Polycarbonate Component Research Articles

Investigation of the Interfacial Fusion Bonding on Hybrid Additively Manufactured Components under Torsional Load.

Hybrid manufacturing processes integrate multiple manufacturing techniques to leverage their respective advantages and mitigate their limitations. This study combines additive manufacturing and injection molding, aiming to efficiently produce components with extensive design flexibility and functional integration. The research explores the interfacial fusion bonding of hybrid additively manufactured components under torsional loading. Specifically, it examines the impact of various surface treatments on injection molded parts and the influence of different build chamber temperatures during additive manufacturing on torsional strength. Polycarbonate components, neat, with glass or carbon fiber-reinforcement, are produced and assessed for dimensional accuracy, torsional strength, and fracture behavior. The findings emphasize the critical role of surface treatment for the injection molded components before additive manufacturing. Additionally, the study identifies the influence of chamber temperatures on both dimensional accuracy and torsional strength. Among all investigated materials, plasma-treated neat samples exhibited the best torsional strength. The torsional strength was increased by up to 87% by actively heating the build chamber to 186 °C for neat polycarbonate. These insights aim to advance the quality and performance of hybrid additively manufactured components, broadening their application potential across diverse fields.

Manipulating epoxy-polycarbonate sandwich films with enhanced dielectric performance via solution-immersion process

Epoxy-polycarbonate sandwiched films with enhanced dielectric performance were prepared in this study. Unlike traditional tedious multiple scratch-coating approach, the sandwich dielectric films were prepared based on a convenient solution-immersion process. Polycarbonate solutions with different concentration were applied to adjust the film composition and compared with epoxy-polycarbonate blending film. We found that rather than deteriorating the breakdown strength as shown in the blending counterpart, sandwiched films prepared by solution immersion shows superior breakdown strength (709.6 MV/m), almost 40 % better than both epoxy and polycarbonate components. Moreover, tan δ of the films prepared from solution-immersion (<0.005) is apparently smaller than blending samples (∼0.008). Both factors lead to admirable ideal dielectric energy storage performance (8.44 J/cm3) of the film, better than many conventional polymers.

Determination of optimum printing direction of the polycarbonate parts produced by additive manufacturing

In this study, the effect of printing direction on the tensile properties of polycarbonate (PC) parts produced using a 3D printer was investigated. A total of 9 samples were produced with printing directions of 0°, 45° and 90° with infill density of 20%. Tensile tests were carried out to determine the maximum tensile strength (UTS) of the samples. As a result of the research, it was determined that the samples produced in the same direction as the tensile direction (0° printing direction) had the highest strength values; on the other hand, samples produced in the 90° printing direction have the lowest strength values. While the ultimate tensile strength values for samples produced in 0° printing direction were measured respectively as 22.4 MPa, 21.6 MPa and 20.7 MPa; as 7.1 MPa, 9.1 MPa and 9.2 MPa in 45° printing direction; it was determined as 7.2 MPa, 5.4 MPa and 5.8 MPa in the 90° printing direction. In addition, UTS/mass ratios were calculated by measuring the mass of the samples after the tensile test. According to the results obtained, samples in the 0° printing direction have the highest UTS/mass ratio compared to other printing directions, making them the most durable option for applications requiring lightweight structures. Tensile samples produced in FDM were analyzed with the finite element method (FEM) and analysis results were found to be equivalent to physical tests. This study contributes to examination of the influence of 3D printing direction, especially exposed to tensile, on material properties, and provides important information for the production of lightweight and high strength PC components in industries such as medicine, aerospace and automotive.

