Papers by Keyword: Polycarbonate

Abstract: In this paper we present comparative study of frequency dependencies of an effective nonlinear elastic modulus of the three widely used glassy polymers, polystyrene, PMMA and polycarbonate. For measurements we use the methodology based on the acousto-elastic effect and analysis of variations in ultrasonic wave velocities under static stress applied to samples. The absolute values of the effective modulus γ = l − 2m, representing a combination of the Murnaghan moduli l and m, demonstrated pronounced nonlinear dependencies on the ultrasonic wave frequency for polystyrene and PMMA. At higher frequencies above ∼1 MHz no significant variations of the modulus occurred, while at lower frequencies down to 400 kHz its absolute value demonstrated a rapid rise of more than an order of magnitude. In polycarbonate the dependence was much less evident, the modulus γ also demonstrated some slight rise in the absolute value at lower frequencies, but the rise was not profound, less than two-fold and almost within the experimental error bars. The origin of the differences in nonlinear elastic properties of polystyrene/PMMA and polycarbonate requires further and more detailed investigation.

Abstract: Recently, the development of eco-friendly 3D filaments became a focus of researchers in additive manufacturing. Polycarbonate is one of the common 3D printing materials made from petroleum and non-biodegradable materials. In this research, to create ecological filament, polycarbonate from water gallon plastic waste was recycled through the extrusion process. To produce a filament with a diameter of 1.75 ± 0.1mm, the rate of the screw used in the range of 17-19 rpm, and the puller speed in the range of 10 – 11 rpm. The obtained filament was printed by using Creality Ender 3 S1 Pro machine. Printability properties such as defects and adhesion to the bed were investigated. The tensile strength and impact resistance of the product in longitudinal and transversal infill directions was measured according to ASTM D638 and ASTM D6110 respectively. It was found that in general, the tensile strength, modulus elasticity, and elongation in longitudinal directions are higher than in transversal directions. The tensile strength of recycled filament and commercial filament in the longitudinal direction was 39.54 ± 2.53 MPa and 37.38 ± 5.91 MPa respectively. The results show that filament from polycarbonate plastic waste is a promising material used as an eco-friendly filament.

Abstract: In the present study, a quasi-static compression test and impact test are carried out on a Polycarbonate plate with thickness of 2.66 mm and an effective diameter of 205 mm. The impact test is carried out on a pneumatic gun using a hardened truncated cone projectile of mass 25.8 g at different velocities. On the other hand, a servo mechanical universal testing machine with a 50 kN capacity is used to carry out the quasi-static compression test at a speed of 2 mm/min adopting an indenter of truncated nose shape. The Dynamic Enhancement Factor, or DEF, is computed as the ratio of quasi-static perforation energy to impact perforation energy. The measured DEF in the present study is compared with previously published results for metal and polycarbonate. Also local deformation of the plate after perforation is compared for both quasi-static test and dynamic test.

Abstract: Fracture mechanics has been a crucial aspect in the field of engineering science as technologies are rapidly growing nowadays. Various numerical methods have been developed to analyze fracture behaviour in different types of materials used in industries. Meanwhile, the application of polymers garners attention worldwide due to outstanding characteristics such as good strength, lightweight, and high temperature resistance, exemplified by polymers like polycarbonate (PC) and polypropylene (PP). Hence, failure aspects of such materials must be taken into consideration when conditions arise that may lead to failure, such as high-load impact, fatigue, and extreme temperatures. In this study, a bond-based Peridynamic model (PD) for the tensile behaviour, including fracture, of polymers has been developed. The PD model is constructed using the Centos software and encompasses both brittle and ductile fracture behaviours. Numerical results, including crack propagation, damage zone, and force-extension curves of notched specimens, are validated by comparison with experimental results of PC and PP. Through the validation process, PC specimens exhibit a difference percentage range for maximum load and rupture extension of 2.9% to 18.8% and 2.4% to 4.6%, respectively. PP specimens show a difference percentage range for maximum load and rupture extension of 31.2% to 43.5% and 0.9% to 30%, respectively. Consequently, the validation results indicate that the PD model for brittle specimens aligns more closely with experimental data compared to the PD model for ductile specimens.

