Neat PBT Research Articles

The Impact of Artificial Marble Wastes on Heat Deflection Temperature, Crystallization, and Impact Properties of Polybutylene Terephthalate.

As artificial marble is abundant and widely used in residential and commercial fields, the resource utilization of artificial marble wastes (AMWs) has become extremely important in order to protect the environment. In this paper, polybutylene terephthalate/artificial marble wastes (PBT/AMWs) composites were prepared by melt blending to maximize resource utilization and increase PBT performance. The research results showed that the filling of AMWs was beneficial to the improvement of PBT-related performance. X-ray diffraction analysis results indicated that after filling AMWs into the PBT matrix, the crystal structure of PBT was not changed. Heat deflection temperature (HDT) analysis results indicated that the HDT of PBT composites with 20 wt% AMWs reached 66.68 °C, which was 9.12 °C higher than that of neat PBT. Differential scanning calorimetry analysis results showed that heterogeneous nucleation could be well achieved when the filling content was 15 wt%; impact and scanning electron microscope analysis results showed that due to the partial core-shell structure of the AMWs, the impact strength of PBT was significantly improved after filling. When the filling amount was 20 wt%, the impact strength of the PBT composites reached 23.20 kJ/m2, which was 17.94 kJ/m2 higher than that of neat PBT. This research will not only provide new insights into the efficient and high-value utilization of AMWs, but also provide a good reference for improved applications of other polymers.

UV resistant PBT nanocomposites by reactive compatibilization and selective distribution of tailor-made double-shelled TiO2 nanohybrids

The application and service life of poly (butylene terephthalate) (PBT) is limited by its brittleness and ultraviolet (UV) instability. Titanium dioxide (TiO2) in PBT matrix can shield for UV light, but it triggers further photo-degradation of PBT via a photocatalytic effect. In this work, both toughness and against prolonged UV radiation of PBT from recycled source are significantly improved by reactive compounding with ethylene-vinyl acetate-glycidyl methacrylate copolymer (EVMG) and tailor-made double-shelled TiO2@SiO2-g-EVMG nanohybrids. The inner SiO2 shell prevents direct contact of TiO2 and the PBT matrix, while the grafted EVMG outer shell promotes a selective distribution and uniform dispersion of TiO2 in the EVMG phase only. Consequently, the impact toughness of PBT/EVMG/TiO2@SiO2-g-EVMG nanocomposites is 18 times higher than that of neat PBT. Moreover, the tensile strength and the elongation at break of the nanocomposites remain 95% and 87% respectively after 48-h accelerated UV irradiation. Meanwhile, 90% UV light can be shielded by the PBT/EVMG/TiO2@SiO2-g-EVMG nanocomposites. Therefore, this work provides a facile route to make PBT nanocomposites with superior mechanical and UV resistant performances, which may broaden the application range of (recycled) PBT and e.g. PBT/Polycarbonate blends.

Influence of nano-Sb2O3 particles on mechanical properties of PBT flame retardant composites

In order to improve the comprehensive properties of PBT flame retardant composites. Nano-Sb2O3/BPS/PBT composites were prepared by a melt blending method. Mechanical properties of neat PBT and its composites were analyzed by XRD, DSC, SEM, tensile and impact test. The results showed that nano-Sb2O3 particles played the role of nucleating agent and induced formation of nucleation. With the addition of nano-Sb2O3 particles, tensile and impact properties of PBT composites increased at first and then decreased. When nano-Sb2O3 content was 1.5 wt%, mechanical properties of composites were optimal. The soft agglomeration occurred and mechanical properties tended to decline when nano-Sb2O3 content exceeded 1.5 wt%. Fracture mechanism was further analyzed by tensile and impact fracture morphology.