Reinventing waste: Transforming discarded optical discs into polycarbonate-organosilane adsorbent for effective removal of mercury(II) in water

Polycarbonate, renowned for its versatile properties, has become indispensable in numerous domestic applications. However, the escalating rates of consumption and disposal raise significant concerns for sustainable development. Of particular concern is the inadequate management of obsolete optical discs, which pose a serious environmental threat due to the non-biodegradable polycarbonate component. To address this challenge, this study aimed to repurpose polycarbonate derived from optical disc waste into adsorbent materials using 3-aminopropyl triethoxysilane (APTES) coupling. The waste-derived products underwent comprehensive characterization employing Fourier transform infrared spectroscopy, field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, and Barrett-Joyner-Halenda techniques. Additionally, batch experiments were conducted to evaluate the mercury(II) adsorption behaviours. The successful immobilisation of APTES on polycarbonate surfaces was confirmed by the detection of nitrogen, silicon, and urethane groups. Notably, the product modified with 3 mL of APTES exhibited the highest surface area (61.992 m2 g−1), suggesting its potential for the adsorptive removal of mercury(II). Analysis based on the Langmuir (R2 =0.9824) and Redlich-Peterson (R2 =0.9834) isotherm models suggested a predominantly monolayer adsorption mechanism with an estimated maximum capacity of 1.284 mg g–1, while the adsorption process followed pseudo second-order kinetics (R2 =0.9998). The results highlight the efficacy of waste-derived polycarbonate-organosilane adsorbents in removing mercury(II) from diverse water matrices, rendering them attractive from both economic and environmental sustainability perspectives.

Building a Flexible and Highly Ionic Conductive Solid Electrolyte Interphase on the Surface of Si@C Anodes by Binary Electrolyte Additives.

Si@C as a high specific capacity anode material for lithium batteries (LIBs) has attracted a lot of attention. However, the severe volume change during lithium de-embedding causes repeated rupture/reconstruction of the solid electrolyte interphase (SEI), resulting in poor cycling stability of the Si-based battery system and thus hindering its application in commercial batteries. Using electrolyte additives to form an excellent SEI is considered to be a cost-effective method to meet this challenge. Here, the classical film-forming additive vinyl carbonate (VC), and the newly emerging lithium salt additive lithium difluorophosphate (LiDFP), are chosen as synergistic additives to improve the electrode-electrolyte interface properties. Final results show that the VC additive generates flexible polycarbonate components at the electrode/electrolyte interface, preventing the fragmentation of Si particles. However, the organic components show high impedance, inhibiting the fast transport of Li+. This defect can be supplemented from the decomposition substances of the LiDFP additive. The derived inorganic products, such as LiF and Li3PO4, can strengthen the reaction kinetics of the electrode, reduce the interfacial impedance, and promote the Li+ transport. Thus, the synergistic effect of VC and LiDFP additives builds an effective SEI with good flexibility and high ionic conductivity and then significantly improves the cycling and rate stability of Si@C anodes. The experimental results show that the utilization of LiDFP and VC additives to modify the Si@C anode interface enhances the capacity retention of the Si@C/Li half-cell after 100 cycles from 68.2% to 85.1%. Besides, the possible mechanism of action between VC and LiDFP is proposed by using the spectral characterization technique and density functional theory (DFT) calculations. This research opens up a new possibility for improvement of SEI, and provides a simple way to achieve high-performance Si-based LIBs.

Biodegradable Poly(trehalose) Nanoparticle for Preventing Amyloid Beta Aggregation and Related Neurotoxicity.

Trehalose is a disaccharide that is capable of inhibiting protein aggregation and activating cellular autophagy. It has been shown that a polymer or nanoparticle form, terminated with multiple trehalose units, can significantly enhance the anti-amyloidogenic performance and is suitable for the treatment of neurodegenerative diseases. Here, we report a trehalose-conjugated polycarbonate-co-lactide polymer and formulation of its nanoparticles having multiple numbers of trehalose exposed on the surface. The resultant poly(trehalose) nanoparticle inhibits the aggregation of amyloid beta peptides and disintegrates matured amyloid fibrils into smaller fragments. Moreover, the poly(trehalose) nanoparticle lowers extracellular amyloid β oligomer-driven cellular stress and enhances cell viability. The presence of biodegradable polycarbonate components in the poly(trehalose) nanoparticle would enhance their application potential as an anti-amyloidogenic material.