Abstract: Polycarbonate is a tough, amorphous and transparent high performance thermoplastic polymer. It is used in many fields of application due to its versatile thermophysical, mechanical and optical properties. However, one of its drawbacks is its relatively high thermal conductivity which prevents its application as an insulating material. An appropriate heat treatment can therefore be a useful route to improve the thermal insulating property. The objective of this work is to study the effect of heat treatment; namely the influence of the quenching temperature above and below the glass transition temperature (Tg) on the thermophysical properties of neat polycarbonate (PC). The effect of the quenching temperature above Tg was also studied for neat poly (methyl methacrylate) (PMMA). The effect of residual stresses (RS) generated by the free quenching process on the thermophysical properties of neat PC was investigated. The thermal conductivity (k) and thermal diffusivity (a) of neat PC were measured using a periodic measurement method (DICO), (DIffusivity and COnductivity), at room temperature. The DICO method developed in the CERTES laboratory (Center for Studies and Research in Thermal, Environment and Systems of Paris 12 University), allows simultaneous access to the conductivity and thermal diffusivity from which the specific heat (Cp) can then be deduced. This work showed that the quenching from a high temperature above Tg did not affect the thermal conductivity and thermal diffusivity of both PC and PMMA. However, quenching from a temperature below Tg (130 ° C) caused a decrease of both the thermal. In fact the thermal conductivity of PC annealed at 130 ° C which is 0.22 W. m^-1 .K^-1 decreased to 0.06 W. m^-1 .K^-1 and 0.14 W. m^-1 .K^-1 after quenching at 0° C and 40 ° C respectively. This means that quenching would therefore improve the insulating capacity of PC compared to the material which has undergone only annealing. Contrary to the thermal conductivity, the values of the specific heat capacity in this temperature range ( 0° C – 40° C) significantly increased as a result of quenching. They increase from 1118 J. kg^-1. K^-1 for the annealed sample to 1290 J. kg^-1. K^-1 for PC quenched at 0° C and increased to 2221 J. kg^-1. K^-1 for PC quenched at 40 ° C which corresponds to an increase by 98 %. It was also found that the values of thermal conductivity and specific heat were in good agreement with those reported in the literature for neat PC samples quenched below Tg.

Abstract: Bacteria form biofilms to facilitate colonization, and biofilm formation on polymeric medical devices is a common cause of hospital-acquired infection. Simulated body fluid (SBF) is a supersaturated calcium-phosphate solution with ionic composition nearly equal to that of human blood plasma, and has been used to test the bioactivity of materials. The purpose of this work was to understand whether SBF influenced surface structure on bacterial adhesion and biofilm formation on polycarbonate, a polymer commonly used in medical devices. In this study, polycarbonate coupons were immersed in a SBF solution at 37 oC for 7 and 14 days and air-dried for 30 minutes, and compared with deionized water immersion. Colony biofilms of P. aeruginosa were then investigated by growing bacteria on top surface of immersed coupons for 24 and 48 hours, and observed by the quantitative assay (areal cell density) and visualized using a field emission scanning electron microscopy (FESEM). Results stated that a prolonged immersion time of coupons in deionized water enhanced biofilm growth. Immersion in SBF for a period of 14 days showed a significant reduction in the viability following 24 hours of incubation compared to that in deionized water incubated for 48 hours. FESEM further demonstrated that P. aeruginosa had a tendency to form biofilm on a polycarbonate substrate, and was able to develop biofilms on both the SBF and deionized water. Significant cell clusters and bacterial adhesion was observed at 48-hour incubation. These insights can potentially assist in the establishment of infection and colonization of this opportunistic pathogen, and will aid the development of strategies to prevent biofilm formation.

