied that the presence of PAID only slightly decreased the thermal stability of PLLA. The mechanical testing showed that, in contrast with the elongation at break, the existence of PAID enhanced the tensile strength of PLLA.
41 – 51
Analysis of Ageing Processes of Semi-Crystalline Materials
ALEKSANDRA KALWIK, PRZEMYSLAW POSTAWA, MARCIN NABIALEK
Open Access DOI: 10.37358/MP.20.3.5378
HTML PDF
Abstract: The article presents the influence of accelerated UV ageing on the structural properties of selected polymer materials. In this study, 3 types of materials from a group of thermoplastics known as PP30T, PE, POM were used. The test samples were prepared by injection moulding. In turn, an accelerated UV ageing process (600 h) was carried out in the UV Test chamber with fluorescent lamps characterized by a wavelength of 313 nm. Changes in the structure of the tested materials were observed by using an optical microscope. Measurements of gloss on the surface of primary samples that were exposed to UV rays were also taken. In addition, the structure of primary and aged samples was tested by differential scanning calorimetry (DSC). The conducted studies have demonstrated the impact of UV radiation on the changes in the surface layer of tested materials.
52 – 60
Characterization of Ceramic Waste Filled Unsaturated Polyester Resin
MOHAMED FARSANE, ABDELLAH ANOUAR, SOUAD CHAH, MILOUD BOUZZIRI
Open Access DOI: 10.37358/MP.20.3.5379
HTML PDF
Abstract: In this study, the composites of ceramic waste filler polyester were produced with ceramic waste as the filler and unsaturated polyester resin as the matrix. Various weight of filler loads (particle size [180 µm) were used; 0, 28.5, 41 and 50 wt% in view to better understand the effect of filler content on the mechanical, thermal properties and water absorption of the composites. Additionally, Fourier transform infrared spectroscopy was used to characterize the samples, from the findings, it is noticed an increase in the level of porcelain powder decreased the flexural strength and Hardness and increased the density. The results of water absorption have shown the composites absorbs fewer water. Thermal degradation indicates that the composite is more resistant to temperature than unsaturated polyester matrix due to the effect of porcelain powder incorporated. Moreover, the results reveal an opportunity for using the ceramic waste as filler in unsaturated polyester resin formulation.
61 – 69
Specific Heat and Thermal Expansion Coefficient of Hybrid Epoxy Composites
GEORGEL MIHU, VASILE BRIA, ADRIAN CIRCIUMARU, IULIAN GABRIEL BIRSAN, MARINA BUNEA
Open Access DOI: 10.37358/MP.20.3.5380
HTML PDF
Abstract: Thermal behavior of hybrid epoxy composites reinforced with different types of plain weave fabrics and ply orientation at various angles was investigated in this research. It was analyzed their thermal linear expansion coefficient and specific heat measured with Thermomechanical Analyzer (TMA) and Differential Scanning Calorimeter (DSC) respectively. Also, in this paper was studied the influence of carbon black - aramid powder and carbon black - barium ferrite mixtures added into epoxy matrix between certain plies of the hybrid composites. The experimental results showed that the addition of filler mixtures led to a significant decreasing of thermal expansion coefficient and specific heat of the hybrid epoxy composite with carbon outer plies. It was recorded a good structural stability in case of hybrid carbon-glass composite in the temperature range of 40-60°C.
70 – 80
Hybrid Dental Composites Biomechanical Properties
CLAUDIA NICOLETA FEURDEAN, ANIDA-MARIA BABTAN, ANCA IONEL, ARANKA ILEA, DAN BUHATEL, ARIN SAVA, et al.
