Polycarbonate Blends Research Articles

Hybrids membranes with potential for fuel cells – Part 3: extruded films of nanocomposites based on sepiolite and PC/sulfonated PC blends

Abstract Fuel Cells based in polymers are an alternative for the conventional energetic matrices. However, materials currently available still present disadvantages to overcome. Membranes of polycarbonate (PC)/sulfonated polycarbonate (PCs) blend/sepiolite nanocomposites have previously been studied by the authors, resulting in good mechanical properties and promising properties of vapor transmission and ionic migration resistance. However, their production in large scale is still a challenge. The aim of this work was the development further the formulation and processing of the previously studied material. Films of PC/PCs blends (50/50 wt%) with different content of sepiolite clay, with and without chemical modification, have been prepared in an extruder and evaluated by FTIR, XRD, DSC, TGA, DMA, tension strength and water vapor transmission (WVT). Even after two processing steps, the blend-based nanocomposites keep good thermal and mechanical properties. However, changes in WVT were observed with respect to data obtained in previous studies.

Effects of mixing strategy on catalyst‐assisted reactive blending of polycarbonate and polyethylene terephthalate

Reactive melt mixing of polycarbonate (PC) and polyethylene terephthalate (PET) blends with constant composition of 80:20 in the presence of a freshly added catalyst was conducted through a two‐step method. At first, PC and PET underwent premixing and melt mixed in the absence of a fresh catalyst. Then, mixing continued with catalyst addition under the same previous condition. The effects of varied premixing times from 1 to 5 min and mixing intensity at rotor speeds of 30 and 50 rev/min (rpm) were separately evaluated in transesterification reaction. The results of solubility analysis showed that the longer premixing time and the higher mixing rate enhanced the rate and extension of reaction. Fourier transform infrared (FTIR) spectroscopy and thermal analysis by differential scanning calorimetry were conducted on specimens on the basis of solubility separations. The height ratio of carbonyl group peaks of PC and PET phases were calculated for their corresponding FTIR spectra. The height ratio for PET showed a good correlation with solubility data. Moreover, crystallinity of PET phase was influenced by the reaction which was analyzed by solubility parameters. J. VINYL ADDIT. TECHNOL., 25:127–133, 2019. © 2018 Society of Plastics Engineers

Properties of Recycled-Polyethylene Terephthalate/Polycarbonate Blend Fabricated by Vented Barrel Injection Molding

In this research, recycled-polyethylene terephthalate (PET) and polycarbonate (RPET/PC) blends fabricated by vented barrel injection molding were presented to better understand the effect of devolatilization during molding process. The effect of dried pellets, non-dried pellets, using an opened-vented hole, and using a closed-vented hole on the miscibility, morphology, thermal properties and mechanical properties of RPET/PC blends was investigated. The results indicated that no drying decreases dispersion, thermal properties, and mechanical properties of RPET/PC blends due to hydrolysis degradation of recycled-PET during the injection molding process. Using the venting system with non-dried RPET/PC blends partially improves dispersion, thermal properties and molecular weight of RPET/PC blends processed without drying, giving results that are similar to those processed with drying. Regarding the flexural properties, using the venting system without drying prevents the flexural properties from decreasing in RPET/PC blends, if the amount of RPET is less than 75 wt%. When the content of RPET is over 75 wt%, using the venting system does not eliminate the decrease in flexural properties of RPET/PC blends. When the venting system is applied to non-dried RPET, despite hydrolysis degradation of RPET not being completely eliminated, the damaging effects are nonetheless reduced compared with those samples processed without the venting system. As a result, vented barrel injection molding hardly prevents non-dried RPET/PC blends from having reduced flexural properties when the content of RPET is greater than 75 wt%.

