Search

Poly(butylene adipate-co-terephthalate) (PBAT) is one of the solutions to the energy crisis and white pollution. However, the poor thermo-oxidative stability limits its wide applications. In this work, Chrysanthemum morifolium extract (CME) as a natural additive was used to modify the PBAT. The oxidation onset temperature (OOT) results showed that the CME could provide PBAT with high thermal oxidation stability. By the presence of 2.5 wt% CME, the OOT value of PBAT-[CME.sub.2.5] increased by 52[degrees] C compared with the neat PBAT. The outstanding antioxidant capacity is attributed to the excellent free radical quenching capacity of CME, whose main components consist of six kinds of phenolic compounds. Moreover, the PBAT-[CME.sub.1.5] composite could achieve the balance between the mechanical property and thermo-oxidative stability, the OOT result of PBAT-[CME.sub.1.5] increased by 42[degrees]C, the tensile strength reached 103.1%, and the elongation at break could retain 91.4% of that of neat PBAT. Besides, the processing property, degradation performance, and surface hydrophobic nature of modified PBAT samples were all improved. This work proposes a facile method to obtain completely natural biodegradable composites to expand the practical applications of PBAT. Highlights * The main components in CME are phenolic compounds. * CME showed high free radical scavenging efficiency. * CME improved the thermal oxidation stability of the PBAT matrix. * The addition of CME could still maintain good mechanical properties of PBAT. * The introduction of CME promoted the degradation of PBAT films. KEYWORDS antioxidants, biodegradable, thermal properties, 1 | INTRODUCTION The accumulation of plastic waste has brought about increasing environmental pollution, which is mainly due to the massive use of nonbiodegradable, fossil fuel-based polymers, whose degradation time [...]

Abstract Despite the advantage of biodegradability, polylactic acid (PLA) has some processing and application drawbacks, such as poor thermal oxygen stability. Herein, the modified PLA samples were prepared by mixing [...]

A fresh phosphorus‐containing fireproofing agent (oxybis(4,1‐phenylene))bis((2,5‐dihydroxyphenyl)(phenyl)phosphine oxide) (ODDPO‐HQ) was synthesized by a simple two‐step reaction. The effect of ODDPO‐HQ on the glass transition temperature (Tg), crosslinking density, thermal stability, fire resistance, dielectric performances, hydrophobicity, and water absorption of epoxy resin (EP) was studied. EP/ODDPO‐HQ containing 1.2 wt% phosphorus not only achieved the vertical burning V‐0 grade with a limited oxygen index of 28.9% but also maintained good thermal stability. Compared to unmodified EP, its Tg value has only decreased by 7.2°C. Detailed studies revealed that the excellent flame resistance of ODDPO‐HQ for epoxies was ascribed to the flame suppression both in the gaseous phase and condensed phase, especially the obvious barrier effect. Although the water uptake of the modified epoxies slightly rose with the content of ODDPO‐HQ caused by the reduction of the crosslinking density within the matrix, it did not adversely affect the properties of the polymer. The modified epoxies showed reduced dielectric constant and dielectric loss values, and the contact angle of EP/ODDPO‐HQ samples increased as the flame retardant content rose, which might be due to the symmetrical structure of ODDPO‐HQ reducing the polarity. Our study presents an easy approach for producing high‐performance epoxies. [ABSTRACT FROM AUTHOR]

A phosphorus-containing compound, (oxybis(4,1-phenylene))bis(phenylphosphine oxide) (ODDPO), was successfully synthesized and used as a flame retardant for epoxy resin (EP). The results demonstrated that EP/ODDPO, containing 1.2 wt% phosphorus, achieved a vertical burning V-0 rating, with a limited oxygen index value of 29.2%, indicating excellent flame retardancy. Comprehensive evaluations revealed that ODDPO exhibited both gas-phase and condensed-phase flame-retardant effects on EP, with a particularly notable barrier effect. In addition, the incorporation of ODDPO had a minimal negative impact on the glass transition temperature (Tg) and thermal stability of the EP matrix. Compared to unmodified EP (EP-0), the Tg value and initial decomposition temperature of EP/ODDPO-1.2 decreased by only 7.6 °C and 10.0 °C, respectively. Moreover, the introduction of ODDPO significantly improved the hydrophobicity and water absorption resistance of epoxy materials, which is attributed to ODDPO's rigidity and symmetric structure, reducing water molecule permeation. Furthermore, the dielectric properties of ODDPO-modified EP samples were strengthened compared to EP-0, due to the ODDPO's symmetric structure reducing the polarity of the matrix. The above results indicated that ODDPO serves as an excellent flame retardant while enhancing other properties of the EP matrix, thereby contributing to the preparation and application of high-performance epoxy materials. [ABSTRACT FROM AUTHOR]