Effect of low vacuum environment on the fused filament fabrication process

The purpose of this research was to investigate the suitability of the Fused Filament Fabrication (FFF) process for low pressure/vacuum environment. This included investigating the ability of an FFF printer to function in a vacuum and evaluation of the dimensional accuracy and mechanical properties of the manufactured components. For this purpose, a commercially available FFF printer using polycarbonate as raw material was placed in a vacuum environment of 10 mbar. Test components were then fabricated in vacuum with a control group fabricated in a normal atmosphere (1 bar). Test components were evaluated for dimensional and mass accuracy, quality and presence of defects. Flexural, tensile and compressive testing was carried out according to ASTM D790, D638 and D695 respectively. Dimensional analysis of components showed equivalent small deviation for both environments. Components fabricated in the vacuum environment had 5.4% higher tensile yield strength and 59% higher extension at break compared to components printed in a normal atmosphere indicating an increased strength and ductility. Components tested in compression had approximately 11.2% higher compressive strength when printed in a vacuum environment. No differences were observed during the flexural test. In space, due to the vacuum environment, polymers and organic material are susceptible to release molecules via an outgassing process. Assessment of the molecular organic contamination generate during the printing process in vacuum is low and seems to mostly originated from the components of the printer. The results provided demonstrated the possibility to use the FFF process in a vacuum environment to fabricate dimensionally accurate, high-quality polycarbonate components with a variety of geometries without loss of mechanical performance. This work provides a proof of concept that FFF can be used to develop out-of-earth manufacturing technologies (in orbit/in space/on planet) allowing part production for new maintenance and repair strategy or to potentially manufacture entire structure more efficiently overpassing launch constrain by using only raw material brought from earth.

The Localization Behavior of Different CNTs in PC/SAN Blends Containing a Reactive Component.

Co-continuous blend systems of polycarbonate (PC), poly(styrene-co-acrylonitrile) (SAN), commercial non-functionalized multi-walled carbon nanotubes (MWCNTs) or various types of commercial and laboratory functionalized single-walled carbon nanotubes (SWCNTs), and a reactive component (RC, N-phenylmaleimide styrene maleic anhydride copolymer) were melt compounded in one step in a microcompounder. The blend system is immiscible, while the RC is miscible with SAN and contains maleic anhydride groups that have the potential to reactively couple with functional groups on the surface of the nanotubes. The influence of the RC on the localization of MWCNTs and SWCNTs (0.5 wt.%) was investigated by transmission electron microscopy (TEM) and energy-filtered TEM. In PC/SAN blends without RC, MWCNTs are localized in the PC component. In contrast, in PC/SAN-RC, the MWCNTs localize in the SAN-RC component, depending on the RC concentration. By adjusting the MWCNT/RC ratio, the localization of the MWCNTs can be tuned. The SWCNTs behave differently compared to the MWCNTs in PC/SAN-RC blends and their localization occurs either only in the PC or in both blend components, depending on the type of the SWCNTs. CNT defect concentration and surface functionalities seem to be responsible for the localization differences.

Surface Treatments with Dichloromethane to Eliminate Printing Lines on Polycarbonate Components Printed by Fused Deposition Modelling Technology.

Additive manufacturing, framed within the Industry 4.0. concept, is one of the processes that has witnessed greater development in the last years. Within this subject fused deposition modelling (FDM) printing technology is mainly dedicated to polymers and capable of providing components or elements of sufficient quality for different sectors. However, due to the process there can be a series of surface irregularities, which although they do not affect the required dimensional tolerances, they can cause problems in the useful life of the printed object in its interactions with the environment, as well as poor aesthetic qualities. Based on the above, this paper presents a series of chemical surface treatments capable of providing a surface that avoids undesired printing lines. For this purpose, fast, economical and environmentally sustainable treatments are used that obviously do not deteriorate the structure of the component or degrade the material surface. A complete study is therefore presented in which the different variables of the process are evaluated, as well as those of the printing technology, such as the layer height, coating, infill density, etc. The development of this project achieves a field of application of the detailed chemical treatment to obtain smooth surfaces, without degradation of the final part and with the appropriate dimensional tolerances.

