Cyclic Butylene Terephthalate Research Articles

A General and Efficient Approach for the Dual-Scale Infiltration Flow Balancing in In Situ Injection Molding of Continuous Fiber Reinforced Thermoplastic Composites.

In situ injection molding of continuous fiber reinforced thermoplastic composites is challenged by unbalanced dual-scale infiltration flow due to the pronounced capillary effect. In this paper, a general and efficient approach was proposed for dual-scale infiltration flow balancing based on numerical simulation. Specifically, Stokes and Brinkman equations were used to describe the infiltration flow in inter- and intra-fiber bundles. In particular, capillary pressure drop was integrated in the Brinkmann equation to consider the capillary effect. The infiltration flow front is tracked by the level set method. Numerical simulation and experimental results indicate that the numerical model can accurately demonstrate the unbalanced infiltration flow in inter- and intra-fiber bundles caused by the changes of the injection rate, the resin viscosity, the injection rate, the fiber volume fraction and the capillary number. In addition, the infiltration flow velocity in inter- and intra-fiber bundles can be efficiently tuned by the capillary number, which is mainly determined by the injection rate for a specified resin system. The optimal capillary numbers obtained by simulation and experiment are 0.022 and 0.026, which are very close to each other. Finally, one-dimensional in situ injection molding experiments with constant injection pressure were conducted to prepare fiber reinforced polymerized cyclic butylene terephthalate composite laminate with various flow rates along the infiltration direction. The experimental results confirmed that the lowest porosity and the highest interlaminar shear strength of the composite can only be obtained with the optimized capillary number, which is basically consistent with the simulation results.

Study on Copolymer from Cyclic Butylene Terephthalate and Polycaprolactone by In-Situ Polymerization

Study on Copolymer from Cyclic Butylene Terephthalate and Polycaprolactone by In-Situ Polymerization

An Innovative Approach for Restoring the Mechanical Properties of Thermoplastic-Matrix Nanocomposite by the Use of Partially Polymerized Cyclic Butylene Terephthalate

This work is focused on the production of a smart material from cyclic butylene-terephthalate (CBT), characterized by the built-in capability to recover its damage, through the catalyzed ring opening polymerization (ROP) of its oligomers; in particular, molten CBT, after filling the damaged zone, can be converted into poly-butylene terephthalate (PBT), thus promoting a join of the broken surfaces and fixing the crack. To obtain a material with self-healing potential, the production of a partially polymerized system is required. For this purpose, two solutions were studied: the first one involved the use of two catalysts with different activation times, whereas the second solution implied the intercalation of the faster catalyst inside the nanoclay lamellae. Since the intercalation allowed slowing the activation of the catalyst, residual CBT can be converted in a second step. Mechanical properties of partially reacted PBT samples and their healing ability were checked by flexural analyses; in order to promote the healing process, samples were notched to simulate partial damage and left in oven for different times and temperatures, to allow the activation of the unreacted catalyst with the consequent ROP of the residual CBT; flexural tests on samples after healing showed a good recovery of mechanical properties.

Temperature effect on the mechanical properties of GF/pCBT and its nanosilica-modified composites

Glass fiber/polymerized cyclic butylene terephthalate (GF/pCBT) and its nanosilica-modified thermoplastic composites were manufactured via vacuum-assisted molding pressing process. Subsequently, the effects of temperature and nanosilica fillers on the macroscopic mechanical behavior of glass fiber-reinforced pCBT composites were discussed. Failure morphologies of specimens were observed by scanning electron microscopy (SEM). Experimental results show that pure GF/pCBT composites have good mechanical properties, whereas their half-strength degradation temperature ( TS = 0.5) is relatively lower. It is also found that nanosilica-modified composites have higher heat resistance performance, and TS = 0.5 point of the modified composites enhanced by 10°C. SEM observations show that the smooth fracture surface in the broken composites appears at higher temperatures, which indicates that the toughness of nanosilica-modified GF/pCBT composites is improved.

