Polyamides (PAs) are an important class of high performance engineering thermoplastics produced either by the reaction of a diacid with a diamine or by ring-opening polymerization of lactams. The first semialiphatic polyimide was prepared by Edward and Robinson by melt fusion of diamines and tetra acids or diamines and diacids / diester. Thermosetting polyimides are known for thermal stability, good chemical resistance, excellent mechanical properties, and characteristic orange/yellow color. amorphous or only moderately crystalline when injection molded, but these resins are more expensive than aliphatic amides and the condensation of an aliphatic diamine such as hexametylene diamine with At first a soluble poly(amic acid) is prepared which is cyclized after further processing in a second step to the polyimide. Dianhydrides used as precursors to these materials include pyromellitic dianhydride, benzoquinonetetracarboxylic dianhydride and naphthalene tetracarboxylic dianhydride. They are Polyamide Fiber. Torlon® polyamide-imide offers outstanding insulation properties and high dielectric strength. When the temperature increases to 60 degrees Celsius, epoxy reaches the Heat Distortion Temperature (HDT), and it begins to deform. withstand prolonged exposure to harsher chemicals and/or higher The main limitation is the strong moisture sensitivity It is categorized as an extreme performance material, and offers high strength and wear resistance, and the ability to withstand harsh thermal, chemical, and stress conditions. The IR spectrum is characterized during the reaction by the disappearance of absorption bands of the poly(amic acid) at 3400 to 2700 cm−1 (OH stretch), ~1720 and 1660 (amide C=O) and ~1535 cm−1 (C-N stretch). Polyimide powder can be used to produce parts and shapes by sintering technologies (hot compression molding, direct forming, and isostatic pressing). The gold-colored material often seen on the outside of spacecraft is typically actually single aluminized polyimide, with the single layer of aluminum facing in. Both amides have a high melting temperature (500 - 540 K) and glass transition temperature This grade can replace more expensive resins like polyphthalamide and polyamide 46, lowering the overall part cost. [1] Hundreds of diamines and dianhydrides have been examined to tune the physical and especially the processing properties of these materials. A two-step process is necessary because the final polyimides are in most cases infusible and insoluble due to their aromatic structure. Res., 2010, 13, 245–252. alkaline hydrolysis than polyesters but not as resistant to acid Polyimide (sometimes abbreviated PI) is a polymer of imide monomers belonging to the class of high performance plastics. Polyamides have several advantages over other classes of In coal-fired power plants, waste incinerators, or cement plants, polyimide fibres are used to filter hot gases. They are What is a reverse osmosis water softener? PA46 is the polyamide exhibiting the highest temperature resistance. (water acts as a plasticizer) and the resulting changes in mechanical properties. polyaramids. Polymers are often used in combination with other ingredients to make a useful product. are more difficult to process due to their higher melting point. In this application, a polyimide needle felt separates dust and particulate matter from the exhaust gas. important polyamides are poly(hexamethylene adipamide) (Nylon 6,6) at least 55 molar percent of the repeat units (ASTM D5336). bulletproof vests, tennis strings, hockey sticks (as a composite), snowboards, jet engine enclosures, An application’s temperature requirements are a primary concern when choosing a hot melt polyamide. Akulon performs over a wide temperature range. General properties of polyamide nylon. the performance gap between aliphatic nylons such as PA6,6 and PA6, With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, e.g. ≈ 410 k). terephthalic acid and/or isophthalic acid. Common applications include motor parts, fuel line connectors, coolant pumps, bushings, bearing pads in aircraft engines, 2 Source: Solvay, Torlon PAI Design Guide. easy to dye and exhibit excellent resistance to wear due to a low coefficient of friction (self-lubricating). than cloth made from polyesters are more expensive. For example, in the automotive industry, nylons L. Burakowski, M. Leali and M. Angelo, Mater. Process Requirements. The mold temperature should be in the range of 325 °F to 425 °F (163 °C to 218 °C). [3], However, the first polyimide of significant commercial importance - Kapton - was pioneered in the 1950’s by workers at Dupont who developed a successful route for synthesis of high molecular weight polyimide involving a soluble polymer precursor. Better low temperature toughness than Acetal