Rheological Behavior of Silver Paste Prepared from Nanoparticles

2011 ◽  
Vol 327 ◽  
pp. 120-123
Author(s):  
Shi Yong Luo ◽  
Juan Chen ◽  
Wen Cai Xu ◽  
Xin Lin Zhang ◽  
Li Xia Huo

A paste with as low as 300°C sintering temperature was prepared by using nano silver particles and ethyl cellulose solution. The rheological and thixotropic behaviors of the typical paste were characterized and their effects on the screen printing ability were analyzed in details. The paste demonstrates a typical shear thinning rheological behavior and thixotropic of pseudoplastic fluid. The apparent viscosity decreased rapidly with the increase of the shear rate. The paste is proper for the manufacturing electrical components at a low temperature as low as 300°C.

2011 ◽  
Vol 391-392 ◽  
pp. 745-748
Author(s):  
Shi Yong Luo ◽  
Juan Chen ◽  
Wen Cai Xu ◽  
Xin Lin Zhang ◽  
Li Xia Huo

A paste with as low as 300°C sintering temperature was prepared by using nano silver particles and nitrocellulose ethyl acetate solution. The rheological and thixotropic behaviors of the typical paste were characterized and their effects on the screen printing ability were analyzed in details. The paste demonstrates a typical shear thinning rheological behavior and thixotropic of pseudoplastic fluid. The apparent viscosity decreased rapidly with the increase of the shear rate. The paste is proper for the manufacturing electrical components at a low sintering temperature as low as 300°C.


2012 ◽  
Vol 519 ◽  
pp. 252-255
Author(s):  
Jun Yan Zhao ◽  
Shi Yong Luo ◽  
Xin Lin Zhang ◽  
Wen Cai Xu ◽  
Man Zhao

Vacuum glass is a new building material with excellent energy conservation and sound insulation properties. Usually, the spacers between two pieces of flat glass substrates are mini-rings of metal. In the present research, the spacers were prepared with a glass dielectric paste by screen printing, and then sintered till them transparent. The glass dielectric paste for the preparation of transparent spacers of vacuum glass was prepared by using low melting glass powder and terpineol ethyl cellulose solution. The composition of the paste with preferable properties was evaluated as in mass percent: organic vehicle 20-25, and low melting glass powder 73-80. The rheological behaviors of the typical paste were characterized by using an ARES (RFS-III) rheometer. It is found that a weak flocculated network structure is formed in the paste for the high solid filler. The spacers were prepared by screen printing the paste on the glass substrate and then sintered. The transparent, Vickers hardness of the spacers as well as the binder forces between the spacers and the substrate is reported. The reliability of the prepared transparent spacers for the vacuum glass was discussed.


2014 ◽  
Vol 33 (1) ◽  
pp. 21-25
Author(s):  
Shiyong Luo ◽  
Xinlin Zhang ◽  
Xiaojun Huang ◽  
Wencai Xu

AbstractNanosilver 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 paste's 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.


2011 ◽  
Vol 284-286 ◽  
pp. 2230-2233
Author(s):  
Shi Yong Luo ◽  
Juan Chen ◽  
Wen Cai Xu ◽  
Li Xia Huo ◽  
Jun Yan Zhao

A lead free graphite conducting pastes were prepared by using graphite powder, lead free low-melting glass and terpineol ethyl cellulose solution. By analyzing the sheet resistance, Vickers hardness as well as the adhesion strength of the sintered film prepared by the pastes formulated with different composition, the composition of the paste with preferable properties was evaluated as in mass percent: organic vehicle 60, graphite powder 15~20, and low melting glass 20~25. The films, prepared by the pastes using the lead free glass with a glass transition temperature of 476°C, were perfectly flat and compact after fired at a peak temperature within the range from 520°C to 580°C. The sheet resistance of the fired film with glass content of 25wt% was 135Ω/mm2when the thickness of the film was 25±3μm, while the Vickers hardness and the binder force between the sintered film and the substrate were favorable. In addition, the rheological behaviors of the typical paste were characterized by using an ARES (RFS-III) rheometer. It is found that a weak flocculated network structure is formed in the paste for the high solid filler.


2012 ◽  
Vol 510 ◽  
pp. 13-17
Author(s):  
Yong Yan Cui ◽  
Zhen Lun Zhao ◽  
Ai Chao

The effect of dynamic vulcanization on mechanical, rheological, thermal properties and morphology of ABS were studied in this paper. And the effect of shear stress, shear rate on melt rheological behavior were discussed. The results showed that: the melt of dynamic vulcanization modified ABS was pseudoplastic fluid, and its apparent viscosity was increased. Tensile strength, notched impact strength of dynamic vulcanization modified ABS increased gradually, and the melt flow rate decreased gradually .


