عنوان

Molecular and rheological studies to understand slow crack growth in polyethylene pipe grade materials

Number

TL48309

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Molecular and rheological studies to understand slow crack growth in polyethylene pipe grade materials

General Material Designation

[Thesis]

First Statement of Responsibility

Joel Elias Fawaz

Subsequent Statement of Responsibility

Mittal, Vikas

Name of Publisher, Distributor, etc.

The Petroleum Institute (United Arab Emirates)

Date of Publication, Distribution, etc.

2014

Specific Material Designation and Extent of Item

101

Text of Note

Committee members: Alhassan, Saeed; Wang, Kean

Text of Note

Place of publication: United States, Ann Arbor; ISBN=978-1-321-96058-7

Dissertation or thesis details and type of degree

M.S.

Discipline of degree

Chemical Engineering

Body granting the degree

The Petroleum Institute (United Arab Emirates)

Text preceding or following the note

2014

Text of Note

Slow crack growth (SCG) is a time-dependent brittle-type failure that polyethylene (PE) pipes suffer from when under low stress levels. In order to achieve a required lifetime of minimum 50 years, a deep understanding of material's properties is needed. The general accepted mechanism of SCG heavily depends on the degree of entanglement and tie molecules present in the material. Therefore, the long-term mechanical properties are influenced by the molecular properties such as molecular weight and distribution, comonomer content, branching, and degree of crystallinity. The purpose of this project is, thus, to understand and correlate the properties of 6 PE samples (materials A, B, C, P, E and F) with their SCG resistance property. Various characterization instruments were used to conduct the study; according to its objectives (rheological, thermal, molecular and morphological analyses). Normalized SCG properties were obtained from the crack round bar (CRB) test, strain hardening (SH) test and notched pipe test (NPT). From the different analyses conducted, the highest SCG resistance of material F was explained. Moreover, several correlations with SCG were determined; such as: increasing the molecular weight and its distribution, short chain branches, comonomer content and length, lateral lamellar area and zero shear viscosity will increase the SCG resistance and its subsequent time to failure. This was attributed to the enhanced interlamellar entanglement and tie molecules that resist deformation for a longer time. In addition, SCG resistance was found to decrease with decreasing lamella thickness and degree of crystallinity (within similar molecular weight range). In order to elaborate more on this project, a list of future work actions were recommended by the end of this report.

Polymer chemistry; Chemical engineering; Plastics

Subject Term

Pure sciences;Applied sciences;Crystallinity;Mechanical properties;Polyethylene;Structure-property correlations

Koren, Toni

Mittal, Vikas

Subdivision

Chemical Engineering

The Petroleum Institute (United Arab Emirates)

Call Number

1703434126; 1596162

Electronic name

p

[Thesis]

276903

a

Y