Effect of adjustable molecular chain structure and pure silica zeolite nanoparticles on thermal, mechanical, dielectric, UV-shielding and hydrophobic properties of fluorinated copolyimide composites

Zhang³

et al. 2018

Materials

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The effects of soil burial on the biodegradation of biocomposite flower pots (BFP) made from straw fiber (SF) and hydrolyzed soy protein isolate/urea/formaldehyde (HSPI/U/F) copolymer resin were studied in detail. The microstructure, crystallinity, functional groups, mechanical, degradation and thermal property of the prepared SF with HSPI/U/F copolymer resin have been studied, and the degradation mechanism was also elucidated. XRD results showed that the bond breakage between SF and HSPI/U/F copolymer resin induced a decrease in relative degradation-resistant crystal structures. FTIR spectra showed that the methylolated HSPI units could form a cross-linking network with U/F and SF. The BFP degradation after soil burial was mainly attributed to the effects of microorganisms. The degradation products were environmentally friendly, because they were degradable and could fertilize the soil. In addition, the U/F adhesives were slightly degraded by the microorganisms due to the HSPI in the pots. The TG and DSC results showed that the molecular motion of the BFP matrix could be restricted by the degradation action and the content of HSPI, resulting in decreased crystallization enthalpy and showing good thermal property. The tensile strength of different reinforced samples was not significantly reduced in comparison to U/F resin, and still kept good mechanical performance. Thus, the prepared SF reinforced HSPI/U/F copolymer resins could have good potential for use in the field of biodegradable flower pots because of their good thermal property, mechanical property, biodegradability, and relatively low cost.

Section: Resultsmentioning

confidence: 99%

Green Preparation of Straw Fiber Reinforced Hydrolyzed Soy Protein Isolate/Urea/Formaldehyde Composites for Biocomposite Flower Pots Application

Sun

Zhang³

et al. 2018

Materials

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“…As a class, aromatic polyimides are very promising high‐performance polymers due to their high thermal stability, excellent mechanical and electrical properties, and outstanding chemical and radiation resistance. As a result, they are widely used in the fields like aviation, microelectronics, liquid crystals, and separation films, as well as in the aerospace industry and the military . Aromatic polyimides are composed of alternating electron donor (aromatic amine monomeric units) and electron acceptor (aromatic dianhydride monomeric units) groups, which results in the formation of abundant charge transfer complexes (CTCs) in the molecule or between molecules .…”

Section: Introductionmentioning

confidence: 99%

Preparation of Novel Fluorinated Copolyimide/Amine‐Functionalized Sepia Eumelanin Nanocomposites with Enhanced Mechanical, Thermal, and UV‐Shielding Properties

Tian

et al. 2017

Macro Materials & Eng

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Novel fluorinated copolyimide/amine‐modified sepia eumelanin (ASE) nanocomposites are successfully fabricated via covalent bonds. To achieve this, the polyimide (PI) is synthesized by random co‐polycondensation. The effects of ASE on the structure and properties of the PI are investigated. A multilinked network is formed with ASE acting junctions in the nanocomposites. The mechanical properties of the PI are significantly improved by the addition of ASE, and the optimal tensile strength and elongation at break are 79.7 MPa and 85.42%, respectively. UV–vis transmittance, methylene blue (MB) photodegradation, and recyclability measurements confirm that the PI/ASE nanocomposites are transparent to visible light at low ASE loadings and show outstanding UV‐shielding properties and lifetimes under intense UV irradiation owing to the synergistic absorption of UV light by the PI matrix and ASE. Furthermore, the PI/ASE nanocomposites have enhanced thermal properties with initial degradation temperatures above 500 °C. These properties endow the nanocomposites with great potential for UV‐shielding in the conditions with high temperature and intense ultraviolet light.

“…The IR bands positioned at 1400 and 1600 cm −1 respectively were due to the typical O–C–O asymmetric and symmetric stretching of benzenedicarboxylate ligand. Besides, the small spectral band located at 1660 cm −1 represented the stretching vibrations of C=O of the carboxylic acid in benzenedicarboxylate [ 29 , 30 ]. After reaction with dopamine, we could see that a weak peak appeared at 1514 cm −1 which was attributed to the bending vibration of -NH group.…”

Section: Resultsmentioning

confidence: 99%

A Novel Fluorescent Biosensor for Adenosine Triphosphate Detection Based on a Metal–Organic Framework Coating Polydopamine Layer

2018

Materials

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In this work, a novel and sensitive fluorescent biosensor based on polydopamine coated Zr-based metal–organic framework (PDA/UiO-66) is presented for adenosine triphosphate (ATP) detection. This PDA/UiO-66 nanoparticle which holds a great potential to be excellent fluorescence quencher can protect the 6-carboxyfluorescein (FAM)-labeled probe from cleaved by DNase I dispersed in solution and the flurescence of labeled FAM is quenched. When ATP molecules exist, aptamers on the PDA/UiO-66 nanoparticles can hybridize with ATP molecule to form complex structure that will be desorbed from the PDA/UiO-66 and digested by DNase I. After that, the released ATP molecule can react with another aptamer on the PDA/UiO-66 complexes, then restarts a new cycle. Herein, the excellent strong fluorescence quenching ability and uploading more amount of aptamer probes of PDA/UiO-66 composites make them efficient biosensors, leading to a high sensitivity with detection limit of 35 nM. Compared with ATP detection directly by UiO-66-based method, the LOD is about 5.7 times higher with PDA/UiO-66 nanoparticle. Moreover, the enhanced biocompatibility and bioactivity with PDA layer of the composites render a proposed strategy for clinical diagnosis field of detecting small biological molecules in vivo in the future.