Enhanced electrical and electromagnetic interference shielding properties of uniformly dispersed carbon nanotubes filled composite films via solvent-free process using ring-opening polymerization of cyclic butylene terephthalate

In order to develop a nanocomposite film based on multi-walled carbon nanotubes (MWCNTs) as an electromagnetic wave shielding material, we propose a solvent-free melting process for fabricating highly dispersed MWCNT-filled polymer composite films with high electrical conductivity and electromagnetic interference (EMI)-shielding properties. By observing aggregates (particles larger than 0.7 μm) using X-ray micro-computed tomography (micro-CT), the uniform dispersion of the MWCNT fillers in the composite films was confirmed. Furthermore, the electrical conductivity and EMI shielding effectiveness (SE) values calculated using percolation and Simon's equations, respectively, were confirmed to agree with experimental data, indicating excellent MWCNT dispersion. The fabricated composites exhibited excellent electrical conductivity, EMI SE, and EMI specific SE (SSE) values of 4.33 S/cm, 30 dB, and of 24.8 dBcm3g−1, respectively, and the EMI SSE value was as good as metal levels. The proposed solvent-free process can be contributed to the commercialization of EMI SE composite films based on MWCNTs.

Swarm intelligence integrated micromechanical model to investigate thermal conductivity of multi-walled carbon nanotube-embedded cyclic butylene terephthalate thermoplastic nanocomposites

With the recent demand for miniaturization and integration of electronic devices, there has been a growing interest in device malfunction due to high temperature. In this study, a experimental and theoretical study on the composites with improved thermal conductivity by dispersing multi-walled carbon nanotubes (MWCNTs) in the thermoplastic resin was carried out. A micromechanical model was derived based on the ensemble volume-averaging method and the modified Eshelby’s tensor reflecting the interface properties. The effects of the waviness, interface, and orientation of fillers on the thermal conductivity of composites were numerically analyzed. A computational intelligence-based particle swarm optimization (PSO) algorithm was adopted to the proposed model for optimizing the model constants. The thermal conductivity of the polymerized cyclic butylene terephthalate (pCBT)/MWCNT composites was experimentally measured according to the content of MWCNT. Finally, the experimentally measured data were utilized in the PSO to improve the predictive capability of the proposed model.

Fabrication of Piezoelectric Composites Using High-Temperature Dielectrophoresis

In this paper, we present a method to create a highly sensitive piezoelectric quasi 1–3 composite using a thermoplastic material filled with a piezoelectric powder. An up-scalable high-temperature dielectrophoresis (DEP) process is used to manufacture the quasi 1–3 piezoelectric polymer-ceramic composites. For this work, thermoplastic cyclic butylene terephthalate (CBT) is used as a polymer matrix and PZT (lead zirconium titanate) ceramic powder is chosen as the piezoelectric active filler material. At high temperatures, the polymer is melted to provide a liquid medium to align the piezoelectric particles using the DEP process inside the molten matrix. The resulting distribution of aligned particles is frozen upon cooling the composite down to room temperature in as little as 10 min. A maximum piezoelectric voltage sensitivity (g33) value of 54 ± 4 mV·m/N is reported for the composite with 10 vol% PZT, which is twice the value calculated for PZT based ceramics.

The Preparation of Cyclic Butylene Terephthalate Fibers with Novel Morphology Based on Melt Electrospinning.

Electrospinning of low molecular weight compounds is relatively under-investigated compared to that of polymers. In this paper, cyclic butylene terephthalate oligomers (CBT) were fabricated into a novel fiber structure without any carrier polymer or template via melt electrospinning technique. The electrospun CBT fibers were prepared at 190 °C and characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). SEM images of the CBT fibers showed that they had a mean diameter of 1.8-2.6 μm. In contrast to most electrospun fibers, the CBT electrospun fibers were discontinuous and exhibited a rod-like morphology with an average length of 6.8-7.1 μm. This kind of morphology is rare in products made by electrospinning or electrospraying. In addition, the fiber morphology was not significantly affected by varying the preparation parameters, such as by collection distance or electric voltage value. FTIR and DSC results showed that CBT structure was not changed in the preparation process, but the degree of polymerization of CBT may be changed because of transesterification reaction. Furthermore, the formation mechanism of the discontinuous fibers was also discussed in this work.

