Advanced Industrial and Engineering Polymer Research最新文献

Polyethylene Glycol (PEG)-based flexible phase change materials have broad and practical application value in thermal management of flexible electronic devices. Considering the typical application cases and safety of phase change materials (PCMs), in this work, we grafted molecular nanoparticles, POSS, with both hydrophobic and flame retardant functions to the surface of PLR sheets through amidation reaction. The successful grafting of POSS has been fully verified by Fourier-transform infrared spectroscopy, energy dispersive spectroscopy and surface contact angle. The formation of the cross-linked structure and the introduction of POSS make the phase change latent heat of the phase change material slightly decrease from 102.4 J g⁻¹ to 94.4 J g⁻¹, but there is still a high retention rate. It is worth pointing out that the PCMs have excellent shape stability and leakage resistance, cycle stability, and shape memory performance (R_f-99%, R_r-99%). The introduce of cross-linked structure and POSS significantly enhanced the Young’s modulus and tensile strength of the PCM. The surface POSS functionalization endowed the PCM with significantly enhanced hydrophobicity. Specifically, the contact angle of the material was significantly increased from 71° for PLR to 123° for POSS-PLR, and it also had enhanced fire safety with pHRR reduction by 18.4% and THR reduction by 19.1%.

To address the shortcomings of traditional intumescent flame retardants (IFRs), a novel four-in-one IFR (M [APP/NiCo₂O₄]) was constructed for the first time. It integrates acid source, gas source, carbon source (crosslinking β-CD), and synergistic agent (NiCo₂O₄ nanoparticles) into a single entity by a co-encapsulation technology. Under the loading of 20 wt%, its flame retardant performance was significantly better than that of simple mixed flame retardants, and it could increase the limiting oxygen index of polypropylene (PP) from 18 to 30.2 and pass the UL-94 V-0 rating. At the same time, it could reduce the peak of heat release rate, total heat release, and peak of CO production of PP by 77%, 22%, and 80%, respectively, showing excellent flame retardant performance. The excellent flame retardant performance is mainly because the synergist NiCo₂O₄ nanoparticles in the four-in-one flame retardant can easily combine and efficiently interact with the acid source, carbon source, and gas source in the intumescent flame retardant to form a more stable protective char residue. In addition, the crosslinking β-CD shell enhances both the water resistance and initial thermal decomposition temperature of PP containing the four-in-one IFR compared to PP with simple mixed control samples. After 72 h of water resistance test, it can still maintain the UL-94 V-0 rating. The presence of the crosslinking β-CD shell also improves the compatibility of the four-in-one flame retardant in PP, and its adverse effects on the mechanical properties of PP are also significantly smaller than those of the mixed control sample.

Understanding the external and internal factors during an additive manufacturing (AM) process is crucial, as they can significantly affect the final product's performance. Efforts have been made to unwind the product, process, property, and performance (PPPP) relationships. The conventional experimental approaches can lead to boundless runs, resulting in exorbitant costs for research and development. Hence, developing, adapting, and validating numerical models is essential to achieving the desired performance of 3D-printed products with lesser resource utilization. In this study, numerical and experimental techniques were used to perform the PPPP relationship assessment on material extrusion 3D-printed parts. Three infill designs (rectangular, triangular, and hexagonal), with layer heights (0.1 mm, 0.125 mm, and 0.2 mm), and three different materials (carbon fiber-reinforced polyamide-6 (PA6-CF), polyamide-6 (PA6), and acrylonitrile butadiene styrene (ABS)), were selected for the investigation. Taguchi's design of experiments (DOE) method was used to limit the number of numerical simulations and experimental runs. A thermomechanical numerical model was utilized to perform the material extrusion process simulations and mechanical performance prediction of the specimens. Subsequently, the samples were 3D-printed and tested mechanically to validate the numerical simulation results. The dimensional, distortion, and mechanical analysis performed on numerical simulation results agreed well with the experimental observations.

A bimodal impact strength distribution was found in notched impact specimens of HDPE composites with calcium carbonate, carbon black, SEBS and stabilisers. The bimodal distribution was only found at moderate-to-high calcium carbonate loadings, with the likelihood of low impact strength increasing with increasing stabiliser loading and decreasing with increasing SEBS/CB masterbatch loading. Bayesian methods were used first to confirm bimodality and then to investigate the effects of formulation on the performance of the system, based on a hierarchical model with quadratic and interactive terms and switching based on the sampling of a Bernoulli distribution with a logistic regression informing the probability of high or low impact strength. The results are contextualised through micrograph fractography and, briefly, differential scanning calorimetry. Results are also reported for unnotched impact tests, with negative correlations for impact strength with calcium carbonate and stabilisers, a positive correlation with SEBS/CB and interactive effects.

The brittle fracture pattern in plastics associated with low toughness performance have a negative effect on their performance especially for long-term and specialized applications. This review provides a comprehensive understanding of toughening mechanisms in polyethylene (PE) and the details of different techniques for achieving a balance between strength and toughness in PE-based composites. Various strategies for toughening, along with the parameters involved in processing and materials development, such as matrix chemical modification, use of a second phase, and incorporation of coupling agents are discussed in detail. Current challenges and future opportunities for simultaneous toughening and strengthening in PE-based composites are outlined for further research and development in academia and industry to expand the applications of PE composites, overcome current challenges, and provide useful insights for further advancements, particularly in the area of toughened composites.

