Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The stu... more Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The study examined the influences of primer and its major component, acetone, on CPVC’s mechanical properties. Two types of CPVC product, sheet and pipe, were used in the mechanical testing. Sheet specimens were immersed in acetone or primer for 40 and 10 min, respectively, i.e., the maximum allowable time without mass loss, and then dried in air before the mechanical testing. Pipe (ring) specimens were treated either through immersion in acetone or primer for 30 min or in contact with these solvents locally on the inner surface for 2.5 h, and then air dried for 10.5 days before the mechanical testing. Results showed that CPVC’s strength decreased after the absorption of these solvents, and air dry could remove acetone but not completely primer. The study also showed that pipe specimens by local contact with primer could generate brittle fracture. In view that sheet specimens always fractured i...
A novel multi-relaxation-recovery (RR) test was proposed based on cyclic stages of stress relaxat... more A novel multi-relaxation-recovery (RR) test was proposed based on cyclic stages of stress relaxation and stress recovery. Three nonlinear visco-elastic models, that is, the standard model and two models with two dashpots connected either in parallel or in series, were examined for the analysis of the test results. Each model contains a time-dependent, viscous branch and a time-independent, quasi-static branch. The examination suggests that the standard model can determine the long-term, load-carrying performance of polyethylene (PE) and identify a transition point for the onset of plastic deformation in the crystalline phase, but the models with two dashpots connected either in parallel or in series are needed to provide a close simulation of the experimentally measured stress response in both relaxation and recovery stages of the RR test. In this work, the mechanical performance of two PEs was compared based on RR test results at room temperature. The RR tests were also conducted a...
The multi-relaxation (MR) test was developed based on the concept that stress relaxation behavior... more The multi-relaxation (MR) test was developed based on the concept that stress relaxation behavior can be used to reflect the material state of polyethylene (PE) under tension. On the basis of this concept, critical stroke for the onset of plastic deformation in the crystalline phase, named the first critical stroke, was determined using the MR test. Results from wide angle X-ray scattering suggest that phase transformation occurred in the crystalline phase of PE after the specimen was stretched beyond the first critical stroke. In this work, the MR test was applied to six PEs of different mass densities to determine their first critical strokes and the corresponding total and quasi-static (QS) stress values. The results show that the first critical stroke had very similar values among the six PEs. More interestingly, the ratio of the QS stress at the first critical stroke to the yield stress from the standard tensile test showed little dependence on PE density. Therefore, it was pos...
... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lo... more ... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lowe 1 , ... Raman spectra were obtained using a Renishaw Raman Imaging Microscope, model 2000 with a 718 nm NIR laser source. ...
Tensile strength of polyethylene is examined at various crosshead speeds using cylindrical specim... more Tensile strength of polyethylene is examined at various crosshead speeds using cylindrical specimens of 20 mm in gauge length. Through monotonic stretch with intermittent halt for load relaxation, the study shows that long-term tensile strength of polyethylene should be around half of the short-term strength determined in the standard test conditions. The study discovers a transition in the localized deformation (commonly known as necking), of which the appearance changes from opaque white to translucent when the crosshead speed is reduced from 0.05 to 0.01 mm/min, possibly due to the suppression of cavitation damage at the low crosshead speed. At a sufficiently high crosshead speed, damage generation can occur at a threshold strain as low as 4% which is way below the yield strain of the material. It is therefore concluded that determining long-term tensile strength of polyethylene needs to consider accumulation of the damage. Since this type of damage is not quantified in any of cu...
A new test method has been developed to evaluate environmental stress cracking resistance (ESCR) ... more A new test method has been developed to evaluate environmental stress cracking resistance (ESCR) for polyethylene (PE). The new test method applies transverse loading to the central area of a plate specimen, to generate local stretch that results in a truncated cone. Time for crack initiation in the truncated cone, during the exposure to an aggressive agent (10% Igepal CO-630 solution), is used to characterize ESCR. Results from the new test method are consistent with those from ASTM D1693, but the former does not require any pre-notch and takes less than 3% of the time required for the latter. Based on the new test method, a stand-alone device has been developed to characterize ESCR, which uses change in electrical conductivity to measure the time for the crack development. The device is compact and easy to operate. Using this device, time for crack initiation can be determined automatically and accurately without the use of a commercial test machine.