EU moves toward strict controls on 3 plastics chemicals and PFBS

The European Union is taking aim at two chemicals used in polymer production, a phthalate, and a perfluorinated compound and its salts. All are now on a list of substances that are candidates for strict regulation. If the listed chemicals are selected for further controls, companies would be allowed to use them only if the European Chemicals Agency (ECHA) authorizes specific uses. ECHA says it added the two chemicals used in polymer production and diisohexyl phthalate to the list Jan. 16 because they are reproductive toxics. Also added to the list were perfluorobutanesulfonic acid (PFBS) and its salts. These are used as processing aids in the manufacture of fluoropolymers and as flame retardants in polycarbonate components for electronic equipment, according to ECHA. PFBS chemicals are also used to make water- and stain-resistant coatings for fabrics, carpets, and paper. PFBS has been linked to adverse thyroid and kidney effects in laboratory

In Situ Reactive Compatibilization of Polyamide 6 and Polycarbonate Blend by the Catalytic Effect of Phenol Novolac

Ternary polymer blends of polyamide 6 (PA6), polycarbonate (PC), and phenol novolac (PN) were prepared by a melt mixing process. PN catalyzes the exchange reaction between PA6 and PC and promotes the generation of a copolymer, which improves the compatibility. Herein, the catalytic effect of PN was experimentally supported by an increase in torque during melt mixing and mass signals from copolymer fragments detected by mass spectroscopy. The characteristic behavior of the exchange reaction changed significantly with increasing PN amount. The promotion of in situ copolymer generation led to the formation of ternary blends, which show homogeneous morphologies and superior mechanical properties, such as high stiffness and good elongation, compared with those of the binary blends without PN. Using excess PN causes some drawbacks like brittleness due to the decomposition of the PC component. A loading amount of 1–3 wt % PN was suitable for achieving a ternary blend with improved properties.

Does the Processing Method Resulting in Different States of an Interconnected Network of Multiwalled Carbon Nanotubes in Polymeric Blend Nanocomposites Affect EMI Shielding Properties?

Electromagnetic interference (EMI), an unwanted phenomenon, often affects the reliability of precise electronic circuitry. To prevent this, an effective shielding is prerequisite to protect the electronic devices. In this study, an attempt was made to understand how processing of polymeric blend nanocomposites involving multiwalled carbon nanotubes (MWCNTs) affects the evolving interconnected network structure of MWCNTs and eventually their EMI shielding properties. Thereby, the overall blend morphology and especially the connectivity of the polycarbonate (PC) component, in which the MWCNTs tend to migrate, as well as the perfectness of their migration, and the state of nanotube dispersion are considered. For this purpose, blends of varying composition of PC and poly(methyl methacrylate) were chosen as a model system as they show a phase diagram with lower critical solution temperature type of characteristic. Such blends were processed in two different ways: solution mixing (from the homogeneous state) and melt mixing (in the biphasic state). In both the processes, MWCNTs (3 wt %) were mixed into the blends, and the evolved structures (after phase separation induced by annealing in solution-mixed blends) and the quenched structures (as the blends exit the extruder) were systematically studied using transmission electron microscopy (TEM). Both the set of blends were subjected to the same thermal history, however, under different conditions such as under quiescent conditions (in the case of solution mixing) and under shear (in the case of melt mixing). The electrical volume conductivity and the evolved morphologies of these blend nanocomposites were evaluated and correlated with the measured EMI shielding behavior. The results indicated that irrespective of the type of processing, the MWCNTs localized in the PC component; driven by thermodynamic factors and depending on the blend composition, sea-island, cocontinuous, and phase-inverted structures evolved. Interestingly, the better interconnected network structures of MWCNTs observed using TEM in the solution-mixed samples together with larger nanotube lengths resulted in higher EMI shielding properties (−27 dB at 18 GHz) even if slightly higher electrical volume conductivities were observed in melt-mixed samples. Moreover, the shielding was absorption-driven, facilitated by the dense network of MWCNTs in the PC component of the blends, at any given concentration of nanotubes. Taken together, this study highlights the effects of different blend nanocomposite preparation methods (solution and melt) and the developed morphology and nanotube network structure in MWCNT filled blend nanocomposites on the EMI shielding behavior.