Thermoplastic poly(ether ester) elastomer (TPEE) is a highly flammable material with severe melt‐dropping, which greatly limits its range of applications. Here, black phosphorus nanosheets (BPs) and aluminum diethylphosphinate (ADP) were used to improve the fire safety of TPEE for the first time. Results demonstrated that ADP/BPs as a synergistic combination exhibits good dispersity and excellent flame retardancy, also has minimal negative effects on the mechanical performances of the TPEE composites. By comparing TPEE/ADP‐22 and TPEE/ADP‐10/BPs‐4, the introduction of BPs significantly reduced the addition of ADP while keeping the material at the higher vertical burning grade, ~54.5% reduction in ADP usage. Compared with neat TPEE, TPEE/ADP‐10/BPs‐4 fulfilled V‐0 level, avoided dripping, and the limiting oxygen index value increased to 34.0%. Moreover, TPEE/ADP‐10/BPs‐4 performed the best in cone calorimetry test, both the peak heat release rate and total heat release reduced the largest, by 44.2% and 25.3%, respectively. The detailed studies of the flame‐retardant mechanism found that ADP/BPs showed the fire‐retardant impact of the condensed phase and gaseous phase. This work expands BPs in the flame‐retardant application and could facilitate to prepare the anti‐dripping flame‐resistant TPEE. Highlights: BPs as an efficient flame retardant were added into TPEE for the first time.ADP/BPs as a synergistic combination has an excellent fire‐retardant effect.The introduction of BPs significantly reduced the addition of ADP.TPEE/ADP‐10/BPs‐4 showed the highest FPI and the lowest FGI.ADP/BPs has lowest negative effects on the mechanical performances of matrix. [ABSTRACT FROM AUTHOR]

Scutellaria baicalensis extract (SBE), as a natural phenolic antioxidant, was added to poly(butylene adipate‐co‐terephthalate) (PBAT) matrix. With the addition of SBE, both the short‐term and long‐term antioxidant activity of PBAT samples noticeably improved. The results showed that the oxidation onset temperature (OOT) value of the modified sample (PBAT‐SBE2.5 sample) is increased by 62°C versus neat PBAT. Compared with neat PBAT with decreased OOT value after 240 days of storage, the OOT values of modified samples showed no significant change after long‐term storage. The excellent antioxidant activity is attributed to the high total phenolic content in SBE, which provides significant free radical scavenging efficiency. Additionally, the introduction of SBE could effectively enhance the processing performance of the PBAT matrix, the melt flow rate of PBAT‐SBE2.5 increased by ca. 42.6%. Compared with neat PBAT, the addition of SBE has no obvious effect on the mechanical properties of the matrix, the tensile strength remains unchanged and the elongation at break of PBAT‐SBE2.5 retains 74%. Composting degradation experiment indicated that the SBE promoted the degradation of PBAT. Moreover, SBE could reduce the surface hydrophilic tendency of the film materials. All results reveal that SBE was a good natural multifunctional stabilizer for PBAT. Highlights: SBE shows high total phenolic content and free radical scavenging activity.SBE improves the short‐term and long‐term antioxidant activity of PBAT.The addition of SBE promoted the degradation of PBAT films.SBE could effectively enhance the processing performance of the PBAT matrix. [ABSTRACT FROM AUTHOR]