Bimodal Crystallization Kinetics of PBT/PTHF Segmented Block Copolymers: Impact of the Chain Rigidity

By combining linear rheology and differential scanning calorimetry experiments performed under isothermal and nonisothermal conditions, we clarify the mechanisms of crystallization occurring in three industrially relevant PBT/PTHF segmented block copolymers. After a careful and systematic analysis of the crystallization kinetics based on “classic” Avrami-like models (1 < n < 2), we reveal (and quantify) the two-step nature of the PBT segments’ association. Besides, we discuss the role of the hard (PBT) and soft (PTHF) segments’ length by confronting our results to PBT homopolymers. As expected, while 2 kg mol–1 PTHF segments are found to delay substantially the crystallization of the PBT within the copolymers, we demonstrate that shortening them down to 1 kg mol–1 results in similar kinetics as for neat PBT lamellar crystallization. This result, raising fundamental questions on the chains’ conformation, is finally discussed jointly with our rheological tests (gelation) and recent theoretical predictions w...

In Situ Network Formation in PBT Vitrimers via Processing-Induced Deprotection Chemistry.

Although the network dynamics and mechanical properties of poly(butylene terephthalate) vitrimers can to some extent be controlled via chemical and physical approaches, it remains a challenge to be able to process PBT vitrimers with the same processing conditions via, for example, injection molding as neat PBT. Here, it is shown that the use of protected pentaerythritol as a latent cross-linker and the use of a Zn(II) transesterification catalyst allows for the in situ dynamic network formation in PBT during processing, with a delayed onset of gelation. This process can be controlled by adjusting the processing temperature, (protected) cross-linker content, and the type of protection group. This solvent-free deprotection strategy opens the way to high production rates of PBT vitrimer products via injection molding with the combination of low viscosity during processing and vitrimer characteristics in the final product.

Study of Morphological and Mechanical Properties of PBT/PTT Blends and Their Nanocomposites and Their Correlation

Impact modified PBT/PTT blends based nanocomposites having organoclay content varying from 2, 3 and 5 wt% were prepared using corotating twin-screw extruder. Organoclay (Cloisite 30B) was used as nanofiller. Ultra-low-density polyethylene-grafted glycidyl methacrylate (ULDPE-g-GMA) was used as an impact modifier to toughen the polymeric matrices. In all the prepared nanocomposites, the amount of impact modifier (ULDPE-g-GMA) remains constant, i.e., 2 wt%. Izod impact testing showed that only 2 wt% impact modifier (ULDPE-g-GMA) was enough to improve the notched Izod impact strength of the neat PBT and neat PTT by 85.6 and 98.6 %, respectively. It shows an excellent toughening of PBT and PTT with ULDPE- g-GMA rubber. It was further found that the incorporation of only 3 wt% organoclay significantly improved the tensile strength, tensile modulus values of PBT/PTT blends. The result of FEG-SEM indicated that nanocomposite with 3 wt% organoclay in PBT/PTT/2wt% ULDPE-g-GMA did not show phase separation. It showed that 3 wt% organoclay was homogeneously dispersed in impact modified PBT/PTT blends based nanocomposites. POM studies revealed that the well-defined spherulites are present in neat PBT and neat PTT when $$T_{\mathrm{c}}$$ was 205 $${^{\circ }}$$ C.

Study on the Synergetic Fire-Retardant Effect of Nano-Sb₂O₃ in PBT Matrix.

Nano-Sb2O3 has excellent synergistic flame-retardant effects. It can effectively improve the comprehensive physical and mechanical properties of composites, reduce the use of flame retardants, save resources, and protect the environment. In this work, nanocomposites specimens were prepared by the melt-blending method. The thermal stability, mechanical properties, and flame retardancy of a nano-Sb2O3–brominated epoxy resin (BEO)–poly(butylene terephthalate) (PBT) composite were analyzed, using TGA and differential scanning calorimetry (DSC), coupled with EDX analysis, tensile testing, cone calorimeter tests, as well as scanning electron microscopy (SEM) and flammability tests (limiting oxygen index (LOI), UL94). SEM observations showed that the nano-Sb2O3 particles were homogeneously distributed within the PBT matrix, and the thermal stability of PBT was improved. Moreover, the degree of crystallinity and the tensile strength were improved, as a result of the superior dispersion and interfacial interactions between nano-Sb2O3 and PBT. At the same time, the limiting oxygen index and flame-retardant grade were increased as the nano-Sb2O3 content increased. The results from the cone calorimeter test showed that the peak heat release rate (PHRR), total heat release rate (THR), peak carbon dioxide production (PCO2P), and peak carbon monoxide production (PCOP) of the nanocomposites were obviously reduced, compared to those of the neat PBT matrix. Meanwhile, the SEM–energy dispersive spectrometry (EDX) analysis of the residues indicated that a higher amount of C element was left, thus the charring layer of the nanocomposites was compact. This showed that nano-Sb2O3 could promote the degradation and charring of the PBT matrix, improving thermal stability and flame retardation.