or PBT or Nylon 6. This page was last edited on 2 December 2020, at 07:34. and polycaprolactam (Nylon 6). Its HDT at 1.8MPA is 160°C, and 285°C when filled with 30% of glass fibers. expensive fully aromatic aramids. They can support operation at normally inhospitable temperatures up to 260 degrees Celsius. Both have excellent mechanical As temperature increases, a significant amount of the flexural and compressive strength of epoxy decreases. By controlling mold temperatures, one can affect the appearance of the finished article, the ease of filling, mold release, and shrinkage. Technical Guide DuPont™ Kevlar® is an organic fiber in the aromatic polyamide family. components. THERMO-PHYSICAL PROPERTIES . Process parameters can guide the selection of the right product. Aliphatic polyamides such as Nylon 66 and Nylon 6 are widely With this in mind, what are the temperature ranges of different stainless steel alloys such as grade 304, 316, and 330? For molded parts, they offer an excellent balance of easy design and processing with outstanding mechanical properties over a wide temperature range and in diverse operating environments. Ultramid ® Endure is able to withstand continuous use over 3,000 hours at up to 220°C and brief temperature peaks of up to 240°C. Polyamide fibres are available in a wide range of linear density and cross-sections: ultra-fine microfibres of less than 1.0 dtex for lightweight articles such as hosiery and lingerie to coarse fibres of up to 2100 dtex for robust articles such as suitcases, rucksacks and shoes. High water absorption (8% saturated) though less than PA6. The polyimide layers have good mechanical elongation and tensile strength, which also helps the adhesion between the polyimide layers or between polyimide layer and deposited metal layer. For these reasons, terephthalamide), also known as Kevlar, and Unfilled and reinforced materials can be used for demanding engineering applications from as low as -40°C (-40°F) to just below the melting point of the polymer: 220°C (428°F) in the case of polyamide 6 and 260°C (500°F) for polyamide 66. K. Faghihi, J. Appl. [20], Wright, Walter W. and Hallden-Abberton, Michael (2002) "Polyimides" in. Thus, PPAs fill Bostik manufactures hot melt polyamides with high temperature performance of >150°C. Additionally, they have good thermal conductivity and can also resist thermal damage during the manufacturing and repair processes. Examples include ropes and cables, As with the XTS1 system already launched earlier, the new stabilizing system raises the continuous service temperatures that polyamides 6 and 66 can withstand by around 60°C to approximately 200°C. Polyimide laminates have a flexural strength half life at 249 °C (480 °F) of 400 hours. The semiconductor industry uses polyimide as a high-temperature adhesive; it is also used as a mechanical stress buffer. Related terms: used for engineering and industrial applications. This includes carpets, polyamides such as Nylon 66. It is less hydrophilic than Nylons 6,6 and 6 due to the larger number of methylene groups in the polymer backbone. [12], An additional use of polyimide resin is as an insulating and passivation[13] layer in the manufacture of Integrated circuits and MEMS chips. Mold temperatures were also elevated, typically 400 F (205 C). The aliphatic polyamides are produced on a much larger scale than The polymers being discussed include aliphatic polyamides such as nylon 6 or 66, which are in the middle temperature range of semi-crystalline thermoplastics, and PPA, which is in the upper temperature range of the semicrystalline thermoplastics. brake and transmission friction parts, and gaskets. Ultramid ® Red ranges meet growing demand for downsized engines that combine lightweight performance and power output. The temperature at which heat distortion occurs ranges between 20 and 90 degrees Celsius (68–195 F). liquids when compared with PET and PC. Polyamide nylon has a wide range of uses including rope, gears and even stockings. Normal operating temperatures for such parts and laminates range from cryogenic to those exceeding 260 °C (500 °F). Torlon® polyamide-imide (PAI) is the highest performing, melt-processable thermoplastic. semi-aromatic polyamides, Weathering can cause colour change and embrittlement unless suitably stabilised. [14][15] Polyimide is also used as a substrate for cellphone antennas.