Application of supercritical water for green recycling of epoxy-based carbon fiber reinforced plastic

The objective of this study is to fabricate conductive carbon fiber composites with thermal and electrical properties by degradation carbon-fiber-reinforced plastics (CFRPs) and recycled carbon fibers using only supercritical water without any catalyst or oxidant. We focused on a recycling method that is harmless to the human body and environment-friendly, by using supercritical fluid water rather than recycling CFRP by physical or pyrolysis methods. In particular, we recycled carbon fibers (R-CFs) in which up to 99.5% of epoxy resin was removed, by optimizing the conditions of supercritical fluid water (SCF-W) treatment, and we fabricated conductive R-CFs composites with thermal and electrical properties by combining the R-CFs with cyclic butylene terephthalate (CBT), which is a polymerizable low-viscosity thermoplastic resin. The fabricated composites had a thermal conductivity of 1.35 ± 0.05 (W/mK) and an electrical conductivity of 11.23 × 10−6 (S/cm) when the added amount of recycled carbon fibers was 5 wt%.

Hybrid multi-scale thermoplastic composites reinforced with interleaved nanofiber mats using in-situ polymerization of cyclic butylene terephthalate

Abstract Mechanically flexible electrospun carbon and glass nanofiber mats (i.e., ECNF-mats and EGNF-mats) were prepared by electrospinning followed by thermal treatments; subsequently, a technique was applied to fabricate two types of multi-scale thermoplastic composites, involving infiltration of molten cyclic butylene terephthalate (CBT) followed by in-situ polymerization under compression. For the first composite type, eight conventional carbon fabrics were interleaved with seven ECNF-mats. For the second composite type, eight conventional glass fabrics were interleaved with seven EGNF-mats. Compared to the values acquired from the corresponding control samples without nanofiber mats, the interlaminar shear strength, flexural strength, flexural modulus, and work of fracture acquired from the hybrid multi-scale composite containing ECNF-mats were increased by 32%, 25%, 19%, and 33%, respectively; while the values acquired from the hybrid multi-scale composite containing EGNF-mats were increased by 66%, 43%, 17%, and 64%, respectively. Furthermore, the enhancements of out-of-plane properties were not at the expense of in-plane tensile strength or modulus. The study indicated that the employed fabrication technique could be adopted as an efficient approach to produce polybutylene terephthalate (PBT) thermoplastic composites through in-situ polymerization of CBT oligomer; and the ECNF-mats and EGNF-mats could be utilized as innovative reinforcement fillers for enhancing the performance of structural thermoplastic composites.

Electrically and Thermally Conductive Carbon Fibre Fabric Reinforced Polymer Composites Based on Nanocarbons and an In-situ Polymerizable Cyclic Oligoester

There is growing interest in carbon fibre fabric reinforced polymer (CFRP) composites based on a thermoplastic matrix, which is easy to rapidly produce, repair or recycle. To expand the applications of thermoplastic CFRP composites, we propose a process for fabricating conductive CFRP composites with improved electrical and thermal conductivities using an in-situ polymerizable and thermoplastic cyclic butylene terephthalate oligomer matrix, which can induce good impregnation of carbon fibres and a high dispersion of nanocarbon fillers. Under optimal processing conditions, the surface resistivity below the order of 10+10 Ω/sq, which can enable electrostatic powder painting application for automotive outer panels, can be induced with a low nanofiller content of 1 wt%. Furthermore, CFRP composites containing 20 wt% graphene nanoplatelets (GNPs) were found to exhibit an excellent thermal conductivity of 13.7 W/m·K. Incorporating multi-walled carbon nanotubes into CFRP composites is more advantageous for improving electrical conductivity, whereas incorporating GNPs is more beneficial for enhancing thermal conductivity. It is possible to fabricate the developed thermoplastic CFRP composites within 2 min. The proposed composites have sufficient potential for use in automotive outer panels, engine blocks and other mechanical components that require conductive characteristics.