Commercial conductive polymer composites (CPCs) with positive temperature coefficient (PTC) behavior usually suffer from inherent poor reproducibility of pyroresistive property. Herein, a conductive carbon black (CB)/high density polyethylene (HDPE)/polyvinylidene fluoride (PVDF) composite with outstanding PTC reproducibility were prepared through introducing cellulose nanocrystals (CNCs) grafted with methyl methacrylate (CNC‐g‐PMMA). Following the minimum interfacial energy mechanism, the CNC‐g‐PMMA tends to locate in PVDF of binary polymer composites. A much finer morphology of conductive CB/HDPE phase is hence obtained owing to the increasement of PVDF/HDPE viscosity ratio by introducing CNC‐g‐PMMA. Undergoing multiple repeated temperature cycles, the room temperature resistance and PTC intensity of as‐prepared material keep almost unchanged, which demonstrates superior PTC reproducibility. The improving mechanism of PTC reproducibility has also been illustrated in detail. This research provides a facile and valid strategy to enhance the PTC reproducibility and will vastly expand the application of PTC composites in the field of intelligent temperature management. Highlights: Assembling binary polymer‐based PTC materials with cocontinuous structureNanocrystals enables conductive HDPE phase with finer morphology.The precise ranges of viscosity ratio ensure the co‐continuous morphology.Small conductive phase size enhances P reproducibility.Narrow spatial domain restricts the self‐aggregation of conductive fillers. [ABSTRACT FROM AUTHOR]

Rich oxygen atom-decorated conjugated microporous polymers (O-CMPs) have been synthesized for CO2 uptake. The controlled porosity, good stability, and rich oxygen atoms within the O-CMPs indicate their high potential for CO2 capture. Notably, we observed an enhancement in capacity and selectivity through the improvement of adding oxygen atoms, facilitated by quadrupole interactions. [ABSTRACT FROM AUTHOR]

Polyolefin suffers from degradation during processing and application. To prolong the service life, antioxidants are needed in the packing formula of polyolefin products. The usage of natural antioxidants could avoid potential health hazards aroused by synthetic ones. Pine needles have long lives and hardly rot, suggesting their high resistance to degradation. To provide a new candidate of natural antioxidants and add more value to pine needles, pine needle extracts (PNE) were investigated as the antioxidant of linear low-density polyethylene (LLDPE). PNE-modified LLDPE (PE-PNE) exhibited much better short-term and long-term aging resistance than pure LLDPE (PE): Oxidation induction time (OIT) of PE-PNE was 52 times higher than that of PE, and the increments of carbonyl index (CI) of PE-PNE-1st samples placed under daylight and in the dark were approximately 75% and 63% of PE under the same conditions. It could be attributed to the attractive antioxidant capacity of PNE (IC50 of DPPH radical scavenging was 115 μg/mL). In addition, the PE-PNE sample showed high processing stability and maintenance of the mechanical property during multiple extrusions: only a 0.2 g/10 min decrease in melting flow rate was found after five extrusions; the tensile strength and elongation at break were almost unchanged. All results reveal that pine needle extracts could play a role in LLDPE stabilization. Moreover, as pine needles are mainly considered a kind of waste, the present study would benefit the budget-reducing polyolefin industry. [ABSTRACT FROM AUTHOR]

The chiral nematic liquid crystalline phase (CNLCP) of noble metal nanorods induces a strong chiroptical response due to their intrinsic physical and chemical properties. Here, we demonstrate that the formation of CNLCP of Ag nanorods (AgNRs) originates from their bent-shape and is the result of purely entropic effects. The chirality of the liquid crystalline phase of AgNR@CuO hyper branched coaxial nanorods (HBCNRs) can be switched from left-handed to right-handed by increasing CuO thickness. It is proposed that the increase of coating thickness decreases the curvature of nanorods, which induces variation of the twist constant ( K) and bend elastic constant ( K). The increased thickness also changes the direction of director with respect to the helical axis. In addition, hydrogen bonds can break the CNLCP, which can be attributed to their stronger effection compared to van der Waals forces and electrostatic interactions. In contrast to the variation of coating thickness, the surface morphology, constituents of the hybrid building blocks and polarity of the solvents do not play important roles in the handedness transition of the liquid crystalline phase. Furthermore, the results presented here give insight into the structure-property relationship and our strategy provides guidance for the synthesis of other inorganic chiral suprastructures driven by entropic effects. [ABSTRACT FROM AUTHOR]