Yusi Luo

Bio: Yusi Luo is an academic researcher from University of Electronic Science and Technology of China. The author has contributed to research in topics: Curing (chemistry) & Dielectric. The author has an hindex of 4, co-authored 6 publications receiving 80 citations.

Studied on mechanical, thermal and dielectric properties of BPh/PEN-OH copolymer

Abstract: The thermosetting 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPh) was modified with the hydroxy-terminated poly(aryl ether nitrile) (PEN-OH). Two different crosslinking reactions including the polymerization of the nitrile groups and the formation of triazines were coexisted in the BPh/PEN-OH system, which depended on the different curing temperature. Moreover, along with the processing of crosslinking, the microstructure changed to plastic fracture first and then became brittle fracture (T > 320 °C), which was observed from SEM. The copolymer system showed good mechanical properties, outstanding thermal stability (over 520 °C) and high char yield (86.1% at 600 °C). Furthermore, they exhibited excellent dielectric properties. Both the dielectric constant and dielectric loss were found to be relatively stable over a wide range of frequencies ranging from 100 Hz to 200 kHz. Moreover, the dielectric stability was also found with respect to temperature.

Curing behavior and processability of BMI/3-APN system for advanced glass fiber composite laminates

Abstract: The prepolymers containing bismaleimide (BMI) and 3-aminophenoxyphthalonitrile (3-APN) were prepared through simple solution prepolymerization, and the corresponding curing behaviors and processability were investigated by differential scanning calorimetry and dynamic rheological analysis. The results showed that the processability of the prepolymers could be controlled by temperature and time on processing, also depended on the relative content of 3-APN and BMI. The possible curing reactions of the prepolymers were studied by Fourier transform infrared spectroscopy, which involved the Michael addition between BMI and 3-APN and self-polymerization of BMI or 3-APN. The resulting polymers displayed high thermo-oxidative stabilities (T5% > 425 °C) and good adhesion capability. Furthermore, BMI/3-APN systems were employed to prepare BMI/3-APN/glass fiber (GF) composite laminates and their morphological, mechanical, and electrical stable properties were also investigated. The BMI/3-APN/GF laminates exhibited the improvement of the mechanical properties (the maximum flexural strength is 633.5 MPa and flexural modulus is 38.7 GPa) compared with pristine BMI/GF laminates because of the strong interfacial adhesions between GF and matrices, which was confirmed with SEM observations. This study provides a concise strategy for diversifying the preparation of BMI/3-APN prepolymers to obtain advanced GF composite laminates with various properties which have potential applications in industrial manufacture or electronic circuit, and so on. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43640.

Effect of ortho-diallyl bisphenol A on the processability of phthalonitrile-based resin and their fiber-reinforced laminates

Abstract: Sluggish and narrow process window of phthalonitrile resin has tremendously limited their wide applications. In this work, a novel phthalonitrile containing benzoxazine (4,4′-(((propane-2,2-diylbis (2H-benzo [e] [1,3]oxazine-6,3 (4H)-diyl) bis(3,1-phenylene))bis(oxy)) diphthalonitrile, BA-ph) with ortho-diallyl bisphenol A (DABPA) was investigated. The processing window of the BA-ph/DABPA blends were found from 50°C to 185°C, which was significantly broader than that of the pure BA-ph (120–200°C). The composites were prepared through a curing process involving sequential polymerization of allyl moieties, ring-opening polymerization of oxazine rings and ring-forming polymerization of nitrile groups. BA-ph/DABPA/GF(glass fiber) composite laminates were prepared in this study, and the composite laminate with BA-ph/DABPA molar ratio of 2/2 showed an outstanding flexural strength and modulus of 560 MPa and 37 GPa, respectively, as well as a superior thermal and thermo-oxidative stability up to 408 and 410°C. These outstanding properties suggest that the BA-ph/DABPA/GF composites are suitable candidates as matrices for high performance composites. POLYM. ENG. SCI., 56:150–157, 2016. © 2015 Society of Plastics Engineers

Aromatic nitrile resin prepolymer and polymer for RTM (resin transfer molding) as well as preparation and application methods of prepolymer and polymer

Abstract: The invention discloses an aromatic nitrile resin prepolymer and polymer for RTM (resin transfer molding) as well as preparation and application methods of the prepolymer and the polymer. Low-melting-point aromatic nitrile resin with excellent heat stability, mechanical performance and flame retardancy and diallyl bisphenol A with lower viscosity at the room temperature are blended and pre-polymerized in proportion, and the heat-resisting matrix resin suitable for an RTM process is provided. The prepolymer is solid at the normal temperature, is liquid at the temperature of 120 DEG C-150 DEG C, maintains the viscosity smaller than 0.5 pa.s in 2 hours and becomes gel after a reaction is performed for 3.5 hours at the temperature of 150 DEG C. The prepolymer at the temperature ranging from 120 DEG C to 150 DEG C has the characteristics of lower volatility, low curing shrinkage, low exothermic peak, excellent wettability and the like and is applicable to the RTM process. According to the prepolymer, a high-temperature-resisting, high-performance nitrile polymer composite can be obtained through the RTM process, and the prepolymer can be used for the field of aerospace, ship and warship machinery and the like. The invention simultaneously provides conditions and methods for controlling blending and pre-polymerization of the prepolymer. The methods have the characteristics of simplicity and feasibility of operation and suitability of industrial production.

Mechanical, hydrophobic and thermal properties of an organic-inorganic hybrid carrageenan-polyvinyl alcohol composite film

Abstract: This paper presents that carrageenan (CG) extracted with ultrasonic assisted alkali treatment has good physicochemical properties like uniform porosity and high gel-strength. After grafting with polyvinyl alcohol (PVA), the CG-PVA film was novel plasticized and strengthened by bio-polyol and common cation (Ca2+ or K+). The bio- plasticizer derived from liquefied lignocellulosic biomass (banana pseudo-stem). The elongation of the composite film is significantly increased by 439.31% when adding 3 wt% bio-polyol. Compared with calcium ion, potassium ion is more effective on promoting copolymer chains helix transition and up to 44.30 MPa higher tensile strength was obtained. FTIR analysis verifies the crosslinking reaction among frameworks of composite films. SEM characterization and contact angle measurement indicate that surface roughness of the hybrid film increases because of CaCO3 deposition caused by Ca2+ reacted with CO2 in the air or artificial produced. TG results show that the thermal stability of the hybrid film is also improved. The renewable and degradable organic-inorganic hybrid film has potential for packaging applications.

Modification on glass fiber surface and their improved properties of fiber-reinforced composites via enhanced interfacial properties

Abstract: For fiber reinforced composite laminates, properties of laminates can be significantly affected by interfacial properties. In this work, a kind of phthalonitrile containing aromatic ether nitrile linkage (PEN-BAPh) was applied to modify glass fibers (GFs). Cured PEN-BAPh on GFs surface were investigated by Fourier transform infrared spectroscopy (FT-IR) and Ultraviolet–visible spectroscopy (UV–Vis). Scanning electron microscope (SEM) and thermogravimetry (TGA) testing were also applied to confirm the modification. Then, modified fiber-reinforced phthalonitrile-based resin composite laminates were fabricated. As the results indicated that all of the composite laminates showed improved flexural strength, flexural modulus and glass transition temperature (Tg = 296.8–299.6 °C). Improved interfacial adhesion was also studied via interlaminar shear strength (ILSS), impact strength test and monitoring the fracture surfaces. Stable dielectric constants, relative low dielectric loss and outstanding thermal stability (T5% > 350 °C) were obtained for designed composite laminates.