Search Results (77)

Poly(propylene thiophenedicarboxylate) (PPTh) is a new type of fully biobased polyester with excellent thermal, mechanical, and barrier properties; however, its practical application has been seriously restricted by the relatively slow crystallization rate. To further improve the crystallization rate and broaden the potential application field of PPTh, PPTh/multi-walled carbon nanotubes (MWCNTs) composites were successfully synthesized via an in situ melt polycondensation process in this research. Low contents of MWCNTs were well dispersed in the PPTh matrix. MWCNTs significantly increased the melt crystallization temperature and isothermal crystallization rate of PPTh, indicating the effective heterogeneous nucleating agent role. PPTh/MWCNTs composites displayed the same crystal structure as PPTh. In addition, the introduction of MWCNTs significantly enhanced both the Young’s modulus and the tensile strength of PPTh. From a sustainable viewpoint, biobased PPTh/MWCNTs composites reported in this research were of significant importance and interest as they showed remarkably improved crystallization rates and mechanical properties. Full article

Long-time exposure to volatile organic compounds (VOCs) in the atmosphere can have negative health effects on humans and other living organisms. In order to purify ambient air, these VOCs can be degraded using photocatalysis. In this research, commercially available TiO₂ nanoparticles were immobilized in a porous poly(vinylidene fluoride-co-hexa-fluoropropylene) (PVDF) polymer matrix, synthesized using the phase inversion method. The most used solvent for PVDF is N-methyl-2-pyrrolidone (NMP). However, this solvent is known to be harmful to humans and the environment, and there is a need to replace NMP with a more ecological ‘green’ solvent. Here, triethyl phosphate (TEP), methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv^® PolarClean) and propylene carbonate (PC) were used to dissolve PVDF for the phase inversion synthesis of porous photocatalytically active PVDF/TiO₂ hybrid layers onto aluminium slides. The photocatalytic degradation under UV (365 nm) of gaseous ethanol in an argon/oxygen (Ar/O₂) atmosphere shows that these solvents are suitable replacements for NMP, but optimization is required to improve the performance of the layers. Apart from changing the solvent for PVDF, the UV and photocatalysis stability of PVDF has been determined, as well as the repeatability of the photocatalytic reaction, to prove that PVDF is a suitable polymer for this application. Full article

Natural rubber is widely used in various engineering fields due to its excellent properties, particularly as an anti-corrosion and wear-resistant lining for metal pipelines. The defects in rubber linings are typically detected using the electrical spark test. Carbon black can enhance the strength, modulus, and wear resistance of natural rubber. However, conventional carbon black-filled natural rubber composites exhibit a certain level of electrical conductivity, making them unsuitable for defect detection via the electrical spark test. In this study, a silica/carbon black hybrid filler system was selected, and different types of amino-terminated poly(propylene oxide) were employed as novel interfacial dispersants to develop a low-conductivity natural rubber composite suitable for electrical spark testing while meeting general industrial mechanical performance requirements. The role of amino-terminated poly(propylene oxide) was first explored in a pure carbon black system, and then the optimized types and dosages of amino-terminated poly(propylene oxide) were added into a mixed filler system of silica and carbon black to explore the silica dosage that could balance the resistivity and mechanical properties. The results showed that the amino-terminated poly(propylene oxide) could improve the dispersion of carbon black and silica, thus increasing the mechanical properties of natural rubber composites. In the pure carbon black system, the tensile strength of natural rubber composites increased by 18.2%, the 300% modulus increased by 74.6%, and the Akron abrasion decreased by 42.7%. In the mixed filler system, the tensile strength of the natural rubber composites with 20 phr of silica and 30 phr of carbon black was 24.03 MPa, the 300% modulus was 15.16 MPa, and the Akron abrasion was 0.223 cm³. In addition, the volume resistivity was 5.52 × 10⁹ Ω·cm, which is suitable for detecting defects with the spark test. Full article