Evaluation of the role of carbon nanotubes on the electrical properties of poly(butylene terephthalate) nanocomposites for industrial applications

In this article, innovative electrically conductive polymer nanocomposites based on poly(butylene terephthalate) (PBT) filled with carbon nanotubes (CNTs) at different concentrations, to be used in the automotive field, have been investigated. Field emission scanning electron microscopy (FESEM) analysis revealed how a good nanofiller dispersion was obtained, especially by using surface treated nanotubes and by processing these materials using a more restrictive screw configuration. Melt flow index measurements highlighted that the processability of these nanocomposites was reduced at elevated filler amounts, even if CNT surface treatment promoted a partial retention of the fluidity of the neat PBT. Thermal degradation stability was improved upon the addition of CNT, even at limited filler amounts. Differential scanning calorimetry measurements evidenced how the presence of CNT slightly increased both the crystallization temperature and the crystalline fraction of the materials. The additivation of CNTs promoted a stiffening effect at elevated CNT contents, associated to an evident embrittlement of the samples. Electrical resistivity measurements showed that the most interesting results (i.e. 2.6 × 101 Ω·cm) were obtained for nanocomposites with a total filler content of 3 wt%, processed using the more restrictive screw configuration. For these materials, it was possible to obtain a rapid surface heating through Joule effect at applied voltages of 12 V.

Miscibility, Crystallization Behaviors and Toughening Mechanism of Poly(butylene terephthalate)/Thermoplastic Polyurethane Blends

Blends of poly(butylene terephthalate) (PBT)/thermoplastic polyurethane (TPU) were prepared by melt compounding. The miscibility, crystallization behaviors and toughening mechanism of the PBT/TPU blends were studied. Dynamic mechanical analysis results demonstrated that PBT was immiscible with TPU. Differential scanning calorimetry and wide angle X-ray diffraction results showed that the crystallinity of PBT decreased with increasing TPU content. Furthermore, blending with TPU did not modify the crystal structure of PBT. The small angle X-ray scattering results indicated that the crystal layer thickness decreased and the amorphous layer thickness increased with increasing TPU content, indicating that TPU mainly resided in the interlamellar region of PBT spherulites in the blends. An obvious improvement in toughness of PBT was achieved with addition of TPU. Neat PBT had elongation at break and impact strength of about 15 % and 2.9 kJ/m2, respectively. However, the elongation at break and impact strength of the 70/30 PBT/TPU blend reached 410 % and 62.9 kJ/m2, respectively. The morphology of the PBT/TPU blends after tensile and impact tests was investigated, and the corresponding toughening mechanism is discussed. It was found that the PBT showed obvious shear yielding in the blend during the tensile and impact tests, which induced dissipation of energy and, therefore, led to the improvement in toughness of the PBT/TPU blends.

Evaluation of thermal transitions in Poly (butylene terephthalate)/15A MMT nanocomposites: Nonisothermal experiments and modelling using isoconversional methods

Friedman’s differential isoconversional approach is applied to obtain effective activation energy (Eα) for Poly (butylene terephthalate) and PBT/15AMMT nanocomposites. The presence of 15AMMT content has largely affected Eα values. Further Vyazovkin and Sbirrazzuoli’s approach is used to determine Hoffman-Lauritzen parameters (Kg &U*). The crystallization regime transition (II–III) occurs for neat PBT at 189 °C and its nanocomposites is at 189–192 °C. Kg(III)/Kg(II) ratios are closer to theoretical value of 2. However the corresponding value of U* is inappropriately too low with negative sign (Correlation coefficient R2 = 0.9–0.99) and which is however highly anomalous when compared to other polymers. Setting U* to 6300 J/mol, 4300 J/mol and 0 J/mol, resulted in poor Kg(III)/Kg(II) ratios and R2. This imply that there is a considerable chain mobility during regime II crystallization which is explained in terms of rapid extraction of PBT chain segments by the force of crystallization, following the tube-reptation postulate.