Open Access DOI: 10.37358/MP.20.3.5381
HTML PDF
Abstract: In the last two decades, both general and oral health status became more important for individuals, being associated to their quality of life, social provenance and income. Society’s evolution is associated to high expectations regarding edentulous and decays treatment. Metal filling such as gaudent or amalgam have been replaced by aesthetic materials, to achieve similarity to the patient’s genuine biological tissue. Along with the aesthetic demand, dental materials have to fulfill biocompatibility and mechanical properties proximate to healthy soft either hard tissues. Composite materials have the advantages of accomplishing biological and mechanical demands and to be accessible financially, compared to ceramics. Composites are classified according to the main monomer, filling, particles’ dimension, addition of external molecules, this entirety having a direct influence on materials’ properties. The objective of this prospective interventional in vitro study was to evaluate biomechanical properties of four different hybrid composites: Premise direct™ – Premise indirect™ (Kerr, Orange, California, USA), Gradia® Direct (GC, Alsip, Illinois, USA) and Ceramage® (SHOFU Dental, Ratinger, Germany). Vickers microhardness, compressive strenght, direct tensile strenght, water absorption and solubility were assessed. The results showed that microfilled hybrid composites UDMA (urethane dimethacrylate)-based monomer had the highest evaluations regarding Vickers microhardness, compressive strenght and tensile strenght, whereas water absorption was the highest for nanofilled hybrid Bis-GMA (bisphenol A-glycidyl methacrylate)/TEGDMA (triethylene glycol dimethacrylate), and solubility for microfilled hybrid UDMA based monomer.
81 – 88
Assessment of Water Sorption, Solubility and Interface Properties for Two Different Pit and Fissure Sealants
ALEXANDRINA MUNTEAN, SORINA SAVA, SAROSI CODRUTA, MARIOARA MOLDOVAN, MARIANA PACURAR, ADA GABRIELA DELEAN
Open Access DOI: 10.37358/MP.20.3.5382
HTML PDF
Abstract: The purpose of modern dental medicine is to prevent dental caries and promote minimally invasive techniques at the expense of invasive methods. Dental sealants are largely recommended for occlusal surfaces protection, but concerns are related about microleakage at material-enamel interface. This in vitro study aimed to investigate the association between chemical structure, sealing capacity and marginal infiltration for 2 fluoride F containing commercially available resin-based sealants: Pit&Fissure® Sealant (DMP) and Fissurit FX® (Voco) in order to achieve a better description and ensure adequate material selection in every day practice. An optimal resin-based sealant should mimic the structural, physical and mechanical characteristics of enamel. The main difference between the sealing materials tested is based on the amounts of inorganic filler and on the various shapes of the particles in the filler. Pit&Fisure® Sealant express less attachment at enamel interface, higher sorption and greater water solubility, when compared to Fissurit FX®. The better sealing capacity of Fissurit FX® can be described by the homogeneity of the material and the very small size of the inorganic fillers. Dental materials properties used as pit and fissure sealants are sensitive to mechanical, thermic and chemical stress from oral cavity. Regular dental check-up can detect the presence and integrity of sealant and ensure preventive effect in time.
89 – 96
Morphometric Characteristics of Renal Vessels and Ureter Concerned on Mulages Obtained by Plastic Injections
PETRU BORDEI, CONSTANTIN ANDREI RUSALI, CONSTANTIN IONESCU, VALERIU ARDELEANU
Open Access DOI: 10.37358/MP.20.3.5383
HTML PDF
Abstract: The study was performed on a number of 48 plastic molds, obtained by injection of Technovit 7143. Technovite is a self-curing resin based on methyl methacrylate. Technovite no longer requires the use of dyes that can adversely affect the polymerization process and has a short polymerization time, making corrosion possible shortly after injection.
