Journal of Applied Polymer Science最新文献

In this study, a novel biodegradable coir fiber (CF) reinforced thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) composites (CF/TPS/PBAT) with a constant TPS: PBAT weight ratio of 70:30 and 5, 10, 15, and 20 wt% additions of CF were prepared by the melt blending and injection molding. The effects of fiber content and fiber surface modification on the mechanical and thermal properties of the prepared biocomposites were investigated. The incorporation of fibers effectively enhanced the mechanical and thermal properties of TPS/PBAT blends. Due to the removal of hemicellulose and impurities on the fiber surface after alkali treatment, the interfacial adhesion of the fiber was enhanced, thus improving the compatibility between the fibers and the matrix. At 20 wt% CFs with alkali treatment, the tensile strength exhibited 393% improvement and flexural strength exhibited 536% improvement over TPS/PBAT blends. Thermal analysis showed that the thermal stability, storage modulus, and glass transition temperature of the composites increased with the increase of fiber content. This work is significant for the development of biodegradable materials.

Lignocellulosic fiber-reinforced composites exhibit enhanced physical properties and eco-friendliness, which has resulted in extended application of these biocomposite materials in important engineering sectors. In this study, we investigated the synergistic impacts of dune sand (DS)-based silica (SiO₂) and alkali-treated date palm fiber (ADPF) fillers on the thermophysical and viscoelastic characteristics of epoxy (EP) hybrid composites. A hand layup procedure was employed to produce EP hybrid composites reinforced with 20 wt.% ADPF as well as 5, 7, and 10 wt.% DS. Compared to the other composite samples, the EP matrix reinforced with 20 wt.% ADPF and 10 wt.% DS (HC5) exhibited better thermal (T_max = 380°C, T_g = 63.13°C) and dynamic mechanical properties (storage modulus = 2700 MPa). Additionally, Cole–Cole plots revealed the excellent interaction between ADPF, DS, and epoxy matrix. Scanning electron microscopy (SEM) measurements further confirmed that the development of an effective interface between DS particles, ADPF fiber, and epoxy matrix caused a decrease in water absorption (1.5%). The best wetting conditions with the lowest thickness swelling (2.8%) were obtained by increasing the DS content up to 10 wt.%. Based on these findings, it can be concluded that, owing to their superior dynamic mechanical characteristics, hybrid composites containing 10 wt.% DS may be employed in important aircraft and aeronautic applications.

Renewable resources based polymers have been the focus of materials science scientists since they help to protect the environment in addition to reducing the petroleum resources use. Among renewable polymers poly (lactic acid) (PLA) has emerged due to its biodegradable character and proper performance similar to engineering resins, which afford wide field of applications. In this work the thermal degradation of esterified PLA with itaconic acid (PLA ITA) and the biocomposite PLA ITA FLAX was investigated using thermogavimetry (TG) which data were corroborated through Fourier transform infrared spectroscopy (FTIR). Isothermal TGs scans and FTIRs spectra were acquired from 150 to 600°C, collected data evidenced that FLAX improved PLA ITA thermal stability, delaying the decomposition of PLA ITA by up to 100 min at 250°C, ensuring safer processability at higher temperatures. From the deconvolution of the DTG peaks, the peak at lower temperature is suggested to be linked to itaconic anhydride decomposition which undergoes macromolecule dissociation, converting into itaconic anhydride and releasing water and afterwards being converted into citraconic anhydride, while the peak at higher temperature is associated to the thermal degradation of telechelic PLA. Degradation mechanism is proposed, evidenced by changes in the wavelength of CO group under the effect of temperature, as evidenced in TG-IR spectra.

