Collectively under the polyethylene class of materials, LDPE (low-density polyethylene) and HDPE (high-density polyethylene) have shaped the landscape of the packaging and manufacturing industry. LDPE is well known for being widely used in plastic bags as its low density makes it light and flexible, rendering it perfect for this kind of makingoz.com, on the other hand, is harder and offers. Dec 28, · Low-density polyethylene, or LDPE, is number 4-coded plastic, commonly used to manufacture shopping bags, dry cleaning bags and flexible bottles and lids (see References 3).
A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid or gas migration in a human-made project, structure, or system.
Geomembranes are made from relatively thin continuous polymeric sheets, but they can also be made from the impregnation of geotextiles with asphaltelastomer or polymer spraysor as multilayered bitumen geocomposites. Continuous polymer sheet geomembranes are, by far, the most common. The manufacturing of geomembranes begins with the production of the raw materials, which include the polymer resin, and various additives such as antioxidants, plasticizers, fillers, carbon black, and lubricants as a processing aid.
These raw materials i. Projections for future geomembrane usage are strongly dependent on the application and geographical uses. Of course, individual countries and manufacturers often have specific and sometimes proprietary test methods. There are a number of mechanical tests that have been developed to determine the strength of polymeric sheet materials. Many have been adopted for use in evaluating geomembranes. They represent both quality control and design, i.
Any phenomenon that causes polymeric chain scissionbond breaking, additive depletion, or extraction within the geomembrane must be considered as compromising to its long-term performance. There are a number of potential concerns in this regard. While each ofr material-specific, the general behavior trend is to cause the geomembrane to become brittle in its stress-strain behavior over time.
There are several mechanical properties to track in monitoring such long term degradation: the decrease in elongation at failure, the increase in modulus of elasticitythe increase then decrease in stress at failure i. Obviously, many of the physical and mechanical uses could be used to monitor the polymeric degradation process.
Geomembranes degrade slowly enough that their lifetime behavior wha as yet uncharted. Lifetime prediction methods use the following means of interpreting the data:. The fundamental mechanism of seaming polymeric geomembrane sheets together is to temporarily reorganize the polymer structure by melting or softening of the two opposing surfaces to be joined in a controlled manner that, after the application of pressure, results in the two sheets being bonded together.
This reorganization results from an input of energy that originates from either lpe or chemical processes. These processes may involve what is the definition of complex addition of additional polymer in the area to be how to reinstall internet explorer 8 on windows xp. Ideally, seaming two geomembrane sheets should result in no net loss of tensile strength across the two sheets, and the joined sheets should perform as one single geomembrane sheet.
The characteristics of the seamed area are a function of the type of geomembrane and the seaming technique used. Geomembranes have been used in the following environmental, geotechnical, hydraulic, transportation, and private development applications:. From Wikipedia, the free encyclopedia.
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Designing With Geosynthetics 6th ed. Xlibris Publishing Co. Science and Technology of Advanced Materials. Bibcode : STAdM. PMC PMID August, H. Kays, W. Rollin, A. Sharma, H. Geotechnical engineering. Offshore geotechnical engineering. Core drill Cone penetration test Geo-electrical sounding Permeability test Load test Static Dynamic Whaf Pore pressure measurement Piezometer Well Ram sounding Rock control drilling Rotary-pressure sounding Rotary weight sounding Sample series Screw fr test Deformation monitoring Inclinometer Settlement recordings Shear vane test Simple sounding Standard penetration test Total sounding Trial pit Visible bedrock Nuclear densometer test Exploration geophysics Crosshole sonic logging Pile integrity test Wave equation analysis.
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LDPE is used for both rigid containers and plastic film applications such as plastic bags and film wrap. In , the global LDPE market had a volume of almost US$33 billion. The radical polymerization process used to make LDPE does not include a catalyst that "supervises" the . A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (or gas) migration in a human-made project, structure, or system. Geomembranes are made from relatively thin continuous polymeric sheets, but they can also be made from the impregnation of geotextiles with asphalt, elastomer or polymer sprays. Aug 12, · Dichroic ratio of LDPE, HDPE, PE-BIO and PE-OXO exposed to UV-B is shown in Figure 5. The increase of the dichroic ratio for LDPE and HDPE films is due to the embrittlement process since the breakdown branches was oriented parallel to the polymer backbones; these molecular chains were oriented in the same direction of lamination of the films.
Plastic bags are made from a ubiquitous polymer substance known as polyethylene. This begins as ethylene, commonly extracted from natural gases, then treated to become the polymer, forming long chains of carbon and hydrogen atoms. These chains can vary depending on what type of polyethylene is being used, but they all help create various types of plastic bags.
Plastics are created from a group of synthetic molecules known as polymers. Polymers are large, easy to create and made up of a repeating molecular pattern created by units called monomers. In plastic bags, these repeating structures are made of ethylene. Ethylene is chemically changed into polyethylene, the building block of all plastic bags. Polyethylene is made up of many winding chains of carbon atoms, interlaced with and bonded to hydrogen atoms.
Because plastic is formed in this patterned structure, it is easy to manipulate into a variety of shapes and densities. The source substances of polyethylene vary, but are almost always some form of fossil fuel. Both petroleum and natural gas are common sources and vital ingredients in almost all plastic bags available today. Properly refined, they yield ethylene, which is in turn made into polyethylene. This process is used mostly with natural gas, which yields a very flexible polyethylene substance that can be formed into nearly any shape and manufactured in any color.
HDPE stands for high density polyethylene, and is the most common type of polyethylene used to create shopping bags. This plastic is made of straight molecule chains that branch very little, staying linear from beginning to end. This linear structure creates a very strong material, which is why the common grocery bag is light yet can hold many times its own weight without tearing.
LDPE plastic is made from low density, branching chains of polymer materials. These polyethylene chains, rather than staying linear, spread out in many different combining lines.
This creates a very light, almost filmlike plastic that is used to make the tear-away bags dry cleaners use for wrapping cleaned clothes. Referring to linear low density polyethylene, these plastics do not branch, but also do not have the same strength as HDPE versions. This means that shopping bags created from LLDPE plastics need to be thicker and heavier that traditional grocery bags. The shiny bags using in clothing stores are a common example of bags made from this substance.
While shopping bag plastic is recyclable, it cannot be remade into an organic state, and once created must stay as a synthetic substance for the rest of its life. Instead of being recycled as new plastic bags, many bags are used to create other synthetic materials such as composite lumber. In general, plastic bags are the preferred environmental choice, not because of their recyclable qualities but because of their manufacturing process, which uses around 70 percent less energy and releases 50 percent fewer greenhouse gas particles than alternatives like paper bags.
What Is a Thermoplastic Polymer? What Is Opaque Plastic? HDPE Vs. Differences Between Polyethylene and Polyurethane. Types of Plastic Bags. Life Cycle of a Plastic Bottle.
Things Made From Recycled Plastic. How to Recycle Polystyrene Foam. The Disadvantages of Using Plastic Products. What Is Tyvek? Process for Making Paper Towels. References Plastic Bags Plastics. Copyright Leaf Group Ltd.