Morphology, Nucleation, and Isothermal Crystallization Kinetics of Poly(Butylene Succinate) Mixed with a Polycarbonate/MWCNT Masterbatch.

In this study, nanocomposites were prepared by melt blending poly(butylene succinate) (PBS) with a polycarbonate (PC)/multi-wall carbon nanotubes (MWCNTs) masterbatch, in a twin-screw extruder. The nanocomposites contained 0.5, 1.0, 2.0, and 4.0 wt% MWCNTs. Differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) results indicate that the blends are partially miscible, hence they form two phases (i.e., PC-rich and PBS-rich phases). The PC-rich phase contained a small amount of PBS chains that acted as a plasticizer and enabled crystallization of the PC component. In the PBS-rich phase, the amount of the PC chains present gave rise to increases in the glass transition temperature of the PBS phase. The presence of two phases was supported by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis, where most MWCNTs aggregated in the PC-rich phase (especially at the high MWCNTs content of 4 wt%) and a small amount of MWCNTs were able to diffuse to the PBS-rich phase. Standard DSC scans showed that the MWCNTs nucleation effects saturated at 0.5 wt% MWCNT content on the PBS-rich phase, above this content a negative nucleation effect was observed. Isothermal crystallization results indicated that with 0.5 wt% MWCNTs the crystallization rate was accelerated, but further increases in MWCNTs loading (and also in PC content) resulted in progressive decreases in crystallization rate. The results are explained by increased MWCNTs aggregation and reduced diffusion rates of PBS chains, as the masterbatch content in the blends increased.

Morphology, Nucleation, and Isothermal Crystallization Kinetics of Poly(ε-caprolactone) Mixed with a Polycarbonate/MWCNTs Masterbatch.

In this study, nanocomposites were prepared by melt blending poly (ε-caprolactone) (PCL) with a (polycarbonate (PC)/multi-wall carbon nanotubes (MWCNTs)) masterbatch in a twin-screw extruder. The nanocomposites contained 0.5, 1.0, 2.0, and 4.0 wt % MWCNTs. Even though PCL and PC have been reported to be miscible, our DSC (Differential Scanning Calorimetry), SAXS (Small Angle X-ray Scattering), and WAXS (Wide Angle X-ray Scattering) results showed partial miscibility, where two phases were formed (PC-rich and PCL-rich phases). In the PC-rich phase, the small amount of PCL chains included within this phase plasticized the PC component and the PC-rich phase was therefore able to crystallize. In contrast, in the PCL-rich phase the amount of PC chains present generates changes in the glass transition temperature of the PCL phase that were much smaller than those predicted by the Fox equation. The presence of two phases was corroborated by SEM, TEM, and AFM observations where a fair number of MWCNTs diffused from the PC-rich phase to the PCL-rich phase, even though there were some MWCNTs agglomerates confined to PC-rich droplets. Standard DSC measurements demonstrated that the MWCNTs nucleation effects are saturated at a 1 wt % MWCNT concentration on the PCL-rich phase. This is consistent with the dielectric percolation threshold, which was found to be between 0.5 and 1 wt % MWCNTs. However, the nucleating efficiency was lower than literature reports for PCL/MWCNTs, due to limited phase mixing between the PC-rich and the PCL-rich phases. Isothermal crystallization experiments performed by DSC showed an increase in the overall crystallization kinetics of PCL with increases in MWCNTs as a result of their nucleating effect. Nevertheless, the crystallinity degree of the nanocomposite containing 4 wt % MWCNTs decreased by about 15% in comparison to neat PCL. This was attributed to the presence of the PC-rich phase, which was able to crystallize in view of the plasticization effect of the PCL component, since as the MWCNT content increases, the PC content in the blend also increases. The thermal conductivities (i.e., 4 wt % MWCNTs) were enhanced by 20% in comparison to the neat material. The nanocomposites prepared in this work could be employed in applications were electrical conductivity is required, as well as lightweight and tailored mechanical properties.