97 – 110
Dimensional Accuracy of Digitalized Stone Models Obtained from Alginic Acid Polymer and Poly-dimethyl-siloxane Impressions
LUMINITA OANCEA, CORINA MARILENA CRISTACHE, ALEXANDRU EUGEN PETRE, EUGENIA PANAITESCU, MIHAI BURLIBASA, LUCIAN TOMA CIOCAN
Open Access DOI: 10.37358/MP.20.3.5384
HTML PDF
Abstract: The prognosis of the prosthetic rehabilitation is linked to the proper transfer of the clinical data to the dental laboratory, in the digital or conventional workflow. The aim of the present study was to compare the dimensional accuracy of analog and digitalized models, focusing on the influence of impression polymeric materials on the final digital model. Methods: The master model with standard reference points and the three groups of test models, obtained by alginic acid polymer impression (group A) and condensation-cured poly(dimethyl siloxane) in two impression techniques (1-step putty/light-body-group 1T, 2-steps putty/ light-body-group 2T), were measured in four standardized points before and after digitization. The differences from the master model and between the pair analog and digital models was calculated and statistically analysed using Mann-Whitney tests (2 groups), and one-way Anova (3 groups) with post-hoc Tukey`s Test was applied for pairwise analysis (á=0.05). Results: All analog and digitalized model tests showed altered dimensions from the master model. A general reduction of the digitalized models, in sagittal and transversal dimensions, was observed, comparing to the reference model. The impression material was a significant factor influencing dimensional accuracy. Conclusions: a statistically significant difference was found between most of the models and the master model. However, through digitalization, some of the errors were compensated. The digital models from alginic acid polymer group (group A) registered the highest trueness, with no statistically significant difference (P > 0.05) from the reference model.
111 – 116
The Flexural Strength of Traditional and Modern Acrylic Prosthetic Bases
LIVIU GAVRILA-ARDELEAN, MIHAELA GAVRILA-ARDELEAN
Open Access DOI: 10.37358/MP.20.3.5385
HTML PDF
Abstract: The aim of this paper is to investigate the resistance to flexure of traditional and modern dental acrylic prosthetic bases. The practical utility of the laboratory studies carried out in this research is to apply the physical properties of plastic in medical technology, for improved clinical practice. The clinical utility of this research on prosthetic acrylic bases resistance is reflected in the quality of life of patients, the quality of mastication and durability of the prosthesis. Material and methods: experimental research, using a mechanical test machine. The results were analysed through quantitative methodes. Statistical correlations were made in the final experimental part. In conclusion, the values obtained in our experiments are comparable with those found in scientific literature. This fact enables us to recommend the use of the injection molding technique in clinical practice in our country, as well as the abandonment of the traditional manual stuffingpressing process.
117 – 124
Polymeric Geomembranes Used in Municipal Waste Facilities
DORU MIHAI, NARCISA ELENA POGURSCHI, NICOLETA DANIELA SARBU, CONSTANTA VALENTINA TUDOR, ADINA HORABLAGA, ROXANA SALCIANU, et al.
Open Access DOI: 10.37358/MP.20.3.5386
HTML PDF
Abstract: This research aims to establish the behaviour of geomembranes used for base sealing and for covering municipal waste facilities. The geomembranes used for base sealing are subjected to leachate pressure and to the action of chemical and microbiological pollutants. Geomembranes used for covering waste facilities are subjected to the action of precipitation water and released gases. This paper analyzes the following: the permeability mechanism of geomembranes made of polymers, the process of water vapours diffusion through polymers, diffusion flow, characteristic of permeability and influencing factors. The study also presents data on the permeability of some polymers - the most commonly used in the structure of geomembranes used in household waste facilities - as well as some of the results of ongoing research on the behaviour of high density polyethylene geomembranes in contact with the waste facilities’ leachate. Diffusion was determined by measuring the weight of the vessel (water loss) daily for 30 days. The polymer influences the permeability and diffusion through the molecular and intermolecular chemical structure, the packing density, the degree of crystallinity, the crosslinking density and through the flexibility of the macromolecular chains. The results show that the permeability of polymeric geomembranes is comparable to that of a microporous material (cement stone, bentonite).
125 – 136
Hybrid Beads Bearing Immobilized Bacteria as Advanced Means for the Removal of Acid Blue 93 Dye
TEODOR SANDU, MARIA LUIZA JECU, IULIANA RAUT, MARIANA CALIN, ELVIRA ALEXANDRESCU, TANTA VERONA IORDACHE, et al.
