Material displays property retention and resistance to environmental stress cracking when exposed to a wide variety of chemicals. Unlike most other amorphous thermoplastics, ultem machining resins retain strength and resist stress cracking when exposed to automotive and aircraft fluids, aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions. Ultem resin sabic ultem emco industrial plastics. Unsuitable coolants used during machining can lead to subsequent stress cracking. Annealing radel greatly reduces the likelihood that surface cracks and internal stresses will occur from the heat generated. Ultem resin 1010r sabic datasheet plastic materials. Ultem machining sentinel plastics experts in all plastic. Environmental stress cracking may account for around 1530% of all plastic component failures in service. The ultem 2000 series are glass reinforced resins to provide greater stability and improved dimensional stability while retaining excellent processibility. Stress cracks or surface crazing near stress concentrators like threads can be a sign of future problems. The bondit b45th has sufficient elasticity to absorb stresses and minimize risk of stress cracking of the ultem. High stress levels in plastic are a common cause of component field failures. Stress cracking is a frequent problem in plastic applications. Why its ideal for aircraft interiors if you are looking for a thermoplastic resin that allows for outstanding flexibility and freedom in design, ultem is the plastic for you.
Pei resins are used in medical and chemical applications due to their. Jansen stork technimet new berlin, wisconsin e nvironmental stress cracking esc is a phenomenon in which a plastic resin is degraded by a chemical agent while under stress, and it is the leading cause of plastic component failure. Ultem offers high strength and excellent resistance to flame and heat. As a guideline, for turned or milled parts, a machining tolerance of 0. Machining guide for engineering plastics suppliers. It is very aggressive and usually produces cracks in all but the most stress free abs parts. Prone to stress cracking poor fatigue resistance structural applications only. Ultem can be received in the form of rods, sheets, tube or film. They have outstanding thermal, mechanical, and chemical properties and are often the best choice for the most demanding applications where very high mechanical strength in combination with high temperature, corrosion, and wear resistance is required. Machining forces being lower for engineering plastics than for metals and the former deforming more easily if clamped too tightly, clamping pressures should be reduced. Environmental stress cracking resistance of polyethylene. The stress that is introduced into the material during extrusion is not relieved in this part of the process because the plastic resin sets up as soon as it comes out of the extruder.
View plastic materials found under a specific property group. Selecting a thermoplastic for your injectionmolded part. Ultem resin 1010 sabic datasheet plastic materials. Glass filled grades appear tan or greenish in color. Part designers rarely attempt to estimate the amount of internal moldedin stress because this stress can vary widely due conditions during the injection molding cycle. On clear plastic parts, you can check for changes in the orientation and stress of parts by putting the part between crosspolarized plastic sheets. Environmental stress cracking is involved with some 25% of plastic part failures. The ultem resin family of amorphous thermoplastic pei polyetherimide resins offers outstanding elevated thermal resistance, high strength, stiffness and broad chemical resistance. Ultem stock shapes display property retention and resistance to environmental stress cracking when exposed to a wide variety of chemicals. Ultem is resistant to hot water and steam and can withstand repeated cycles in a steam autoclave. Pei glass fiber reinforced tecapei gf30 natural ensinger. Stress relieving before machining through an annealing process is crucial, as it reduces the likelihood that surface cracks and internal stresses will occur from the heat generated. This high strength material offers excellent chemical resistance and ductile properties suitable for various applications, even those including steam exposure. The beneficial property features of ultem plastic resin include the following.
Ultem plastic resin beneficial properties with a wide range of ultem material options, there is an ultem resin that can meet or exceed your project requirement needs. Plastic failure through environmental stress cracking. Contact stack plastics for ultem injection molding plastics today. The behavior of other, untested liquids can be estimated from hsp correlations based on a limited number of test liquids. Diagnose it before it ruins your parts residual stress is an inherent result of plastics manufacturing processes and occurs when molten polymer is cooled and shaped. This type of cracking is caused by molecular orientation at the surface of the plastic part. Environmental stress cracking can take place through continuous crack growth or via a stepwise progressive mechanism of cracking and arrest, depending on the molecular structure of the plastic, the composition of the chemical agent, the level of stress, and other environmental conditions. Environmental stress cracking the the chemical agent does. Too low or too high temperature, poor cooling or storage makes even filaments like pet, abs and ultem perform weak, crack, bound or warp. Resistance to this mode of failure can be best gauged through constanttensileload testing, while taking into account the differences in yield point among various polyethylenes. Offers high flow, durability, excellent mechanical properties, excellent dimensional stability and easy processability with low toxicity and smoke evolution. The standard color of ultem unfilled stock shapes is light amber. Typical properties of ultem resins 6000 series high temperature. High performance plastics materials guide tactical sealing.