Ulcerative colitis (UC) is a chronic, recurring inflammatory condition triggered by immunological imbalances in the digestive tract, leading to weight loss, diarrhea, rectal bleeding, and an increased risk of colon cancer. Existing UC treatments encounter significant limitations, such as primary non-responsiveness, secondary loss of efficacy, and adverse effects. This necessitates the development of drugs and drug formulations to broaden UC treatment options. This study describes the extended retention of poly(maleic anhydride)-drug conjugates in the large intestine of a DSS-induced acute colitis mouse model and highlights their potential for treating UC. Anti-inflammatory sirolimus (Siro) is considered an alternative drug for UC treatment, which however also has side effects due to nonspecific systemic delivery. Accordingly, poly(malic anhydride)-sirolimus (pSiro) is synthesized by linking Siro, a representative immunosuppressant and anti-inflammatory drug used in clinical practice, to anhydride groups of poly(maleic anhydride) via ester bonds. In a biodistribution study, poly(maleic anhydride) increases drug retention in the large intestine. Histochemical staining reveals the reduced inflammation degree in the treatment of pSiro, which leads to the decline of systemic inflammatory markers such as plasma TNF-α, NO, and LPS levels. These results suggest pSiro as a potential therapeutic option for the treatment of UC.

Near-infrared laser-activated gold nanorods (AuNRs) with excellent photothermal property and tunable surface functionalization are considered as an ideal platform for biomedical applications. However, bare AuNRs have cytotoxicity against normal cells and are prone to agglomeration during laser irradiation. Herein, multivalent polymer-functionalized AuNRs (AuNRs@pDMAEMA-C₄) was constructed as a highly stable and biocompatible photothermal agent for enhanced antibacterial therapy. The functionalized polymer was synthetized via the reversible addition-fragmentation chain transfer polymerization and subsequently quaternized. Moreover, positively charged AuNRs@pDMAEMA-C₄ can easily capture the bacterial surface via electrostatic interactions. The integration of photothermal therapy of AuNRs and chemotherapy of functionalized polymer can achieve enhanced antibacterial effects. Under 808 nm laser irradiation, AuNRs@pDMAEMA-C₄ possessed excellent photothermal conversion capability and can kill gram-positive and gram-negative bacteria. Study of the antibacterial mechanism indicated that the antibacterial action of the prepared photothermal antibacterial agent can cause serious damage of the bacterial outer membranes, result in cytoplasm leakage and bacterial death. The nanocomposites combining with near-infrared laser irradiation can facilitate rapid healing of bacteria-infected wound by rat model of wound infection and histological analysis of the wound tissues. These results suggest that the surface functionalization can be used as potential strategy to fabricate light-activated therapeutic agent for biomedical applications.

Developing bio-based plasticizers not only aids in the reduction of fossil fuel consumption but also presents a lower risk to human health. In this study, a fully biodegradable plasticizer—levulinate malate ethanol lactates (LMEL) was successfully synthesized from L-lactic acid, DL-malic acid, levulinic acid, and ethanol, and was compared with commercially plasticizers (acetyl tributyl citrate (ATBC), dioctyl phthalate (DOP) and di-2-ethylhexyl terephthalate (DOTP)). 40 phr LMEL plasticized polyvinyl chloride (PVC) (40LMEL) yielded a remarkable elongation at break of 526.9%, compared with the pure PVC resin (4.5%), thereby significantly enhancing the flexibility of PVC. Moreover, the optical transparency of 40LMEL samples was found to be equivalent to PVC plasticized with three commercial plasticizers. Most importantly, compared with three commercial plasticizers, 40LMEL exhibited superior resistance to migration and volatility, with mass losses of 1.055% in H₂O, 13.601% in n-hexane, 14.636% in ethanol, and 1.496% in activated carbon, respectively. Soil degradation experiments have demonstrated that LMEL can be broken down by microorganisms in the soil into nontoxic aliphatic compounds (e.g., 4-oxo-pentanoic acid, and 4,5,7-trihydroxy 2-octenoic acid, et al.). Collectively, LMEL exhibited better overall performance than three commercial plasticizers. This work provides new options for the design of efficient fully bio-based plasticizers.