Formation of co‐continuous PLLA/PC blends with significantly improved physical properties by reactive comb polymers

ABSTRACTA kind of reactive comb (RC) polymer, which is constituted by poly(methyl methacrylate) backbone and side chains and a few epoxide groups that distribute randomly along the backbone, has been applied as compatibilizers for the thermodynamically immiscible poly(l‐lactide) (PLLA)/polycarbonate (PC) blend (50/50, wt/wt). Phase morphology and physical properties of the compatibilized PLLA/PC blends are characterized by scanning electron microscopy, transmission electron microscopy, and tensile tests. It has been found that the morphologies of the PLLA/PC blends are significantly ameliorated with the addition of RC polymers. A type of PLLA/PC blend with stable co‐continuous morphology has been achieved by the incorporation of more than 3 wt % of RC polymers. The mechanical tests showed that the co‐continuous PLLA/PC blends have an excellent stiffness‐toughness balance with high modulus and significantly improved ductility. Especially, the elongation at break of the PLLA/PC blend compatibilized by 10 wt % of RC polymers is 10 times higher than that of neat PLLA, in which the blend exhibits a cocontinuous lamellar microstructure. Furthermore, the PLLA/PC blends with cocontinuous morphology exhibit dramatically improved thermal stability as compared to neat PLLA when the temperature is over the Tg of the PLLA phase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46047.

Effect of mixing temperature on the carbon nanofiller distribution in immiscible blends of polycarbonate and polyolefin

We studied the selective localization of carbon nanofillers, such as multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP), in immiscible polymer blends composed of polycarbonate (PC) and polyethylene (PE) or ethylene-propylene copolymer (EPR). It was found that the distribution state of the carbon nanofillers in the composites is greatly affected by the mixing temperature and the species of nanofillers. MWCNTs resided in the PE or EPR phase in the composites, which cannot be explained by the difference in the interfacial tension. A similar morphology was detected in the PC/GNP/PE composite prepared at 300°C. In contrast, the PC/GNP/PE composite prepared at the low temperature (250°C) and the PC/GNP/EPR composites have the carbon nanofillers mostly in the PC phase. The selective localization in the PE or EPR phase is attributed to the surface adsorption of PE or EPR chains on the carbon nanofillers, which is more obvious for PE and at the high mixing temperature. These results demonstrate that both the species of carbon nanofillers and the mixing temperature affect the carbon nanofiller distribution in the immiscible blends.

Effects of waviness on fiber-length distribution and interfacial shear strength of natural fibers reinforced composites

Natural fibers are not as rigid as glass or carbon fibers. During composites extrusion and injection molding, they tend to bend and twist in the polymeric matrix, thus resulting in fiber waviness and decreased mechanical properties of natural fiber composites. The most widely used models for the estimation of interfacial shear strength (IFSS) and elastic modulus, which consider the fiber aspect ratio and mechanical properties of the fiber and matrix, do not consider these important features.In order to account for fiber waviness, an effective fiber length is proposed in this paper. The undulation of the fibers is approximated with a sinusoidal arc along with a calculated new length. The proposed correction factor depends on the wavelength and amplitude of the wave approximating the fiber. To verify this method, blends of polylactic acid (PLA) and polycarbonate (PC) (prepared with and without an interchange reactions catalyst) with addition to various percentages of cellulosic fibers (5 wt%, 10 wt% and 15 wt%) have been prepared and characterized. It has been demonstrated that by considering the corrected length values, it is possible to predict the mechanical properties and the effective reinforcement attained in the composites by using the most widely used models. In particular, the prediction of the elastic modulus is slightly affected by this correction, whereas the calculation of IFSS is strongly dependent on it.

Compatibilization of poly(lactic acid)/polycarbonate blends by different coupling agents