Rubber tires are fundamental components of modern society and industrial operations, holding an irreplaceable position in the global manufacturing and transportation sectors. The potential for traditional rubber tires to enhance performance is gradually approaching its limits, rendering it challenging to further improve low rolling resistance, high wet-skid resistance, and high wear resistance (called “magic triangle”). Moreover, the reliance on petroleum resources for rubber hinders the sustainable development of rubber tires. In this work, a series of novel polyurethane (PU) elastomers with potential applications in high-performance automotive tires were synthesized by CO₂-based poly(propylene carbonate) diol and bio-based poly(propylene oxide) glycol (PO3G). The comprehensive influences of PO3G on the thermal, mechanical, rolling resistance, and wear properties of the elastomers were systematically investigated. The results illustrated that increasing the PO3G content significantly enhanced the wear resistance by 98.43% and the wet-skid resistance by 73.21% and reduced the rolling resistance by 15.38% of the elastomers compared to commercial green tires (HT166). The rational design strategy of PU elastomers not only effectively addresses the “magic triangle” challenge in the tire industry but leverages CO₂ to contribute to the sustainable development of the automotive sector. Full article

Pyrene (Pr) was used to improve the electrochemical and electrochromic properties of polythiophene copolymerized with 3,4-ethylenedioxythiophene (EDOT). The corresponding product, poly(3,4-ethylenedioxythiophene-co-Pyrene) (P(EDOT-co-Pr)), was successfully synthesized by electrochemical polymerization with different monomer concentrations in propylene carbonate solution containing 0.1 M lithium perchlorate (LiClO₄/PC (0.1 M)). The homopolymer and copolymer films were analyzed by Fourier transform infrared spectroscopy (FT-IR), color-coordinate and colorimetric methods, cyclic voltammetry (CV), spectroelectrochemistry (SEC), and UV–visible spectroscopy (UV-Vis). Homopolymer poly(3,4-ethylenedioxythiophene) (PEDOT) and the P(EDOT-co-Pr) copolymer were investigated, which included examining their colorimetric, electrochemical, and electrochromic characteristics. The color shifts resulting from redox reactions of the polymers were also observed. The copolymers with different monomer concentrations achieved multicolor shifts, such as light purple, dark blue, dark red, green, and earthy yellow. Moreover, P(EDOT-co-Pr) had a small optical bandgap (1.74–1.83 eV), excellent optical contrast (31.68–45.96%), and high coloring efficiency (350–507 cm² C⁻¹). In particular, P(EDOT1-co-Pr3) exhibited outstanding cycling stability, retaining 91% of its initial optical contrast after cycling for 10,000 s, and it is expected to be a promising candidate copolymer for electrochromic applications. Full article

The simple approach of increasing the elastic properties of atactic poly(propylene carbonate) (PPC) with Mn = 71.4 kDa, ĐM = M_w/M_n = 1.86, and predominantly carbonate units (>99%) is suggested by selecting the appropriate hot pressing temperature for PPC between 110 and 140 °C. Atactic PPC is synthesized through ring-opening copolymerization of (rac)-propylene oxide and CO₂ mediated by racemic salen complex of Co(III). Hot pressing PPC results in the release of a small amount of propylene carbonate (PC), sufficient to lower the glass transition temperature from 39.4 to 26.1 °C. Consequently, increasing the pressing temperature from 110 to 140 °C generates materials with a reduced modulus of elasticity (from 1.94 to 0.09 GPa), yield strength (from 38 to 2 MPa) and increased tensile elongation (from 140 to 940%). Thermomechanical analysis has shown a significant expansion in sample volume by hundreds of percent within the 80–130 °C range. PPC also displays large, reversible deformations, which can be utilized by creating shape memory materials. Full article

The cathode affects the capacity, working voltage, and cost of lithium-ion batteries. Although the binder is a small part of the cathode material, it is particularly important to the performance of the batteries. Therefore, the design and development of polymer binders with different structures and characteristics is an important topic. In this paper, an NCM811 cathode (PPC-NCM) was prepared by a solvent-free method using poly (propylene carbonate) (PPC) as the binder, with an active substance loading of 10 mg/cm². To explore the effect of the PPC binder on the electrochemical performance of the NCM811 cathode, the discharge capacity was 112.2 mAh/g with a 76.1% capacity retention after cycling more than 200 cycles at 1 C, which has a significantly better cycling performance than that of a PVDF-NCM/Li battery. The PPC/NCM/graphite full cells were also assembled to demonstrate the practical application potential of this work. It was shown that PPC as a binder can improve the cycling stability of NCM811/Li and NCM811/graphite full cells. The PPC binder used in the NCM811 cathode not only makes it extremely easy to prepare dry electrodes, but also makes it very simple to recover the electrode material by heating in the case of battery failure. This paper provides a new idea for the industrialization and development of a novel binder. Full article