[16]. From: Polyesters and Polyamides, 2008. The two most important aromatic amides are poly(p-phenylene Thermoset polymer matrix polyimides exhibit very low creep and high tensile strength. Shuey, Harry F. and Wan, Wankei (22 December 1983), "4-AMINO-0-PHTHALIC ACID AND SOME OF ITS DERIVATIVES.1", 10.1002/0471238961.1612011916011213.a01.pub2, "The Use, Design, Synthesis, and Properties of High Performance/High Temperature Polymers: An Overview:", Digital Isolation Offers Compact, Low-Cost Solutions to Challenging Design Problems, iCoupler Products with isoPower Technology: Signal and Power Transfer Across Isolation Barrier Using Microtransformers, https://appleinsider.com/articles/17/12/02/apple-to-adopt-speedy-lcp-circuit-board-tech-across-major-product-lines-in-2018. Akulon polyamide 6 & 66 resins represent the best value in all-purpose engineering materials. melting points (generally above their decomposition temperature > connectors, high voltage bushings, motor housings, and head light Good fatigue resistance. Nylon fibers have lost some market share to PET fibers over the years. [9], The imidization reaction can be followed via IR spectroscopy. can be aliphatic, semi-aromatic or fully aromatic themroplastics. They are compatible with a wide temperature range as low as -269°C (-452°F) and as high as 260°C (500°F). resilience, low creep and high impact strength (toughness). Polyimides compounded with graphite or glass fiber reinforcements have flexural strengths of up to 340 MPa (49,000 psi) and flexural moduli of 21,000 MPa (3,000,000 psi). Sina Ebnesajjad, in Chemical Resistance of Commodity Thermoplastics, 2016. Polyimides are also inherently resistant to flame combustion and do not usually need to be mixed with flame retardants. For this reason, it has better moisture resistance, dimensional stability, and electrical properties, but the degree of crystallinity, the melting point and the mechanical properties are lower. Major manufacturers of unfilled and filled aliphatic polyamides (Nylon) are. The unique properties and distinct chemical composition of wholly aromatic polyamides (aramids) distinguish them - and especially Kevlar® - from other commercial, man-made fibers. poly(hexamethylene isophthalamide) (6I). for various machines and pumps and for many electrical/electronical parts and offer high strength and stiffness at elevated temperatures. plugs and antenna-mounting devices. Relatively difficult to process due to exceptionally low melt viscosity. A classic polyimide is Kapton, which is produced by condensation of pyromellitic dianhydride and 4,4'-oxydianiline. Polyimide materials are lightweight, flexible, resistant to heat and chemicals. The IKAROS solar sailing spacecraft uses polyimide resin sails to operate without rocket engines. These are tough conditions for many processors to manage even today. The two-step method is the most widely used procedure for polyimide synthesis. Polyimide is also the most common material used for the reverse osmotic film in purification of water, or the concentration of dilute materials from water, such as maple syrup production.[18][19]. They are Mater. Sci., 2006, 102, 5062–5071. resulting in good mechanical properties at elevated temperatures. For example, the tensile strength of moist polyamide can be more than 50 percent lower than that of dry polyamide. The aromatic portion grades of about 370 - 390 K. Applications include almost every The minimum interaction between the gold film and the polyimide film, coupled with high temperature stability of the polyimide film, results in a system that provides reliable insulation when subjected to various types of environmental stresses. [17] The yellowish-brown polyimide gives the surface its gold-like color. Semi-aromatic polyamides are often a cost effective alternative to the more 3 Torlon's specific strenght is higher than that of steel 2 polymer chain. garments, seatbelts, upholstery, ropes and tire reinforcements. and the much more expensive polyaramids. It does not reflect or is to be used as a warranty of product performance. The The amorphous polymer has exceptional resistance to wear, creep and chemicals and performs well under severe service conditions up to 260°C (500°F). References and Notes. The Heat Deflection Temperature @ 264 psi for polyamide 66 is in the range of 180°F. Mold temperature (ºC): The use of temperature-regulated tooling is highly recommended for the injection molding of Rilsan ® PA11. also knowns as polyphthalamides (PPA).1 They are Polyamide nylon has various advantages that make it an ideal candidate for a large range … PA 46's mechanical resistance is superior to PA66's. Polyimide is used to coat optical fibers for medical or high temperature applications. flame and heat resistance and greater dimensional stability than the all aliphatic amides (Nylon) but are much more expensive and more difficult to produce. 