NUEVAS MEZCLAS CON BASE EN POLIPROPILENO DE BAJA VISCOSIDAD EN FUNDIDO OBTENIDAS MEDIANTE LA ADICIÓN DE CICLOBUTILENTEREFTALATO

In this work, polymeric blends based on polypropylene (PP) combined with cyclic butylene terephthalate (CBT) and maleic anhydride grafted polypropylene (PP-g-AM) have been prepared and studied for applications in thermoplastic composites and as multimaterial composites for automotive industry. The principal aim has been to reduce the melt viscosity of thermoplastic matrixes to values similar to thermosetting ones in order to be able to use more economic equipment for the thermoplastic composites development.. For that purpose, different polymeric blends of CBT/PP have been prepared, and the effect of the addition of a PP-g-AM compatibilizer in the fibrillar morphology and in the rheological behavior of the compounds has been analyzed. For compatibilized blends, apart from a substantial reduction of the size of CBT, a thixotropic behavior has been observed, with a marked reduction of the viscosity at the beginning of the shear test followed by a slight restoration at the conclusion of the shear stress. Stationary values as low as 20000 mPa.s have been registered which corresponds with a reduction greater than 90% from PP viscosity. Keywords: Polymer blending, thermoplastic composites, compatibilizer , fibrillar morphology, viscosity, thixotropic.

Improvement of adhesive bonding of polypropylene and maleic anhydride grafted polypropylene blends to aluminium by means of addition of cyclic butylene terephthalate

ABSTRACTIn this work the adhesive bonding of polymeric blends based on polypropylene (PP), cyclic butylene terephthalate (CBT) and maleic anhydride grafted polypropylene (PP-g-MA) to aluminium was studied, with the aim of developing metal/polymer hybrid laminates for a multitude of applications among which the automotive and aeronautic sectors stand out. Different films with homogeneous compositions have been prepared and joined to aluminium (with any previous surface treatment) and the adhesive bonding has been characterized under the standard UNE-EN 1465. For binary blends, there is a critical PP-g-MA and CBT composition from which the shear strength declines. The combined presence of the PP-g-MA and CBT in the blend prevents this critical composition due to the possible Van der Waals forces and/or esterification/transesterification reactions created between the reactive chains. In addition, if the transformation from CBT to pCBT takes place at the same time as the joining process, the shear resistance of the laminated increases between 10% and 25%. The adhesive bonding between layers improves in two ways: the lower viscosity of the developed blends makes an easier substrate impregnation, and the active sites created during the ring opening polymerization (ROP) are capable of forming chemical bonds.

Thermal analysis of self-healing thermoplastic matrix nanocomposite from cyclic butylene terephthalate

This work is aimed to the development of a self-healing thermoplastic matrix nanocomposite, obtained through the ring-opening polymerization of cyclic butylene terephthalate (CBT) to polybutylene terephthalate (pCBT); a partial polymerization allows obtaining a mixture of CBT and pCBT, being the two materials characterized by a difference in the melting temperature of about 80 °C. Healing of the material requires heating to a temperature higher than melting of CBT, but lower than melting of pCBT; therefore, the molten CBT is able to weld the surfaces of the growing crack, thus restoring mechanical properties. The presence of solid pCBT allows retaining the geometry of the material. In order to produce a partially polymerized material, two different systems were studied: a first one with two catalysts, with different activation temperatures, and a second one with one single catalyst partially intercalated in nanoclay layers. Rheological analysis was used in order to study the viscosity evolution associated with the conversion of CBT to pCBT during thermal treatment. Differential scanning calorimetry (DSC) was used in order to measure the amount of unreacted CBT after processing, and to verify the further conversion of CBT to pCBT during healing. Also, DSC analysis highlighted the structural changes of pCBT crystallinity during healing. Flexural tests were performed on partially reacted pCBT samples, highlighting the relevant effect of the addition of nanoclay on the mechanical properties of the material. Adhesion tests performed after healing evidenced the efficacy of the proposed approach for development of self-healing thermoplastic polymers.

A Practical Synthesis of the Cyclic Butylene Terephthalate Trimer

A Practical Synthesis of the Cyclic Butylene Terephthalate Trimer

Effect of Cyclic Butylene Terephthalate Oligomer on the Properties of Styrene-Butadiene and Acrylonitrile-Butadiene Rubbers

In this work the effect of cyclic butylene terephthalate (CBT) was studied on the curing, rheological, morphological and mechanical properties of styrene butadiene rubber (SBR), oil extended styrene butadiene rubber (oSBR), acrylonitrile butadiene rubbers (NBR) with various acrylonitrile (AN) content and a carboxylated acrylonitrile butadiene rubber (XNBR). The effect of CBT on the oil resistance of the NBR and XNBR based compounds was also investigated. Viscosities of the uncured compounds were significantly decreased by CBT and it also acted as a semi-active filler, effectively reinforcing the tested rubbers, therefore it is suggested to be a bifunctional additive for tested rubbers. CBT also showed to have a positive effect on the oil resistance of NBR compounds.

