Advances in Polymer Technology最新文献

Lignin is one of the available biopolymers on earth, so it can play a vital role in moving toward a bio-based society. In this paper, lignin derived from non-wood sources like bagasse and kash was characterized in order to facilitate its valorization. Lignin obtained from the soda liquor was considered as technical lignin, and it was compared with the acidic dioxane-extracted lignin from the corresponding non-wood. The isolated lignins were characterized using elemental analysis, methoxyl content determination, molecular weight distribution, FT-IR spectroscopy, and advanced NMR techniques (quantitative ³¹P and 2D HSQC). The methoxyl groups per C₉ unit in dioxane lignin from bagasse were 1.20, which was slightly higher than that of kash dioxane lignin (1.16/C₉). Technical lignins showed comparable or slightly lower methoxyl content per C₉ unit. The weight-average molecular weight (Mw) of technical lignin was lower than that of corresponding dioxane lignin. The phenolic hydroxyl groups in technical lignin were higher than those of corresponding dioxane lignin, as observed from ³¹P NMR analysis. Furthermore, 2D HSQC NMR analysis showed that both lignins were primarily composed of syringyl (S) and guaiacyl (G) units, with the S-unit type being dominant. These findings provide valuable information on the structural and chemical properties of non-wood lignins, supporting their potential utilization in bio-based applications.

In recent years, increased plastic usage has led to huge amounts of blended plastic waste moving into the environment without proper control. Packaging plastics make up one-half of all waste and plastics disposal poses a significant environmental issue. Consequently, the need for improved recycling of waste plastics and their conversion into new products to decrease the need for additional virgin plastics has increased overtime. Given the growing demand for sustainable packaging solutions, this study examines various converting techniques, including extrusion and injection molding, to assess their effectiveness in the production of food and nonfood packaging from recycled plastics. The study underscores the role of advances in recycling technology and considers how challenges like variability in quality and process compatibility can be addressed. It is noted that enhanced sorting and cleaning methods and chemical recycling play a critical role in the quality and performance improving of recycled plastics. The article emphasizes the potential of recycled plastics for creating high-quality packaging while reducing environmental impact. Future research efforts should focus on enhancing recycling techniques and expanding applications of recycled plastics to promote increased sustainability within the packaging industry.

Despite efforts to develop polymeric materials using renewable feedstocks, there is a continued reliance on (meth)acrylates for several additive manufacturing (AM) technologies, diminishing their overall sustainability. On the other hand, itaconic acid presents itself as an opportunity to resolve these shortcomings as a biobased source of unsaturation, produced through enzymatic transformation of starches. A variety of unsaturated oligomers (e.g., poly[ester], poly[ester amide] and poly[ester thioether]) and monomers (e.g., monoesters, diesters, hydroxyesters and non-isocyanate urethanes) have been developed and used in various AM technologies. These materials have been demonstrated across a broad scope of applications, from mechanically competitive materials and nanoparticle-reinforced composites to self-healing and shape memory polymers, as well as biocompatible and biomedical materials. Despite this encouraging progress, however, the synthetic transformations of itaconic acid as well as processing considerations for AM have made advancement within the field a non-trivial task. Herein, the use of itaconic acid is critically examined, highlighting the diversity and challenges of sustainable synthetic avenues, processing constraints in AM, and achieving competitive and advanced materials applied across a range of AM technologies and useful within several important contemporary engineering fields.

Piezoelectric polymer nanofibers are promising for wearable electronics due to their mechanical compliance and electromechanical responsiveness. Poly(vinylidene fluoride)-trifluoroethylene (PVDF-TrFE) is widely used for its ferroelectric β-phase and favorable piezoelectric properties, yet its limited elasticity hinders applications in soft bioelectronics. Electrospun PVDF-TrFE mats can stretch through fiber rearrangement but lack true elastic recovery unless molecular interactions and junctions are modified. Achieving nanofiber networks that are both stretchable and piezoelectrically stable under cyclic strain remains a challenge. Here, we report a strategy combining PVDF-TrFE with a small fraction of poly(ethylene glycol) bis(amine) (PEG-diamine) and thermal annealing to form fused nanofibrous mats with enhanced elasticity and stable piezoelectric output. The blended mats doubled the strain-to-failure (~30%) compared to pure PVDF-TrFE (~14%) and showed Mullins-like elastic recovery up to approximately 9% with reduced hysteresis. Piezoelectric response improved by approximately 25% in peak voltage (~150 mV), with greater signal stability. Structural analyses (Fourier-transform infrared [FTIR], differential scanning calorimetry [DSC], and X-ray diffraction [XRD]) confirmed increased β-phase content and selective cross-linking in amorphous domains without compromising ferroelectric order. This work demonstrates a scalable material-based approach to improve elasticity and durability in electrospun piezoelectric fibers, enabling stretchable and skin-conformable sensors for smart fabrics, wearable health monitors, and energy harvesting.

