Xinlin Zhang

Influence of Glycerol on Potato Starch-Based Biodegradable Packaging Films

Low price of potato starch as a wide range of sources of biodegradable packaging film substrate, glycerol as a plasticizer, polyvinyl alcohol as a film-forming agent, potato starch-based biodegradable packaging films were prepared by solution casting. Tests were run on potato starch-based biodegradable packaging films to determine mechanical properties, transparency, and color evaluation. It was observed that the increase of the glycerol content in the films increased the macromolecular mobility, and the potato starch films became less stiff and more flexible. Meanwhile, the transparency was decreased obviously.

Preparation and rheological behaviors of a nano-yttria anti-bonding paste

Anti-bonding pastes are used on areas that should not be welded during superplastic forming/diffusion bonding processes in multi-layer, complex metal structures. We prepared a nano-Y2O3 anti-bonding paste to prevent the coated anti-bonding paste from flowing to unwanted areas and to improve the thickness uniformity of the coated paste. Nano-spherical Y2O3 powders with a purity of more than 99.99 wt% and a narrow size distribution of 50 to 100 nm were prepared by liquid precipitation followed by sintering. The relationship between the rheological behaviors and dispersion structure of both pastes with and without 1.5 wt% rheology control additive was analyzed in detail. The results indicated that a strong three-dimensional network flocculation structure had formed in the pastes, especially in those with a rheology control additive. The resulting large yield stress, high thixotropy, and solid-like elastic behavior of the paste are favorable for maintaining the original coated shape and offer long-term stability, but are unfavorable for the screen printing (coating) process and thickness uniformity. To solve these problems, a high printing pressure and the use of a screen with high tension and large mesh count (325 mesh) could be adopted. The thermal analysis results show that the paste after SPF/DB processing was easy to clear with no negative influence on the process.

Low-Temperature Sintering of Nanosilver Paste on a Gold Film Surface

Abstract Nanosilver paste with a low sintering temperature is a high-demand interconnection material for electronic devices and components due to its superior electrical, thermal, and thermomechanical properties, as well as the fact that it is lead free. This study presents a nanoscale silver paste that can be sintered at 300 °C using 60-nm silver particles and an ethyl cellulose solution. The rheological and thixotropic behaviors of the typical paste were characterized, and the pastes screen printing ability was analyzed in detail. The paste demonstrates typical shear thinning rheological behavior and thixotropy of pseudoplastic fluids. Thermal characteristics of the 60 nm silver particles were measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to obtain a proper sintering temperature schedule. In this report, we also discussed the solid content, thermodynamic driving force for densification, and sintering process of the nanosilver particles. A 83 wt% of silver solid content at a heating rate of 20 °C/min was favorable for achieving a proper sintering densification.

Rheological Behaviors of the Glass Paste for Hermetic Sealing the Edge of the Vacuum Glazing

Abstract Vacuum glazing is a new building material with excellent energy conservation and sound insulation properties. Usually, the edge sealing layer between two sheets of glass substrates is prepared by spraying the seal glass paste and then sintering. In the present research, a more effective preparation method is reported. The edge sealing layer is prepared with a glass paste by screen printing and then sintering. The glass paste for the preparation of edge sealing layer of vacuum glazing was composed of low melting glass powder, ZrW2O8 powder with negative coefficient of thermal expansion and ethyl cellulose terpineol solution. The rheological, thixotropy and the screen printing behaviors of the typical paste were characterized and discussed. To get a thicker as-printed layer, the paste has high solid content and little thixotropy. The typical paste behaves a typical rheological behavior of pseudoplastic fluid. The test result of the shear strength of the sealing layer indicated that the sealing is reliable.