A comparative study of the copolymerization of racemic propylene oxide (PO) with CO₂ catalyzed by racemic (salcy)CoX (salcy = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF₅) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO₂. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity. Full article

A series of partially bio-based and biodegradable poly(propylene terephthalate-co-adipate) (PPTA) random copolymers with different components were prepared by the melt polycondensation of petro-based adipic acid and terephthalic acid with bio-based 1,3-propanediol. The microstructure, crystallization behavior, thermal properties, and enzymatic degradation properties were further investigated. The thermal decomposition kinetics was deeply analyzed using Friedman’s method, with the thermal degradation activation energy ranging from 297.8 to 302.1 kJ/mol. The crystallinity and wettability of the copolymers decreased with the increase in the content of the third unit, but they were lower than those of the homopolymer. The thermal degradation activation energy E, carbon residue, and reaction level n all showed a decreasing trend. Meanwhile, the initial thermal decomposition temperature (T_d) was higher than 350 °C, which can meet the requirements for processing and use. The PPTA copolymer material still showed excellent thermal stability. Adding PA units could regulate the crystallinity, wettability, and degradation rate of PPTA copolymers. The composition of PPTA copolymers in different degradation cycles was characterized by ¹H NMR analysis. Further, the copolymers’ surface morphology during the process of enzymatic degradation also was observed by scanning electron microscopy (SEM). The copolymers’ enzymatic degradation accorded with the surface degradation mechanism. The copolymers showed significant degradation behavior within 30 days, and the rate increased with increasing PA content when the PA content exceeded 45.36%. Full article

Degradable and high-barrier plastic packaging materials draw more attention with the development of a social economy and the demands of environmental protection. In this study, poly(propylene carbonate phthalate) (PPC-P) and poly(butylene adipate-co-terephthalate) (PBAT) blends with different ratios were designed and prepared, marked as PPC-P/PBAT. Chain extenders were introduced into the blends, and the mechanical properties, thermal properties, and barrier properties of the composites were studied. The 75PPC-P/PBAT with 2% extenders represent the best performance. The addition of the chain extender has significantly improved the thermal stability and tensile elongation of PPC-P/PBAT. On this basis, the PPC-P/PBAT composite film was coated with PVA and borax using the dipping and pulling method. The oxygen barrier properties have been further improved for the composite film with a coating layer. Considering the characteristics of biodegradability and a high-barrier property, the 75PPC-P/PBAT/2MDI@Gly blend coated with 2 wt% PVA and 3 wt% borax exhibits potential as a superior food/pharmaceutical plastic packaging material with excellent tensile and barrier properties. Full article

This study investigates the relationship between the molecular structure and foaming of poly(ethylene glycol) and poly(propylene glycol) triblock copolymers in Portland cement pastes. Four copolymers with different molecular structures were studied at varying concentrations. All copolymers showed a reduction in surface tension of the cement pore solution; however, only some of them demonstrated foaming and air entraining in cement paste. The results indicated that the molecular structure parameter, hydrophilic-to-lipophilic balance (HLB), has a direct relationship with the foaming and air-entraining performance of the copolymers. The total organic carbon measurements showed very small adsorption of these non-ionic copolymers on hydrating cement particles due to the lack of surface charge needed to interact with the heterogeneously charged surface of hydrating cement. In addition, these copolymers did not seem to affect the flow of cement paste due to a lack of adsorption on cement particles. The cement paste modified with the copolymers showed increased water sorption compared to the control paste due to the increased capillary porosity and slight increase in pore surface hydrophilicity. However, the freeze-thaw resistance was shown to improve with an increase in the number of air voids in the modified cement pastes. The findings establish the relationship between molecular properties of copolymers and their air-entraining performance in cement paste to mitigate the damages caused by freeze-thaw action. Full article

