Mechanical, thermal and physico-chemical behavior of virgin and hydrothermally aged polymeric pipes (original) (raw)
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Annales de Chimie - Science des Matériaux
Thermal aging below the glass transition temperature (Tg), during three months, of Poly (vinyl chloride) (PVC) under its three different aspects, powder (p-PVC), dry-blend and Unplasticized (u-PVC) or rigid form was performed. The stabilizing system used is a commercial compound constituted by lead based stabilizers, internal and external lubricants. The ageing of PVC under these three different aspects was performed in a thermo-regulated oven at 60 °C, temperature close of the ground temperature in Sub-Sahara region (Ghardaï a, Algeria). A sampling at regular interval allowed following the microstructural changes undergone by these materials. Such an approach revealed that the additives used in the PVC recipe not only assist processing but also ensured a good material stabilization when thermal aged. The results obtain can help producers to modify the PVC recipe to improve the heat resistance of the PVC tubes to make them more performing in the very hot and deleterious Saharan environment.
Materials Sciences and Applications
For water and sewer pipes, PVC is considered to be one of the best row materials. Due to its physical, chemical and industrial significant properties, PVC is commercially invited to be in the first position. Many other traditional raw materials; e.g. iron, concrete, polyethylene and vitrified clay (VC), are coming in second position. This work is conducted to study the tensile properties of two different types of PVC raw materials (named as gray and white) for water pipe manufacturing by implementing different test conditions. The samples were prepared by cutting off the pipe to an individual cross sectional size rings. Afterward, they were softened smoothly by heating the ring samples to obtain flat standard tensile test specimen. The influence of strain rate (crosshead speed), temperature and UV radiation on the tensile properties of PVC pipe's row material were investigated. The selected experimental test temperatures are (28˚C, 50˚C and 70˚C), the selected crosshead speeds are (5, 50 and 100 mm/min) and the UV treatment exposure times are (168, 408, 744 and 1080) hours. The result shows that the gray PVC pipes have tensile strength greater than white PVC pipes. The yield stress and modulus of elasticity are directly proportion to strain rate and inversely proportion to the treatment temperature of both PVC samples. However, the fracture strain was increased with temperature and decreased with strain rate. UV treatment didn't show a significant effect on the yield stress and modulus of elasticity. This is an indication of PVC long time stability.
The Effect of Several Service and Weathering Parameters on Tensile Properties of PVC Pipe Materials
Materials Sciences and Applications, 2012
For water and sewer pipes, PVC is considered to be one of the best row materials. Due to its physical, chemical and industrial significant properties, PVC is commercially invited to be in the first position. Many other traditional raw materials; e.g. iron, concrete, polyethylene and vitrified clay (VC), are coming in second position. This work is conducted to study the tensile properties of two different types of PVC raw materials (named as gray and white) for water pipe manufacturing by implementing different test conditions. The samples were prepared by cutting off the pipe to an individual cross sectional size rings. Afterward, they were softened smoothly by heating the ring samples to obtain flat standard tensile test specimen. The influence of strain rate (crosshead speed), temperature and UV radiation on the tensile properties of PVC pipe's row material were investigated. The selected experimental test temperatures are (28˚C, 50˚C and 70˚C), the selected crosshead speeds are (5, 50 and 100 mm/min) and the UV treatment exposure times are (168, 408, 744 and 1080) hours. The result shows that the gray PVC pipes have tensile strength greater than white PVC pipes. The yield stress and modulus of elasticity are directly proportion to strain rate and inversely proportion to the treatment temperature of both PVC samples. However, the fracture strain was increased with temperature and decreased with strain rate. UV treatment didn't show a significant effect on the yield stress and modulus of elasticity. This is an indication of PVC long time stability.
Natural and accelerated weathering of PVC and polypropylene waste-water pipes
Materials and Structures, 1989
Plastic pipes and plumbing accessories for waste water are gaining popularity and replace the more conventional metal and asbestos-cement products. The main disadvantage of these pipes is their relative poor durability when exposed to external weathering conditions, particularly to the UV solar radiation. The work presented deals with the weathering behaviour of polyvinylchloride (PVC) and polypropylene (PP) pipes. Commercial pipes were exposed to natural and artificial-accelerated conditions and their mechanical properties tested after various periods of exposure. The results show that both the PVC and PP pipes are damaged by the accelerated and natural weathering within a short time, resulting in a rapid deterioration in the ultimate elongation. The drop in the extensibility of the PVC pipe is more gradual than that of the PP. The tensile strength, in both cases, is hardly affected-as expected-proving that the deterioration is mainly a surface phenomenon and depends on the cracking of the exposed surface.
Influence of chlorinated water on mechanical properties of polyethylene and polyvinyl chloride pipes
WIT Transactions on The Built Environment, 2016
Water chlorination is one of the most popular ways of disinfection used in potable water distribution systems. Nevertheless, chlorinated water does influence mechanical properties, structure and characteristics of the surface of plastic water pipes forming the system. This paper presents tests of HDPE and PVC water pipes in different ageing solutions of specific chlorine concentration, pH and CaCO 3 content and in different temperatures. Strength, structure and the chemical stability of samples were determined following different immersion periods in ageing solutions. Static tensile strength tests have not indicated any significant changes in the selected mechanical properties of either HDPE or PVC pipes samples. Infrared spectrometry tests of the chemical structure, however, showed changes in the tested samples indicating material degradation caused by chlorinated water.