Ultem stock shapes uniquely balance both mechanical properties and processability, offering design engineers exceptional flexibility and freedom. Spray mists and pressurized air are very effective means of cooling the cutting interface. Stress relieving of engineering plastics thyssenkrupp. This high strength material offers excellent chemical resistance. Polyetherimide is able to resist high temperatures with stable electrical properties over a wide range of frequencies. Aug 01, 2008 get a handle on stresscracking in hdpe bottles one of the first applications for blow molded hdpe bottles was the replacement of glass for bleach packaging. Nov, 2012 this type of cracking is caused by molecular orientation at the surface of the plastic part. Key properties of the ultem resin base polymer are. Due to ultem s high mechanical strength and heat resistant composition, it is ideal for use in harsh environmental conditions needing chemical resistant features and high temperature resistance. This is a special 30% glass fibre reinforced pei, manufactured by ensinger under the tradename tecapei gf30 natural.
Prediction of environmental stress cracking in plastics with. To avoid problems, select your material with care and employ the fundamental rules of good design and processing. Acrylic can be brittle and thus more susceptible to stress cracking. Plastic stress test protocols connecticut plastics. Ultem is an unreinforced grade offering a heat deflection temperature of 200c 392f at 264 psi and a ul 94 flammability rating of vo at 0. The material is an unfilled polyetherimide, made by g. The combination of stress and molecular orientation will show as color patterns. The ultem tm family of amorphous thermoplastic polyetherimide pei resins offers outstanding elevated thermal resistance, high strength and stiffness, and broad chemical resistance.
Plastics, that is chemically resistant and displays excellent property retention and resistance to environmental stress cracking when exposed to most commercial automotive and aircraft fluids, fully halogenated hydrocarbons, alcohols. Ultem this unfilled, generalpurpose grade combines exceptional mechanical, thermal, and electrical properties. Ultem stock shapes are inherently flame resistant with low smoke emission. Pei resins are used in medical and chemical applications due to their heat resistance, solvent. Ultem resin 1010r is an amorphous, opaque polyetherimide pei grade containing internal mold release. Duratron u ultem thermoplastic is high strength at high.
Ultem has outstanding electrical properties and one of the highest dielectric. There is always some stress on the surface of a plastic part. Ultem resin offers great property retention after repeated washing cycles and multiple sterilizations by autoclave. Mechanical properties ldpe is semirigid, translucent, very tough, weatherproof, good chemical resistance, low water absorption, easily processed by most methods, and low cost. An introduction to the grades of ultem plastic reading plastic. The results reported here confirm that environmental stress cracking phenomena in plastics depend on the size and shape of the test liquids molecules as well as their hansen solubility parameters hsp relative to those of the polymer. Environmental stress cracking is considered to be the most frequent mode of failure of plastic materials. According to astm d883, stress cracking is defined as an external or internal crack in a plastic caused by tensile stresses less than its shortterm mechanical. Ultem plastic offers high strength and stiffness, superior elevated thermal resistance, and broad chemical resistance with enhanced properties. If, during the machining process, significant material is removed, annealing is recommended to relieve machinedinstress and minimize possibility of premature part failure.
If you are looking for a thermoplastic resin that allows for outstanding flexibility and freedom in design, ultem is the plastic for you. While this can occur under high stress conditions, one of the most common forms of failure for plastic components is low stress failure. Unlike most other amorphous thermoplastics, ultem resins retain strength and resist stress cracking when exposed to automotive and aircraft fluids, aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions. Jun 25, 2018 as we mentioned before, amorphous thermoplastics like radel are especially sensitive to stress cracking, so stress relieving through an annealing process is highly recommended before machining. Environmental stress crack resistance escr is a vital property required in plastics for its longevity. Despite materials being able to handle stress, under bad printing conditions, strings of filament dont bond with each other well resulting in failure. The glass transition temperature of pei is 420 f and is prone to stress cracking in chlorinated solvents. The more patterns, the more orientation and stress in the molded parts. Provides longterm heat resistance and stability of physical and mechanical properties at elevated temperatures with high stiffness and strength up to 200 c. Discover aips process of machining ultem plastics in this informational. Ultem resins uniquely balance both mechanical properties and processability. Weaknesses the cost is higher than conventional engineering plastics. Prediction of environmental stress cracking in plastics.
