Journal of Applied Polymer Science最新文献

Twenty types of polyethylene (PE) including high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) with various viscosity were used to study the in-situ formation of PE- ethylene propylene rubber (EPR) core-shell rubber particles (CSRP) in polypropylene (PP) matrix by melt blending. The results show that PE and EPR cannot form CSRP if PE melt flow index (MFI) is lower than about 0.3 g/10 min. As a result, the impact fracture of PP/PE/EPR composite is brittle. If PE MFI is higher than 0.3 g/10 min, PE and EPR can form CSRP, leading to the ductile impact fracture of PP/PE/EPR composite. Interestingly, upper limit content of PE for the formation of CSRP depends on the type and viscosity of PE. For HDPE, upper limit content of PE tends to increase with the increase of its MFI, whereas it drops considerably for LLDPE. Understanding these relationships provides insights into optimizing the selection of core types and viscosity for enhancing the mechanical properties of polymer composites with core-shell structure. This may potentially guide the development of cost-effective and high-performance polymer composites.

Poly(butylene adipate-co-butylene terephthalate) (PBAT)/thermoplastic starch (TPS) blends were prepared by melt blending. However, the processability and practical application of PBAT/TPS blends are limited by their poor compatibility. To enhance the compatibility between PBAT and TPS, PBAT was functionalized by maleic anhydride (MA) to prepare PBAT-MA, and then it was employed as a compatibilizer for PBAT/PBAT-MA/TPS blends. The effects of PBAT-MA on the tensile properties, rheological properties, morphology, and dynamic mechanics of PBAT/PBAT-MA/TPS blends were studied in detail. Rheological results revealed that the interaction between PBAT-MA and TPS enhanced the segment entanglement ability and improved the compatibility of the blends, which enhanced the tensile properties of the blends. Compared with the PBAT/PBAT-MA/TPS (50/0/50) blend, the tensile strength of the PBAT/PBAT-MA/TPS (40/10/50) blend increased from 9.2 to 15.8 MPa, and the elongation at break increased from 326.9% to 1017.6%. The dynamic mechanical results showed that the T_g of PBAT and TPS were close to each other after the addition of PBAT-MA, which confirmed that the compatibility of the blend was improved. This study provides a feasible approach to preparing high-performance and cost-effective PBAT/PBAT-MA/TPS blends while expanding the application prospects of PBAT in the packaging industry and agricultural film.

In this study, two cardanol based epoxidized resins, NC514 with less than two epoxies per molecule and side chain epoxidized cardanol glycidyl ether (SCECGE) with approximately 2.45 epoxies (1.0 phenolic+1.45 aliphatic epoxies) per molecule were methacrylated. The methacrylated versions of cardanol based NC514 (NC514VE) and SCECGE (SCECGEVE) epoxy resins were used as cross-linker units in vinyl ester formulations with methacrylated lauric acid (MFA) and styrene (ST) as bio-based and synthetic based reactive diluents respectively, at various concentrations (10–40 wt%). The curing reactions of the resins were studied via FTIR and the extent of polymerization was determined for different cross-linker units in the presence of ST and MFA. Our mechanical and thermomechanical characterizations showed that VER formulations prepared with cardanol based SCECGEVE cross-linker unit have significantly improved properties than the samples prepared with commercially available counterpart NC514VE using either reactive diluent. These properties of SCECGEVE were also comparable with to that of methacrylated petroleum-based diglycidyl ether of bisphenol A vinyl ester (DGEBAVE) formulations unlike NC514VE formulations due to more effective side chain functionalization and cross-linking.