Metallurgical and Materials Engineering
Thermal aging of standard samples of rigid PVC (u-PVC) taken from plastic tubes near and above the glass transition temperature (Tg) was used to investigate the effect of elevated temperatures on the mechanical properties of rigid (u-PVC) tubes used in industrial areas. Three aging protocols were used, each lasting 90 days at 80 °C, 100 °C, and 120 °C. Crosslinking and chain scission reactions changed the tensile properties, either increasing them or decreasing them. For all three aging protocols, it was discovered that Young's modulus increased with aging time. Furthermore, the rate of increase of the modulus was observed to increase with aging temperature. The Yield stress showed the same pattern. Their increase in both cases is due to material stiffening caused by a crosslinking process. This last one was revealed by DSC, where Tg increased as a result of the chemical process. The decrease in elongation at break, which occurred progressively in all aging protocols and more pr...
Experimental Study of Thermal Effect on Performance of PVC Pipes Using ANOVA Analysis
University of Thi-Qar Journal for Engineering Sciences
In this study thermal effect at high pressure on Chlorinated Polyvinyl Chloride (CPVC) pipes studied where a test rig is built and the pipe has a diameter (d=0.5 in). The temperatures of water are varied (40, 60 and 80 cº) and the pressure is raised by using tester to reach (700 psi). The relationship between pressure and Reynolds number is discussed for the pipe used in this study with another pipe has a dimension (d= 0.75 in). ANOVA Analysis used to find the correlation of parameters effect the performance of CPVC pipes. The experimental results showed that the pressure drop increases with discharge increased at different values of temperature, when the pressure increased at constant temperature the friction losses is increased, where the values of friction losses were 4.8 ×10-4 , 8×10-4 and 2.4×10-3 mm at 100, 300 and 500 psi respectively. Thus the pipe is damage at pressure (500 psi) and temperature (80 Cº) when the thickness is (3.1 mm).
Physical and water aging of glass fiber-reinforced plastic pipes
Composite Interfaces, 2006
Physical and water aging of glass/epoxy composite -GFRE -pipes used for oil transport were investigated with special emphasis on their effect on the flexural and impact behavior. Different aging conditions were selected in order to simulate in-service environments trying to obtain reliable results from accelerated laboratory tests. In water uptake experiments at 80 • C, the mass increases continuously, suggesting that an irreversible process occurs. In addition, samples aged in air at 80 • C exhibit a DSC endothermic peak that can be related to physical aging. The calorimetric curve for specimens water aged at 80 • C shows combined effects of water absorption and physical aging. On the other hand, while the independent effect of temperature and water aging on the composites mechanical response is only moderate, their combined effect seems to be dramatic. This result is mostly attributed to the weakening of the fiber-matrix interface induced by the water aging at high temperature, which consequently affects flexural and impact properties. SEM observations confirm the irreversible damage observed in water uptake experiments. Good interfacial adhesion between fiber glass and epoxy resin is observed for unaged specimens, whereas completely clean fibers are seen for specimens water aged at 80 • C, indicating that the fiber-matrix interface is completely removed as a result of this aging condition.
Effect of filler addition and weathering conditions on the performance of PVC/CaCO3composites
Polymer Composites, 2015
This study deals with the effects of calcium carbonate (CaCO 3) fillers and hygrothermal aging on the performance of polyvinylchloride (PVC). The properties of the PVC/CaCO 3 composite were studied before and after aging in water up to 3 months at 24 C 6 3 C, 70 C, and 90 C. In terms of fillers effect, it was found that the incorporation of fillers in PVC induces an increase in both T g value and storage modulus; however, it had no significant effect on the water absorption. However, the addition of fillers has resulted in an improvement in the elastic modulus, whereas it has shown harmful effect on the tensile strength and elongation at break. Concerning flexural properties, an important filler percentage, that is, 35 wt%, is proved to be the optimum content to achieve maximum strength and modulus as well as wear properties. In terms of aging impact, it was found that shift in color on aging occurs noticeably. Elastic modulus, tensile strength, flexural strength, and flexural modulus increase with increasing temperature from ambient to 70 C, whereas they decrease at 90 C. Dynamic mechanical thermal analysis confirmed that at high temperature, the absorbed water affects the PVC matrix during aging. As a result, a loss in strength and stiffness but a gain of ductility was observed. The great quantity of absorbed water acts as a barrier layer and, thus, minimizes the wear.
Weathering degradation mechanisms of chlorinated PVC
International Journal of Plastics Technology, 2013
This paper reports the effects of natural and accelerated artificial weathering on the physical, chemical and mechanical properties of Chlorinated PVC (CPVC) pipe material. Natural outdoor exposures were carried out for periods ranging from 2 weeks to 18 months. The accelerated artificial weathering was conducted by exposing samples to UV radiations for periods ranging from 100 to 3000 h. The tensile test results show that natural and accelerated weathering had limited effects on the strength and stiffness of the material. However, the fracture strain was noticeably reduced after natural weathering for periods as low as 15 days and artificial UV exposure of 100 h. Physical examination of specimens revealed that both types of weathering resulted in gradual discoloration of the specimens. ATR-FTIR spectroscopy and UV-vis analyses of exposed surfaces showed that the photoreaction responsible for degradation of CPVC is most likely dehydrochlorination.