Comparison of Tensile Properties of Different Types of Polyethylene Geonets
Abstract: The tensile parameters of raw materials have an important influence on the performance of polyethylene HDPE geonet for sale. In order to improve the application performance of the slope protection of polyethylene high quality 3D geonet, three kinds of single-layer nets, composite blankets, and three-dimensional net mats are used. A large number of automatic loading tests were carried out on the type of polyethylene high quality HDPE geonet. The relationship between elongation and load of the material at the same rate was obtained. The longitudinal and transverse elongation-load variation of the material was obtained, and the average tensile force of different elongation was determined. The average value of the break is equal to the value. The results show that the average tensile strength of longitudinal and transverse fractures is a composite blanket, three-dimensional mesh mat and single-layer net from large to small; the average time of fracture is from single to large, composite blanket and three-dimensional mat. As a new material, the composite blanket has a good tensile strength compared with the traditional single-layer net and three-dimensional mesh mat, and realizes the full play of the overall function of the HDPE geonet manufacturers, avoiding material waste, and should be promoted and used more.
Keywords: polyethylene high quality 3D geonet; tensile properties; fracture failure
Polyethylene is a polymer formed by covalent bonding of carbon atoms and hydrogen atoms and is one of the five most widely used resin materials in modern industrial applications. The linear polyethylene containing less branching is high-density polyethylene, which has high crystallinity, high resin density, and excellent chemical and physical stability. The polyethylene HDPE geonet manufacturers are made of high-density polyethylene material through an extruder equipped with a rotary machine and produced through a specific process. The high quality 3D geonet can be divided into a single-layer China 2D geonet suppliers, a three-dimensional plastic geonet manufacturers mat, a composite blanket, etc. according to the form of the constituent materials. The HDPE geonet for sale mainly combines with related plants to form a protective layer of surface reinforcement in the shallow area of the slope, thereby improving the growth environment of the slope plant, enhancing the shear resistance of the soil, and realizing slope protection. In the study of the effects of different coverage measures on slope soil erosion, Deng Cong et al. pointed out that China 2D geonet suppliers can reduce the erosion of rain on slopes and reduce flow and reduce sand. M.O.A.Bazne et al. found that the high quality HDPE geonet can improve the bearing capacity of low-pressure soft clay by considering indoor experiments and simulation experiments on the number and length of high quality 3D geonet. B.J.Nareeman et al., through the China 2D geonet suppliers-soil direct shear test and consolidation experiment, pointed out that the plastic geonet manufacturers can effectively reduce the settlement of the foundation, and it can better improve the shear strength of the soil by placing it at a certain inclination. N.Yarahmadi et al. obtained the relationship between the in-plane flow capacity and the material thickness by measuring the thickness of different HDPE geonet manufacturers under different conditions under creep experiments. Wang Guangyue et al pointed out that the three-dimensional plastic geonet manufacturers can improve the overall stability of the slope to a certain extent. Xiao Chengzhi et al pointed out that the three-dimensional high quality 3D geonet can effectively reduce the rainwater flow rate of the slope. Although the above reports all indicate the advantages of the application of polyethylene plastic geonet manufacturers, they do not analyze the tensile characteristics of polyethylene China 2D geonet suppliers materials from the material point of view. Since tensile strength is one of the important characteristics of geomaterials, it is necessary to study the tensile properties of China 2D geonet suppliers.
The author uses the electronic fabric strength machine to carry out a large number of automatic loading tests on three types of polyethylene plastic geonet manufacturers, such as single-layer net, composite blanket, and three-dimensional net mat, to analyze the tensile properties of the material at the same rate.