Graphene Derivatives Doped with Nickel Ferrite Nanoparticles as Excellent Microwave Absorbers in Soft Nanocomposites

AbstractHerein, we report the development of soft polymeric composites containing multiwall carbon nanotubes (MWNTs, 1–3 wt%) and graphene derivatives doped with nickel ferrite nanoparticles (rGO@NF, 10 wt%) as lightweight microwave absorbers. The soft nanocomposites were designed using melt‐mixed blends of varying compositions of PC (polycarbonate) and SAN (poly styrene acrylonitrile) by compartmentalized functional nanoparticles in one of the components of the blend (here PC). Maximum attenuation of the incoming electromagnetic (EM) radiation mainly through absorption was achieved. The hetero‐dielectric media at microscopic length scale in the PC component provided large interfaces which facilitated multiple scattering thereby attenuating the incoming EM radiation. This strategy of positioning the functional nanoparticles in one of the components in the blends resulted in significantly enhanced shielding effectiveness (SE), at any given concentration of MWNTs, in contrast to PC based composites. This enhancement in SE was realized in the special morphology of the bicomponent PC/SAN=60/40 wt% blends where both the components are continuous. The enhanced SE in co‐continuous blends is due to combined effect of enhanced electrical conductivity (more precisely due to interconnected network of the nanoparticles) and the presence of a hetero‐dielectric media generating large scattering interfaces. For instance, the PC/SAN (60/40 wt%) co‐continuous blend containing 3 wt% MWNTs and 10 wt% rGO@NF manifested in a total shielding effectiveness (SET) of −32.3 dB (i. e. more than 99.9 % attenuation of incoming EM radiation) mainly through absorption.

Toughening modification of polycarbonate/poly(butylene terephthalate) blends achieved by simultaneous addition of elastomer particles and carbon nanotubes

Small quantities of maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MAH) copolymer and carbon nanotubes (CNTs) were introduced into polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends. The results demonstrated that simultaneously adding SEBS-g-MAH and CNTs greatly enhanced the fracture toughness of the samples and the impact strength increased with increasing CNT content. The morphologies, the dispersion of CNTs, the relaxation behaviors and the crystallization behaviors of samples were systematically investigated. SEBS-g-MAH formed the dispersed particles in the system. The particle diameter was decreased in the blend composites. CNTs exhibited homogeneous dispersion in the blend composites and they also formed a percolated network structure at relatively high content. The transesterification between PC and PBT components was suppressed by SEBS-g-MAH, and the crystallization ability of the PBT component was greatly enhanced. The toughening mechanisms were mainly related to the suppressed transesterification, the decreased elastomer particle size, and the formation of a CNT network structure.

Miniaturized Enzymatic Biosensor via Biofunctionalization of the Insulator of Nanoelectrode Ensembles

AbstractAn innovative second generation enzymatic microbiosensor was developed exploiting the properties of nanoelectrode ensembles (NEEs) prepared by electroless gold deposition in track‐etched polycarbonate (PC) membranes. As a case study, a miniaturized glucose biosensor was developed and characterized. The micro‐NEE glucose biosensor was obtained by immobilizing glucose oxidase (GOx) on the nonconductive PC component of the NEE, while the Au nanoelectrodes were used exclusively as transducers. (Ferrocenylmethyl)trimethylammonium cation (FA+) was used as the redox mediator. The immobilization of GOx on the PC did not affect the electrochemical performances of the NEE nor the catalytic activity of the enzyme. The proposed biosensor showed outstanding analytical performances with a detection limit of 36 µM. The nanostructured biosensor was miniaturized down to a micro‐NEE with overall radius of 400 µm, without any degradation of the analytical performances.

Preparation, mechanical, and in vitro properties of glass fiber-reinforced polycarbonate composites for orthodontic application.

