EFFECT OF STRUCTURAL PARAMETERS ON RCP IN POLYETHYLENE

Fracture - RCP # 2004 Milan

Changing the catalyst composition, it allowed us to alter placement of comonomer from lower to higher polymer molecular weight fractions together with a certain reduction of molecular weight distribution (MWD). Using this catalyst several polymer samples differing in level of branching, in comonomer unit placement and in MWD broadness were prepared on plant facility. These polymer samples were then used to study relationship between material structure and critical pressure below which RCP does not occur. Several analytical methods were employed in the polymer samples evaluation (TREF, SIS/DSC, IR) and results of these techniques were correlated with polymer performance characteristics obtained from S4 test, notch pipe test (NPT) and modified Charpy test (PSI - plane stress impact). The correlation between the fracture and structural parameters has been found. Further more, the decisive structure of the polymer matrix for high resistance against RCP has been proposed.

Please note that the whole article content is available on PPCA website onlySource : 2004 Milan


Related papers

MULTILAYER POLYMER PIPES - POSSIBLE UTILIZATION OF RECYCLED MATERIAL

Author(s) : Pavel Hutar, Jan Poduska, Pavol Dlhy, Andreas Frank, Jaroslav Kucera, Jiri Sadilek, Gerald Pinter, Lubos Nahlik 2018 Las-Vegas

This paper investigates possible use of recycled material as a part of a multilayer polyethylene pressure pipe system. Crack propagation in different configurations is simulated. Lifetimes of pipes containing recycled material are calculated. Results are compared with lifetimes of pipes made of virgin...

THE USE OF TEMPERATURE, LUBRICATION, AND SUPPLIED HYDRAULIC PRESSURE IN THE PRODUCTION OF ORIENTED PVC PIPE

Author(s) : Jie Feng, Michael Petr, Jeff Wenzel, Mark Mirgon, Sam Crabtree, Alan Nakatani 2018 Las-Vegas

Through tensile tests, simulated orientation, tribology, and finite element analysis, this study explored the effect of temperature, lubrication and applied hydraulic pressure in the PVC orientation process. It was demonstrated that tight control of these parameters is critical in a continuous PVC orientation process...

LIFETIME PREDICTION OF PE100 AND PE100-RC PIPES BASED ON SLOW CRACK GROWTH RESISTANCE

Author(s) : Andreas Frank, Isabelle J. Berger, Florian Arbeiter, Pavel Hutař, Gerald Pinter 2016 Berlin

Due to the high slow crack growth resistance of modern polyethylene pipe grades a reliable lifetime assessment of pipes with focus on stage II failure has become challenging. The current paper presents a scientific approach for a fracture mechanics lifetime prediction based on Cyclic Cracked Round Bar (CRB) Tests....

RESIDUAL STRESS DISTRIBUTION IN THE EXTRUDED POLYOLEFIN PIPES

Author(s) : Pavel Hutař, Jan Poduška, Jaroslav Kučera, Eva Nezbedová, Andreas Frank, Jiří Sadílek, Gerald Pinter 2016 Berlin

Residual stresses can significantly influence the lifetime of polymer pipes. Therefore, realistic estimation of residual hoop stress can contribute to accurate lifetime estimations. The previously used “accurate method” is quite time consuming and needs a lot of specimens to be prepared and treated. A simplified...

Polypropylene Multi Layer Pipe Lifetime Assessment Under Realistic Loading Conditions

Author(s) : Florian Arbeiter, Martin Ševčík, Gerald Pinter, Frank Andreas, Pavel Hutař 2014 Chicago

Multi-layer pipes made from polypropylene have been widely used in sewerage applications for several years. Due to good material properties and generally low mechanical loads not many critical failures occur. Aim of this work is to determine, whether slow crack growth, consisting of crack initiation and crack growth,...

COMPARISON OF ACCELERATED TESTS FOR PE GRADES LIFETIME ASSESSMENT

Author(s) : Andreas Frank, Gerald Pinter, Mridula Kapur, E. Nezbedová 2012 Barcelona

Results from cracked round bar tests (CRB) and pennsylvania notch tests (PENT) for several polyethylene (PE) pipe grades are compared. The CRB tests were conducted at 23 °C and 80 °C, the PENT tests only at 80 °C. A material ranking based on the CRB tests was in good accordance to PENT failure times, although a...

EFFECT OF THE RESIDUAL STRESSES ON THE SLOW CRACK GROWTH

Author(s) : Pavel Hutař, Martin Ševčík, Jaroslav Kučera, Michal Zouhar, Robin Luky, Luboš Náhlík 2012 Barcelona

Using linear elastic fracture mechanics a new methodology for a lifetime assessment of internally pressurized polymer pipes was developed. The concept is based on the numerical calculation of stress intensity factors for pipes under different loading conditions in combination with experimentally determined creep crack...

PENT test versus time to rupture curve for HDPE

Author(s) : E.Nezbedova 2010 Vancouver

The service life for HDPE (PE 80, PE 100) materials used in plastic pipes application covers a time span of up 50 years. The new type of PE 100 (PE 100 RC) should achieve the life time over 100 years. Conventional hydrostatic pressure test to qualify a new resin must last 104 hours (ISO 1167). In the last twenty...

Analysis of the Fracture Behaviour of Multi-Layer Pipes

Author(s) : Nezbedova, Vlach, Knesl 2006 Washington DC

A multilayer pipe consisting of two different layers, namely of PE and PPH, was analysed. The relevant numerical model based on the Finite Element Method (FEM) was used to calculate the stress and strain distribution and to estimate the fracture characteristics. As variables the thickness of the material layers and...

Effect of Processing on the Lifetime of Pipe HDPE Grade

Author(s) : Sindelar, Nezbedova, Buran 2006 Washington DC

The influence of processing conditions on molecular structure and microstructure of highdensity polyethylene pipe material has been studied. By modifying the segment arrangement and package of additives, conditions during pelletising in the extruder have been changed. Structural analyses obtained by gel permeation...

Members of the Association

BOREALISBOROUGEINEOS O&PIRPCKorea Petrochemical IND. Co., LTDLyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE
TOP