1. Experimental part
1.1 main materials
Three commonly used polyethylene HDPE geonet for sale samples produced by Shandong Hongxiang New Materials Co., Ltd. were selected for tensile testing of the three-layer composite blanket, EM4 three-dimensional mesh mat, and CE111 single-layer mesh material. The composite blanket is composed of two upper and lower rhombic biaxially stretched flat nets, and the middle layer of pleated biaxially stretched web is compounded by a seaming process; the three-dimensional mesh mat is composed of an upper layer of diamond-shaped concave and convex net, and the middle two layers of biaxially stretched flat yarn The net, the bottom layer of stretched net is bonded by hot melt at the junction, and the single-layer net is extruded and woven. The relevant parameters are shown in Table 1.
1.2 main instruments and equipment
Electronic fabric strength machine: YG (B) 026H type, Wenzhou Darong Textile Co., Ltd.
1.3 Test conditions and requirements
Five specimens each having a length and a width of (200 ± 1) mm were taken for the longitudinal and lateral directions of the three samples. The sample was placed at (20 ± 2) °C for at least 24 h before the test and tested in this environment. A wide strip tensile test was performed on three materials using a loose clamp method. Refer to JT/T513-2004, GB/T19470-2004, GB/T18744-2002 for the tensile rate requirements of single-layer high quality HDPE geonet and three-dimensional mesh mats. The test’s constant-speed drawing rate is 200mm/min, and the material is guaranteed. The length direction is parallel to the load direction of the test machine, and the sample clamping length is 100 mm. The peak tensile force of the material is the tensile strength of the material, and the experiment is stopped after all layers of the material are broken.
Five sets of parallel tests were carried out for each sample in the longitudinal and transverse directions. The phenomenon of the tensile test and the damage characteristics during the tensile process of the material were observed, and the corresponding elongation-tensile force curves were collected. The tensile strength values of the three materials at 2%, 5%, 10%, 20%, 50%, breaking conditions and breaking conditions were averaged to obtain the corresponding curves.
2. Results and discussion
2.1 Composite blanket tensile test
After the tensile starting sample moves upward with the clamp, the overall elongation deformation begins, and then the upper and lower biaxially stretched flat layer of the sample reaches the yielding and then continues to tear until all the disconnection, and finally the middle layer of the fold is biaxially pulled. The stretched net continues to break. The pleated area of the longitudinally pulled sample is first straightened, and then begins to break along the curved fold line; the pleated layer of the transversely pulled sample is broken one by one along the horizontal line direction of the vertical stretching, mostly at the fixture The damage occurred nearer, and the damage photo is shown in Figure 1.
The longitudinal and transverse tensile curves of the single test of the composite blanket are shown in Fig. 2. It can be seen from Fig. 2 that the elongation-tensile force is linear before the material reaches the maximum tensile stress point in the longitudinal and transverse stretching process of the composite blanket; beyond this point, the longitudinally stretched sample is stretched. The elongation rate increases the tensile force decreases, and the tensile force value of the transversely tensile specimen decreases as a whole, and multiple stress peaks appear. The lateral part curve does not start from the origin, and the flatness of the material clamping may be poor, causing no elongation force but elongation change.
Figure 3 is a graph showing the longitudinal and transverse elongation-average tensile force curves of the composite carpet. It can be seen from Fig. 3 that as the elongation increases, the tensile stresses in the longitudinal and transverse directions increase first and then decrease, mainly because the pleated layer of the constituent material finally breaks, and the direction of the longitudinally stretched pleat line is perpendicular to the pull. Stretching direction, the area of force is small. Under the high-speed stretching of polyethylene material, the movement of molecular segments can not keep up with the external force, and brittle behavior occurs. The direction of the laterally-pulled fold line is parallel to the direction of the applied tensile force, and multiple fold lines increase the actual acceptance of the sample. Pulling area, molecular chains can be displaced and rearranged, and tough behavior occurs. The average tensile strength of longitudinal fracture is 2,48.74N and the elongation is 22.94%; the average tensile strength of transverse fracture is 2018.11N, the elongation is 40.25%, the difference of tensile force is small, and the elongation is different. Big. Mainly because the mesh of the pleated layer is a square mesh, the direction of the tensile force is perpendicular to the direction of the side length and should be equal according to the theoretical calculation, so the difference of the tensile force of the breaking is small. The relationship between the pleated layer and the direction of stretching results in a poor extension of the longitudinal direction.