In order to compare the effect of the monophenyl ring terephthalic acid (TPA) and biphenyl rings 4,4′-oxybisbenzoic acid (OBBA) with ether bond on poly(butylene adipate) (PBA)-based copolyesters properties, two copolyester series poly(butylene adipate-co-butylene terephthalate)s (PBATs) and poly(butylene adipate-co-butylene oxybisbenzoate)s (PBAOs) were synthesized, and comparatively investigated. All the synthesized copolyesters had satisfactory number-average molecular weights in the range of 26,500–73,000 g/mol. For PBATs copolyesters, the crystalline structure gradually transitioned from the monoclinic crystal structure of poly(butylene adipate) to poly(butylene terephthalate) (PBT) with increasing TPA because of the crystalline segments transformation from butylene adipate to butylene terephthalate, while PBAO copolyesters progressively shifted from the crystalline structure of PBA to the amorphous structure of poly(butylene oxybisbenzoate) (PBO) as increasing content of OBBA. The incorporation of either TPA or OBBA comonomers with rigid cyclic structure into PBA chain noticeably increased the glass transition temperature (T_g). With the same monomer molar ratio, PBAOs because of incorporation of the bicyclic comonomers presented higher T_g (range from −24.2 to 49.5°C) than that of PBATs (range from −56.5 to 22.4°C). It was found that copolyesters with bicyclic and ether bond OBBA comonomers exhibited a better flexibility in property than that with monocyclic TPA comonomers.

This article researches a superhydrophobic anti-fouling material that can be used for agricultural medicine boxes, aiming to solve the problems of residual medicine, difficult recovery, and low reuse rate in medicine boxes. Double modification (volume and surface modification) is carried out on the ultra-high molecular weight polyethylene (UHMWPE) matrix, and the high fluidity of melted snow wax is connected to UHMWPE and gas-phase silica (SiO₂) to prepare superhydrophobic composite materials U-C-WSiO₂, achieving multiple combinations of superhydrophobicity, high mechanical properties, and high stability. The high-strength bonding between snow wax and UHMWPE matrix acts as an adhesive, strengthening the bonding degree between silica particles and the matrix, achieving excellent superhydrophobicity, static contact angle reaches 157.0° on its surface while maintaining a relatively stable hydrophobic surface after multiple droplet impacts. In addition, unique surface modification methods endow U-C-WSiO₂ composite materials with high stability, which can resist pesticide erosion and maintain surface corrosion resistance. This superhydrophobic composite material can solve the problem of pesticide residue in medicine boxes and has broad prospects for agricultural applications. Its surface water repellent and drug repellent properties further expand the application of thermoplastic engineering plastics in agricultural production.

The integration and portable development of electronic devices urgently require flexible films with high thermal conductivity and insulation to overcome heat accumulation. The layered heterojunction composite films are prepared by the stacking technique for the first time. The morphology, structure composition and thermal stability of heterojunction films are studied. Compared with pure epoxy resin (EP), the heterojunction film still has good thermal stability at 600°C. At the same time, the plane heat conduction network constructed by the expanded graphite (EG) plane of the heterojunction film enables the film to dissipate heat effectively. In the simulation process of actual heat dissipation, the chip surface temperature can be reduced by 10°C. The thermal conductivity of the heterojunction film is 2.49 Wm⁻¹ K⁻¹ when the mass fraction of boron nitride- γ aminopropyl triethoxysilane (BN-KH550) is 50 wt%. Compared with pure epoxy resin, the thermal conductivity is increased by 1464%. The boron nitride (BN) surface resistance of the heterojunction film is large, which can isolate the conductive path of the EG layer and provide effective electrical insulation.

Ammonium polyphosphate (APP) and montmorillonite (MMT) have been widely used in the flame-retardant of polypropylene (PP), but the low synergistic flame-retardant efficiency and their poor compatibility with PP matrix need to be greatly improved. In this work, APP and MMT were encapsulated in the one microcapsule (PU@A-M) at the determined optimal ratio through the “bridging” reactions of diethylenetriamine (DETA) with APP and MMT. Compared with the PP/A + M composites with the physical mixture of APP and MMT, the limiting oxygen index, peak of heat release rate, total heat release, and total smoke production of PP/PU@A-M were decreased by 5.7%, 48.8%, 3.1%, and 20%, respectively. The well-dispersed PU@A-M with charring-forming agent (CFA) generated continuous and compact char layers with COP, COSi, and SiOP crosslinking structure. Furthermore, the tensile strength and elongation at break of PP/PU@A-M were enhanced by 4.8% and 36.9%, respectively, as compared with PP/A + M because of good dispersibility and compatibility of PU@A-M in PP matrix.