Polymer International最新文献

Poly[(butylene adipate)-co-terephthalate] (PBAT) is currently the most widely used and versatile petroleum-based fully biodegradable polyester, drawing extensive attention from researchers. However, the high production cost of PBAT restricts its widespread application. Currently, incorporating fillers into PBAT materials is considered the most effective approach to reduce production costs, with thermoplastic starch recognized as the optimal filler for PBAT base materials. Nevertheless, the low mechanical strength of thermoplastic starch significantly compromises the performance of PBAT base materials. In this study, thermoplastic starch with higher mechanical strength was prepared by partially substituting commonly used glycerol with a higher molecular weight sorbitol as the plasticizer. The enhanced thermoplastic starch was then used as a filler for PBAT materials, leading to the fabrication of PBAT-based blend films with high starch content. Mechanical property tests revealed a 52.2% and 65.3% increase of tensile strength in the transverse and longitudinal directions, respectively, when sorbitol partially replaced glycerol as the plasticizer for thermoplastic starch. Scanning electron microscopy results demonstrated improved dispersion of thermoplastic starch particles in PBAT when sorbitol and glycerol were used together. Meanwhile, the thermal performance and stability of PBAT were not significantly affected by the thermoplastic starch filling. © 2024 Society of Chemical Industry.

This study explored the impact of hot press parameters on lead zirconate titanate (PZT)/poly(vinylidene fluoride) (PVDF) composite films designed for force-sensing applications. The systematic fraction (PZT/PVDF), pressure, temperature, and time during hot pressing processes are subject to variation. The focus is on the resulting composite film thickness and its subsequent influence on the piezoelectric properties, which are essential for the performance of force sensors. The present study investigated the characteristics and performance of PZT/PVDF composite films with fraction ratios 2/5, 5/5, and 7/3 and hot pressure of 10, 40, and 60 MPa and temperature at 150 °C for 2 h. The characterization of these films was conducted using X-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. The piezoelectric properties (d₃₃ and d₃₁) were measured using impact and extraction tests to evaluate the performance of films with applied forces. The results show that the highest piezoelectric coefficients (d₃₃ and d₃₁) were determined to be 35.8 and 12.60 pC N⁻¹, with fraction ratios of 7/3 and 2/5. The study revealed a positive correlation between the PZT/PVDF ratio and sensitivity, indicating that an increase in the ratio leads to an increase in sensitivity. Conversely, a negative relationship was observed between the impact load and the sensor sensitivity, suggesting that an increase in the impact load results in a sensitivity decrease. The results of this work demonstrate the great potential of piezoelectric PZT/PVDF composite films in force sensors for small load applications. © 2024 Society of Chemical Industry.

In this study, onium-ion-added nanoclay (NC)/microcellular polypropylene (PP) composites were created using a conventional injection molding machine. A chemical foaming agent was utilized to facilitate mixing. The primary focus was to analyze how altering the NC content affects the mechanical characteristics and the properties of the endothermic chemical foaming agent added PP/NC composites. The composites were created using a chemical foaming agent at a weight ratio of 1 wt% and NC at weight ratios of 0 wt%, 2.5 wt% and 5 wt%. The findings indicated that an increase in the NC ratio led to higher cell count and cell density, along with a reduction in cell diameter. Additionally, the outcomes demonstrated that the foaming of PP/NC composites resulted in decreased modulus of elasticity and tensile strength while enhancing impact strength. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Soft actuators belong to a type of actuators made of soft materials which are capable of converting applied energy to mechanical motion. They have been utilized in several fields due to their flexibility, low weight, inexpensiveness and simple fabrication. In this work, iota-carrageenan (𝑖C) was chosen as the starting material for a hydrogel-based actuator. The 𝑖C hydrogels were fabricated via a simple solvent-casting technique at various concentrations: 2.4% (v/v), 2.8% (v/v) and 3.2% (v/v). All 𝑖C hydrogels were characterized for their chemical, thermal, rheological and morphological properties as well as the actuation performances under applied electric field. The 𝑖C hydrogels showed monotonic increases in the static bending distance and dielectrophoretic force with increasing electric field strength. Above the critical electrical field strengths, the ribbon-like 𝑖C hydrogels oscillated back and forth due to the competition between the dielectrophoresis force, the resisting elastic force, the weight and the inertia force. Stability diagrams were constructed for the first time separating static bending from oscillation behavior under constant applied electric fields. © 2024 Society of Chemical Industry.

Although epoxy resin (EP) has been widely used in many fields, it is still urgent to effectively improve its flame retardancy by halogen-free strategies. Herein, a silicon-containing cyclotriphosphazene derivative (HEP-Si) was synthesized by nucleophilic substitution and silicon–hydrogen addition reaction using eugenol, hexachlorophosphazene and triethylsilane as raw materials. Then it served as a halogen-free flame retardant for an EP/4,4′-diaminodiphenylmethane system, and its performance was compared with that of commercial flame retardant hexaphenoxycyclotriphosphazene (HPP). The results showed that although the initial thermal decomposition temperature (T_5%) of the cured products of EP/HEP-Si was slightly lower than that of pure EP, T_5% did not decrease further as the amount of HEP-Si increased, indicating that good thermal stability was maintained. In addition, the char yield of the cured products of EP/HEP-Si was significantly increased (more than 20 wt%) compared to that of pure EP. The cured EP with the addition of HPP and HEP-Si both achieved a V-0 rating in UL-94 vertical burning test at 0.5 wt% phosphorus content, while the limiting oxygen index of the EP/HEP-Si system was higher, reaching 33.2%. From cone calorimetric test results, the peak heat release rate, total heat release and total smoke production of the cured products of EP/HEP-Si decreased by 61.5%, 37.1% and 26.2%, respectively, compared with that of pure EP. The cured EP/HEP-Si materials also exhibited good thermomechanical and mechanical properties. Therefore, HEP-Si is suggested to be a promising P/N/Si-containing halogen-free flame retardant for EP. © 2024 Society of Industrial Chemistry.