Quasi-static stress–strain relationship of polyethylene (PE) pressure pipe that plays an importan... more Quasi-static stress–strain relationship of polyethylene (PE) pressure pipe that plays an important role on its long-term performance has been established by removing the viscous stress component from the experimentally measured total stress. Work reported here is focused on the influence of crosshead speed on the notched pipe ring (NPR) specimens that are prepared from PE pressure pipe of 2 in. in diameter. Viscous component of the stress–strain relationship was determined using a spring–damper–plastic element model, calibrated using results from stress relaxation tests. Crosshead speeds considered for the initial stretch of the stress relaxation tests are 0.01, 1, and 10 mm/min which due to the relatively uniform deformation in the gauge section generate the same order of difference in the strain rates. Results from the study suggest that the quasi-static stress–strain relationship is affected by the crosshead speed used to generate the deformation, and the trend of change is oppos...
... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lo... more ... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lowe 1 , ... Raman spectra were obtained using a Renishaw Raman Imaging Microscope, model 2000 with a 718 nm NIR laser source. ...
A new test method, named multi-relaxation test, is proposed for detecting on-set of delamination ... more A new test method, named multi-relaxation test, is proposed for detecting on-set of delamination in fibre-reinforced polymers. Multi-relaxation test is based on the principle that uses change of stress relaxation behaviour of fibre-reinforced polymer to detect the occurrence of delamination. In this study, angle-ply laminated fibre-reinforced polymer (APL-FRP) is used to demonstrate and evaluate multi-relaxation test for detection of the delamination occurrence. The stress relaxation behaviour is characterized using a standard, three-element viscoelastic model in which the Eyring’s law is used to govern the time-dependent stress response to deformation. Results suggest a high possibility of using the trend line change of viscous stress at the beginning of stress relaxation to determine the critical stroke for the onset of delamination. The results also suggest that value for the corresponding static stress is very close to the value reported in the literature for APL-FRP of the same...
Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The stu... more Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The study examined the influences of primer and its major component, acetone, on CPVC’s mechanical properties. Two types of CPVC product, sheet and pipe, were used in the mechanical testing. Sheet specimens were immersed in acetone or primer for 40 and 10 min, respectively, i.e., the maximum allowable time without mass loss, and then dried in air before the mechanical testing. Pipe (ring) specimens were treated either through immersion in acetone or primer for 30 min or in contact with these solvents locally on the inner surface for 2.5 h, and then air dried for 10.5 days before the mechanical testing. Results showed that CPVC’s strength decreased after the absorption of these solvents, and air dry could remove acetone but not completely primer. The study also showed that pipe specimens by local contact with primer could generate brittle fracture. In view that sheet specimens always fractured i...
A novel multi-relaxation-recovery (RR) test was proposed based on cyclic stages of stress relaxat... more A novel multi-relaxation-recovery (RR) test was proposed based on cyclic stages of stress relaxation and stress recovery. Three nonlinear visco-elastic models, that is, the standard model and two models with two dashpots connected either in parallel or in series, were examined for the analysis of the test results. Each model contains a time-dependent, viscous branch and a time-independent, quasi-static branch. The examination suggests that the standard model can determine the long-term, load-carrying performance of polyethylene (PE) and identify a transition point for the onset of plastic deformation in the crystalline phase, but the models with two dashpots connected either in parallel or in series are needed to provide a close simulation of the experimentally measured stress response in both relaxation and recovery stages of the RR test. In this work, the mechanical performance of two PEs was compared based on RR test results at room temperature. The RR tests were also conducted a...
The multi-relaxation (MR) test was developed based on the concept that stress relaxation behavior... more The multi-relaxation (MR) test was developed based on the concept that stress relaxation behavior can be used to reflect the material state of polyethylene (PE) under tension. On the basis of this concept, critical stroke for the onset of plastic deformation in the crystalline phase, named the first critical stroke, was determined using the MR test. Results from wide angle X-ray scattering suggest that phase transformation occurred in the crystalline phase of PE after the specimen was stretched beyond the first critical stroke. In this work, the MR test was applied to six PEs of different mass densities to determine their first critical strokes and the corresponding total and quasi-static (QS) stress values. The results show that the first critical stroke had very similar values among the six PEs. More interestingly, the ratio of the QS stress at the first critical stroke to the yield stress from the standard tensile test showed little dependence on PE density. Therefore, it was pos...
... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lo... more ... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lowe 1 , ... Raman spectra were obtained using a Renishaw Raman Imaging Microscope, model 2000 with a 718 nm NIR laser source. ...
Tensile strength of polyethylene is examined at various crosshead speeds using cylindrical specim... more Tensile strength of polyethylene is examined at various crosshead speeds using cylindrical specimens of 20 mm in gauge length. Through monotonic stretch with intermittent halt for load relaxation, the study shows that long-term tensile strength of polyethylene should be around half of the short-term strength determined in the standard test conditions. The study discovers a transition in the localized deformation (commonly known as necking), of which the appearance changes from opaque white to translucent when the crosshead speed is reduced from 0.05 to 0.01 mm/min, possibly due to the suppression of cavitation damage at the low crosshead speed. At a sufficiently high crosshead speed, damage generation can occur at a threshold strain as low as 4% which is way below the yield strain of the material. It is therefore concluded that determining long-term tensile strength of polyethylene needs to consider accumulation of the damage. Since this type of damage is not quantified in any of cu...
A new test method has been developed to evaluate environmental stress cracking resistance (ESCR) ... more A new test method has been developed to evaluate environmental stress cracking resistance (ESCR) for polyethylene (PE). The new test method applies transverse loading to the central area of a plate specimen, to generate local stretch that results in a truncated cone. Time for crack initiation in the truncated cone, during the exposure to an aggressive agent (10% Igepal CO-630 solution), is used to characterize ESCR. Results from the new test method are consistent with those from ASTM D1693, but the former does not require any pre-notch and takes less than 3% of the time required for the latter. Based on the new test method, a stand-alone device has been developed to characterize ESCR, which uses change in electrical conductivity to measure the time for the crack development. The device is compact and easy to operate. Using this device, time for crack initiation can be determined automatically and accurately without the use of a commercial test machine.
Quasi-static stress–strain relationship of polyethylene (PE) pressure pipe that plays an importan... more Quasi-static stress–strain relationship of polyethylene (PE) pressure pipe that plays an important role on its long-term performance has been established by removing the viscous stress component from the experimentally measured total stress. Work reported here is focused on the influence of crosshead speed on the notched pipe ring (NPR) specimens that are prepared from PE pressure pipe of 2 in. in diameter. Viscous component of the stress–strain relationship was determined using a spring–damper–plastic element model, calibrated using results from stress relaxation tests. Crosshead speeds considered for the initial stretch of the stress relaxation tests are 0.01, 1, and 10 mm/min which due to the relatively uniform deformation in the gauge section generate the same order of difference in the strain rates. Results from the study suggest that the quasi-static stress–strain relationship is affected by the crosshead speed used to generate the deformation, and the trend of change is oppos...
... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lo... more ... TEMPERATURE CARBON FIBRE COMPOSITE Bronwyn Fox 1 , Jonathan Hodgkin 2 , Ben Jar 1 , Adrian Lowe 1 , ... Raman spectra were obtained using a Renishaw Raman Imaging Microscope, model 2000 with a 718 nm NIR laser source. ...
A new test method, named multi-relaxation test, is proposed for detecting on-set of delamination ... more A new test method, named multi-relaxation test, is proposed for detecting on-set of delamination in fibre-reinforced polymers. Multi-relaxation test is based on the principle that uses change of stress relaxation behaviour of fibre-reinforced polymer to detect the occurrence of delamination. In this study, angle-ply laminated fibre-reinforced polymer (APL-FRP) is used to demonstrate and evaluate multi-relaxation test for detection of the delamination occurrence. The stress relaxation behaviour is characterized using a standard, three-element viscoelastic model in which the Eyring’s law is used to govern the time-dependent stress response to deformation. Results suggest a high possibility of using the trend line change of viscous stress at the beginning of stress relaxation to determine the critical stroke for the onset of delamination. The results also suggest that value for the corresponding static stress is very close to the value reported in the literature for APL-FRP of the same...
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