Effect of Additive on Hardness and Brittleness in Polycarbonate Films

2007 ◽  
Author(s):  
Suresh Ahuja
Keyword(s):  
Molecular Weight ◽  
Elastic Modulus ◽  
Polymer Surfaces ◽  
Contact Deformation ◽  
Nano Indentation ◽  
Chain Mobility ◽  
Brittle Ductile Transition ◽  
Different Strains ◽  
Number Of Segments ◽  
Weight Number

Hardness and modulus of a polymer composite is known to depend on its structure, molecular weight, number of segments between entanglements and additives (filler). Nano-indentation is used increasingly as a powerful tool to determine hardness and visco-elastic modulus of polymer surfaces linear, cross-linked or composites. Hysitron Nanoindenter was used in our investigation of contact deformation of surfaces of filled polycarbonates supported on aluminum substrate. Bar coatings of polymer films were made from solution and dried all at 110C for half an hour. The results show that filled polycarbonate gives higher hardness than unfilled polycarbonate, which can give significantly different temperature dependence depending on molecular weight of the polycarbonate and structure of the filler. Depending on the type of filler and its concentration, the polycarbonate composite exhibits brittle-ductile transition at different strains. This behavior is analyzed in terms of chain mobility and free volume in the composite.

Effect of Interface and Depth on Hardness and Viscoelastic Modulus in Polycarbonate and Polyester Films

2007 ◽  
Author(s):  
Suresh Ahuja
Keyword(s):  
Molecular Weight ◽  
Elastic Modulus ◽  
Polymer Films ◽  
Dynamic Deformation ◽  
Polymer Surfaces ◽  
Contact Deformation ◽  
Nano Indentation ◽  
Viscoelastic Modulus ◽  
The One ◽  
Number Of Segments

Hardness and modulus of a polymer is known to depend on its structure, molecular weight and number of segments between entanglements. Nano-indentation is used increasingly as a powerful tool to determine hardness and visco-elastic modulus of polymer surfaces linear, cross-linked or composites. Hysitron Nanoindenter was used in our investigation of contact deformation of surfaces of polyester and polycarbonate supported on an aluminum substrate. Bar coatings of polymer films were made from solutions and dried all at 110C for half an hour. The coatings were subjected to indentation including sinusoidal deformation at various contact depths and hardness as well as modulus is computed. The results show that hardness of surface of polycarbonate on polyester is higher than hardness of surface of polycarbonate, which in turn is higher than polyester surface. It appears that diffusion of polyester chains into compatible polycarbonate chains results in higher modulus of the surface than the modulus of either of the two polymers. Hardness and modulus of polycarbonate is found to decrease with contact depth and reaches a plateau around 600nm while that of polyester keeps on decreasing. Differences in contact deformation including the one arising from dynamic deformation between polycarbonate from that of polyester is analyzed in terms of morphology, molecular weight and entanglements.

Elastic Modulus of Pb/Sn Solder Joints in Microelectronics

2002 ◽  
Author(s):  
Cemal Basaran ◽  
Jianbin Jiang
Keyword(s):  
Grain Size ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Solder Alloy ◽  
Ultrasonic Testing ◽  
Heterogeneous Materials ◽  
Testing Methods ◽  
Nano Indentation ◽  
Deformation Kinetics ◽  
Kinetics Of

Young’s modulus (E) values published in literature for the eutectic Pb37/Sn63 and near eutectic Pb40/Sn60 solder alloy vary significantly. One reason for this discrepancy is different testing methods for highly rate sensitive heterogeneous materials, like Pb/Sn alloys, yield different results. In this paper, we study different procedures used to obtain the elastic modulus; analytically, by single crystal elasticity and experimentally by ultrasonic testing and Nano indentation. We compare these procedures and propose a procedure for elastic modulus determination. The deformation kinetics of the Pb/Sn solder alloys is discussed at the grain size level.