Poly (lactic acid) (PLA) foams have demonstrated a high variety of functional characteristics, still, the rigidity of this cellular material remains a major limiting factor when it comes to implementation options. In this contribution, PLA foams with outstanding flexibility were created for the first time by a new approach of uniaxial stretching and immediate relaxation following supercritical CO₂-assisted extrusion foaming. Instead of improving the resilience of the PLA raw material, structural elasticity of the foam was achieved via altering the deformation mechanism from cell wall collapse or rupture towards reversible and extensive flexural strain. In addition, PLA foams with excellent piezoelectric properties were also achieved via high-voltage corona poling, giving additional function to the lens-like anisotropic foam cells. This foaming technology creates the opportunity to produce PLA piezoelectrets in a way entirely different from the state-of-the-art methods. Correlation between the tensile as well as compression elongations and moduli, cell morphology and longitudinal piezoelectric coefficients (d₃₃) of electretized foam samples were studied. Unprecedented reversible tensile elongations of up to 16% and total elongations of up to 35% were reached, as well as considerable d₃₃ values in the range of 50–320 pC/N were obtained for PLA ferroelectrets.

To develop metal-free magnetic resonance imaging (MRI) contrast agents, organic radical based contrast agents have been proposed as a promising alternative to obtain less toxic and safer MRI contrast agents. However, the low relaxivity and rapid in vivo reduction have limited the application of organic radicals as MRI contrast agents. As a special class of polymer, dendrimers with three-dimensional molecular structure and multiple tunable functional groups on surface, enable the facile chemical modification with organic radicals. With dendrimer as scaffold, a considerable amount of effort has been made to develop completely organic contrast agents. Herein, this mini review reports the recent advances of contrast agents with dendrimers as scaffold functionalized with radicals on the surface.

Theoretical research has predicted high thermoelectric performance for bismuthene nanosheets, but it is a great challenge to prepare these nanosheets due to low efficiency and intensive oxidation. We herein report an efficient, environmentally friendly preparation method for bismuthene nanosheets, each being 1–1.5 nm thick in average, through mechanochemical treatment with an ethanol system. The system was found to prevent adverse oxidation in comparison with a pure water system. Although neither the oxidation reactions nor the exfoliation could significantly change the Seebeck coefficient of bismuthene nanosheets, their power factor was measured as 155.6 ± 15.4 μW·m^-1K^-2. An epoxy nanocomposite was prepared containing 99 vol% of bismuthene nanosheets, to create a thermoelectric generator. It converted a temperature gradient of 11°C generated by human body into an electrical output of 18.62 nW. Our mechanochemical exfoliation method for the preparation of low-oxidation bismuth nanosheets offers insights for large-scale fabrication of nanosheets and their composites for industrial applications. It advances the field of thermoelectric nanocomposites.

Highly ordered porous structures of PLA composite films can be designed with the addition of calcium carbonate nanoparticles (CCN) in polymeric film formation using the breath figure (BF) technique at controlled humidity. Both 2D and 3D monodispersed honeycomb-like porous structures of the PLA composite films are achieved by the adding CCN at the concentration of up to 1.00 phr, whereas hierarchically multiscale porous structures of the PLA/CCN films are obtained when the CCN concentration in the composites increases to more than 1.00 phr. These structures can be fabricated due to three mechanisms: water absorption and condensation, nano-Pickering emulsion, and capillary flow by self-assembly of the nanoparticles. Moreover, the nano effects of CCN on polymeric film fabrication are maximized by increasing the relative humidity to 90%, resulting in the formation of porous multilayers up to 95–120 μm in thickness. The application of the prepared porous composite films of PLA/CCN in the food and medical industries was illustrated. A model colorimetric sensor is made from PLA/CCN composite films enriched with bromothymol blue. The color of the films quickly changes from yellow to blue within 10 min after coming into contact with histamine, a representative gas generated from spoiled food.

Nowadays there are many attempts for sustainable development due to rapid industrialization. In this context, thymol and carvacrol, which are obtained from many plants, are highly promising components in many industries due to their multifunctionalities. However, their water insolubility, instability, and volatility are significant drawbacks that must be addressed. To overcome these issues, they are commonly incorporated into fibrous structures for applications in the food and human health-related industries. With advances in technology, thymol/carvacrol containing fibrous structures have been generated using various techniques, widening their applications in the related fields. While their anti-bacterial properties have been widely exploited in various applications, this review article covers their anti-oxidant, anti-inflammatory, anti-septic, anti-cancer, anti-microbial (anti-bacterial, anti-fungal, anti-biofilm, and anti-viral), anti-parasitic (insecticidal, anti-malaria, anti-acaricidal (anti-mite and anti-tick), anti-toxoplasmosis, and anti-leishmaniasis) properties, considering all the broadened applications of thymol/carvacrol containing fibrous structures. Ever-increasing food and human health-related incidences will accelerate the uttermost exploitation of all functionalities of thymol and carvacrol in multifaceted ways. Nanoscale containers and fibrous structures will be the pioneers for finding new and more effective applications of thymol and carvacrol. For example, they could find applications not only in packaging for market shelves but also in entire food chain, including plant protection in agriculture (pre-harvest and post-harvest), transportation, and storage of food/crop. Fibrous structures containing thymol/carvacrol will also enable new and diverse applications in hygiene & preventive care, comfort & well-being in addition to wound healing and tissue engineering in the human health. A detailed future perspective is provided related to all these applications.