Open Access DOI: 10.37358/MP.20.3.5387
HTML PDF
Abstract: This paper describes the preparation of three- component hybrid copolymer beads, with water purification features. These newly developed hybrid beads were prepared starting from a mixture of poly(acrylonitrile- co- methacrylic acid) (PAN-co-PMAA), polyvinyl alcohol (PVA) and magnetite (Fe3O4), respectively. The preparation itself involved a Wet Phase Inversion (WPI) process. A Pseudomonas sp. strain was immobilized onto previously mentioned beads, before and after activation of the beads surface with glutardialdehyde, and afterwards used for the amendment of simulated water bearing an azo- blue dye, i.e. Acid Blue 93. In order to highlight the immobilization of Pseudomonas sp. strain, FTIR spectra and TGA results were recorded. CFU measurements as well as SEM images further provided evidence towards the occurrence of immobilization. The biodegradation studies of Acid Blue 93were carried out by means of UV spectroscopy at various contact times (24; 72 and 144 h) of the hybrid beads with the targeted dye.
137 – 146
Optimization of Variables Influencing the Thermal Conductivity and Fracture Strength of Reinforced PMMA by Using the Taguchi Method
ESRA KUL, FARUK YESILDAL, EMRE MANDEV, CAFER CELIK
Open Access DOI: 10.37358/MP.20.3.5388
HTML PDF
Abstract: How the particle size and volumetric ratio of silicon carbide (SiC) powder additions will strengthen polymethyl methacrylate (PMMA) is unclear. The purpose of this in vitro study was to optimize the reinforcement parameters of PMMA with SiC powder by using the Taguchi experimental design method. Particle size, volumetric rate, silane coupling rate, and mixing type were determined as parameters that would affect the reinforcement of PMMA with SiC powder. Using the Taguchi L9 orthogonal array, test specimens with different parameter combinations were fabricated and tested. The fracture load (in newtons) of each specimen group was recorded with the 3-point bend test. The thermal conductivity values of 60x50-mm and 3-mm-thick rectangular specimens were measured by using the Linseis THB100 thermal conductivity unit. The thermal diffusivity values were then calculated. Thermal analysis indicated improvement in the thermal conductivity of PMMA after reinforcement with SiC. The maximum thermal diffusivity was obtained with 15% SiC powder by volume. Thermal conductivity and flexural strength increased with an increase in particle size. The maximum flexural strength value was obtained with 5% SiC powder by volume. Increasing the particle size of the filler SiC powder resulted in increased thermal conductivity and flexural strength. Increasing the SiC filler powder by volume increased the thermal conductivity of PMMA but reduced its flexural strength. This study helped determine the optimum conditions for the use of SiC powder. Knowledge of the importance of these variables will help in more effective modification of denture base resin with SiC powder to improve heat transfer without adversely affecting strength.
147 – 159
Impact of Aging Effect and Heat Treatment on the Tensile Properties of PLA (Poly Lactic Acid) Printed Parts
MOHAMMAD SAKIB HASAN, TONI IVANOV, MILOS VORKAPIC, ALEKSANDAR SIMONOVIC, DAVID DAOU, ALEKSANDAR KOVACEVIC, et al.
Open Access DOI: 10.37358/MP.20.3.5389
HTML PDF
Abstract: Rapid innovations in 3D printing technology have allowed highly complex parts to be manufactured quickly and easily, particularly for prototyping purposes. Fused Deposition Modeling of thermoplastic materials is one of the most commonly used techniques in three-dimensional (3D) printing. The major aim of Fused Deposition Modeling (FDM) is to design and manufacture usable parts for fields such as engineering and medicine. Therefore, it is essential to investigate the mechanical properties of such FDM processed structures. One of the most commonly used materials currently on the market is Polylactic Acid (PLA). The main purpose of this paper is to investigate the effects of aging and heat treatment on the tensile properties of PLA printed test specimens. The tensile properties of parts manufactured by the 3D printer are influenced by various parameters such as extrusion temperature, infill density, building direction, layer height, etc. A total of 96 specimens were built by altering building orientation and layer height to estimate and compare the tensile properties of the printed parts. To investigate the aging effect, 30 of 96 specimens were printed 6 months before the tensile experiment. Half of both aged and new specimens were cured in an oven at 57.5 [¢ªC] for 3 hours while the other half endured no heat treatment. After the performed measurement, it can be concluded that heat treatment generally improves structural strength of the printed parts, while aging decreases it. However, these effects are highly dependent on the layer thickness and printing quality. The tensile test is conducted according to the ASTM D638 standard. The fractured samples were further characterized using an electron microscope.