2020 ◽  
Vol 10 ◽  
Author(s):  
Rupali Singh ◽  
Rishabha Malviya

Background: The chronotherapy concept attains considerable focus towards itself due to its pulsatile fashion rather than continuous delivery. The delivery of the right amount of drug to the target organ at the most appropriate time is fulfilled by using the chronotherapeutic dosage form. Aim: The present study aims to develop and evaluate a chronotherapeutic drug delivery system by using natural polymer for time specific drug delivery at the target site. Material and Method: Tamarind seed polysaccharide was extracted and used in the preparation of core tablets. Nine formulations of core tablets were prepared with nifedipine at 5 tonnes of pressure on 6 mm punch. The core tablets were prepared by using the compression coating method. The three batches F1, F2 and F3 were prepared by using tamarind gum in different concentration i.e. 45%, 22.5% and 67.5% respectively and compressed at 8 tonnes of pressure on 12 mm of punch. The finally compressed tablet was coated with different concentrations of ethyl cellulose in which isopropyl alcohol used as a solvent. In a controlled medium, a stability study was performed to evaluate the physical appearance, drug content and release of the prepared core tablet. Result: All the nine formulations of tablets were prepared successfully and the evaluation studies (thickness, weight variation, hardness, friability etc.) revealed that all the formulations were within the official range. The release study of the drug revealed that the formulation F7 containing 67.5% of tamarind polymer, coated with 2%, 4% and 5% of ethyl cellulose solution released 59.68±1.03% (Q50%) drug within 5 h whereas, 87.09±2.08% (Q80%) within 6 h and within 12 h 97.74±2.19% of the drug was released. The formulation F7 was found to be more effective as it released the maximum amount of drug in a short period as compared with other formulations. Conclusion: The coating of core tablets allowed to prepare pharmaceutical dosage form for time specific drug delivery. These chronotherapeutic core tablets can be used for the treatment of angina pectoris and hypertension etc.


2015 ◽  
Vol 29 (10n11) ◽  
pp. 1540027 ◽  
Author(s):  
Jun Qin ◽  
Weijun Zhang ◽  
Zhuofeng Liu ◽  
Shuxin Bai

The purpose of the study is to characterize and improve the fundamental understanding of the effects of Ethyl Cellulose (EC) binder on the rheological properties of silver pastes for screen printing front electrode films of solar cells. Dispersions of silver particles (surface modified with oleic acid) in EC polymer solutions with and without thixotropic agent were prepared; and yield stress values were measured by setting shear stress to characterize the strength of interaction in pastes. Week flocculation network of silver particles is produced due to depletion of flocculation. EC polymer also has a significant interaction with thixotropic agent. Down-sweep flow curves of dispersions without thixotropic agent were measured and well fitted by Generalized Casson model. The model parameters p indicated that EC polymer with high molecular weight has a stronger shear-thinning ability. Steady-state flow, three interval thixotropy shear test (3ITT) and oscillatory measurements were conducted to study the effect of EC content on viscosity, structure rebuilding and viscoelastic properties of electrode pastes. Increasing EC polymer is not the best way to prevent the layer printed from laying down.


2020 ◽  
Vol 30 (1) ◽  
pp. 130-137
Author(s):  
Hengxiao Yang ◽  
Qimian Mo ◽  
Hengyu Lu ◽  
Shixun Zhang ◽  
Wei Cao ◽  
...  

AbstractTo describe uncured rubber melt flow, a modified Phan–Thien–Tanner (PTT) model was proposed to characterize the rheological behavior and a viscoelastic one-dimensional flow theory was established in terms of incompressible fluid. The corresponding numerical method was constructed to determine the solution. Rotational rheological experiments were conducted to validate the proposed model. The influence of the parameters in the constitutive model was investigated by comparing the calculated and experimental viscosity to determine the most suitable parameters. The uncured rubber viscosity was 3–4 orders larger than that of plastic and did not have a visible Newtonian region. Compared with the Cross-Williams-Landel-Ferry (Cross-WLF) and original PTT models, the modified PTT model can describe the rheological characteristics in the entire shear-rate region if the parameters are set correctly.


2011 ◽  
Vol 233-235 ◽  
pp. 1998-2001 ◽  
Author(s):  
Ming Zhao ◽  
Xiao Zhong Lu ◽  
Kai Gu ◽  
Xiao Min Sun ◽  
Chang Qing Ji

The rheological behavior of PA6/montmorillonite(MMT) by reactive extrusion was investigated using cone-and-plate rheometer. The experimental results indicated that PA6/MMT exhibited shear-thinning behavior. The shear stress of both neat PA6 and PA6/MMT increased with the increase in the shear rate. The reduction of the viscous activation energy with the increase of shear stress reflected PA6/MMT can be processed over a wider temperature.


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