Modelling the nano indentation behaviour of recast layer and heat affected zone on reverse micro EDMed hemispherical feature

2021 ◽  
pp. 1-15
Author(s):  
Tribeni Roy ◽  
Anuj Sharma ◽  
Prabhat Ranjan ◽  
R. Balasubramaniam
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Heat Affected Zone ◽  
Parent Material ◽  
Recast Layer ◽  
Machined Surface ◽  
Nano Indentation ◽  
Fea Simulation ◽  
Load Displacement ◽  
Good Agreement

Abstract Electrical discharge machined surfaces inherently possess recast layer on the surface with heat affected zone (HAZ) beneath it and these have a detrimental effect on the mechanical properties viz. hardness, elastic modulus, etc. It is very difficult to experimentally characterise each machined surface. Therefore, an attempt is made in this study to numerically calculate the mechanical properties of the parent material, HAZ and the recast layer on a hemispherical protruded micro feature fabricated by reverse micro EDM (RMEDM). In the 1st stage, nano indentation was performed to experimentally determine the load-displacement plots, elastic modulus and hardness of the parent material, HAZ and the recast layer. In the 2nd stage, FEA simulation was carried out to mimic the nano indentation process and determine the load-displacement plots for all the three cases viz. parent material, recast layer and HAZ. Results demonstrated that the load'displacement plots obtained from numerical model in each case was in good agreement with that of the experimental curves. Based on simulated load-displacement plots, hardness was also calculated for parent material, HAZ and the recast layer. A maximum of 11% error was observed between simulated values of hardness and experimentally determined values.

The Influence of Molecular Weight on the Orientation and Properties of Polymethyl Methacrylate Sheets

2018 ◽  
Vol 45 (2) ◽  
pp. 47-51
Author(s):  
I.D. Simonov-Emel'yanov ◽  
K.V. Shirshin ◽  
P.V. Motsinov ◽  
S.V. Vlasov
Keyword(s):  
Molecular Weight ◽  
Elastic Modulus ◽  
Polymethyl Methacrylate ◽  
Considerable Increase ◽  
Deformation Characteristics ◽  
Physicomechanical Characteristics

The influence of molecular weight on the process of orientation stretching and the combination of physicomechanical characteristics of specimens of polymethyl methacrylate (PMMA) is examined. Orientation stretching and increase in the molecular weight of PMMA from 0.52 to 4.6 × 106 g/mol lead to a considerable increase in strength and elastic modulus (σt by a factor of 2.6, E by a factor of 2.5). It is established that the deformation characteristics of oriented PMMA specimens increase by a factor of 10 when the molecular weight is increased from 0.52 to 4.6 × 106 g/mol, which opens up new possibilities in the processing of sheets and films of PMMA.

Research on Ceramic-Glass′s Brittle-Ductile Transition Based on Nano-Indentation Fatigue Experiment

2013 ◽  
Vol 33 (9) ◽  
pp. 0922004
Author(s):  
王景贺 Wang Jinghe ◽  
李顺增 Li Shunzeng ◽  
宋晓莉 Song Xiaoli ◽  
宋玮 Song Wei ◽  
王洪祥 Wang Hongxiang ◽  
...  
Keyword(s):  
Nano Indentation ◽  
Brittle Ductile Transition ◽  
Ceramic Glass ◽  
Indentation Fatigue ◽  
Fatigue Experiment

PEG Cross-Linked Alginate Hydrogels with Controlled Mechanical Properties

1998 ◽  
Vol 530 ◽  
Author(s):  
Petra Eiselt ◽  
Jon A. Rowley ◽  
David J. Mooney
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Molecular Weight ◽  
Elastic Modulus ◽  
Cell Transplantation ◽  
Cross Linking ◽  
Cross Link ◽  
Link Density ◽  
A Cell ◽  
Cross Link Density

AbstractReconstruction of tissues and organs utilizing cell transplantation offers an attractive approach for the treatment of patients suffering from organ failure or loss. Highly porous synthetic materials are often used to mimic the function of the extracellular matrix (ECM) in tissue engineering, and serve as a cell delivery vehicle for the formation of tissues in vivo. Alginate, a linear copolysaccharide composed of D-mannuronic acid (M) and L-guluronic acid (G) units is widely used as a cell transplantation matrix. Alginate is considered to be biocompatible, and hydrogels are formed in the presence of divalent cations such as Ca2+, Ba2+ and Sr2+. However, ionically cross-linked alginate gels continuously lose their mechanical properties over time with uncontrollable degradation behavior. We have modified alginate via covalent coupling of cross-linking molecules to expand and stabilize the mechanical property ranges of these gels. Several diamino PEG molecules of varying molecular weight (200, 400, 1000, 3400) were synthesized utilizing carbodiimide chemistry. Sodium alginate was covalently cross-linked with these cross-linking molecules, and mechanical properties of the resulting hydrogels were determined. The elastic modulus of the cross-linked alginates depended on the molecular weight of the cross-linking molecules, and ranged from 10-110 kPa. The theoretical cross-link density in the hydrogels was also varied from 3 to 47% (relative to the carboxylic groups in the alginate) and the mechanical properties were measured. The elastic modulus increased gradually and reached a maximum at a cross-link density of 15%. In summary, covalently coupled hydrogels can be synthesized which exhibit a wide range of mechanical properties, and these materials may be useful in a number of tissue engineering applications.