Contaminated water sources from various industries pose severe environmental challenges due to their complex compositions, high toxicity, and fluctuating qualities. This study introduces a groundbreaking strategy for fabricating advanced polysulfate (PSE) ultrafiltration membranes using a novel reverse thermally induced phase separation (RTIPS) process. By manipulating the cloud point through the DMAc/DEG solvent/nonsolvent system, our work innovatively controls membrane microstructure, overcoming limitations of conventional nonsolvent-induced phase separation (NIPS). Our findings reveal that RTIPS, when employed above the cloud point, yields PSE membranes with a unique bicontinuous sponge-like structure, significantly improving upon conventional NIPS products. Specifically, the optimized RTIPS membranes exhibit enhanced pure water flux (916.23 vs. 336.23 LMH), larger pore sizes (0.083 vs. 0.054 μm), increased tensile strength (1.32 vs. 0.84 MPa), and improved fouling resistance (FRR 65.5% vs. 55.2%). This research pioneers a facile yet potent method for tailoring membrane properties, achieving a balance between permeability, mechanical stability, and filtration efficacy. The demonstrated success of RTIPS in enhancing PSE membrane performance not only contributes to the development of high-performance water treatment technologies but also charts a new course in membrane science, offering a promising avenue for sustainable wastewater management solutions.

With the development of electronic devices and wireless communication technology, the quality of human life has improved. However, shielding from electromagnetic interference (EMI) is required due to device malfunctions and harmful effects on human health. Polymer-based shielding materials getting much attention due to their light weight, flexibility, good processability, and other desirable traits. However, achieving consistent dispersion of conductive fillers and optimizing the balance between electrical, mechanical, and thermal properties remain challenges despite the advantages of polymer-based materials. Especially, epoxy resins are promising polymer materials for EMI shielding applications due to their excellent mechanical strength, chemical resistance, and excellent adhesive properties. Additionally, epoxy resin exhibits remarkable processability allowing for various fabrication techniques such as casting, molding, and three-dimensional printing. However, one of the significant drawbacks of epoxy resin is the difficulty in achieving uniform dispersion of conductive fillers within the epoxy matrix. In this study, we propose an iron-nickel alloy (FeNi) embedded in an epoxy matrix (FeNi/Epoxy) for EMI shielding material. It is manufactured by facile fabrication process due to the advantages of epoxy, which has excellent processability. EMI shielding effectiveness at 12 GHz is enhanced from 9.12 to 17.86 dB by the increase of FeNi concentrations. Furthermore, thermal and mechanical properties were improved by the increase of FeNi concentration. Thermal conductivity for efficient heat dissipation is increased from 0.63 to 1.49 Wm⁻¹ K⁻¹. Moreover, polydopamine (PDA) was employed as a surface coating material for FeNi to overcome the non-uniform dispersion of FeNi particles in the epoxy matrix. Surface coating by PDA significantly enhanced the dispersion uniformity and strengthened the adhesion between the filler and matrix. Elastic modulus is greatly increased from 83.03 MPa to 1.29 GPa by the surface coating. The enhancement of mechanical properties is derived from the chemical bonds between the filler and matrix.

This research explores the development of new composite material by integrating Azadirachta Indica (AI) with LLDPE to create wood-plastic composites using the rotational molding process. By examining various proportions of AI wood flour blended with LLDPE, we investigated their impact on mechanical and physical properties. Our tests elucidate a clear correlation between mechanical properties and composite morphologies. Despite identical molding conditions, higher wood particle concentrations reduced mechanical properties compared to lower concentrations. Remarkably, a 12% wood content emerges as optimal, yielding a tensile modulus of 3.69 MPa and a flexural modulus of 468.5 MPa, with an acceptable reduction of 11% density and 13% porosity versus pure LLDPE. Additionally, we observed declines in tensile strength, impact strength, and hardness by up to 23%, 62%, and 11%, respectively, compared to neat LLDPE. Natural fillers enhance aesthetics, making these materials ideal for consumer products like garden equipment and furniture accessories.

Shape memory polymers typically utilize the glass transition or melting temperature to switch from one shape to another. The goal of this work is to check if the α-relaxation, which is attributed to the migration of chains through lamellar crystals, can be utilized as novel switch for any crosslinkable semi-crystalline thermoplastic. Using cross-linked low-density polyethylene (x-LDPE) as an example, it is shown that the α-relaxation is indeed suitable as switch, when the polymer is crystallized under strain to an intermediate shape. It is demonstrated that post-stretching at a temperature between the α-relaxation and the melting temperature, followed by subsequent cooling to room-temperature switches x-LDPE from the intermediate to a temporary shape and that reheating to this temperature initiates the retraction back to the intermediate shape. Switching between intermediate and temporary shapes is shown to be accompanied by a reversible change in morphology.