Fiber and film developments from immiscible blends of cellulose acetate propionate and poly(butylene terephthalate)

ABSTRACTBinary blends of cellulose acetate propionate (CAP) and poly(butylene terephthalate) (PBT) in the composition range of 5–15 wt % for CAP were prepared in the form of films and fibers by compression molding and spinning, respectively. The presence of two invariant glass‐transition temperatures corresponding to the CAP and PBT components and viscosities lower than those of the neat PBT of the CAP–PBT blends implied that the CAP–PBT blends were immiscible. Moreover, the crystallinity of the PBT component was higher in the spun fibers than in the films; this was possibly due to the different cooling methods or the chain orientation in the spinning process. In the meantime, the CAP component could not undergo crystallization because of its rigid structure and alkyl substituents. For the CAP–PBT films, the amorphous CAP was present as dispersed particles in the PBT matrix; but it became rods in the spun fibers. In addition, the presence of the amorphous CAP resulted in a decrease in the tensile strength and an increase in the elongation at break for the CAP–PBT fibers. The CAP–PBT films and fibers could be applied in a wide range of applications requiring renewable properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45013.

Characterization of clay filled poly (butylene terephthalate) nanocomposites prepared by solution blending

Kaolin clay/poly (butylene terephthalate) (clay/PBT) composites films were prepared by solution casting technique. The scanning electron microscope (SEM) study showed that clay particles were well dispersed and embedded within the PBT matrix. The TGA thermograms showed that the thermal stability of PBT matrix was slightly improved by the incorporation of clay into the polymer matrix. The polarized optical microscopy (POM) study presented that the size of spherulites of PBT was decreased by the incorporation of clay into matrix, which might be due to nucleation effect of kaolin clay. The tensile strength and modulii of PBT polymer matrix were also significantly improved by the addition of clay polymer matrix. The solvent uptake study showed that the uptake of various solvents by clay/PBT nanocomposite were lower than neat PBT.

Fabrication and characterization of thermally conductive composites based on poly(butylene terephthalate)/glass fiber-silicon carbide

Abstract A new method is reported for preparing poly(butylene terephthalate) (PBT)/glass fiber (GF)-silicon carbide (SiC) composites. GFs were coated with SiC particles firstly and then the treated GFs (GF-SiC) were mixed with PBT. Scanning electron microscopy (SEM) images showed that some SiC particles dispersed on the surfaces of GFs, and other particles fell off from surfaces of GFs and dispersed around GFs after processing. The thermal conductivities of composites are increased with increase of GF-SiC. At 30 wt% GF-SiC, the thermal conductivity of composites reached 0.6392 W/mK, which improved nearly 160% compared to that of neat polymer. Differential scanning calorimetry (DSC) results indicated that GF-SiC increased crystallinity of PBT compared with that of neat PBT and had no obvious influence on the melting temperature of PBT. The crystallization temperature (Tc) and glass transition temperature of all samples shifted to a higher temperature. The addition of GF-SiC can improve the thermal stability of PBT/GF-SiC composites obviously. Dynamic mechanical properties and dielectric properties were also discussed in this paper.

Facile preparation of modified carbon nanotube‐reinforced PBT nanocomposites with enhanced thermal, flame retardancy, and mechanical properties

