Additional Information - Posters
Plastic Pipes Conference Association # 2006 Washington DC
Niebergall, Mertlova, Nezbedova
Full Notch Creep Test (FNCT) is widely used to characterize the slow crack growth behavior of particularly pipe and blow moulding PE materials, especially in Europe. However, the validity of the FNCT data is not satisfactory, as the results show large variability so far. Among other SCG tests, which exist and are used nowadays, the FNCT method has been selected for standardization as a relatively simple and still sensitive SCG test method to characterize primarily PE materials (not products), to give fully comparable data. The method should be feasible to perform for common labs of PE material manufacturers, processors, testing institutes, etc. The ISO 16770 has been developed by ISO TC 61/SC 9/WG 6 Polyolefins and published in 2004. After publication, precision data were to be investigated for incorporation into the standard. Therefore, several round robin tests (RRT) have been organized by ISO working group to obtain the necessary data.
Related papers
Author(s) : Pavel Hutař, Jan Poduška, Jaroslav Kučera, Eva Nezbedová, Andreas Frank, Jiří Sadílek, Gerald Pinter
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...
Author(s) : Andreas Frank, Gerald Pinter, Mridula Kapur, E. Nezbedová
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...
Author(s) : E.Nezbedova
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 years...
Author(s) : Nezbedova, Vlach, Knesl
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...
Author(s) : Sindelar, Nezbedova, Buran
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...
Author(s) : Eva Nezbedová, Pavel Šindelář and Petr Bohatý
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...
Author(s) : Nezbedova, Zahradnickova, Salajka
High-density polyethylene (HDPE) is being used more and more in critical long-term application, such as in pipes for the distribution of water and gas. For this reason it is important to have a strong understanding of those parameters which control the fracture behaviour of HDPE. The main parameters are : i. Chain...
Author(s) : Nezbedova, Salajka, Kucera
Structural and morphological parameters together with processing conditions determine the type of fracture behaviour of polyethylenes. Long time brittle failure which occurs under low stresses and at room temperature limits the lifetime of polyethylens used as pipes for water and gas distribution. In order to...
Author(s) : Nezbedova, Knesl, Sestakova, Vlach
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