160 – 173
Prediction of Surface Roughness in Drilling of Polymers using a Geometrical Model and Artificial Neural Networks
NICUSOR BAROIU, GEORGIANA-ALEXANDRA COSTIN, VIRGIL GABRIEL TEODOR, DUMITRU NEDELCU, VALENTIN TABACARU
Open Access DOI: 10.37358/MP.20.3.5390
HTML PDF
Abstract: Polymeric materials are synthetic macromolecular products, of which, by mechanical or thermal processing, objects of various shapes can be obtained, with wide uses in industry and commerce. This paper deals with the roughness of surfaces obtained during drilling of three polymeric materials: polyamide - PA6, polyacetal - POM-C and high density polyamide - HDPE 1000. In the experimental research was used a EMCO MILL 55 milling machine numerical controlled and HS steel helical drills with two straight cutting edges with the diameter of Ø8 mm and Ø10 mm, respectively. Experimental determinations consisted in drilling of the polymeric materials by modifying some parameters of the cutting regime, and determining the roughness of the surface of the holes machined, using the Mitutoyo Surftest SJ-210 rough meter. The purpose of the paper is to predict the roughness of the machined surfaces as one of the important surface quality indicators by using a geometrical model and an artificial neural network (ANN) methodology.
174 – 179
Study on the Surface Condition of Composite Biomaterials Related to Saliva pH
IRINA GRADINARU, LEONARD IGNAT, LEVENTE-CRISTIAN GIURGIU, CRISTINA GENA DASCALU, LOREDANA LILIANA HURJUI, MAURUSA-ELENA IGNAT, et al.
Open Access DOI: 10.37358/MP.20.3.5391
HTML PDF
Abstract: In the context of an extremely diverse offer of composite materials, the clinical reality permanently offers data about the way in which the individual feeding behavior, correlated with the salivary structure definitely have an impact on the structure, namely the quality of fillings made of various composite materials.The purpose of this study is represented by the analysis of the behavior of 6 types of composite materials that are frequently used in the dental medical practice in the presence of an acidic pH. The composite materials analyzed were Premise (Kerr) - P1, Polofil Supra (Voco) - P2, Nexcomp (Meta Biomed) - P3, Point 4 (Kerr) - P4, Pekalite (Heraeus Kulzer) - P5, and Progress (K.B. Mutsumi) - P6. The images of scanning electron microscopy clearly indicate that all samples are affected by acidic conditions (pH 4) after a moderately, but continuous exposure of 3 months. Signs of abrasions structural deterioration and leaks are obvious after pH 4 saliva treatments within all samples and magnifications, being marked by texture decay, rust-like presentation, and shallows, holes and cracks rise and enlargement. The intensity of deterioration processes varies between the studied commercial samples, with Pekalite (Heraeus Kulzer) followed by Point 4 (Kerr) being the most resistant to degradation in the current experimental conditions.
180 – 188
5-Fluorouracil Release from Chitosan-Based Matrix.Experimental and Theoretical Aspects
ROXANA IANCU, STEFAN ANDREI IRIMICIUC, MARICEL AGOP, MIHAIL FRASILA, MARIA-ALEXANDRA PAUN, VLADIMIR-ALEXANDRU PAUN, et al.