Cyclic oligoesters as potential materials for polymer nanocomposite production

Publications dedicated to cyclic oligoesters based on cyclic butylene terephthalate were analyzed and summarized. The features of their preparation and structure and their properties were considered with a special focus on advantages and disadvantages of the methods of their preparation: polycondensation at high dilution and depolymerization. The prospects of application of cyclic butylene terephthalate for polymer nanocomposite production were demonstrated. A development strategy for this research area was suggested.

CYCLIC BUTYLENE TEREPHTHALATE AND PROMISING FIELD OF APPLICATION

Due to its unique characteristics, cyclic butylene terephthalate is used in novel developments of chemical industry. This article represents the review of the latest achievements in the field of processing, structure, properties of cyclic butylene terephthalate, its physical and chemical modifications as well as composites and nanocomposites based on it. In recent years, cyclic butylene terephthalate oligomers have drawn the attention of scientists. The oligomers can be acquired through the chemical reaction of cyclo-depolymerization and used as materials for ring-opening polymerization reactions. This method of polymerization has a variety of advantages compared to a standard method of synthesis polyesters. One of the main advantages of this method includes the capability to make polymerization reactions at standard atmospheric pressure, low required temperature, no side effects and obtaining a completely finished product as an outcome. The unique qualities of cyclic butylene terephthalate make it a promising material to be used as matrix for a variety of nano- and microcomposites and super concentrate. This study analyzes some of the examples of applying CBT as a super concentrate for creating materials like carbon nanotubes, laminated silicates, carbon fibers and glass fibers. In the majority of studies, the addition of nano-sized fillers into CBT leads to amplification of mechanical properties. In the cases of usage as fillers for carbon fibers and glass fibers, the possibility of replacing thermosetting resins with CBT is currently being researched. It could possibly lead to increase in manufacturability of carbon fibers and fiberglass and increase its possible area of application. Cyclic butylene terephthalate can also be used as a viscosity modifier for synthetic rubbers. In this case it can be both plasticizer and enhancing agent.For citation:Chukov N.A., Mikitaev M.A., Ligidov M.Kh., Bashorov M.T., Shogenov V.N., Pakhomov S.I. Cyclic butylene terephthalate and promising field of application. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 4-13.

Mechanical and optical properties of electrospun nylon-6,6 nanofiber reinforced cyclic butylene terephthalate composites

Abstract In this study, electrospun Nylon-6,6 nanofiber (Nylon-6,6 NFs) reinforced cyclic butylene terephthalate (CBT) composites were prepared by electrospinning process followed by hot press method and compared with the pristine Nylon-6,6 nanofiber in terms of tensile properties and light transparency. The formation of hydrogen bonds between CBT and nylon-6,6 molecules results enhancement of the mechanical property of the composite. Further, the high optical transmittance of the composite was achieved.

Properties of polymerized cyclic butylene terephthalate and its composites via ring-opening polymerization

Continuous glass fiber (GF)-reinforced polymerized cyclic butylene terephthalate (pCBT) composites were prepared via vacuum-assisted resin transfer molding using butyltin tris(2-ethylhexanoate) as the catalyst. The relationship between melt viscosity and polymerization time was examined in the ring-opening polymerization of CBT resin. The effects of polymerization conditions such as catalyst content and polymerization temperature on viscosity average molar mass ( Mv), crystallization, mechanical properties, and microstructure of GF/pCBT composites were also investigated in detail. It is found that both high molecular weight and high degree of crystallinity of resin matrix can lead to high mechanical properties of composites. The composites prepared with 0.5% catalyst at 190°C show the best mechanical properties with tensile strength of 549 MPa, flexural strength of 585.2 MPa, and interlaminar shear strength of 47.1 MPa. The scanning electron microscopy analysis also demonstrates that good interfacial adhesion exists between fiber and resin, which agrees very well with experimental results.