The longitudinal and transverse tensile curves of the single test of the three-dimensional mesh mat are shown in Fig. 5. As can be seen from Fig. 5, both the longitudinal and transverse elongation-tensile force changes are hump-type softening damage. The tensile force changes linearly first and then decreases in the upper and lower fluctuations after reaching the peak value. Mainly because polyethylene is used as a viscoelastic material, it will produce some drawing phenomenon during the stretching process, which can absorb more tensile energy and hinder molecular chain breakage. At the same time, the three-dimensional mesh mat is a composite material. The pre-curve curve on the graph shows the tensile stress of the whole material. In the later stage, the tensile force of the remaining unbroken layer is shown, so the material is resistant with the decrease of the remaining layers and the mesh. The force value of the stretching is also reduced.
2.2 Three-dimensional net mat tensile test phenomenon
The longitudinal and transverse specimens of the three-dimensional mesh mat are also deformed from the overall elongation to the filament shape at the beginning of the stretching, and then the surface layer of the sample layer is fractured one by one, and a significant break can be heard. sound. The biaxially stretched screen in the middle of the sample begins to break along the horizontal grid line, leaving only the bottom layer of the diamond flat web to continue to stretch. The longitudinally pulled sample is elongated in two diagonal directions along with the mesh, and finally reaches the limit state and then mostly breaks from the joint portion; the transversely pulled sample starts to break along the middle of the mesh ribs on both sides of the tensioned mesh. The direction of the fracture line and the direction of the tensile force are at an angle, which may be caused by a slight unevenness in the initial prestress loading. The destruction photo is shown in Figure 4.
Figure 6 is a longitudinal and transverse elongation-average tensile force curve of a three-dimensional mesh mat. It can be seen from Fig. 6 that the average tensile strength of longitudinal fracture is 489.45 N, the elongation is 16.09%, the average tensile force of transverse fracture is 446.7 N, and the elongation is 16.05%. The difference is small, indicating that the sample is two. The direction is relatively uniform. Through the analysis of experimental phenomena, it may be that the concavo-convex layer of the material is welded to the underlying flat layer, and the stretching action causes the solder joint to be peeled off first, leaving only the bottom flat-layer diamond-shaped biaxially stretched net, and the diamond-shaped mesh is equally stressed, so the two are broken. The tensile force value is small.
2.3 Single layer net tensile test
The longitudinal and transverse directions of the single-layer net sample are in the initial stage of the tensile action, and the deformation increases with the deformation. The fiber of the mesh rib is broken after being pulled into a filament shape, and the number of fiber breakage increases and the deformation accumulates to a certain extent. Suddenly “breaking” damage. At the same time, the stretched mesh edge breaks first and then extends to the middle. Sometimes the middle part of the sample holding sample is broken first, which may be caused by the uneven or insufficient clamping force of the sample. Therefore, care should be taken to insure that it is flat and uniform when clamping the sample. The tensile damage photo is shown in Figure 7.
The longitudinal and transverse tensile curves of a single test of a single layer web are shown in Fig. 8. It can be seen from Fig. 8 that the longitudinal and transverse tensile relationships of the single-layer net before the yield point increase linearly first. After reaching the yield point, the tensile stress continues to increase, but the growth rate becomes slow until the maximum tensile stress is reached. The tensile stress is rapidly reduced. Mainly because the single-layer net is a single-layer planar structure and there are many meshes. As one of the mesh ribs is necked and fractured at the edge of the mesh, the remaining mesh ribs generate local stress concentration under tensile force and can continue to resist external stretching. Therefore, as the elongation increases, the rate of increase in tensile force decreases.
