Jing Dang

Ideal dielectric thermally conductive bismaleimide nanocomposites filled with polyhedral oligomeric silsesquioxane functionalized nanosized boron nitride

Silane coupling reagent γ-glycidoxy propyl trimethoxy silane/polyhedral oligomeric silsesquioxane (KH-560/POSS) functionalized nanosized boron nitride (POSS-g-nBN) fillers were performed to fabricate thermally conductive bismaleimide/diallylbisphenol A (BMI/DABA) nanocomposites combining excellent dielectric properties and outstanding thermal stability. POSS molecules have been grafted on the surface of the nBN fillers. The POSS-g-nBN/BMI/DABA nanocomposite with 15.4 vol% POSS-g-nBN is an excellent dielectric composite material with high thermal conductivity and outstanding thermal stability; the corresponding dielectric constant e is 3.42, the dielectric loss factor tanδ is 0.0085, the thermally conductive coefficient λ is 0.607 W m−1 K−1 (increased by 266% compared to that of pure BMI/DABA), and the 5 wt% thermal weight loss temperature (T5) reaches up to 428 °C, which holds potential for use in the integration and the miniaturization of microelectronic devices.

Thermal conductivities, mechanical and thermal properties of graphite nanoplatelets/polyphenylene sulfide composites

Functionalized pristine graphite nanoplatelets (fGNPs) by methanesulfonic acid/isopropyltrioleictitanate (MSA/NDZ-105) are used to fabricate fGNPs/polyphenylene sulfide (fGNPs/PPS) composites by mechanical ball milling followed by a compression molding method. The thermal conductive coefficient of the fGNPs/PPS composite with 40 wt% fGNPs is greatly improved to 4.414 W m−1 K−1, 19 times higher than that of the original PPS. For a given GNP loading, the surface functionalization of GNPs by MSA/NDZ-105 results in the fGNPs/PPS composites improving thermal conductivities by minimizing the interfacial thermal resistance. The thermal stabilities of the fGNPs/PPS composites are increased with the increasing addition of fGNPs.

Flame-Retardant, Thermal, Mechanical and Dielectric Properties of Structural Non-Halogenated Epoxy Resin Composites

First, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and epoxy resin (E-51) were employed to synthesize a structural non-halogenated epoxy resin (ED). And a novelphenolic aldehyde curing agent, 2,4,6-tri (phenol-methylene-amide)-triazine (MFP) was also synthesized for preparing high-performance MFP/ED composites. Results showed that, the flame-retardant and thermal stabilities of the composites were improved with the increasing phosphorus content. When the content of phosphorus was 3wt%, the initial decomposing temperature of the composite was over 325°C, and the charring rate was 30.3% at 650°C, could meet the requirements of UL 94-V0 rating. However, all the flexural and impact, dielectric constant and loss and the glass transition temperature (Tg) of the composites were decreased with the increasing phosphorus content.

Study on Preparation of SiO2/Epoxy Resin Hybrid Materials by Means of Sol-Gel

Silicon dioxide/epoxy resin hybrid material was prepared by means of Sol-Gel based on epoxy resin, tetraethyl orthosioate (TEOS), [H2N(CH2)3Si(OC2H5)3](KH-550), Methyltetrahydrophthalic anhydride (MeTHPA), dimethyl phthalate (DMP-30) and (HOCH2CH2)N. The contents of TEOS, KH-550 and reacting temperature influencing on the properties of hybrid materials were studied. The behaviors of the hybrid materials were characterized by differential scanning calorimentry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform-infrared ray (FT-IR) spectroscopy. The results showed that the properties of the material was optimal at approximately 3% TEOS, 2% KH-550, reacting at 60°C, and the mechanical and thermal properties were significantly improved compared with the pure epoxy resin. The dimension of SiO2 particles was about 20 nm, and distributed homogeneously in the system.

Surface modification of HMPBO fibers by silane coupling agent of KH-560 treatment assisted by ultrasonic vibration

The surface modification of poly (p-phenylene-2,6-benzobisoxazole) (HMPBO) fibers by silane coupling agent of γ-aminopropyl triethoxy silane (KH-560) treatment assisted by ultrasonic vibration was investigated. The chemical composition and surface morphologies of the HMPBO fibers were analyzed and characterized by XPS, FTIR, TGA and SEM. The tensile properties of the HMPBO fibers were also studied. The results indicated that polar hydroxyl groups were successfully introduced on the HMPBO surface after the proposed treatment processes, and the surface roughness of HMPBO fibers was increased. Moreover, the treated HMPBO maintained relatively excellent tensile strength, and the single fiber pull-out strength of HMPBO was improved from 0.94 MPa to 1.07 MPa.