In this study, the carbon nanotube was modified by inorganic acids to introduce the carboxylic acid groups on the surface. The modified carbon nanotube (m‐CNT)‐reinforced poly(1,4‐butylene terephthalate) (PBT) nanocomposites were prepared through melt blending method. Morphological observations revealed that the m‐CNT particles were homogeneously dispersed in PBT matrix. Differential scanning calorimeter (DSC) analysis showed that a very small quantity of m‐CNT can significantly increase the crystallization temperature of PBT. The improvement of thermal stability and tensile strength/modulus of the nanocomposites strongly depended on the uniform dispersion of m‐CNT and the interactions between m‐CNT and PBT through hydrogen‐bonding formation. In the cone calorimeter testing, the PHRR decreased from 1189 kW/m2 for neat PBT to 737 kW/m2 for PBT/0.9m‐CNT containing 0.9 wt% m‐CNT with a reduction of 38%. The remarkable enhancement of flame retardancy properties was attributed to the condensed‐phase effect acted by the m‐CNT. POLYM. COMPOS., 37:1812–1820, 2016. © 2014 Society of Plastics Engineers

The effect of electron-beam irradiation and halogen-free flame retardants on properties of poly butylene terephthalate

Abstract Engineering plastics like Poly (butylene terephthalate) due to their desirable properties have various industrial applications. Neat PBT is highly combustible, so it is necessary to improve significantly its fire retardancy to meet the fire safety requirements. The combustion performance of PBT can be improved by addition of appropriate flame retardant additives. In this study we have investigated the effect of halogen free flame retardants, i.e. melamine and aluminum phosphate, and instantaneously electron beam radiation-induced crosslinking in the presence of Triallyl cyanurate on various properties of PBT. The results of gel content showed that a dose range of 200–400 kGy leads to high cross linked structure in this polymer. Also mechanical experiments showed that its structure became rigid and fragile due to irradiation. Radiation crosslinking of this polymer made its dielectric loss coefficient ten times lower than non-irradiated polymer, but had no effect on its dielectric constant. Moreover the addition of the fire retardant additives as impurity decreased the dielectric loss coefficient. TGA analysis in nitrogen exhibited that irradiation increases char formation and use of the fire retardant additives leads to reduction of onset temperature and formation of higher char quantity than pure PBT. According to the results of UL-94, irradiated samples burned with lower speed and less dripping in vertical and horizontal positions than pure polymer. Finally irradiation of the polymers containing fire retardant additives with a dose of 400 kGy led to self-extinguishing and non-dripping and reach to V-0 level in the UL-94 V.

Nonisothermal crystallization kinetics of poly(butylene terephthalate)/multiwalled carbon nanotubes nanocomposites prepared by in situ polymerization

ABSTRACTPoly(butylene terephthalate)/multiwalled carbon nanotubes (PBT/MWNT) nanocomposites were prepared by in situ ring‐opening polymerization of cyclic butylene terephthalate oligomers (CBT). The nonisothermal crystallization behavior of the neat PBT and the PBT/MWNT nanocomposites was analyzed quantitatively. The results reveal that the combined Avrami/Ozawa equation exhibits great advantages in describing the nonisothermal crystallization of PBT and its nanocomposites. The presence of MWNTs has the nucleation effect promoting crystallization rate for the nanocomposites, and the maximum one is observed in the nanocomposite having 0.75 wt % MWNT content. On the other hand, the addition of MWNTs has the impeding effect reducing the chain mobility and retarding crystallization, which is confirmed by the crystallization activation energies. However, the nucleation effect of MWNTs plays the dominant role in the crystallization of PBT/MWNT nanocomposites, in other words, the incorporation of MWNTs is increasing the crystallization rate of the nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40849.

Efeito da modificação de superfície de fibras nas propriedades mecânicas de compósitos a base de poli( tereftalato de butileno) reforçado por fibras naturais inorgânicas

O presente trabalho visa investigar a viabilidade de utilizacao de fibras naturais de silica amorfa (FNSA) como agente de reforco em polimeros de engenharia, assim como avaliar o seu potencial como alternativa as fibras de vidro curtas em aplicacoes industriais. Diferentes modificacoes na quimica de superficie dessas fibras foram avaliadas buscando melhorar a adesao na interface entre fibras e matriz, e consequentemente, melhorar as propriedades mecânicas do composito. As modificacoes superficiais das FNSA foram realizadas atraves de agentes de acoplamento do tipo silano, providos com funcoes orgânicas distintas. O PBT foi selecionado como matriz devido a sua conhecida facilidade de processamento, mesmo apos a incorporacao de grandes quantidades de aditivos. A modificacao das FNSA foi avaliada a partir da analise termogravimetrica acoplada a espectroscopia no infravermelho com transformada de Fourier. A resistencia mecânica e fratura dos compositos foi investigada por ensaios de tracao e microscopia eletronica de varredura. Finalmente, obtiveram-se compositos com fibras modificadas com resistencia a tracao 40% superior ao material base puro.