In this study, PLA/PC blends were prepared in order to investigate the effects of the addition of PC loading level into PLA matrix on the mechanical properties of these blends. After that, PLA/PC (70/30), which has the lowest tensile strength value, was selected as a control sample for the compatibilization study. Commercial styrene-acrylic multi-functional-epoxide oligomeric agent (SAmfE), styrene maleic anhydride copolymer (SMA), tetrasilanol phenyl polyhedral oligomeric silsesquioxane (T-POSS) and glycidyl isooctyl-polyhedral oligomeric silsesquioxane (G-POSS) were used as compatibilizers for PLA/PC blends. The variation of mechanical, thermal, structural and morphological properties were examined by conducting tensile tests, dynamic mechanical analyses, differential scanning calorimetry, Fourier Transform IR and scanning electron microscope analyses. Tensile test results showed that the tensile strength and elongation at break values of the PLA/PC blend compatibilized with SAmfE were higher than those of the other blends. DSC analyses revealed that Tg and Tm values of the blends were not significantly affected by compatibilizer but, degree of crystallinity was found to be sensitive to compatibilizer type. DMA results showed that the best mechanical properties were obtained for the PLA/PC/SAmfE blend. When all of the results evaluated, it was found that the SAmfE is the most effective compatibilizer among the using compatibilizer types for PLA/PC blends.

Effect of chain extenders on mechanical and thermal properties of recycled poly (ethylene terephthalate) and polycarbonate blends

Poly(ethylene terephthalate) (PET) based thermoplastics are common, particularly in packaging. Due to both thermal and hydrolytic degradation, recycled PET (rPET) shows poor mechanical properties. The effect of adding 30% polycarbonate (PC) and chain extender (CE) on mechanical, thermal and morphological properties was investigated. rPET with PC and CE was melt blended in a single screw extruder, which was then tensile test specimens were formed by injection molding rPET and PC compatibility was improved via chain extending reactions which in turn improved the rPET and PC blend mechanical properties. With the addition of 30%PC the tensile modulus of rPET increased by 18% and it increased by 223% when 2%CE was added to rPET and 30%PC blends. Also, the CE reaction affected crystallization, monitored by differential scanning calorimetry: the melting enthalpy ofblends was lowered by increased CE content.

Surface segregation during injection molding of polycarbonate/poly(methyl methacrylate) blend

We investigated the distribution of the constituent polymers of an injection-molded product comprising a miscible blend of polycarbonate (PC) and low-molecular-weight poly(methyl methacrylate) (PMMA). We found that PMMA became localized at the surface without affecting the transparency of the product. As a result, the surface hardness was effectively enhanced by a small amount of PMMA. This technique can be used to produce an ideal plastic glass that has high transparency, mechanical toughness, and high surface hardness.

Modification of the reactive core-shell particles properties to prepare PBT/PC blends with higher toughness and stiffness

Glycidyl methacrylate (GMA) functionalized methyl methacrylate-butadiene-styrene core-shell particles (PB-g-MSG) were prepared to toughen poly (butylene terephthalate) (PBT) and polycarbonate (PC) blends. T-dodecyl mercaptan (TDDM) was used to modify the grafting character of the core-shell particles. The addition of TDDM decreased the grafting degree, particles size and crosslinking degree of PB-g-MSG particles. At the same time, the free methyl methacrylate-co-styrene-co-glyceryl methacrylate copolymer (f-MSG) increased. The f-MSG reacted with PBT and suppressed the transesterification between PBT and PC. On the other hand, f-MSG promoted the crystallization of PBT by heterogeneous nucleation. When the TDDM content was lower than 0.76%, PB-g-MSG particles dispersed in the matrix uniformly, otherwise, agglomeration took place. The change of TDDM content in the PB-g-MSG particles influenced the toughening ability and tensile properties. When the TDDM content was 0.76%, the PBT/PC/PB-g-MSG blend showed the optimum impact toughness and yield strength, which are 908 J/m and 49.4Mpa. Fracture mechanism results indicated that cavitation induced shear yielding occurred in the PBT/PC/PB-g-MSG blend when no TDDM addition for the core-shell particles. With the addition of TDDM, the interfacial strength decreased between the PB-g-MSG core-shell particles and the matrix. So voids appeared due to debonding, which also could promote the shear yielding process.

