Strengthening Epoxy/High Impact Polystyrene Interfaces Using End Grafting Polymer Chains

1996 ◽  
Vol 461 ◽  
Author(s):  
Y. Sha ◽  
C. Y. Hui ◽  
E. J. Kramer ◽  
S. F. Hahn ◽  
C. A. Berglund
Keyword(s):  
Fracture Toughness ◽  
Chain Scission ◽  
High Impact ◽  
Polymer Chains ◽  
Interface Fracture ◽  
High Impact Polystyrene ◽  
Grafting Density ◽  
Interface Fracture Toughness ◽  
Chain Lengths ◽  
Intermediate Chain

AbstractThe fracture toughness Gc of epoxy/high impact polystyrene (HIPS) interfaces was measured as a function of grafting chain density Σ of dPS-COOH chains of various degrees of polymerization N. For short chains, no effective entanglements can be formed between the dPS chains and the PS matrix of the HIPS, thus no enhancement in Gc over that of a bare interface. For very long chains, even though each chain is well entangled with the HIPS, the maximum grafting density achievable is very low and such an interface fails by scission of the grafting chains so that the interface fracture toughness is also low. Large values of Gc are observed at intermediate chain lengths where both effective entanglements can be formed and a large Σ can be achieved. Under these conditions the interface fails initially due to the formation of crazes and the subsequent break down of one of these crazes at the interface. The transition areal chain density from chain scission to crazing, Σc,is independent of N.

scholarly journals INTERFACE FRACTURE TOUGHNESS ASSESSMENT OF SOLDER JOINTS USING DOUBLE CANTILEVER BEAM TEST

2010 ◽  
Vol 24 (01n02) ◽  
pp. 164-174 ◽  
Author(s):  
SHANE ZHI YUAN LOO ◽  
PUAY CHENG LEE ◽  
ZAN XUAN LIM ◽  
NATALIA YANTARA ◽  
TONG YAN TEE ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Solder Joint ◽  
Energy Release Rate ◽  
Release Rate ◽  
Double Cantilever Beam ◽  
Interface Reaction ◽  
Critical Energy ◽  
Interface Fracture ◽  
Critical Energy Release Rate ◽  
Interface Fracture Toughness

In the current work, a test scheme to evaluate solder joint interface fracture toughness using double cantilever beam (DCB) test has been successfully demonstrated. The obtained results, in terms of critical energy release rate, predict the joint failure based on the principle of fracture mechanics. The results can be used as a materials property in the reliability design of various types of solder-ball joined packages. DCB specimens made of 99.9 wt% copper were selected in the current work. Eutectic Sn -37 Pb and lead-free Sn -3.5 Ag -0.5 Cu solders were used to join two pieces of the copper beams with controlled solder thickness. The test record showed steady propagation of the crack along the solder / copper interface, which verifies the viability of such a testing scheme. Interface fracture toughness for as-joined, extensively-reflowed and thermally aged samples has been measured. Both the reflow treatment and the thermal aging lead to degradation of the solder joint fracture resistance. Reflow treatment was more damaging as it induces much faster interface reaction. Fractographic analysis established that the fracture has a mixed micromechanism of dimple and cleavage. The dimples are formed as a result of the separation between the hard intermetallic compound (IMC) particles and the soft solder material, while the cleavage is formed by the brittle split of the IMCs. When the IMC thickness is increased due to extended interface reaction, the proportion of IMC cleavage failure increases, and this was reflected in the decrease of the critical energy release rate.

An Innovative Technique for Bi-Material Interface Toughness Research

2004 ◽  
Author(s):  
John Jy-An Wang ◽  
Ian G. Wright ◽  
Ken C. Liu ◽  
Roy L. Xu
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Coefficient Of Thermal Expansion ◽  
Testing Procedure ◽  
Interface Fracture ◽  
Fracture Toughness Test ◽  
Coating Materials ◽  
Testing Procedures ◽  
Interface Fracture Toughness

