305:, which require higher strength, stiffness and durability. In a geocell application, the high modulus of Novel Polymeric Alloy means stiff and strong cell walls, which provide a very high elastic response to dynamic loading even after millions of cycles without permanent plastic deformation. The strength and stiffness of novel polymeric alloy, as measured by tensile strength, long-term resistance to deformation, coefficient of thermal expansion (CTE) and performance at elevated temperatures (storage modulus), provides a performance lifespan previously available in geocell applications. This is a notable development in the geosynthetic / geocell industry, allowing the use of geocells for example, in structural reinforcement for
309:, earth retention walls, and other heavy-duty geosynthetic applications, where long-term durability under heavy loading is critical (Leshchinsky, et al., 2009). At the same time, novel polymeric alloy properties enable the manufacture of lighter geocells which retain suitable engineering strength for moderate loading as typically found in slopes, channels and retaining wall applications.
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layers are usually made of a polyethylene or polypropylene polymer, with a blend or alloy with other polymers, fillers, additives, fibers and elastomers. The high performance alloys of polyamides, polyesters, and polyurethanes are combined with polypropylene, copolymers, block copolymers, blends and/or other combinations.
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geocells or geogrids. In geocell applications strips are co-extruded in multi-layer strips. Outer layers are a blend of polyolefins while the core layer is formed from a high performance polymer. The blend is generally immiscible (an alloy), where the high performance polymer is dispersed in a matrix
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CTE less than about 135 ppm/°C; resistance to acidic media greater than polyamide 6 resin and/or resistance to basic media greater than PET resin; resistance to hydrocarbons greater than that of HDPE; creep modulus of > 400 MPa at 25 °C at 20% of yield stress load for 60 minutes (ISO 899-1);
396:
Pokharel, S. K., Han, J., Manandhar, C., Yang, X. M., Leshchinsky, D., Halahmi, I., and
Parsons, R. L. (2011). âAccelerated Pavement Testing of Geocell-Reinforced Unpaved Roads over Weak Subgrade.â Journal of Transportation Research Board, the 10th International Conference on Low-Volume Roads, July
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Unlike low crystalline polymers such as polypropylene, which require a post-extrusion processing such as orientation, cross-linking, and/or thermal annealing, higher crystalline polymers such as novel polymeric Alloy can be extruded as strips and welded in section without post-extrusion treatment.
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The novel polymeric alloy core layer/s is made of a high performance polymer compound with a storage modulus of â¥1400 MPa at 23 °C, measured by
Dynamic Mechanical Analysis (DMA) at a frequency of 1 Hz according to ASTM D4065; or an ultimate tensile strength of at least 30 MPa. The outer
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While most polypropylene homopolymers are too brittle and most polypropylene copolymers are too soft, certain grades of polypropylene polymers are stiff enough for engineering purposes, yet soft enough so that a geosynthetic can be handled for installation. These polymers are modified, via
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and stiffness, and is more durable over dynamic loading and under elevated temperatures than those made from HDPE (Han, 2011). The lifespan of NPA based geosynthetics, such as geocells, makes them suitable for long-term design in infrastructure, such as
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may be selected from, among others, nucleating agents, fillers, fibers, hindered amine light stabilizers (HALS), antioxidants, UV light absorbers, and carbon black in the form of powders, fibers, or whiskers.
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formed by the polyolefins. Since polymer blends are basically unstable, they undergo stabilization during melt processing, at a nano-level combined with compatibilized material.
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Han, J., Pokharel, S. K., Yang, X. and Thakur, J. (2011). âUnpaved Roads: Tough Cell â Geosynthetic
Reinforcement Shows Strong Promise.â Roads and Bridges. July, 49 (7), 40-43
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Leshchinsky, D. (2009) âResearch and
Innovation: Seismic Performance of Various Geocell Earth-retention Systems,â Geosysnthetics, No. 27, No. 4, 46-52
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in geosynthetics. Although HDPE is widely used due to its low cost, ease of manufacturing and flexibility, its relatively high
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Halahmi, I., Erez, O., Erez, A., (2009, 2010), High
Performance Geosynthetic Article , US Patents 7,674,516 B2, 7,541,084 B2
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378:
Halahmi, I., Erez, O., Erez, A., (2011), Process for
Producing Compatibilized Polymer Blends, US Patent 8,026,309 B2
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and sensitivity to elevated temperatures limit its use, for example, in long-term, critical geocell applications.
154:. One of the first commercial NPA applications was in the manufacturer of polymeric strips used to form Neoloy®
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The sheet can be extruded into strips and welded, sown, or bonded together to form geosynthetic products. Such
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Halahmi, I., Erez, O., Erez, A., (2012), Multi-layer
Sandwich System for Geocells, US Patent 8,173,241 B2
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Novel polymeric alloy (NPA) is compounded for geosynthetic applications, such as high-
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Novel polymeric alloy was developed for a high-modulus geosynthetics, including
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in the novel polymeric alloy polymer blend provides stress cracking resistance,
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resistance, very low temperature functionality and tear resistance, while the
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proprietary treatment processes and the addition of additives such as
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with enhanced engineering properties. NPA was developed for use in
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and long-term dimensional stability. Novel polymeric alloy has a
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engineering polymer provides strength, stiffness, retention of
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Novel polymeric alloy was developed as an alternative to
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Polyamides, compatibilizers, anti-toxidants, colorants
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319:Cellular Confinement Systems (geocells)
281:in the range of 19.1 to 32 MPa with an
156:cellular confinement systems (geocells)
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397:24â27, Lake Buena Vista, Florida, USA
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237:additives (stabilizers for polymers)
285:of 440 to 820 MPa (at 2% strain).
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148:thermoplastic engineering polymer
270:coefficient of thermal expansion
163:high-density polyethylene (HDPE)
117:Linear expansion coefficient (α)
30:Nano-composite polymeric alloy
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178:cellular confinement system
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264:at elevated temperatures,
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43:Additional ingredients
16:Type of polymeric alloy
22:Novel polymeric alloy
273:and 1 percent secant
133:Novel polymeric alloy
262:mechanical strength
307:flexible pavements
326:(Neoloy Geocells)
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94:Glass temperature
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111:>200 °C
65:Tensile strength
35:Main ingredient
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142:composed of
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222:Manufacture
135:(NPA) is a
59:0.96 g/cm3
38:Polyolefin
336:References
324:PRS-Neoweb
254:hydrolytic
250:polyolefin
244:Properties
205:Production
144:polyolefin
74:19â32 MPa
258:polyamide
197:and high
137:polymeric
121:80 ppm°C
408:Category
313:See also
299:geogrids
295:geocells
191:railways
187:highways
211:modulus
126:Source
52:Density
169:, low
167:creep
140:alloy
84:Yield
27:Type
301:and
248:The
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88:12%
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100:°C
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67:(Ï
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69:t
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