Open Access DOI: 10.37358/MP.20.3.5392
HTML PDF
Abstract: A series of four drug release formulations based on 5-fluorouracil encapsulated into a chitosan-based matrix were prepared by in situ hydrogelation with 3,7-dimethyl-2,6-octadienal. The formulations were investigated from structural and morphological aspects by FTIR spectroscopy, polarized light microscopy and scanning electron microscopy. It was established that 5-fluorouracil was anchored into the matrix as crystals, whose dimension varied as a function of the crosslinking density. The in vitro drug release simulated into a media mimicking the physiological environment revealed a progressive release of the 5-fluorouracil, in close interdependence with the crosslinking density. In the context of Pharmacokinetics behavioral analysis, a new mathematical procedure for describing drug release dynamics in polymer-drug complex system is proposed. Assuming that the dynamics of polymer-drug system’s structural units take place on continuous and nondifferentiable curves (multifractal curves), we show that in a one-dimensional hydrodynamic formalism of multifractal variables the drug release mechanism (Fickian diffusion, non-Fickian diffusion, etc) are given through synchronous dynamics at a differentiable and non-differentiable scale resolutions. Finally, the model is confirmed by the empirical data.
189 – 201
Using PET-G to Design an Underwater Rover Through 3D PrintingTtechnology
LUCIAN STEFANITA GRIGORE, AMADO-GEORGE STEFAN, OCTAVIAN ORBAN
Open Access DOI: 10.37358/MP.20.3.5393
HTML PDF
Abstract: The development of 3D printing technologies has gained considerable momentum. Almost every technical-scientific field uses this technology. The technology of 3D printing thermoplastic materials (or fusible filaments - FFF), is based on the realization of the parts by depositing successive layers of extruded filament at temperatures corresponding to the viscous aggregation state. One of the research activities of the CERAS research center is the realization of collaborative drone systems, drones capable of moving in each of the three unstructured environments: aerial, terrestrial aquatic / underwater. This paper presents a study on the choice of the type of thermoplastic material, for making the structural elements (chassis) of an underwater Rover. The need for this study arose from the fact that the design and construction of underwater vehicles is generally demanding. The materials must be characterized by resistance to compression / stretching / shearing, as in underwater environments the existence of currents, pressures (with increasing depth of immersion). Also, the materials must be chemically neutral, because in aquatic environments we can find various chemicals spilled in water (intentional or not) and finally salinity.
202 – 223
Prediction of Polymer Flow Length by Coupling Finite Element Simulation with Artificial Neural Network
IONUT LAURENTIU SANDU, FLORIN SUSAC, FELICIA STAN, CATALIN FETECAU
Open Access DOI: 10.37358/MP.20.3.5394
HTML PDF
Abstract: In this study, computer-aided engineering (CAE) simulation software and the design of experiments (DOE) method were used to simulate the injection molding process in terms of the melt flow length, using a spiral part. Process parameters such as melt temperature, mold temperature, injection pressure and mold cavity thickness were considered as injection molding variables. A predictive model for the flow length was created using a three-layer artificial neural network (ANN). The ANN model was trained with both simulation and experimental data, and the predictive performances were compared in terms of correlation coefficient, root mean square error and mean relative error. The cavity thickness and melt temperature were found to be the most significant factors for both the simulation and the experiment, while the injection pressure and the mold temperature had little effect on the flow length. The ANN model trained with Moldex3D data shows a significantly higher prediction capacity than the ANN model trained with experimental data. However, the melt flow lengths predicted by the ANN model for both Moldex3D and Moldflow simulation data are statistically significant, indicating that the proposed prediction methodology, which combines the ANN model, DOE method and the CAE simulation technology, can effectively predict the flow length of injection molded parts, with a small number of data.