Skin grafting is a widely used technique for treating extensive skin injuries such as chronic ulcers, wounds, and burns. Traditional grafting techniques face various challenges, including limited availability, risk of infection, donor site morbidity, and immune rejection. Due to their tailored properties, synthetic skin grafts offer a promising alternative solution to these challenges. This study aims to fabricate polymer blends by integrating the bioactivity of chitosan, derived from natural polymer (chitin), with the mechanical resilience of synthetic polymers—poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG). Two Polymer blends, 30CHI:70(PVA/PEG) and 20CHI:80(PVA/PEG), were prepared through physical crosslinking. The pH-responsive and hydrophilic behavior of the blends was evaluated in phosphate-buffered saline (PBS) solution to mimic physiological conditions. Different characterization tests, including tensile testing, scanning electron microscopy (SEM), Fourier transform infrared (FTIR), pH sensitivity, contact angle, antibacterial, cytotoxicity, and thermal analysis, revealed that the 20CHI:80(PVA/PEG) blend demonstrated mechanical resilience, superior hydrophilicity, and pH responsiveness compared to other blends. This polymer also exhibited low shrinkage, controlled swelling, and excellent biocompatibility, making it a suitable candidate for skin graft applications. However, in vivo evaluations are needed to further validate the clinical potential of this blend. The findings of this study highlight the potential of material integration for developing biocompatible, versatile, and viable polymer blends for advanced tissue engineering applications.

Developing new materials by recovering waste materials in the polymer reinforcement process helps to protect the environment and ensure a circular economy for these waste materials when they reach the end of their life cycle. This study shows the possibility of developing a new composite with bilinga and epoxy resin waste. Composites were realised by using cold pressure moulding technique with different pressures, particle sizes and reinforcement rate. Physical tests were carrying out to determine moisture content, water absorption rate and density by using a gravimetric method. Three-point bending tests were used to determine flexural Young modulus and maximum break stress. Asymmetric Hot plane method with insulated rear face were used to determine thermal conductivity of composites. Results obtained show that moisture content varies from 2.3% to 6.65% and water absorption rate from 61% to 191%. These results allow us to say that this composite material has a hydrophilicity character. Young’s modulus of these materials is between 117 and 1951 MPa. Breaking stress of these composite materials is between 0.5 and 12.5 MPa. Results show that increasing compaction pressure also increases the mechanical properties of composite, as shown by standard EN312 for used in dry and humid environments. The thermal conductivity of the composite in between 0.18 and 0.27 W m⁻¹ K⁻¹. These results confirm that the composite materials produced can be used in furniture manufacturing, thermal insulation for homes and ceilings, and the development of sandwich materials.

Innovative advancements in polyolefin chemistries are critically important to develop industrial applications that require an ability of either superior performance levels or minimal expense. While temperature rising elution fractionation (TREF) is a well-established analytical technique for characterising polyolefin heterogeneity, its use as a preparative tool for actively engineering properties remains underexplored. This research investigated the effects of continual extraction of fractions of copolymers, through either molecular fractioning or selective fractions, for propylene–1-pentene copolymers, on structure–property relationships. Moving beyond the established correlation between elution temperature and comonomer content, this study demonstrates how the strategic subtraction of amorphous-rich or crystalline-rich fractions can systematically tune the bulk material’s properties. Conditions were created to allow for systematic removal of selected fractions while characterising the remaining polymer by density-based fractional crystallinity, differential scanning calorimetry (DSC), ¹³C NMR, micro-hardness testing and positron annihilation lifetime spectroscopy (PALS). This study has demonstrated the potential to directly enhance the crystallinity and microhardness of the copolymer by selectively removing amorphous-rich fractions. More importantly, it establishes ‘selective fraction removal’ as a proof-of-concept for a new materials design strategy. In contrast, it is not very likely that removing fractions of highly crystalline-based polymer will create improvements to properties. In addition, this study has shown that selectable fractions provide an effective means to tune polymer properties at the laboratory scale. While the method demonstrates potential, its industrial scalability would require further research and methodological adaptation.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer that represents a potential replacement for some traditional plastics. The properties of PHB are impacted by many variables including its molecular weight. There are many applications that can be fulfilled by low molecular weight PHB (LMWPHB). We have investigated the use of potassium phosphate (K₂HPO₄) as a catalyst for degrading PHB. Potassium phosphate was demonstrated to degrade the polymer in a concentration-dependent manner. Low concentrations (0.2%) of K₂HPO₄ decreased the thermal stability of the polymer and rapidly reduced the molecular weight. Comparisons to related chemicals (potassium sulfate, potassium chloride, calcium phosphate, and sodium phosphate) demonstrated that the K₂HPO₄ had the greatest effect on thermostability. Low amounts of K₂HPO₄, but not other salts, led to a decrease in the crystallization temperature and bimodal melting behavior, indicative of the formation of smaller crystallites. This is the first report of the use of K₂HPO₄ to convert PHB into lower molecular weight species.