A material configuration of central importance in microelectronics, optoelectronics, and thermal barrier coating technology is a thin film of one material deposited onto a substrate of a different material. Fabrication of such a structure inevitably gives rise to stress in the film due to lattice mismatch, differing coefficient of thermal expansion, chemical reactions, or other physical effects. Therefore, in general, the weakest link in this composite system often resides at the interface between the thin film and substrate. In order to make multi-layered electronic devices and structural composites with long-term reliability, the fracture behavior of the material interfaces must be known. Unfortunately, none of the state-of-the-art testing methods for evaluating interface fracture toughness is fully conformed to fracture mechanics theory, as is evident from the severe scatter in the existing data, and the procedure dependence in thin film/coating evaluation methods. This project is intended to address the problems associated with this deficiency and offers an innovative testing procedure for the determination of interface fracture toughness applicable to thin coating materials in general. Phase I of this new approach and the associated bi-material fracture mechanics development proposed for evaluating interface fracture toughness are described herein. The effort includes development of specimen configuration and related instrumentation set-up, testing procedures, and postmortem examination. A spiral notch torsion fracture toughness test (SNTT) system was utilized. The objectives of the testing procedure described are to enable the development of new coating materials by providing a reliable method for use in assessing their performance.

Microstructure based modeling of friction stir welded joint of dissimilar metals using crystal plasticity

2021 ◽  
pp. 1-29
Author(s):  
Shank Kulkarni ◽  
Timothy Truster ◽  
Hrishikesh Das ◽  
Varun Gupta ◽  
Ayoub Soulami ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Crystal Plasticity ◽  
Mg Alloy ◽  
Interface Fracture ◽  
Zone Model ◽  
Dissimilar Metals ◽  
Friction Stir ◽  
Az31 Mg Alloy ◽  
Interface Fracture Toughness

Abstract The friction stir welding (FSW) process shows promising results in joining dissimilar metals which are otherwise almost impossible to join using traditional welding techniques. Being a new technique, the deformation and the failure mechanism of the joints made by the FSW process needs to be investigated. In this work, a joint between AZ31 Mg alloy and DP590 steel is modeled using phenomenological crystal plasticity formulation on the mesoscale in the form of a representative volume element (RVE). The interface of the two materials is modeled using a cohesive zone model. A parametric study has been performed to understand the effect of grain size and interface fracture toughness as well as strength on the mechanical performance of the joint. It was found that the grain size of AZ31 Mg alloy, as well as DP590 steel, has little effect on the overall joint performance. On the other hand, interface fracture toughness and strength have a significant impact on the mechanical properties of the joint.

302 Effect of Hydrogen on Interface Fracture Toughness between Nano-film and Substrate

2009 ◽  
Vol 2009.84 (0) ◽  
pp. _3-2_
Author(s):  
Takeshi YAMADA ◽  
Yoshiki NOBUHARA ◽  
Masayuki SAKIHARA ◽  
Hiroyuki HIRAKATA ◽  
Kohji MINOSHIMA
Keyword(s):  
Fracture Toughness ◽  
Interface Fracture ◽  
Interface Fracture Toughness

Fracture toughness of high-impact polystyrene based on three j-integral methods

1993 ◽  
Vol 47 (10) ◽  
pp. 1867-1880 ◽  
Author(s):  
Chang-Bing Lee ◽  
Ming-Luen Lu ◽  
Feng-Chih Chang
Keyword(s):  
Fracture Toughness ◽  
High Impact ◽  
J Integral ◽  
High Impact Polystyrene ◽  
Integral Methods

A New Approach for Bimaterial Interface Fracture Toughness Evaluation

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
John Jy-An Wang ◽  
Ian G. Wright ◽  
Michael J. Lance ◽  
Ken C. Liu
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Lattice Mismatch ◽  
Coefficient Of Thermal Expansion ◽  
Test Method ◽  
Interface Fracture ◽  
Bimaterial Interface ◽  
Material Interfaces ◽  
Coating Materials ◽  
Interface Fracture Toughness

A material configuration of central importance in composite materials or in protective coating technology is a thin film of one material deposited onto a substrate of a different material. Fabrication of such a structure inevitably gives rise to stress in the film due to lattice mismatch, differing coefficient of thermal expansion, chemical reactions, or other physical effects. Therefore, in general, the weakest link in this composite system often resides at the interface between the thin film and the substrate. In order to make multilayered electronic devices and structural composites with long-term reliability, the fracture behavior of the material interfaces must be known. This project offers an innovative testing procedure of using a spiral notch torsion bar method for the determination of interface fracture toughness that is applicable to thin coating materials in general. The feasibility study indicated that this approach for studying thin film interface fracture is repeatable and reliable, and the demonstrated test method closely adheres to and is consistent with classical fracture mechanics theory.

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