224 – 237
The Clogging Effect in the Process of Protein Separation by Ultrafiltration
GHEORGHE BATRINESCU, ROXANA-ELENA SCUTARIU, NICOLAE-IONUT CRISTEA, IOANA-ALEXANDRA IONESCU, GHEORGHE NECHIFOR
Open Access DOI: 10.37358/MP.20.3.5395
HTML PDF
Abstract: In this study, five ultrafiltration membranes (polysulfone, cellulose acetate and polyethe-rsulfone) were tested in the treatment of aqueous protein solutions similar to wastewater from fermentation industries. The experiments were made in tangential flow filtration. The permeate flux for the five membranes tested at the optimum pressure of 3 bar decreased due to the effect of clogging the pores by the macromolecular protein solutions. Cellulose acetate membranes showed the lowest permeate flux (Ac-Cel1=152.4 L/m2.h and Ac-Cel2=40.3 L/m2.h) which doesn’t recommend them for the ultrafiltration process of bovine serum albumin. When a polysulfone membrane was used in several cycles of protein-containing wastewater ultrafiltration, the permeate flow decreased progressively from one cycle to another due to the internal clogging of the membrane (501.6 L/m2.h up to 444.0 L/m2.h). Regarding the ultrafiltration of protein solutions with a suspended yeast content, the clogging was predominant on the membrane’s surface, which results in a decrease of the permeate flux by over 50%.
238 – 248
Hydrothermal Synthesis of Carbon Nanotubes-Polyaniline(CNT-PANI)Composites and Preliminary Electrochemical Characterization of CNT-PANI Coatings
LAURA-MADALINA CURSARU, ANA-MARIA MOCIOIU, IOAN ALBERT TUDOR, ROXANA MIOARA PITICESCU
Open Access DOI: 10.37358/MP.20.3.5396
HTML PDF
Abstract: Heavy metals have a major contribution to biosphere pollution due to toxicity. The detection and monitoring of the environmental agents in soil, water and air is very important for the general health of humans and animals. It has been recently shown that electrochemical techniques such as differential pulse voltammetry (DPV) and square wave anodic stripping voltammetry (SWASV) using modified electrodes are very attractive methods for detecting heavy metals. The aim of this paper is to demonstrate the potential of hydrothermal process combined with electrochemical techniques to obtain modified electrodes based on functionalized carbon nanotubes (CNTs) and polyaniline (PANI) for metals detection. Commercial multi-walled carbon nanotubes (MWCNT) were functionalized by a mixture of HNO3/H2SO4 and further used for hydrothermal synthesis of CNT-PANI composites with different mass ratios. The resulted powders were analyzed by spectral (Fourier-Transform Infrared Spectroscopy) and thermal (Differential Scanning Calorimetry) methods, and then dispersed in a surfactant/electrolyte solution for preliminary electrochemical experiments (cyclic voltammetry, CV and DPV) to obtain modified electrodes. The influence of the CNT: PANI mass ratio and the synthesis time on the formation of composites with the desired structural and electrochemical properties were studied. It was found that CNT-PANI composite powder having mass ratio 1:4 and synthesis time 3h has the best structural and thermal characteristics and formed a weakly conductive film on the surface of the glassy carbon electrode. Preliminary electrochemical tests revealed the electroactive forms of polyaniline, through the presence of characteristic oxidation peaks but also reduction peaks, corresponding to reversible redox reactions, demonstrating that glassy carbon electrode has been electrochemically modified with CNT-PANI coatings. Further studies will be conducted to test the potential application of glassy carbon electrode modified with CNT-PANI coatings as electrochemical sensor for heavy metals detection.