Figure 9 is a graph showing the longitudinal and transverse elongation-average tensile force curves of a single layer web. It can be seen from Fig. 9 that as the elongation increases, the tensile strength changes in both directions are the same, the longitudinal elongation at break is 432.37%, and the transverse elongation at break is 440.13%; indicating that the overall ductility distribution of the material is uniform. However, the tensile strength values of the two are quite different. The average tensile strength of longitudinal fracture is 438.52N, and the average tensile strength of transverse fracture is 201.6N. The analysis of experimental phenomena is mainly caused by the mesh between the clamps during longitudinal tension. Two triangles, the mesh is two trapezoids when the lateral tension is applied, and the triangle is more stable than the trapezoid. And under the same tensile length, the number of meshes in the longitudinal tension is large and the spacing of the vertical mesh ribs is small, and the overall tensile resistance is large; the number of laterally pulled mesh holes is small and the vertical mesh rib spacing is large, and the whole The resulting tensile resistance is small, so the longitudinal tensile strength is greater than the transverse direction.
2.4 Vertical and horizontal tensile comparison of three geonets
Let X be the elongation, Y be the average tensile force, and R2 be the degree of the fitting. The corresponding curve equation obtained by fitting is shown in equations (1) to (2).
Figure 10 and Figure 11 show the longitudinal and transverse elongation-average tensile force curves of three types of HDPE geonet manufacturers. As can be seen from Fig. 10 and Fig. 11, as the elongation increases, the longitudinal and transverse tensile forces of the three samples first increase and then decrease. The average tensile strength of longitudinal and transverse fractures is from composite to carpet, three-dimensional mesh mat and single-layer HDPE geonet for sale. This is mainly because the superposition layer of the constituent materials is different. The composite blanket and the three-dimensional mesh mat layer are more than the single-layer net, so the tensile force value is larger than that of the single-layer net. At the same time, because the composite blanket is three-layer stitching of the textile rope, the upper and lower flat-layer biaxial stretching nets are first broken, but the middle fold layer can be better tensile in the later stage. The three-dimensional mesh mat has an early interlaminar peeling because the concave and convex layers and the bottom flat layer are bonded, and the bottom flat net can not directly resist the tensile force, thereby reducing the overall tensile strength of the material, so the fracture is pulled. The extension value is lower than the composite blanket.
Figure 12 is a comparison of the average longitudinal and transverse fracture time of three high quality HDPE geonet. It can be seen from Fig. 12 that the average longitudinal and transverse tensile fractures are in the order of single-layer mesh, composite carpet, and three-dimensional mesh mat. The material of the single-layer net has good ductility. This is mainly because the strength of the single-layer net of the other two materials is low, and the order of the layers is broken, which can not better play the material integrity and reduce the overall ductility of the material. Therefore, in the production, attention should be paid to the detection and strengthening of the single-layer strength of composite HDPE geonet manufacturers materials.
(1) The difference between the longitudinal tensile force and the transverse tensile force of the composite carpet and the three-dimensional mesh mat material is small, but the longitudinal direction is larger than the transverse direction. It is indicated that the two materials have uniform tensile strength. In actual use, the material should be laid in the longitudinal direction of the main force direction, and the early tensile effect should be fully exerted. The single-layer net is also the same.
(2) The average tensile strength and the average breaking time of the longitudinal and transverse fracture of the composite carpet material are larger than that of the three-dimensional mesh mat and the single-layer net. It may be that the adhesion between the three-dimensional mesh mats peels during the stretching process to reduce the overall tensile strength of the material. The detection of the solder joints of the three-dimensional mesh mat material should be strengthened. At the same time, the detection of the bending resistance of the composite carpet fold layer is strengthened.
(3) As a new material, the composite blanket has a good tensile strength compared with the traditional single-layer HDPE geonet for sale and three-dimensional mesh mat, and realizes the full effect of the high quality HDPE geonet and avoids material waste.