scholarly journals Correlation of molecular parameters, strain hardening modulus and cyclic fatigue test performances of polyethylene materials for pressure pipe applications

2017 ◽  
Vol 62 ◽  
pp. 246-253 ◽  
Author(s):  
Suleyman Deveci ◽  
Dongyu Fang
Keyword(s):  
Strain Hardening ◽  
Fatigue Test ◽  
Cyclic Fatigue ◽  
Molecular Parameters ◽  
Pressure Pipe ◽  
Hardening Modulus

scholarly journals Comparison of the cyclic fatigue resistance of ProGlider, PathGlider and One G path-finding instruments

2019 ◽  
Vol 13 (1) ◽  
pp. 57-60
Author(s):  
Damla Özsu Kırıcı ◽  
Ertuğrul Karataş ◽  
Ahmet Demirhan Uygun ◽  
Ezgi Doğanay Yıldız ◽  
Kezban Meltem Çolak ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Test ◽  
Fatigue Resistance ◽  
Root Canal ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Curvature Radius ◽  
System A ◽  
Post Hoc ◽  
G 14

Background. The aim of the present study was to compare the cyclic fatigue resistance of novel nickel titanium rotary pathfinding instruments. Methods. Twenty instruments were selected for each file system. A simulated stainless steel root canal, with a 90° angle of curvature and a curvature radius of 3 mm, was used for cyclic fatigue test of the ProGlider (#16, progressive taper: 0.02‒ 0.085), PathGlider (#15, taper: .03), and One G (#14, taper: .03) instruments. Statistical analyses were performed with oneway ANOVA (P=0.05). Post hoc Tukey tests were used to determine any statistically significant differences between the groups. Results. The ProGlider instruments exhibited significantly more cyclic fatigue resistance than both PathGlider and One G instruments (P<0.001). One G instruments had significantly more resistance to fracture than PathGlider instruments (P<0.05). Conclusion. ProGlider instruments had better cyclic fatigue resistance than PathGlider and One G instruments.

scholarly journals Application of short-term methods to estimate the environmental stress cracking resistance of recycled HDPE

2020 ◽  
Vol 27 (11) ◽  
Author(s):  
Anna Gobetti ◽  
Giorgio Ramorino
Keyword(s):  
Environmental Stress ◽  
Strain Hardening ◽  
Draw Ratio ◽  
Slow Crack Growth ◽  
High Rate ◽  
Mechanical And Thermal Properties ◽  
Cracking Resistance ◽  
Stress Cracking ◽  
Hardening Modulus ◽  
Environmental Stress Cracking

AbstractEnvironmental stress cracking is a serious problem for polyethylene because it can cause failure without any visible warning due to the slow crack growth accelerated by aggressive agents. Tie molecules and entanglements are the main macromolecular characteristic increasing environmental stress cracking resistance, thus in this work mechanical and thermal properties governed by those macromolecular characteristics are determined by performing simple tests executable in the industrial laboratories for quality control on recycled high-density polyethylene. The mutual relation between the determined properties confirms their dependence on the investigated macromolecular characteristics and allows to predict in a comparative way the expected environmental stress cracking. The mechanical properties related to the environmental stress cracking resistance are the strain hardening modulus and the natural draw ratio. The strain hardening modulus is an intrinsic property that measure the disentanglement capability of the inter-lamellar links and the natural draw ratio is a highly sensitive parameter to the macromolecular network strength via the intercrystalline tie molecules. Since the measurement of these properties according to the standard ISO 18,488 requires a temperature chamber not often available in the industrial laboratories, the tensile test was performed also at room temperature and displacement rate 0.5 mm/min; a proportionality between the data obtained at different test condition emerged. The thermal property related to the environmental stress cracking resistance is the stepwise isothermal segregation ratio that state the chain fraction that generates a high rate of tie molecules responsible of environmental stress cracking resistance.

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