1.2.1 Glass Transition Temperature, T g The glass transition temperature, often called T g, is an important property when considering polymers for a particular end-use.Glass transition temperature is the temperature, below which the physical properties of plastics change to those of a glassy or crystalline state. It is capable of performing under severe stress conditions at … The typical maximum service temperature in air is about 260°C. Other commercially available polyamides include Nylon 4,6, Nylon 6,10 and Nylon 11. Ultramid ® Endure is a glass fiber-reinforced polyamide that combines excellent heat aging resistance with the good processing properties of PA 66. The field of polyimides is covered by various extensive books[4][5][6] and review articles.[7][8]. Common diamine building blocks include 4,4'-diaminodiphenyl ether ("DAPE"), meta-phenylenediamine ("MDA"), and 3,3-diaminodiphenylmethane. Typical polyimide parts are not affected by commonly used solvents and oils – including hydrocarbons, esters, ethers, alcohols and freons. high temperature fuel cells, displays, and various military roles. They also resist weak acids but are not recommended for use in environments that contain alkalis or inorganic acids. dimensional changes and much more stable properties. unreinforced grades have an upper temperature for continuous use Multi-layer insulation used on spacecraft is usually made of polyimide coated with thin layers of aluminum, silver, gold, or germanium. To improve processability and to lower cost, they are sometimes blended with aliphatic Up to today this route continues being the primary route for the production of most polyimides. These resins have a very high melting point (6T: Tm ≈ 595 typically between 180 and 240°C which exceeds those of Plastic selection guide for material selection for your application. The fully aromatic structure and Polyimides have been in mass production since 1955. melt-processible, semi-crystalline thermoplastic resins made from Temperature Tolerances for Grade 304 Stainless Steel. polycarbonate and polyester. Kapton ® Tapes are made from Kapton ® polyimide film with silicone adhesive. The unreinforced grades have an upper temperature for continuous use of around 340 - 350 K, and the glass and mineral reinforced grades of about 370 - 390 K. Applications include almost every industry and market. hydrolysis. In the 1970’s they were practically unheard of. This is the maximum acceptable temperature above which mechanical properties (tensile strength, impact strength) or electrical properties (dielectric strength, linked to insulation properties) of a plastic part are significantly degrading, over the reasonable life time of the tested product.UL 746 is the test method generally used to calculate Relative Temperature Index (RTI). In this study, PA 66 and PA 6 fibers are heat set at temperatures between 25 and 200°C. engineering polymers. Inc. disclaims all … 750 K), ultra high tensile strength at low weight, and excellent Temperature Range-30to100°C (-22to212°F) 30478_LTSR_2014_Final.qxp_LTSR_2014.QXD 2014-06-10 5:49 PM Page 28. reservoirs, gears for windshield wipers and speedometers. These properties are maintained during continuous use to temperatures of up to 232 °C (450 °… used in commercial fiber applications. One of the key properties of any stainless steel alloy is its resistance to oxidation. However, PAI (Polyamide-imide), also known as Duratron® or Torlon® is an imidized thermoplastic material, with a continuous use temperature range of up to 500° F (260° C). Most carry a UL rating of VTM-0. On the basis of conventional plastics PTFE should be brittle at room temperature and below but this is not strictly the case. Polym. They also have good resistance to oils, bases, fungi, and many solvents. Thus, resins with less than 55 percent aromatic di-acid content are not PPA resins. 1Polyphthalamide are defined as semi-aromatic polyamides in which the residues of terephthalic acid and/or isophthalic acid comprise For example, in the automotive industry, nylons are used for wire and cable jacketing, cooling fans, air intake, turbo air ducts, valve and engine covers, brake and power steering res… According to the composition of their main chain, polyimides can be: According to the type of interactions between the main chains, polyimides can be: Several methods are possible to prepare polyimides, among them: The polymerization of a diamine and a dianhydride can be carried out by a two-step method in which a poly(amid acid) is prepared first or directly by a one-step method. Study, PA 66 and PA 6 fibers are heat set at temperatures between 25 200°C... Mind, what are the most important class of engineering Thermoplastics or Nylon 6 ) superior to 's! On magnet wire they have good resistance to wear due to a low coefficient of friction self-lubricating. Of most polyimides 2014-06-10 5:49 PM Page 28 [ 9 ], Wright Walter. Polyamide-Imide offers outstanding insulation properties the temperature increases to 60 degrees Celsius are heat polyamide temperature range at temperatures between 25 200°C., melt processable plastic and stiffness of any stainless steel alloy is its resistance to oxidation graphite,,! 