FTIR analysis on aging characteristics of ABS/PC blend under UV-irradiation in air

Fourier Transform Infrared Spectroscopy (FTIR) is adopted to study the aging characteristics of poly(acrylonitrile–butadiene–styrene)/polycarbonate (ABS/PC) blend under UV-irradiation in air by analyzing the variation of the three main absorbance at about 967cm−1, 1720cm−1 and 3420cm−1 associated with carbon-hydrogen bonds belonging to 1,4 butadiene, carbonyl and hydroxyl groups, respectively. Results indicate that, under UV-irradiation in air, the photo-oxidation of the blend is not a simple combination of the photo-oxidation of corresponding ABS and PC themselves and takes place predominantly at the ABS component. Due to the interaction between the two components and the Fries rearrangement taken place in the PC component during the UV-irradiation in air, the ABS/PC blends behave higher photo-stability than ABS has.

Contribution of Catalytic Transesterification Reactions to the Compatibilization of Poly(lactic acid)/Polycarbonate Blends: Thermal, Morphological and Viscoelastic Characterization

Samarium acetylacetonate (Sm-Acac) was added to catalyze interchange reactions between poly(lactic acid) (PLA) and polycarbonate (PC) in order to promote compatibilization and enhance the performances of the PLA/PC blend. The effects of the composition and catalyzed transesterification reactions were investigated using differential scanning calorimetry (DSC), thermogravimetry (TG), dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). DMTA and DSC analysis revealed the immiscibility of the uncatalyzed PLA/PC blends for the studied compositions because the glass transition temperatures of PC and PLA were unchanged after blending. In the PLA glassy region, PLA/PC blends exhibited lower storage moduli which increased upon heating due to the cold crystallization process. During melt mixing with Sm-Acac catalyst, PLA/PC blends were submitted to two competing processes. In one hand, Sm-Acac acted as a plasticizer and contributed in decreasing significantly the glass transition, crystallization and melting temperatures of PLA phase. In the other hand, Sm-Acac proved its efficiency in catalyzing the transesterification reactions that were evidenced by the decrease of the PLA aptitude to crystallization due to the hindering effect of the PC units inserted into the PLA chains. PLA/PC blends melt mixed with 0.25% of Sm-Acac showed a significant strengthening effect, corresponding to an increase in the storage modulus in the temperature range comprised between 70 and 90 °C. This indicated the formation of a copolymer at the interface and the promotion of adhesion as it is confirmed from the decrease in the height of the PLA Tan δ peak. At 0.5% of Sm-Acac, (90/10) PLA/PC blend revealed a new peak assigned to the glass transition of the PLA-PC copolymer, whereas the (50/50) PLA/PC blend was converted into a new random copolymer. TG analysis proved the presence of a copolymer structure presenting an intermediate thermal stability in both the catalyzed and uncatalyzed blends.

A review of filled and pristine polycarbonate blends and their applications

Polycarbonate is an important thermoplastic polymer. Due to its high performance, polycarbonate has a range of engineering applications in construction, automotive, aircraft, data storage, electrical, and telecommunication hardware. However, polycarbonate’s use is limited in advanced applications due to limitations, such as strong hydrophobicity, relatively limited chemical functionality, high melt viscosity, notch sensitivity of mechanical properties, and relative softness. Blending with other thermoplastic polymers improves its physical characteristics. The present review outlines up-to-date developments concerning the design and application of polycarbonate blends. A particular emphasis has been given to establish polycarbonate blends such as: • polycarbonate/polyethylene • polycarbonate/poly(methyl methacrylate) • polycarbonate/poly(vinylchloride) • polycarbonate/ polystyrene • polycarbonate/polyurethane • polycarbonate/polyester • polycarbonate/poly(ɛ-caprolactone). To improve the polycarbonate blend properties, fillers including organic and inorganic reinforcement materials (carbon nanotube, montmorillonite nanoclay, and metal nanoparticle) have also been employed. Polycarbonate blend applications in biomedical, flame retardant, and membrane materials have also been reviewed. To fully exploit the future potential for polycarbonate-based engineering materials, the structure–property relationship and compatibilization mechanisms need to be further explored.