249 – 259
Morphology and Mechanical Properties of Polyethylene Terephthalate/Ethylene Propylene Diene Monomer (PET/EPDM) in the Presence of Nanoclay
BAIFEN LIU, MOHAMMAD MIRJALILI, PEIMAN VALIPOUR, SAJAD PORZAL, SHIRIN NOURBAKHSH
Open Access DOI: 10.37358/MP.20.3.5397
HTML PDF
Abstract: This research deals with the mechanical properties, microstructure, and interrelations of triple nanocomposite based on PET/EPDM/Nanoclay. These properties were examined in different percentages of PET/EPDM blend with compatibilizer (Styrene-Ethylene/Butylene-Styrene)-G-(Maleic anhydrate) (SEBS-g-MAH). Results showed that the addition of 15% SEBS-g-MAH improved the toughness and impact strength of this nanocomposite. SEM micrographs indicated the most stable fuzzy microstructure in a 50/50 mixture of scattered phases of EPDM/SEBS-g-MAH. The effects of percentages of 1, 3, 5, 7 nanoclay Cloisite 30B (C30B) on the improvement of the properties were evaluated. With the addition of nano clay, the toughness and impact strength was reduced. Thermal destruction of nanoclay in processing temperature led to the decreasing dispersion of clay plates in the matrix and a reduction in the distances of nano clay plates in the composite compared to pure nano clay. XRD and TEM analysis was used to demonstrate the results. By adding 1% of nanoclay to the optimal sample, maximum stiffness, and Impact strength, among other nanocomposites, was achieved.
260 – 270
Polyethylene Terephthalate Degradation by Microalga Chlorella vulgaris Along with Pretreatment
WAJEEHA FALAH, FU-JIA CHEN, BIBI SAIMA ZEB, MALIK TAHIR HAYAT, QAISAR MAHMOOD, ABDOLGHAFFAR EBADI, et al.
Open Access DOI: 10.37358/MP.20.3.5398
HTML PDF
Abstract: The current research explored the potential of microalgal species Chlorella vulgaris and Pretreatment to remediate plastic waste. It was concluded from the results that Pretreatment had a marked effect on the cracking and alteration of plastic polymer, which helped to grow microbial species on the cracked surface as evident by Compound Microscopy (CM), Scanning Electron Microscopy (SEM), and Fourier Transformed Infrared Spectroscopy (FTIR) analysis. FTIR data also supported the notion that in the absence of any pretreatment, the microbial species were not able to mediate plastic biodegradation efficiently as the nature of functional groups was different in the presence and absence of Pretreatment. GCMS analysis revealed that the microbial specie could produce the biodegradation products which were likely to be found in the structure of PET, including alkanes ester, fatty acids, benzoic acid, and aromatics and the most toxic product of biodegradation is Bis (2-Ethyl hexyl phthalate), which is the biodegradation product of toxic ingredient of plastics that is phthalic acid.
271 – 278
Improvements to Biomaterials Structure Used in Acrylic Prostheses
VICTOR VLAD COSTAN, NORINA CONSUELA FORNA, OANA ELENA CIURCANU, DANIELA SULEA, ANDRADA DOSCAS, ZENOVIA SURLARI, et al.
Open Access DOI: 10.37358/MP.20.3.5399
HTML PDF
Abstract: Achievements in the field of biomaterials have as a basis three scientific domains: chemistry, biology and physics, then the technical application or the putting up culminating with clinical achievements. Dental prostheses, regardless of their type, replaced the lack of teeth. Although, mainly, many people that lost their teeth could continue life with the help of prostheses in a way pretty decent, dental prostheses shows some disadvantages that make them even unbearable for some people. The study aims at analyzing the biological behavior of sandwich type structures that reunite the classic acrylate and a silicone layer, namely the Flexite type elastic acrylate. We used a silicone material, RUBBER 732 RTV, which is frequently used in mucous-bone support deficits, especially in oral maxillofacial surgery post interventions. The tensile strength was tested ona TEXTENSER traction test machine, in view of establishing the chemical analysis of the 2 materials used. Regarding the maximum tensile strength for sandwich-type test samples, the flexible acrylate - silicone RUBBER 732 RTV structure broke at 1125N, while for the classic acrylate – silicone material a fracture value of 950N was recorded. The structure of the two biomaterials within the sandwich type test samples decisively influences the force and tension at which the fracture occurs, as well as the fracture route, which is linear, without the displacement of fragments, both the flexible acrylate and the silicone being affected, respectively a linear route at the level of the acrylic structure, affecting the acrylate – silicone interface for the classic acrylate – silicone test samples.