Abstract: In this study, the impact of tool pin profile on the dissimilar joining characteristics of aluminum alloy AA2017 and polycarbonate in friction stir welding (FSW) was examined. The tool pins made of SKD11 tool steel were used in the experiments of the FSW to join AA2017 and polycarbonate plates in a butt configuration at a tool rotation speed of 1320 and 1760 rpm and tool transverse speed of 60 mm/min. The tool shoulder diameter and tool pin height were set to 10 mm and 2 mm. The shapes of tool pin were cylindrical with and without groove, tapered cylindrical with and without groove, bobbin shaped with and without groove, square, triangular, pentagonal, hexagonal, oval, and ellipsoidal. The measurement of axial force was performed using a dynamometer. The changes in workpiece temperature at six locations during the process were measured using K-type thermocouples embedded in the plates. Microstructures of welded joints were examined by an optical microscope. Vickers Microhardness mapping was performed in and around the weld nugget zone, which is formed by the material flow between the two different base materials. From the result, the grooved tool pins generated less heat; while cylindrical, square, and oval type pins are also result in the superior properties of the welds during joining processes. Each tool pin had unique material flow behavior and weld formation, and the weld defects such as tunnel/voids occurred at the joint interface. The oval tool pin gives rise to the highest joint efficiency at a higher tool rotation speed, and the ellipsoidal tool pin generates the highest joint efficiency at a lower tool rotation speed was noticed.

Abstract: The aim of the article is to highlight the effect of the environment on the properties of a polycarbonate (PC). It consists in aging this material under Ultra-violet (UV) combined with temperature for different periods of time, and to reveal the physicochemical and mechanical changes caused by aging. PC is a highly valued technical material for its various important characteristics and low cost. It finds its application in various fields but mainly in those whose requirements are the transparency and the impact resistance. The physicochemical and mechanicals characterizations of the marketed polycarbonate are necessary in order to highlight its intrinsic properties and to develop strategies that can improve its lifespan. In this work, we highlight the physicochemical and mechanical characteristics of virgin and aged polycarbonate. For this, analytical techniques and mechanical tests were used. A comparison of the characteristics revealed the combined effects of temperature and ultraviolet rays.

Abstract: In this study, cellulose nanofiber (CNF) was prepared from carrot residues and further surface modification was carried out using suspension polymerization. Subsequently, these CNFs were added to polycarbonate (PC) to prepare a series CNF reinforced nanocomposites. TEM results show that the average diameter of the fiber after 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO) radical oxidation is 4.46 nm, and the average diameter of the TEMPO oxidized nanofiber modified by suspension polymerization is 7.65 nm, which confirms that the carrot fiber has been successfully prepared into nanoscale. The results of FT-IR analysis show that the lignin and impurities on carrot fibers can be removed effectively after alkali treatment. In addition, the absorption peak of the functional group analyzed by FT-IR also confirmed that the TEMPO radical oxidation and suspension polymerization method were successfully carried out. Contact angle analysis results show that the contact angle of the CNF modified by suspension polymerization method was increased, indicating that the hydrophobicity of the fiber has been significantly improved. Moreover, this will lead to the better compatibility between CNF and PC matrix. Mechanical property analysis also shows that the surface modified CNF has a stronger reinforcing effect on PC than the unmodified one. Furthermore, the results show that the dispersion of CNF in the matrix of nanocomposite prepared by dilution of masterbatch was better than that of the one prepared by directly adding of CNFs. The better dispersion of CNFs in the PC matrix led to the better mechanical properties. The increment of tensile strength of the nanocomposite prepared by dilution of masterbatch can reach to 21.75%. In the analysis of transparency, the transmittance of modified CNF containing nanocomposite was larger than that of unmodified CNF containing one. The transmittance of the nanocomposites containing modified CNFs was larger than 70%, which was close to that of pure PC.

Abstract: The polycarbonate (PC) is a highly valued polymeric material for its various characteristics and low cost. Its transparency and impact resistance justify its use in a severe radiation and temperature environment. The aim of this article is to subject this material to aging under ultraviolet (UV) radiation with a wavelength of 253 nm and a temperature of 80°C for various times. The physicochemical and mechanical characterizations of the virgin and aged material have allowed the revelation of the aging effects on the properties. The Fourier Transform Infrared Spectroscopy (FTIR) technique highlight breaks in chemical bonds in the molecular chains of the PC subjected to the combined effects of UV and heat. X-ray analysis have showed a reduction in crystallites and a tendency towards an amorphous state at short times, but the degree of crystallinity increases again at long exposure times of the material. As a result, the microhardness of the aged material is strongly affected on the exposed surface with less effect depending on the depth.