Poly(propylene carbonate-co-phthalate) (PPC-P) is an amorphous copolymer of aliphatic polycarbonate and aromatic polyester; it possesses good biodegradability, superior mechanical performances, high thermal properties, and excellent affinity with CO₂. Hence, we fabricate PPC-P foams in an autoclave by using subcritical CO₂ as a physical blowing agent. Both saturation pressure and foaming temperature affect the foaming behaviors of PPC-P, including CO₂ adsorption and desorption performance, foaming ratio, cell size, porosity, cell density, and nucleation density, which are investigated in this research. Moreover, the low-cost PPC-P/nano-CaCO₃ and PPC-P/starch composites are prepared and foamed using the same procedure. The obtained PPC-P-based foams show ultra-high expansion ratio and refined microcellular structures simultaneously. Besides, nano-CaCO₃ can effectively improve PPC-P’s rheological properties and foamability. In addition, the introduction of starch into PPC-P can lead to a large number of open cells. Beyond all doubt, this work can certainly provide both a kind of new biodegradable PPC-P-based foam materials and an economic methodology to make biodegradable plastic foams. These foams are potentially applicable in the packaging, transportation, and food industry. Full article

The binder ratio in a commercial lithium-ion battery is very low, but it is one of the key materials affecting the battery’s performance. In this paper, polycarbonate-based polymers with liner or chain extension structures are proposed as binders. Then, dry LiFePO₄ (LFP) electrodes with these binders are prepared using the solvent-free method. Polycarbonate-based polymers have a high tensile strength and a satisfactory bonding strength, and the rich polar carbonate groups provide highly ionic conductivity as binders. The batteries with poly (propylene carbonate)-plus (PPC-P) as binders were shown to have a long cycle life (350 cycles under 1 C, 89% of capacity retention). The preparation of dry electrodes using polycarbonate-based polymers can avoid the use of solvents and shorten the process of preparing electrodes. It can also greatly reduce the manufacturing cost of batteries and effectively use industrial waste gas dioxide oxidation. Most importantly, a battery material with this kind of polycarbonate polymer as a binder is easily recycled by simply heating after the battery is discarded. This paper provides a new idea for the industrialization and development of a novel binder. Full article

To enrich the properties of polylactic acid (PLA)-based composite films and improve the base degradability, in this study, a certain amount of poly(propylene carbonate) (PPC) was added to PLA-based composite films, and PLA/PPC-based composite films were prepared by melt blending and hot-press molding. The effects of the introduction of PPC on the composite films were analyzed through in-depth studies on mechanical properties, water vapor and oxygen transmission rates, thermal analysis, compost degradability, and bacterial inhibition properties of the composite films. When the introduction ratio coefficient of PPC was 30%, the tensile strength of the composite film increased by 19.68%, the water vapor transmission coefficient decreased by 14.43%, and the oxygen transmission coefficient decreased by 18.31% compared to that of the composite film without PPC, the cold crystallization temperature of the composite film increased gradually from 96.9 °C to 104.8 °C, and PPC improved the crystallization ability of composite film. The degradation rate of the composite film with PPC increased significantly compared to the previous one, and the degradation rate increased with the increase in the PPC content. The degradation rate was 49.85% and 46.22% faster on average than that of the composite film without PPC when the degradation was carried out over 40 and 80 days; the composite film had certain inhibition, and the maximum diameter of the inhibition circle was 2.42 cm. This study provides a strategy for the development of PLA-based biodegradable laminates, which can promote the application of PLA-based laminates in food packaging. Full article

Investigation of chiroptical polymers in the solution phase is paramount for designing supramolecular architectures for photonic or biomedical devices. This work is devoted to the case study of poly(propylene oxide) (PPO) optical activity in several solvents: benzonitrile, carbon disulfide, chloroform, ethyl acetate, and p-dioxane. To attain information on the interactions in these systems, rheological testing was undertaken, showing distinct variations of the rheological parameters as a function of the solvent type. These aspects are also reflected in the refractive index dispersive behavior, from which linear and non-linear optical properties are extracted. To determine the circular birefringence and specific rotation of the PPO solutions, the alternative method of the channeled spectra was employed. The spectral data were correlated with the molecular modeling of the PPO structural unit in the selected solvents. Density functional theory (DFT) computational data indicated that the torsional potential energy—related to the O1-C2-C3-O4 dihedral angle from the polymer repeating unit—was hindered in solvation environments characterized by high polarity and the ability to interact via hydrogen bonding. This was in agreement with the optical characterization of the samples, which indicated a lower circular birefringence and specific rotation for the solutions of PPO in ethyl acetate and p-dioxane. Also, the shape of optical rotatory dispersion curves was slightly modified for PPO in these solvents compared with the other ones. Full article