Polyetherimide pei is ambertotransparent thermoplastic characterized by high heat resistance, high strength and modulus, excellent electrical properties that remain stable over a wide range of temperatures and frequencies. It is prone to stress cracking in chlorinated solvents. See the chart below for more details on ultem material properties. Extem resin is expected to retain the ul performance and flame, smoke and toxicity strengths of ultem resin. It is highly used in medical applications and it is also fda approved. It is also vulnerable to stress cracking, especially if detergents are used. Stress and cracking resistance when exposed to aircraft and automotive fluids, alcohols, acids, and more. These materials are available in transparent and opaque custom colors, as well as glass filled grades. Environmental stress cracking in polyethylene takes place because of interlamellar failure, which in turn is caused by relaxation of tie molecules. Draft is always required in acrylic parts due to its brittleness, often times twice the draft of other materials. An introduction to the grades of ultem plastic reading. Environmental stress cracking esc is one of the most common causes of unexpected brittle failure of thermoplastic especially amorphous polymers known at present. When a plastic part is under mechanical stress it can result in crack formation and propagation, eventually leading to part failure.
This also helps prevent any warping or distortion of your plastic materials. Ultem polyetherimide is a semitransparent high strength plastic material that can operate in high service temperature environments. Troubleshooting cracking in injection molded parts. Troubleshooting cracking in injection molded parts paulson. Of the 3 causes of injection molded part failure, increased internal stress, increased external stress, and reduced plastic strength, the molder has control over 2 of them. Ptfe features impressive heat, mechanical toughness, electrical and low friction properties, making it the material of. Properties of ultem and ultem hp resins are unchanged after.
This materials isan excellent machining amorphous thermoplastic which possesses a combination of useful characteristics, including high strength at elevated temperatures, high modulus, and broad chemical resistance. Vinegar, on the other hand, is 5 percent acetic acid and the rest is mostly water. Duratron u2300 pei is a glass filled amorphous polymer offering high strength and excellent flame and heat resistance. Select two or more materials and then press compare materials. The information contained herein are typical values intended for reference and comparison purposes only. In contrast with parts molded from most other amorphous thermoplastics, parts made of ultem resins retain their strength and resist stress cracking when exposed to fats and oils, automotive and aircraft fluids, aliphatic hydrocarbons, alcohols, acids, and weak aqueous solutions. Stressrelieving before machining through an annealing process is crucial, as it reduces the likelihood that surface cracks and internal stresses will occur from the heat generated. Ultem resin 2310 sabic datasheet plastic materials. Polyetherimides pi, pei are high performance engineering thermoplastics of amber to transparent color. Ultem injection molding ultem plastic molding resin. Environmental stress crack resistance escr testing of. It is ul94 vo rated selfextinguishing and usp class vi compliant.
Capable of withstanding repeated autoclaving cycles. Polyetherimide, acronym pei, is an amorphous engineering thermoplastic resin manufactured by sabic innovative plastics under the trade name ultem developed by ge plastics. Ultem is a high performance engineering plastic offering high mechanical and electrical properties as well as excellent flame and heat resistance. Material properties of thermoplastic ultem polyetherimide, pei. Environmental stress cracking escr is the formation of cracks in a part when exposed to chemicals, if the parts have residual stress in them after molding. However, avoid any unsafe condition where the plastics part could come out of the clamping tools. Sometimes stress is not visible until the component is subject to loading or exposure to chemicals by the end user. According to astm d883, stress cracking is defined as an external or internal crack in a plastic caused by tensile stresses less than its shortterm mechanical strength. Also, the amorphic structure of ultem can cause relaxation under influence of bondings on the long term. Stress crack resistance one of the best chemicals for checking stress crack resistance in abs is concentrated acetic acid, called glacial acetic acid by chemists. It is one of the most common causes of unexpected brittle failure in thermoplastic.
Its environmental stress and crack resistance make it an excellent plastic for any. But there are methods for getting to the root of the problem. Ultem properties include thermal and chemical resistance, high strength and stiffness, and dimensional stability. Mechanical properties ultem resins are used in medical and chemical instrumentation due to their heat resistance, solvent resistance and flame resistance. In particular watch out for notchsensitive geometries. Over time, chemical attack or sunlight will reduce the strength of the plastic until the internal stress causes these cracks. It performs continuously to 340 degreesf, making it ideal for high strength high heat applications, and those requiring consistent dielectric properties over a wide frequency range. Ptfe is a soft fluoropolymer mechanical plastic with exceptional resistance to high temperatures, chemicals, corrosion and stress cracking. Click the down or up arrows triangles or column headings to sort plastic materials or material properties. Cracks in injection molded parts how to correct this.
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