In this study, we delved into innovative strategies to make neat E-glass fabrics (NGFs) more impact- and tensile-resistant by using shear-thickening fluids (STFs). To achieve this goal, the polyethylene glycol (PEG) in STFs has been modified. Subsequently, the STF-impregnated fabric composites were prepared from unmodified PEG and functionally modified PEGs using malonic and tartaric acids, V/S/GF, M/S/GF, and T/S/GF composites, respectively. Fourier-transform infrared spectroscopy (FTIR) analysis was conducted to confirm the chemical modification of PEGs. The rheological tests showed a significant improvement in the peak viscosity of modified STFs compared with virgin STF. Dynamic rheological analysis also studied media-particle interaction, revealing improved media-particle interaction in STFs due to abundant H-bonding. In addition, a series of experimental tests, namely compressive impact resistance and strip tensile strength tests, have been conducted to investigate the effect of STF modification on the NGF. The results revealed notable improvements in tensile strength and energy dissipation in the T/S/GF and M/S/GF composites compared with V/S/GF and NGF. Importantly, this improvement extended to the impact performance of single, triple, and quintuple layers. Notably, we found that the peak load of 5 T/S/GF was 37.71%, 18.57%, and 11.87% lower than that of 5NGF, 5 V/S/GF, and 5 M/S/GF, respectively. The idea that made these improvements possible came from PEG functionalization, which helps hydrogen bonds form between the dispersed phase and the dispersion medium, leading to higher viscosity. This, in turn, increases inter-yarn friction, effectively enhancing the spring-like properties of T/S/GF and M/S/GF compared with V/S/GF. A two-step artificial intelligence regression analysis underpinned these findings, elucidating the interplay of molecular mechanisms in high-performance fabric composites.

Multi-responsive, self-healing hydrogels were developed utilizing positively charged polysaccharides, chitosan, and water-soluble chitosan. This fabrication employed free-radical synthesized polyacrylic acid and polymethacrylic acid along with the cross-linker FeCl₃, resulting in the generation of polyelectrolyte metal complexes, which enhances the properties of the chitosan-based hydrogels, particularly their mechanical strength, self-healing ability, thermal stability, swelling behavior, porous structure, cell viability, and even anticancer activity. Characterization and stability assessment of the hydrogels were performed using FT-IR, nuclear magnetic resonance, gel permeation chromatography, scanning electron microscopy, rheometer, x-ray diffraction, thermogravimetric analysis, DSC, and UV spectroscopy. FT-IR measurements indicated that the facile complexation of the cross-linker's metal ions (Fe³⁺) with the carboxylate (COO⁻), amino (NH), and hydroxyl (OH) groups of the polymers and chitosan chains facilitated rapid gelation. Furthermore, the sustained release of the drug levofloxacin (up to 80%) was observed to increase with increasing pH due to the hydrogels' anionic nature. Biocompatibility and cytotoxicity tests were conducted using the MTT assay on splenocytes and Dalton Lymphoma cancer cell lines. These tests demonstrated the promising potential of these hydrogels for drug delivery applications.

β-phase poly(vinylidene fluoride) (PVDF) film boasts excellent electrical properties and can be used in sensors, micro actuation, and energy harvesting. In this paper, high β-phase PVDF films were stretched by stretch-line equipment (roll to roll) and the β-phase content can reach 60%, realizing the potential for large-scale fabrication. Moreover, the electrical and electrostrictive properties of PVDF films before and after stretching are compared. The stretched film (PVDF-R film) has better piezoelectric properties and electrostrictive properties due to the formation of high β phase in the stretched film and the directional arrangement of PVDF molecular chains in the amorphous region (the formation of directional amorphous). Under the same driving electric field intensity (180 kV/mm), the electrostrictive deformation of PVDF film is 1.5 μm, while that of PVDF-R film is 2 μm. The piezoelectric coefficient of the PVDF-R films can reach 36 pC/N. The output voltage of the PVDF-R film in finger press mode is studied and the peak position of the output voltage signal is obvious, which can be used for pulse monitoring.