Functional PDMS enhanced strain at fracture and toughness of DGEBA epoxy resin

Enhanced Toughness and Sound Absorption Performance of Bio-Aerogel via Incorporation of Elastomer

In this study, Arabic gum/ carboxylic butadiene-acrylonitrite latex aerogels (AG/XNBRL) hybrid aerogel was successfully prepared by a green method, i.e., the combination of latex compounding and vacuum freeze-drying process. After that, the obtained composites were subjected to a high temperature treatment to crosslink the rubber phase. It was found that the AG in the AG/XNBRL hybrid aerogel could act as a framework to improve the dimensional stability of the aerogel, while the XNBRL phase could significantly improve the mechanical flexibility of the ensuing composite. Compared to the AG aerogel which is highly brittle in nature, the AG/XNBRL hybrid aerogel not only exhibits significantly enhanced toughness, but also shows improved thermal stability and sound absorption performances; for instance, the half weight loss (50%) temperature and average sound adsorption coefficient for aerogel containing 30 wt% XNBRL is 344 °C and 0.585, respectively, which are superior to those of neat AG aerogel. Overall, this work provides novel inspiration to prepare the mechanical robust bio-based aerogel for the sound absorption application.

Design of Piezoelectric Ultrasonic Transducer Based on Doped PDMS

The performance of the ultrasonic transducer will directly affect the accuracy of ultrasonic experimental measurement. Therefore, in order to meet the requirements of a wide band, a kind of annular 2-2-2 piezoelectric composite is proposed based on doped PDMS. In this paper, the transducer structure consisted of PZT-5A piezoelectric ceramics and PDMS doped with 3 wt.% Al₂O₃:SiO₂ (1:6) powder, which constituted the piezoelectric composite. MATLAB and COMSOL software were used for simulation. Meanwhile, the electrode materials were selected. Then, the performance of the designed annular 2-2-2 ultrasonic transducer was tested. The simulation results show that when the polymer phase material of the piezoelectric ultrasonic transducer is doped PDMS, the piezoelectric phase and the ceramic substrate account for 70% of the total volume, the polymer phase accounts for 30% of the total volume, and the maximum frequency band width can reach 90 kHz. The experimental results show that the maximum bandwidth of −3 dB can reach 104 kHz when the frequency is 160 kHz. The results of the electrode test show that the use of Cu/Ti electrode improves the electrical conductivity of the single electrode. In this paper, the annular 2-2-2 transducer designed in the case of small volume had the characteristics of a wide frequency band, which was conducive to the miniaturization and integration of the transducer. Therefore, we believe that the annular 2-2-2 piezoelectric composite has broad application prospects.

Preparation of hydrophobic epoxy-polydimethylsiloxane-graphene oxide nanocomposite coatings for antifouling application

Epoxy-polydimethylsiloxane-graphene oxide (EPG) nanocomposite coatings were successfully developed by loading different wt% of graphene oxide nanosheets (GNs) into an epoxy-hydroxy-terminated-polydimethylsiloxane (EP-hPD) matrix via a facile in situ preparation technique. The inclusion of GNs into EPN led to an increase in modulus of elasticity and tensile strength up to 1570.46 MPa and 31.54 MPa, respectively, in the case of 1 wt% loading of GNs in the EP-hPD matrix. Also, an increase in the water contact angle from 90.1° to 115.2°, 104.5° and 101.7° was discerned at 1, 3 and 5 wt% loadings of GNs respectively. Taber abrasion results demonstrated a decrease in abrasion loss by 33.3% at 1 wt% loading of GNs in comparison to the unreinforced coating. An improvement in the glass transition temperature (T_g) was observed from 63.5 °C for the neat sample to 77.6 °C, 76.3 °C and 71.6 °C for the 1, 3 and 5 wt% EPG nanocomposites, respectively. An inevitable enhancement in the properties of the nanocomposites was affirmed due to the synergistic effect of GNs dispersed within the EP-hPD blend matrix. The prominent findings of this work include a minimum corrosion rate of 0.73 × 10^-2 mm per year and upgradation in the antifouling performance of the nanocomposite coatings in comparison to the neat coating.

PDMS Based Hybrid Sol-Gel Materials for Sensing Applications in Alkaline Environments: Synthesis and Characterization

Nowadays, concrete degradation is a major problem in the civil engineering field. Concrete carbonation, one of the main sources of structures' degradation, causes concrete's pH to decrease; hence, enabling the necessary conditions for corrosion reinforcement. An accurate, non-destructive sensor able to monitor the pH decrease resistant to concrete conditions is envisaged by many researchers. Optical fibre sensors (OFS) are generally used for concrete applications due to their high sensitivity and resistance to external interferences. Organic-inorganic hybrid (OIH) films, for potential functionalization of OFS to be applied in concrete structures, were developed. Polydimethylsiloxane (PDMS) based sol-gel materials were synthesized by the formation of an amino alcohol precursor followed by hydrolysis and condensation. Different ratios between PDMS and (3-aminopropyl)triethoxysilane (3-APTES) were studied. The synthesized OIH films were characterized by Fourier-transformed infrared spectroscopy (FTIR), UV-Vis spectroscopy, electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA). The OIH films were doped with phenolphthalein (Phph), a pH indicator, and were characterized by UV-Vis and EIS. FTIR characterization showed that the reaction between both precursors, the hydrolysis and the condensation reactions occurred successfully. UV-Vis characterization confirmed the presence of Phph embedded in the OIH matrices. Dielectric and thermal properties of the materials showed promising properties for application in contact with a high alkaline environment.

Development of reprocessable novel sulfur-containing epoxy based on thermal treatment

Inspired by the Diels–Alder reaction, we synthesized self-healing epoxy resin (EP-DA) containing sulfur and sharing a large amount of π-electrons.