Acoustic Characterization Of Sudan Black Nanobubbles For Multimodal Ultrasound & Photoacoustic Imaging

Dyed, shelled, nanobubbles (NBs) have recently been proposed as contrast agents for multimodal ultrasound-photoacoustic (US-PA) imaging. However, changes to the shell composition due to the presence of the dye can modify the response of bubbles to ultrasound. In this work, the effects of the dye, Sudan Black B, on a formulation of lipid shelled NBs are studied. Formulations were produced with increasing concentration of Sudan Black B. The size and concentration of activated NBs were tested. The surface tension of bulk lipid solution was measured using pendant drop tensiometry and activated bubble solutions were measured for single bubble and bubble population response to incident ultrasound. While results show no statistically significant effect of Sudan Black concentration on bubble concentration or size, surface tension increased linearly with dye concentration to a maximum increase of 13%. With the addition of Sudan Black B, single bubble experiments show an increase in the contribution of bubble growth signals, a decrease in contribution of nonlinear signals, and a decrease in bubble destruction. The results presented in this work indicate that the presence of Sudan Black B in the lipid shell of a nanobubble may increase the shell permeability impacting stability of the bubble population and their potential for multimodal US-PA imaging.

Acrylonitrile-Styrene-Acrylate Particles with Different Microstructure for Improving the Toughness of Poly(styrene-co-acrylonitrile) Resin

Herein, acrylonitrile-styrene-acrylate copolymer (ASA) particles with different microstructure were synthesized by emulsion polymerization and then used for toughening poly(styrene-co-acrylonitrile) (SAN) resin. The structure of ASA particles was confirmed by FTIR. TEM results demonstrated that the particles with different morphologies of multilobe shape, complete core-shell and dumbbell shape were obtained depending on the cross-linker amount. It was found that the toughening efficiency reached the highest when the ASA particles had complete core-shell structure and the shell composition was close to that of the SAN matrix. It was ascribed to the fact that the complete shell layer and similar shell composition provided sufficient interfacial adhesion and transferred stress to induce larger matrix deformation, so that the notched impact strength increased accordingly. Moreover, the notched impact strength of SAN/ASA blend was improved without significantly sacrificing tensile strength when adding 30 wt% ASA particles with the size of around 400 nm. SEM results of the impact-fractured surfaces revealed that irregular fluctuation and numerous microvoids occurred. It was deduced that the toughening mechanism was attributed to the crazings and cavitation of particles. Therefore, this study paved a way of toughening the resin by adjusting the microstructure of the particles including morphology, composition, and size.

Mechanical properties of coconut shell particle board using epoxy resin adhesive

Abstrak. Papan partikel merupakan komposit yang tersusun dari filler (penguat) dan matriks (pengikat). Papan partikel dapat dibuat dari bahan limbah pertanian yang mengandung selulosa seperti tempurung kelapa. Penelitian ini menggunakan limbah tempurung kelapa sebagai filler dan resin epoksi (RE) sebagai matriks. Penelitian dilakukan dengan memvariasikan ukuran partikel tempurung kelapa (60, 80, 100 dan 120 mesh) dan komposisi filler tempurung kelapa:perekat RE (70:30, 75:25, 80:20, dan 85:15 vol.%) untuk memperoleh sifat mekanik yang terbaik. Sifat mekanik yang diuji adalah modulus of elasticity, modulus of rupture, dan kuat tekan. Sifat mekanik papan partikel diuji sesuai standar ASTM. Hasil penelitian menunjukkan bahwa sifat mekanik menurun dengan bertambahnya komposisi tempurung kelapa. Namun sifat mekanik meningkat dengan mengecilnya ukuran partikel dari 60 ke 120 mesh. Papan partikel yang dihasilkan memenuhi persyaratan ANSI untuk ukuran partikel 120 mesh, komposisi tempurung kelapa 80 vol.%, dan RE 20 vol.%.Abstract. Particle board is a composite composed of filler (reinforcement) and a matrix (binder). Particle board can be made of agricultural waste material containing cellulose such as a coconut shell. This study used coconut shell particles as a filler and epoxy resin (RE) as a matrix. The research was conducted by varying the particle size of coconut shells (60, 80, 100 and 120 mesh) and the composition of coconut shell fillers:RE adhesive (70:30, 75:25, 80:20, and 85:15 vol.%) to obtain the best mechanical properties. The mechanical properties tested were modulus of elasticity, modulus of rupture, and compressive strength. Particleboard was tested according to ASTM standards. The results showed that the mechanical properties decreased with increasing coconut shell composition. However, the mechanical properties increased as the particle size decreased from 60 to 120 mesh. The resulting particle board meets ANSI requirements for a particle size of 120 mesh, 80 vol.% of coconut shell composition, and 20 vol.% of RE. Keywords: Coconut Shell, Epoxy Resin, Mechanical Properties, Particle Board