Generally, orthodontic treatment uses metallic wires made from stainless steel, cobalt-chromium-nickel alloy, β-titanium alloy, and nickel-titanium (Ni-Ti) alloy. However, these wires are not esthetically pleasing and may induce allergic or toxic reactions. To correct these issues, in the present study we developed glass-fiber-reinforced plastic (GFRP) orthodontic wires made from polycarbonate and E-glass fiber by using pultrusion. After fabricating these GFRP round wires with a diameter of 0.45 mm (0.018 inch), we examined their mechanical and in vitro properties. To investigate how the glass-fiber diameter affected their physical properties, we prepared GFRP wires of varying diameters (7 and 13 µm). Both the GFRP with 13-µm fibers (GFRP-13) and GFRP with 7 µm fibers (GFRP-7) were more transparent than the metallic orthodontic wires. Flexural strengths of GFRP-13 and GFRP-7 were 690.3 ± 99.2 and 938.1 ± 95.0 MPa, respectively; flexural moduli of GFRP-13 and GFRP-7 were 25.4 ± 4.9 and 34.7 ± 7.7 GPa, respectively. These flexural properties of the GFRP wires were nearly equivalent to those of available Ni-Ti wires. GFRP-7 had better flexural properties than GFRP-13, indicating that the flexural properties of GFRP increase with decreasing fiber diameter. Using thermocycling, we found no significant change in the flexural properties of the GFRPs after 600 or 1,200 cycles. Using a cytotoxicity detection kit, we found that the glass fiber and polycarbonate components comprising the GFRP were not cytotoxic within the limitations of this study. We expect this metal-free GFRP wire composed of polycarbonate and glass fiber to be useful as an esthetically pleasing alternative to current metallic orthodontic wire.

Effects of enhanced compatibility by transesterification on the cell morphology of poly(lactic acid)/ polycarbonate blends using supercritical carbon dioxide

Poly(lactic acid)/polycarbonate blends were prepared by melt mixing. The transesterification reaction between poly(lactic acid) and polycarbonate was promoted by using tetrabutyl titanate as a catalyst. For poly(lactic acid)/polycarbonate (weight ratio of 75/25) blend with catalyst content up to 0.5 wt%, polycarbonate particles finely dispersed in the poly(lactic acid) matrix and the adhesion between the phases were improved, due to the enhanced compatibility by transesterification reaction. The blends were foamed by using batch-foaming process with CO2 as the blowing agent. Cell density of poly(lactic acid)/polycarbonate blend increased at low-catalyst content, while decreased at high-catalyst content, which was due to the changes of interfacial properties of blend phases through transesterification reaction and crystallinity of polycarbonate component. Cell types of poly(lactic acid)/polycarbonate blends were transferred from submicro-sized and even nanoscale cells to microscale cells by the deceased crystallinity of poly(lactic acid) component, which was caused by the increased degree of transesterification reaction and temperature. The declined viscosity of poly(lactic acid)/polycarbonate blend because of degradation during blend processing led to large cell size and low-cell density. However, the improvement of elasticity and viscosity of poly(lactic acid)/polycarbonate blend by transesterification reaction could decrease the cell size.

Achieving Electrical Conductive Tracks by Laser Treatment of non-Conductive Polypropylene/Polycarbonate Blends Filled with MWCNTs

Electrical non-conductive polymer blends consisting of a polypropylene (PP) matrix and dispersed particles of polycarbonate (PC) were melt compounded with 3 wt.% multiwalled carbon nanotubes (MWCNTs) loading and processed into plates by injection molding. The morphological analysis confirmed the selective localization of the MWCNTs in the PC component. By local irradiation with a CO2 laser beam, depending on the laser conditions, conductive tracks with dimensions of about 2 mm width, 80 to 370 μm depth and line resistances as low as 1.5 kΩ · cm−1 were created on the surface of the non-conductive plates. The factors affecting the line resistance are the PC content, the laser speed and laser power, as well as laser direction with respect to the melt flow direction. After the irradiation an enrichment of MWCNTs in the laser lines was detected indicating that conductive paths were generated by percolation of nanotubes selectively within these lines in otherwise non-conductive plates.