Studies on Preparation and Property Researches of EP/SiC Thermal Conductivity Composites

The epoxy resin/silicon carbide thermal conductivity composites were prepared via casting method. The content of SiC and coupling reagents effecting on the thermal conductivity, mechanical and thermal properties of composites were investigated. Results revealed that the thermal conductivity properties of the composites were improved with the increasing mass fraction of SiC, and the thermal conductivity coefficient λ was 0.7152 W/mk with 50% mass fraction of SiC, being over 3 times of that of native epoxy resin. The flexural strength and impact strength of the EP/SiC composites increased firstly, but decreased with excessive addition of SiC, and the properties of EP/SiC composites were maximum with 10 wt% SiC. DSC and TGA analysis showed that the glass transition temperature (Tg) of composites decreased, but the heat resistance increased with the addition of SiC. SEM observation of impact fracture revealed that the impact strength had the relationships of large or small fracturing ability and the fracturing extended ability and the resin elasticity deformation.

Supramolecular Host–Guest Interaction-Enhanced Adjustable Drug Release Based on β-Cyclodextrin-Functionalized Thermoresponsive Porous Polymer Films

Drug delivery systems based on stimuli-responsive porous polymer films (PPFs) have been extensively investigated because of their many advantages. However, the ability to adjust the drug release from PPFs is not always perfect, and at times, it cannot satisfy real-world requirements. In this paper, supramolecular host-guest interactions were harnessed to overcome the difficulties associated with adjustable release from these systems by incorporating host molecules into the pore walls of thermoresponsive PPFs. β-Cyclodextrin-functionalized porous amphiphilic block copolymer films (β-CD-PBCPFs) with controllable pore parameters, high homogeneity, and large areas were prepared by combining the self-assembly and breath-figure methods. Drug-loaded β-CD-PBCPFs displayed thermoresponsive release behavior, which could be tuned by increasing the β-CD content in phosphate-buffered saline. The release was governed by the host-guest interactions of the β-CD moieties and drug molecules. The concept of host-guest interaction-enhanced adjustable release could be applied to different drug molecules, such as doxorubicin and metronidazole.

Mechanical, thermal and dielectric properties of BDM/DBA/HBPSi composites

N, N′-4, 4′-bimaleimide diphenyl methane (BDM), diallylbisphenol A (DBA) and hyperbranched polysiloxane (HBPsi) are performed to fabricate the BDM/DBA/HBPSi composites by one-step method. The contents of HBPSi affecting on the mechanical, thermal and dielectric properties of the BDM/DBA/HBPSi composites are investigated. Results show that the appropriate incorporation of HBPSi into BDM/DBA not only significantly improves the toughness, but also improves the heat resistance and dielectric properties of the BDM/DBA/HBPSi composites. The outstanding comprehensive properties of BDM/DBA/HBPSi composites indicate great potentiality in fabricating advanced polymeric composites.

Improvement of surface property of HMPBO fibers by polyphosphoric acid/absolute alcohol under ultrasonic vibration

The surface treatment of high modulus poly(p-phenylene-2,6-benzobisoxazole) (HMPBO) fibers was performed by using a solution of polyphosphoric acid (PPA)/absolute alcohol (EtOH) (1:1, vol:vol) under ultrasonic vibration. The chemical compositions, crystallinity, and surface morphologies of HMPBO fibers were characterized by contact angles, XRD, XPS, TGA, and SEM. Results showed that the hydrophilicity of treated HMPBO fibers was improved, and the contact angles between treated HMPBO fibers and water were decreased. The treated HMPBO fibers exhibited the slight reduction in the single fiber pull-out strength and crystallinity.

Fabrication of modified bismaleimide resins by hyperbranched phenyl polysiloxane and improvement of their thermal conductivities

Synthetic terminal amine group hyperbranched phenyl polysiloxane (NH2-HBPSi) is introduced into a bismaleimide/diallylbisphenol A (BMI/DABA) prepolymer to fabricate NH2-HBPSi/BMI/DABA resins. Furthermore, functionalized silicon carbide particle/silicon carbide whisker (fSiCp/fSiCw) hybrid fillers are also used to fabricate fSiCp/fSiCw/NH2-HBPSi/BMI/DABA thermal conductivity composites. A NH2-HBPSi/BMI/DABA resin with 20 wt% NH2-HBPSi is an ideal dielectric material with excellent impact strength and outstanding thermal stability, the corresponding dielectric constant (e) is 3.12, dielectric loss (tanδ) is 0.0098, impact strength value is 18.7 kJ m−2, glass transition temperature (Tg) value is 281 °C and the 5 wt% thermal weight loss temperature (T5) value is 424 °C. The thermal conductivities of the fSiCp/fSiCw/BMI/DABA and fSiCp/fSiCw/NH2-HBPSi/BMI/DABA composites are both increased with the increasing mass fraction of fSiCp/fSiCw hybrid fillers.