Isothermal crystallization behavior of PAR/PBT composite prepared by island-in-a-sea fiber method

The PAR fiber reinforced PBT composite was manufactured using the PAR/PBT island-in-a-sea fiber. The isothermal crystallization kinetics of the PAR/PBT composite and the neat PBT resin were investigated in the temperature range of 187–199 °C. To calculate the Avrami parameters for analyzing the crystallization behavior, crystallization peaks were measured and analyzed in terms of the crystallization temperature and the inclusion of the PAR fiber. The crystallization rate of the PBT is faster than that of the PAR/PBT composite from the analysis of their relative crystallinity. Consequently, it is considered that the PAR fiber interrupted the crystal nucleation and growth of the PBT matrix. It can be confirmed with the crystallization half time and the crystalline morphologies at the chosen isothermal temperatures.

Preparation and properties of single-walled carbon nanotubes/poly(butylene terephthalate) nanocomposites

A neat poly(butylene terephthalate) (PBT) polymer and functionalized single-walled carbon nanotubes (F-SWNTs)/PBT nanocomposite films were prepared by solution casting technique. The SWNTs were functionalized by acid treatment, which introduced carboxylic groups onto the SWNTs. The morphological studies showed that the F-SWNTs were embedded and dispersed well within the PBT polymer matrix. The POM study illustrated that a neat PBT showed Maltese-type spherulites. It was also observed that the size of neat PBT spherulites was larger than F-SWNTs/PBT nanocomposite spherulites, which might be due to the nucleation effect of F-SWNTs in the case of nanocomposites. The thermal stabilities and mechanical properties such as stress yield and moduli of F-SWNTs/PBT nanocomposites were enhanced as compared to neat PBT. The DSC study showed that the melting temperature (T m) of PBT was slightly increased by addition of F-SWNTs. This increase in T m might be due to the formation of compact structure, which was formed through different types of molecular interactions with addition of F-SWNTs. It was also found that initially the solvent (distilled water, kerosene, 2 M HNO3 solution) uptake by neat PBT polymer and its nanocomposites increased gradually, which became steady after specific intervals for each sample. The results also exhibited that the solvent uptake of F-SWNTs/PBT nanocomposites was less than neat PBT.

The effect of extrusion conditions and the use of a compatibilizer in the crystallization of PBT/ABS blends

Poly(butylene terephthalate) (PBT)/ acrylonitrile-butadiene-styrene (ABS) terpolymer blends were prepared in a twin screw extruder and the use of methyl methacrylate-glycidyl methacrylate-ethyl acrylate (MGE) terpolymer as compatibilization additive was evaluated. The effect of different screw profiles and mixing conditions were evaluated on the crystallization of the blends. Differential scanning calorimetry (DSC) was used to evaluate melting and crystallization behaviors of the PBT/ABS blends. The binary PBT/ABS blend has shown a double melting peak when cooled at lower cooling rates, mainly due to its melt-recrystallization during the heating up step. ABS has not affected the melting characteristics of neat PBT. The presence of MGE, as a reactive compatibilizer, in the PBT/ABS blends has reduced its heat of fusion and has partially inhibited its melt-recrystallization under heating. As result, it has prevented the occurrence of double melting peak. The epoxy functional groups of the MGE may react in situ to the carbonyls and hydroxyls end groups of the PBT molecules, thereby hindering the mobility of PBT molecules during the crystallization process due to its grafting to the compatibilizer molecules. The melt mixed blends prepared at lower feeding rate have shown a higher degree of crystallinity for the PBT/ABS blend, probably due to degradation of PBT caused by longer residence time in the extruder. The highest shear stress imposed to the blends at higher screw speed increased the degree of crystallinity of PBT, also due to its degradation.