scholarly journals Chromatography of transforming deoxyribonucleic acid on methylated albumin and by gel filtration

1974 ◽  
Vol 137 (3) ◽  
pp. 543-546
Author(s):  
G. R. Barker ◽  
P. Hodges
Keyword(s):  
Molecular Weight ◽  
Bacillus Subtilis ◽  
High Molecular Weight ◽  
Deoxyribonucleic Acid ◽  
Degradation Products ◽  
Gel Filtration ◽  
Agarose Gel ◽  
Transforming Activity ◽  
Different Strains ◽  
Two Peaks

1. Native DNA from two strains of Bacillus subtilis was chromatographed by stepwise elution from MAK (methylated albumin on kieselguhr). 2. Transforming activity was confined to two out of the three main fractions, activity being distributed between the two peaks differently for DNA from the different strains. 3. Fractionation of DNA from both strains on 2% agarose gel gave two components. Approx. 75% of the material was eluted within the void volume of the column. Approx. 25% of the material consisted of degradation products of lower molecular weight. 4. Chromatography on MAK of the material of high molecular weight eluted from agarose gel gave a number of peaks differing in molecular weight, indicating that degradation of the DNA takes place during chromatography on MAK. 5. The distribution of transforming activity among the fractions from MAK suggests that degradation occurs preferentially in certain regions of the DNA.

Experimental Study on the Strength and Deformation Quality of Granite with Effect of High Temperature

2012 ◽  
Vol 226-228 ◽  
pp. 1275-1278 ◽  
Author(s):  
Xiao Li Xu ◽  
Feng Gao
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Reference Value ◽  
Effect Of Temperature ◽  
Rock Crystal ◽  
Brittle Ductile Transition ◽  
Strength And Deformation ◽  
Temperature Strain

Experiments on granite under uniaxial compression at high temperature of 25~850°C and after high temperature of 25~1300°C were conducted to study the effect of temperature on rock strength and deformation quality. The results show that: (1) Fitting curves between temperature strain and thermal expansion coefficient with temperature are closely first order growth exponential function relation at high temperature. Temperature strain has mutagenicity after high temperature, which can not reflect rock deformation law at high temperature exactly. (2)Mechanical properties of granite weak continuously at high temperature. Compressive strength and elastic modulus show second order attenuation trend of exponential law. But mechanical properties show mutation state after high temperature, which is closely related to the alteration of rock crystal form and brittle-ductile transition. Regression curves between compressive strength and elastic modulus with temperature are closely polynomial curve. The results reflect the fundamental regulation of granite’s interior structure changing under the action of different temperature, which will provide some reference value to rock engineering involved in high temperature.

Effect of Oxygen and Nitrogen Doping on Mechanical Properties of Silicon Using Nanoindentation

2004 ◽  
Vol 821 ◽  
Author(s):  
A. Karoui ◽  
G. Rozgonyi ◽  
T. Ciszek
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Nitrogen Doping ◽  
High Hardness ◽  
Near Surface ◽  
Nano Indentation ◽  
Subsurface Region ◽  
Float Zone ◽  
Effect Of Oxygen ◽  
Scratch Tests

AbstractThe effects of oxygen and nitrogen on the mechanical properties of Czochralski (CZ) and float zone silicon have been studied using nano-indentation. Nitrogen free FZ Si exhibited low hardness of 6.49 GPa and elastic modulus of 104 GPa. When doped with 2×1015cm−3 nitrogen, FZ Si hardness and elastic modulus increased to 8.2 and 182 GPa, respectively. In the near-surface denuded zone of N-doped CZ Si (N-CZ) the hardness correlates well with the O and N profiles. Distinct high hardness points, found in the O- and N- rich subsurface region, were attributed to precipitates. Nano-scratch tests of N-CZ Si confirmed the existence of hard phases, mostly small precipitates, whose density, estimated to be 2×1013cm−3, is in the range of previously suggested nuclei density in as-grown N-CZ silicon.

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