Integrating flame-retardant additives into epoxy resins is an essential strategy for improving their fire resistance. However, introducing flame-retardant groups often compromises the processability and mechanical integrity of such resins. In this research, we synthesized a novel, biobased flame retardant, referred to as DPN, using naringenin and chlorodiphenylphosphine as precursors via a straightforward single-step process. The addition of DPN markedly decreased the viscosity of hydantoin epoxy resin, from 7468 to 1285 mPa s. Furthermore, when cured with 4,4-diaminodiphenylmethane, the composite containing five equivalents of DPN (DPN-5) exhibited a marked improvement in mechanical strength, reaching 190 MPa, significantly outperforming the pure thermoset (DPN-0: 104 MPa), while preserving high transparency. Combustion tests further confirmed that DPN significantly boosts the flame resistance of the thermoset, with DPN-5 achieving a limiting oxygen index of 37% and securing a UL-94 V-0 rating. Cone calorimetry analysis showed that DPN-5 effectively reduced heat and smoke production during combustion, achieving a 13.4% reduction in peak heat release rate and a 28.2% decrease in total heat release compared to DPN-0. This study underscores the potential of multifunctional biobased flame retardants derived from renewable resources in advancing the development of high-performance materials. © 2024 Society of Industrial Chemistry.

In this study, we look into how poly[(4-styrenesulfonic acid)-co-(4-vinylpyridine)] crosslinked with divinylbenzene can be used as a copolymeric material to effectively recognize l-epinephrine (L-EP) and chirally separate (±)-EP. It was first possible to synthesize and analyze L-EP-styrene-4-sulfonamide (L-EP-SSA). The resulting chiral sulfonamide was used to copolymerize with a 4-vinylpyridine–divinylbenzene mixture. The integrated L-EP species were removed by heating the polymer materials under strong alkaline conditions to degrade the sulfonamide links, followed by acidification in HCl solution. The imprinted L-EP-IP materials were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy. The produced L-EP-IP displayed selectivity characteristics indicative of an affinity for L-EP almost eleven times higher than that for d-epinephrine (D-EP). At a pH of 7, Langmuir adsorption experiments demonstrated a maximal capacity of 165 mg g⁻¹. Following optical separation by means of a column method, enantiomeric excess levels of L- and D-EP in the initial feeding and subsequent recovering solutions were calculated to be 93% and 80%, respectively. © 2024 Society of Industrial Chemistry.

3D printing is a versatile technology for creating objects with custom geometries and compositions and is increasingly employed for fabricating hybrid solid–liquid composites (SLCs). These composites, comprising solid matrices with integrated liquid components, showcase unique properties such as enhanced flexibility and improved thermal and electrical conductivities. This review focuses on methods to fabricate SLCs directly by different 3D printing techniques, e.g. without needing to backfill or impregnate a porous matrix. The techniques of extrusion, vat photopolymerization and material jetting combined with microfluidics, inkjet printing, vacuum filling and ultraviolet light curing to produce SLCs are emphasized. We also discuss the development of feedstocks, focusing on emulsions and polymer capsules as fillers, and analyze current literature to highlight their significance. The review culminates in a perspective on new directions, highlighting the potential of bicontinuous interfacially jammed emulsion gels (bijels) to facilitate the printing of continuous liquid pathways, alongside the importance of understanding ink formulation and stability. Concluding with future perspectives, we underline the transformative impact of 3D-printed SLCs in diverse applications, signaling a significant advancement in the field. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

The demands of cost-driven industrial applications can be satisfied by manufacturing composites with a low volume fraction of carbon fibres as phenolic carbon fibre-reinforced composites and C/C composites, both with acceptable performances, for low- or high-temperature applications, respectively. Polymeric composites reinforced with a low volume fraction (7.5% v/v) of carbon fibres were fabricated using laboratory-produced phenolic resins, novolac (N) and resole (R), as matrices after different curing/post-curing temperature profiles. By optimising the manufacturing conditions, the N-based polymeric composites exhibited higher flexural strength, whereas the R-based composites showed higher shear strength. C/C composites, namely N-based and R-based, were manufactured by pyrolysis of the previously prepared polymeric composites up to 1000 °C. The pyrolysed composites were then densified by impregnation with an appropriate resin solution, followed by curing and new pyrolysis, and particularly by employing 1 up to 4 consecutive cycles of ‘impregnation–curing/pyrolysis’. Weight changes resulting from the impregnation–curing and pyrolysis stages were determined. The curing of both resins was verified by Fourier Transform Infrared Analysis. The apparent density and X-ray diffraction data of the C/C composites were used to calculate their total percent porosities. The morphology and elemental composition of the C/C composites at their failure region (after flexural testing) were examined by Scanning Electron Microscopy/Energy-Dispersive X-ray Analyses. In comparison to the N-based C/C composites, the R-based ones exhibited: higher shear strength, lower flexural strength, higher Shore D hardness, slightly higher surface conductivity and lower volume conductivity. The optimum conditions for the manufacture of C/C composites were achieved by applying two consecutive cycles of ‘pyrolysis–impregnation–pyrolysis’ to the polymeric composites. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.