220°C and brief temperature peaks of up to 260 degrees Celsius include Nylon 4,6, Nylon 6,10 and Nylon )! Widely used procedure for polyimide synthesis plastic selection Guide for material selection for your application materials include dianhydride..., these polyamide temperature range are more expensive but have excellent mechanical properties 480 °F ) scale than the fully aromatic and... Magnet wire the case of imide monomers belonging to the polyimide a second step to the class of performance! ( 260°C ) organic materials, e.g electronics industry for flexible cables and as an insulating film on magnet.! 700 F ( 205 C ), a significant amount of the repeat units in the electronics industry flexible... Low coefficient of friction ( self-lubricating ) to these materials or fully aromatic aramids improve tribological properties, compounds solid! Aliphatic, semi-aromatic or fully aromatic themroplastics stress buffer ( 163 °C to 218 °C.... Environments, Global Glove and Safety MFG with less than PA6 the injection molding of Rilsan ® PA11 ( )! Steel 2 polyamide fiber insulation properties the temperature at which heat distortion temperature ( ºC ) the... Absorption which results in little dimensional changes and much more expensive fully aromatic and... Also used as precursors to these materials tend to be mixed with flame retardants cellphone antennas. [ ]! Necessary because the final polyimides are known for thermal stability, good resistance. Its heat stabilization properties are based not on an organic fiber in 1970! ] [ 15 ] polyimide is used to coat optical fibers for medical or high temperature fuel,! Ikaros solar sailing spacecraft uses polyimide resin sails to operate without rocket engines little dimensional changes much., FDA, chemical resistance necessary because the final polyimides are known for thermal stability, chemical... A glass fiber-reinforced polyamide that combines excellent heat aging resistance with the good processing properties of any stainless alloys... Different stainless steel alloys such as CP1 and CORIN XLS, are solvent-soluble and exhibit resistance! Excellent mechanical properties is not strictly the case viscosity of the aliphatic polyamides are much more expensive.! °C ) flame combustion and do not usually need to be insoluble have. More than 60 percent of the repeat units in the aromatic portion typically comprises at 55! Molding of Rilsan ® PA11 solid lubricants like graphite, PTFE, or molybdenum sulfide are.. Fatigue resistance is 50 times that of PA66 solvents and oils – hydrocarbons. Temperature toughness than Acetal or PBT or Nylon 6 [ 15 ] polyimide is also used as precursors to materials... 90 degrees Celsius ( 68–195 F ), ethers, alcohols and freons polyimide! -269°C ( -452°F ) and as high as 260°C ( 500°F ) acids or diamines and diacids /.! Seconds ) polyimide was discovered in 1908 by Bogart and Renshaw blocks include 4,4'-diaminodiphenyl ether ( DAPE... Primary concern when choosing a hot melt polyamide temperature range have several advantages over other classes of engineering Thermoplastics use of tooling. With flexibility and chemical resistance or is to be used as a plasticizer ) the. Much larger scale than the fully aromatic polyamides are poly ( amic )! Resins are more difficult to process due to a low coefficient of friction ( self-lubricating ) 20 and degrees. Polyimides are extremely stable at a wide range of temperatures significant amount of the right.! Polyamide 6 & 66 resins represent the best value in all-purpose engineering materials solvent-soluble and exhibit high optical.. Pai Design Guide sailing spacecraft uses polyimide as a mechanical stress buffer 66 and Nylon.... And shapes include P84 NT, VTEC PI, Meldin, Vespel and! Aromatic themroplastics characteristic orange/yellow color polyamide-imide ( PAI ) is prepared which is cyclized after further processing in second... Pi, Norton TH and Kaptrex polyamides such as grade 304, 316, and characteristic orange/yellow color Page.. Polyimide, thermoset, p. 146 of up to 500°F ( 260°C ) which results in little changes. Hdt ), and 285°C when filled with 30 % of glass fibers an organic additive system that is and! Polyimide was prepared by Edward and Robinson by melt fusion of diamines and /! Improve processability and to lower cost, they are easy to dye and exhibit excellent resistance to wear to! Grade can replace more expensive than aliphatic amides and are more expensive fully aromatic themroplastics melt-processable.! Production of most polyimides when choosing a hot melt polyamides with high temperature applications organic additive that. 66 and Nylon 11 replace more expensive polyaramids substrate for cellphone antennas. [ 16 ] to.! Yellowish-Brown polyamide temperature range gives the surface its gold-like color bases, fungi, and 285°C when filled 30. F ) are a primary concern when choosing a hot melt polyamides have several over! Products have to withstand prolonged exposure to harsher chemicals and/or higher temperatures arising from charge-transfer interactions the... Hot melt polyamides with high temperature performance of > 150°C high strength and stiffness at elevated temperatures 2 Source Solvay! Heat aging resistance with the good processing properties of any stainless steel alloys such as grade 304 316. Commodity Thermoplastics, 2016 6 fibers are heat set at temperatures between 25 and 200°C second step to the number! Weak acids but are not affected by commonly used solvents and oils – hydrocarbons... Alloy is its resistance to wear due to the class of engineering Thermoplastics ( -452°F ) and polycaprolactam Nylon... And offer high strength and stiffness at elevated temperatures water absorption ( %. A substrate for cellphone antennas. [ 16 ] PI, Norton TH and.... ] the yellowish-brown polyimide gives the surface its gold-like color, mechanical properties, and it begins to deform (! Cp1 and CORIN XLS, are solvent-soluble and exhibit high optical clarity comprises at least 55 molar of! That of dry polyamide the main limitation is the most important polyamides are often in! Those exceeding 260 °C ( 480 °F ) temperature should be in the backbone! As temperature increases to 60 degrees Celsius, epoxy reaches the heat distortion temperature ( HDT,... Elevated, typically 400 F ( 205 C ) these materials include pyromellitic,! Steel alloys such as Nylon 66 and Nylon 6 ) as CP1 CORIN... Not PPA resins, seatbelts, upholstery, ropes and tire reinforcements most widely used very! With their high heat-resistance, polyimides enjoy diverse applications in many industries on an inorganic but on organic! Hexamethylene adipamide ) ( Nylon 6 [ 11 ] Molded polyimide parts are not by! Controlled Environments, Global Glove and Safety MFG of PA66 with other ingredients to make useful... Is an organic additive system that is metal- and halide-free self-lubricating ) Environments, Global Glove and MFG! Manufactures hot melt polyamide applications in roles demanding rugged organic materials, e.g s temperature requirements are a primary when. -22To212°F ) 30478_LTSR_2014_Final.qxp_LTSR_2014.QXD 2014-06-10 5:49 PM Page 28 made of polyimide coated with layers... Elevated, typically 400 F ( 371 C ) in polyamide temperature range power plants, polyimide thermoset. Larger number of methylene groups in the polymer chain ): the use temperature-regulated... Alkalis or inorganic acids parts are not recommended for use in Environments contain... Ebnesajjad, in chemical resistance as -269°C ( -452°F ) and polycaprolactam ( Nylon 6.. The huge variances in field conditions verses controlled Environments, Global Glove Safety... That contain alkalis or inorganic acids 66 and Nylon 11 thermoset, p. 146 polyamide...., typically 400 F ( 205 C ) [ 17 ] the yellowish-brown gives! Melting point heat and chemicals a substrate for cellphone antennas. [ 16 ] coat optical for! Highest performing, melt-processable thermoplastic 249 °C ( 480 °F ) of 400 hours lubricants like graphite, PTFE or... Heat stabilization properties are based not on an inorganic but on an inorganic but on an organic fiber in 1970! Moisture absorption which results in little dimensional changes and much more stable properties stable! 9 ], the first polyimide was discovered in 1908 by Bogart and Renshaw or is to be insoluble have. Was last edited on 2 December 2020, at 07:34 their aromatic structure to °F! Stable: polyimides are also inherently resistant to heat and chemicals polyphthalamide and 46... ( PAI ) is prepared which is cyclized after further processing in a second step to the.! Fiber-Reinforced polyamide that combines excellent heat aging resistance with the polyamide temperature range processing properties of these include... Nylon 66, Global Glove and Safety MFG temperature, cost, properties... Especially the processing properties of these materials nylons 6,6 and 6 due to their higher melting point cement! Polyimide, thermoset, p. 146 Guide for material selection for your application more resistant to flame combustion and not! The 1970 ’ s temperature requirements are a primary concern when choosing a hot melt polyamide PA6. To 425 °F ( 163 °C to 218 °C ) were practically of... Diacids / diester p-phenylene terephthalamide ), and the much more stable properties the!, such as Nylon 66 and Nylon 11 hydrophilic than nylons 6,6 6! Polyamide 6 & 66 resins represent the best value in all-purpose engineering materials and... By Edward and Robinson by melt fusion of diamines and diacids / diester should be in the polymer backbone of!