“…Creep is the time‐dependent behavior of the material under stress and reveals the usability of a polymer in long term application. Many researchers have shown their interest in creep behavior due to its practical importance in the applications for water/oil tanks, glass‐fiber‐reinforced polymer (GRP) pipes,1 extruded composite profiles2 and bottles/containers 3. High temperature creep test is being used in foam industry, where the polyolefin foam is used, e.g., for camping mats.…”
An ethylene‐octene copolymer (EOC) (45 wt% octene) is crosslinked using dicumyl peroxide (DCP). Differential scanning calorimetry (DSC) reveals a very low melting temperature (50 °C). The network density is evaluated by gel content. While 0.2–0.3 wt% of peroxide leads only to a molecular weight increase (samples completely dissolved in xylene), 0.4–0.6 wt% of peroxide caused network formation. High‐temperature creep was measured at 70, 120, and 200 °C at three stress levels. At 200 °C and above 0.6 wt% of peroxide, degradation due to chain scission is observed by rubber process analyzer (RPA) and is again supported by creep measurements. Residual strain at 70 °C is found to improve with increasing peroxide level. Dynamic mechanical analysis (DMA) reveals a strong influence of peroxide content on storage modulus and tan δ, in particular in the range 30–200 °C.
“…Creep is the time‐dependent behavior of the material under stress and reveals the usability of a polymer in long term application. Many researchers have shown their interest in creep behavior due to its practical importance in the applications for water/oil tanks, glass‐fiber‐reinforced polymer (GRP) pipes,1 extruded composite profiles2 and bottles/containers 3. High temperature creep test is being used in foam industry, where the polyolefin foam is used, e.g., for camping mats.…”
An ethylene‐octene copolymer (EOC) (45 wt% octene) is crosslinked using dicumyl peroxide (DCP). Differential scanning calorimetry (DSC) reveals a very low melting temperature (50 °C). The network density is evaluated by gel content. While 0.2–0.3 wt% of peroxide leads only to a molecular weight increase (samples completely dissolved in xylene), 0.4–0.6 wt% of peroxide caused network formation. High‐temperature creep was measured at 70, 120, and 200 °C at three stress levels. At 200 °C and above 0.6 wt% of peroxide, degradation due to chain scission is observed by rubber process analyzer (RPA) and is again supported by creep measurements. Residual strain at 70 °C is found to improve with increasing peroxide level. Dynamic mechanical analysis (DMA) reveals a strong influence of peroxide content on storage modulus and tan δ, in particular in the range 30–200 °C.
“…Other researchers have observed creep within this time frame of several hours for HDPE, but at three times the loading. 23 Since the creep rate increases significantly as the pre-stress approaches the yield strength, it appears that this effect is negligible within the conditions of our tests. We do not have the ability to measure sample expansion along the thickness of the sample and cannot rule it out.…”
Degradation of material properties by high-pressure hydrogen is an important factor in determining the safety and reliability of materials used in high-pressure hydrogen storage and delivery. Hydrogen damage mechanisms have a time dependence that is linked to hydrogen outgassing after exposure to the hydrogen atmosphere that makes ex situ measurements of mechanical properties problematic. Designing in situ measurement instruments for high-pressure hydrogen is challenging due to known hydrogen incompatibility with many metals and standard high-power motor materials such as Nd. Here we detail the design and operation of a solenoid based in situ tensile tester under high-pressure hydrogen environments up to 42 MPa (6000 psi). Modulus data from high-density polyethylene samples tested under high-pressure hydrogen at 35 MPa (5000 psi) are also reported as compared to baseline measurements taken in air.
“…However, polymers can exhibit a complex nonlinear behavior due to external factors such as strain rate, temperature and hydrostatic pressure (stress triaxiality). This behavior was the subject of various experimental studies [2][3][4]. High-density polyethylene (PE-HD) is one of the widely utilized polymers in a diversity of industrial applications due to its multiple advantages that it has over more conventional materials.…”
Abstract. Despite numerous studies on fatigue of polymer materials under variable loading, there is little work on highdensity polyethylene (PE-HD). In this context, an experimental analysis for determining the fatigue strength of PE-100, under constant and variable amplitude loading is presented. Further, the cumulative fatigue damage behavior of PE-100 was experimentally investigated. First, the fatigue curve (S-N: stress vs. number of cycles) was obtained in order to establish the fatigue life of PE-100 subjected to constant stress amplitude. Secondly, Miner's fatigue rule as well as stress-based and energy-based fatigue damage models were used to estimate the cumulative variable amplitude fatigue damage. Comparison between predictions and experimental results showed different trends depending on the choice of prediction model used implying careful fatigue damage consideration when designing under variable amplitude loading.
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