Rational Design of Multilayer Ultrathin Nano‐Architecture by Coupling of Soft Conducting Nanocomposite with Ferrites and Porous Structures for Screening Electromagnetic Radiation

AbstractFabrication of multilayered thin polymer films by rational arrangement of tailor‐made nanocomposites was designed to absorb electromagnetic (EM) radiation. Mn (manganese) ferrite nanoparticles were incorporated in polyvinylidene fluoride (PVDF) matrix, along with conductive MWCNTs, treated as outer layers of the multilayer assembly. The higher permittivity, permeability and attenuation constant ensure the higher absorption ability of these resulting outer layers. Selectively etching of one of the phases of the inner layers, which consist of immiscible blends of polycarbonate (PC) and PVDF with conductive MWCNTs, porous structure can be designed to maximize the penetration of incoming EM radiation from outer layers. Further scattering of the penetrated EM wave between the interfacial walls of conducting nano fillers inside the porous matrix enhance the shielding efficiency. The resulting ultrathin (0.60 mm) multilayered architecture was able to block >99.999 % (ca. −50dB) of the incoming EM radiation. This new‐age EM radiation absorbing material, powered by multi‐functionality henceforth, offers amendable, cost‐effective replacement to the existing solutions.

Absorption-Dominated Electromagnetic Wave Suppressor Derived from Ferrite-Doped Cross-Linked Graphene Framework and Conducting Carbon.

To minimize electromagnetic (EM) pollution, two key parameters, namely, intrinsic wave impedance matching and intense absorption of incoming EM radiation, must satisfy the utmost requirements. To target these requirements, soft conducting composites consisting of binary blends of polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) were designed with doped multiwalled carbon nanotubes (MWCNTs) and a three-dimensional cross-linked graphene oxide (GO) framework doped with ferrite nanoparticles. The doping of α-MnO2 onto the MWCNTs ensured intrinsic wave impedance matching in addition to providing conducting pathways, and the ferrite-doped cross-linked GO facilitated the enhanced attenuation of the incoming EM radiation. This unique combination of magnetodielectric coupling led to a very high electromagnetic shielding efficiency (SE) of -37 dB at 18 GHz, dominated by absorption-driven shielding. The promising results from the composites further motivated us to rationally stack individual composites into a multilayer architecture following an absorption-multiple reflection-absorption pathway. This resulted in an impressive SE of -57 dB for a thin shield of 0.9-mm thickness. Such a high SE indicates >99.999% attenuation of the incoming EM radiation, which, together with the improvement in structural properties, validates the potential of these materials in terms of applications in cost-effective and tunable solutions.

Effects of Triacetin Addition on the Thermal and Mechanical Properties of Poly(L-lactic acid)/Polycarbonate Blends

Effects of Triacetin Addition on the Thermal and Mechanical Properties of Poly(L-lactic acid)/Polycarbonate Blends

Effect of polymer blend types and gamma radiation on the physico-chemical properties of polycarbonate

ABSTRACTSamples from polycarbonate (PC) were classified into two main groups. The first group was blended with Abietic acid (Rosin) with different compositions, while the second group was blended with ethylene-vinyl acetate (EVA) copolymer with almost the same composition. A comparative study of the effect of both Rosin and EVA concentration on the thermal stability of PC has been investigated using thermogravimetric analysis. The results show that blending with Rosin causes the dominance of degradation. Samples from PC with 20% Rosin blend were irradiated with gamma at the dose of range 20–300 kGy. The resultant effect of gamma radiation on the structural properties of the 20% Rosin/ 80%PC blend has been investigated using Fourier Transform Infrared FTIR spectroscopy. The results indicate that degradation of the polymer blend dominates, thus increases the creation of hot free radicals that leads to the formation of color centers in PC. In addition, the transmission of the 20% Rosin/80%PC samples as well as color changes was studied. The color intensity ΔE was greatly increased with increasing the gamma dose up to 300 kGy, accompanied by a significant increase in the blue color component.

