Ultra-high molecular weight polyethylene (UHMWPE)/high-density polyethylene (HDPE) blend with lower viscosity is more suitable for melt spinning compared to pure UHMWPE; however, the mechanical ...property of the blend fiber is hard to dramatically improve (the maximum tensile strength of 998.27 MPa). Herein, different content modified-nano-SiOsub.2 is incorporated to UHMWPE/HDPE blend fiber. After adding 0.5 wt% nano-SiOsub.2, the tensile strength and initial modulus of UHMWPE/HDPE/nano-SiOsub.2 fiber are increased to 1211 MPa and 12.81 GPa, respectively, 21.57% and 43.32% higher than that of UHMWPE/HDPE fiber. Meanwhile, the influence of the nano-SiOsub.2 content on the performance for as-spun filament and fiber are emphatically analyzed. The crystallinity and molecular chain orientation of as-spun filament reduces with the addition of nano-SiOsub.2. On the contrary, for fiber, the addition of nano-SiOsub.2 promoted the crystallinity, molecular chain orientation and grain refinement more obvious at a lower content. Furthermore, the possible action mechanism of nano-SiOsub.2 in the as-spun filament extrusion and fiber hot drawing stage is explained.
Plastic in any form is a nuisance to the well-being of the environment. The 'pestilence' caused by it is mainly due to its non-degradable nature. With the industrial boom and the population ...explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only resulted in furthering the pollution by releasing toxic gases into the atmosphere; whereas; biological methods have been found to be eco-friendly however they are not cost effective. This paves the way for the current study where fungal isolates have been used to degrade polyethylene sheets (HDPE, LDPE). Two potential fungal strains, namely, Penicillium oxalicum NS4 (KU559906) and Penicillium chrysogenum NS10 (KU559907) had been isolated and identified to have plastic degrading abilities. Further, the growth medium for the strains was optimized with the help of RSM. The plastic sheets were subjected to treatment with microbial culture for 90 days. The extent of degradation was analyzed by, FE-SEM, AFM and FTIR. Morphological changes in the plastic sheet were determined.
The current-integrated charge <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) method used in ...this study can measure all fast-moving carrier charges and accumulated charges, which are shallow and deep trapped charges, respectively. The pulsed electroacoustic (PEA) method is an excellent method for observing the distribution of accumulated charges; however, it is difficult to measure fast-moving carrier charges using the PEA method. Currently, space charge measurement data on a wide range of electric field, temperature, and voltage application time are required. Therefore, this study aims to provide the <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) data of charge accumulation characteristics by examining six types of polymeric insulating materials: low-density polyethylene (LDPE), cross-linked polyethylene (XLPE), polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC), and polyethylene naphthalate (PEN). The space charge accumulation is measured using the <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) method. The <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) measurement results are obtained over a wide range of electric field (1-100 kV/mm), temperature (20 °C-80 °C), and voltage application time (0-5 h). The results show that the space charge accumulation characteristics <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) data of the six types of polymeric insulating materials are significantly dependent on these three factors. We believe that the <inline-formula> <tex-math notation="LaTeX">{Q} </tex-math></inline-formula>(<inline-formula> <tex-math notation="LaTeX">{t} </tex-math></inline-formula>) method used in this study can contribute to further understanding of the charge accumulation properties of dc polymeric insulating materials.
Summary
Synthetic plastics, which are widely present in materials of everyday use, are ubiquitous and slowly‐degrading polymers in environmental wastes. Of special interest are the capabilities of ...microorganisms to accelerate their degradation. Members of the metabolically diverse genus Pseudomonas are of particular interest due to their capabilities to degrade and metabolize synthetic plastics. Pseudomonas species isolated from environmental matrices have been identified to degrade polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polyethylene terephthalate, polyethylene succinate, polyethylene glycol and polyvinyl alcohol at varying degrees of efficiency. Here, we present a review of the current knowledge on the factors that control the ability of Pseudomonas sp. to process these different plastic polymers and their by‐products. These factors include cell surface attachment within biofilms, catalytic enzymes involved in oxidation or hydrolysis of the plastic polymer, metabolic pathways responsible for uptake and assimilation of plastic fragments and chemical factors that are advantageous or inhibitory to the biodegradation process. We also highlight future research directions required in order to harness fully the capabilities of Pseudomonas sp. in bioremediation strategies towards eliminating plastic wastes.
Poly(ethylene-2,5-furandicarboxylate) (PEF) is a new alipharomatic polyester that can be prepared from monomers derived from renewable resources like furfural and hydroxymethylfurfural. For this ...reason it has gained high interest recently. In the present work it was synthesized from the dimethylester of 2,5-furandicarboxylic acid and ethylene glycol by applying the two-stage melt polycondensation method. The thermal behavior of PEF was studied in comparison to its terephthalate and naphthalate homologues poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN), which were also synthesized following the same procedure. The equilibrium melting point of PEF was found to be 265 °C while the heat of fusion for the pure crystalline PEF was estimated to be about 137 J g(-1). The crystallization kinetics was analyzed using various models. PET showed faster crystallization rates than PEN and this in turn showed faster crystallization than PEF, under both isothermal and non-isothermal conditions. The spherulitic morphology of PEF during isothermal crystallization was investigated by polarized light microscopy (PLM). A large nucleation density and a small spherulite size were observed for PEF even at low supercoolings, in contrast to PET or PEN. Thermogravimetric analysis indicated that PEF is thermally stable up to 325 °C and the temperature for the maximum degradation rate was 438 °C. These values were a little lower than those for PET or PEN.
Pluronic polymers (pluronics) are a unique class of synthetic triblock copolymers containing hydrophobic polypropylene oxide (PPO) and hydrophilic polyethylene oxide (PEO) arranged in the PEO-PPO-PEO ...manner. Due to their excellent biocompatibility and amphiphilic properties, pluronics are an ideal and promising biological material, which is widely used in drug delivery, disease diagnosis, and treatment, among other applications. Through self-assembly or in combination with other materials, pluronics can form nano carriers with different morphologies, representing a kind of multifunctional pharmaceutical excipients. In recent years, the utilization of pluronic-based multi-functional drug carriers in tumor treatment has become widespread, and various responsive drug carriers are designed according to the characteristics of the tumor microenvironment, resulting in major progress in tumor therapy. This review introduces the specific role of pluronic-based polymer drug delivery systems in tumor therapy, focusing on their physical and chemical properties as well as the design aspects of pluronic polymers. Finally, using newer literature reports, this review provides insights into the future potential and challenges posed by different pluronic-based polymer drug delivery systems in tumor therapy.
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