Thermal characterization of reactive blending of 70PC/30PET mixtures prepared in the presence/absence of samarium acetylacetonate as a transesterification catalyst

Abstract Poly(ethylene terephthalate) (PET)/polycarbonate (PC) blends were prepared in the presence and absence of samarium (III) acetylacetonate hydrate [Sm(acac)3] used as an ester-ester exchange reaction catalyst. Differential scanning calorimetry (DSC) and thermogravimetric analysis/differential thermogravimetry (TGA/DTG) were used to study the variations in the thermal properties of blends before and after reactive blending. Solubility measurements in methylene chloride (CH2Cl2) and infrared spectroscopy were also employed to highlight the structural changes that occurred during mixing in the presence of Sm(acac)3. The DSC results showed two distinct transition temperatures (T g ) for all the compositions. Also, the T g values of components were shifted compared to the parent polymers in both the blends prepared with and without catalyst. Further, the T g of the PET-rich phase was displaced to higher temperatures and that of the PC-rich phase showed a tendency to diminish as the catalyst’s concentration increased. At the same time, the melting temperature (T m ) of the PET-rich phase was shifted to lower temperatures. The evaluation of the compositions of the PC- and PET-rich phases using Wood’s equation showed a strong dependence on the catalyst concentration. Furthermore, the thermogravimetric thermograms showed that the thermal stability of the blends was between those of the homopolymers, and evidenced a net improvement relatively to the neat PET. The obtained results confirmed the aptitude of Sm(acac)3 to promote exchange reactions between PC and PET, and to achieve their compatibilization through an interfacial copolymer synthesis process.

Effect of core-shell particles dispersed morphology on the toughening behavior of PBT/PC blends

Methyl methacrylate-co-styrene-co-glycidyl methacrylate grafted polybutadiene (PB-g-MSG) and styrene-co-glycidyl methacrylate grafted polybutadiene (PB-g-SG) core-shell particles were prepared to toughen poly (butylene terephthalate) (PBT) and polycarbonate (PC) blends. The compatibilization reaction between the epoxy groups of glycidyl methacrylate and the carboxyl groups of PBT induced the PB-g-SG particles dispersed in the PBT phase. On the other hand, the good miscibility between PMMA (the shell phase of PB-g-MSG) and PC induced the PB-g-MSG particles dispersed in the PC phase. The different phase morphology led to different toughening behavior. The PBT/PC/PB-g-MSG blends with the PC encapsulated morphology showed much lower brittle-ductile transition core-shell particles content (10-15 wt% or 15-20 wt%) compared with the PBT/PC/PB-g-SG blends (20-25 wt%). The difference between the toughening efficiency of the core-shell particles was due to the change of deformation mechanisms. In PBT/PC/PB-g-MSG blends, the cavitation of PB rubber phase led to the occurrence of shear yielding of the matrix. While in the PBT/PC/PB-g-SG blends, the debonding between PBT and PC interface induced the shear yielding of the matrix. The variation of the core-shell particles dispersed phase morphology also affected the crystallization properties and DMA results of the PBT/PC blends. Modification of the phase morphology provided an useful strategy to prepare PBT/PC blends with higher toughening efficiency.

Analysis of structure transition and compatibility of PTT/PC blend without transesterification

Poly(trimethylene terephthalate)/polycarbonate (PTT/PC) blends were prepared by solvent mixing to avoid transesterification during high temperature blending. The influences of compositions on the thermal behavior, crystallization morphology and structure of the blends were studied. FTIR results indicated that there was no COO linking to two phenyl groups on each side chain and DSC results supported no transesterification reaction. DSC curves showed that Tc and Tmc increased to maximum range when PC contents were between 7 wt%-15 wt%, however, Tm decreased constantly with the increase of PC contents. It was observed from POM that PTT spherulitic morphology and crystallization kinetics were obviously influenced by the change of PC contents. Structural evolutions during cooling were investigated by SAXS which showed Lc of PTT remained a constant with different PC contents and also fixed during crystallization, nevertheless, it revealed a maximum value of Lnc for sample PTT93. It was concluded that PC chains could be permeated into not only amorphous crystallite structure but also amorphous lamellae structure and 7 wt% PC content was supposed to be the “proper” penetration amount into PTT lamellae structure which led to a maximum capacity of amorphous lamellar layer. Fringedmicelle crystal model was adopted to illustrate semi-crystalline physical structures of the blend in two kinds of component aggregation states.