general_properties

Figure 1: Chemical Structure of NDC vs. PTAGeneral Properties of Naphthalate-Containing PolymersNDC (dimethyl-2,6-naphthalene dicarboxylate) is a specialty monomer that can be used to make polyester polymers that exhibit physical and mechanical properties generally superior to polymers made from terephthalic acid (TA) or dimethyl terephthalate (DMT). These enhanced performance properties have driven the increased use of naphthalate polymers in a wide range ofapplications including films, fibers, bottles, additives and engineering resins.NDC-based polymers, such as PEN (polyethylene naphthalate) and PBN (polybutylene naphthalate)derive their performance improvement from the double ring structure of the naphthalene molecule (Figure 1).H CO 3OCH 3CO OCHO OCCOH ONDC PTAFigure 2: Comparative Properties of PEN vs. PETWater Vapor T ransmission(g•mm/[m2•day•atm]) Use TY oung’s Modulus (MPa)Strength (MPa)at 360 nm (%)Incorporation of this double ring structure in the polymer chain increases thermal, chemical, mechanical, and barrier performance versus polymers based on single aromatic rings. Figure 2 illustrates the wide variety of property improvements exhibited by PEN versus PET.Partial substitution of terephthalate-based polymers with the naphthalate group, in a copolymer or blend form, can provide enhanced properties that are typically intermediate between the respective homopolymers. Further description of the naphthalate modified polyester key thermal, physical and mechanical properties is provided.Thermal Properties of Naphthalate Containing PolyestersMelting PointHomopolymers of NDC melt at higher temperatures vs. homopolymers of PTA. Table 1 compares the Tm of PEN and PBN versus PET and PBT respectively.Table 1: Melting Point of Polyester HomopolymersHomopolymer Tm, °C PET250PEN268PBT223PBN242For random copolymers, where both PTA and NDC are present, the melting point decreases as NDC partially substitutes PTA (e.g. starting from PET) or when TA partially substitutes NDC (e.g. starting from PEN). This melting point depression effect is caused by a disruption in the regular crystalline pattern by the minor component (Figure 3).Figure 3: Melting Point of PET/PEN Copolymers and Blendsmodified with 8 mole % DMT (PENT-8) equals the melting point of PET homopolymer. Use of the lower melting PENT-8 copolymer in preparing PET/PEN blends is preferred over use of PEN homopolymer. Not only are lower melt temperatures required in the blending process, which reduces the risk of PET degradation, but there is a better viscosity match between the naphthalate and terephthalate polymers which improves mixing and miscibility.Within the range of approximately 10–90 mole % NDC, PETN random copolymers remain essentially amorphous. On the other hand, PET/PEN blends are capable of crystallizing and exhibiting a melting point at any T/N ratio, which depends not only on this ratio but also on the degree of randomness or transesterification present. The yellow area in Figure 3 provides a cursory representation of this behavior.Glass Transition (Tg)Naphthalate homopolymers have a glass transition temperature significantly higher than the corresponding terephthalate homopolymers.Table 2: Tgof Polyester HomopolymersHomopolymer Tg, °CPET 80PEN125PBT46PBN82Unlike Tm, the behavior of Tgvs. NDC content is linear and follows the mixing rule (Figure 4).Figure 4: Glass Transition of PET/PEN Copolymers and BlendsThis linear relationship offers many opportunities for enhancing the thermal resistance of PET by simply blending in varying amounts of naphthalate. Practicalapplications include hot-filled, pasteurized, or washable containers, and outdoor glazing.An increase in Tgalso affords improved long-term aging behavior or reduced embrittlement of amorphous parts. It enables a reduction in cycle time during injection molding (e.g. of bottle preforms), since the parts can be released hotter. A 20% faster cycle time has been achieved in the case of PEN performs vs. PET. Finally, the higher Tgof PEN contributes greatly to the reduction of thermal shrinkage, which is of value in tire cord and other industrial fiber applications as well as films (Table 5).Mole % PEN60%80%020%40%100% ClassTransitionTemperature,˚CPhysical Properties of Naphthalate Containing PolyestersGas PermeabilityThe oxygen, carbon dioxide, and water vapor permeability of polyesters depend not only on composition but also on degree of crystallinity,orientation, and temperature. Regardless of the variable, PEN always exhibits significantly reduced gas permeability relative to PET . Some examples are illustrated in Table 3.Table 3: Gas Permeability, cc-mil/100 in 2-dayPETPEN CO 2 Transmission amorphous sheet 6915oriented film 31 6.0O 2 Transmission amorphous 10.9 4.4oriented film6.1 1.6Water Vapor Transmission amorphous4.312.12The barrier properties of PET/PEN copolymers essentially follow linear behavior between that of PET homopolymer and PEN homopolymer. In some cases involving PET/PEN blends, the barrierperformance can exceed that predicted by a straight-line extrapolation of the rule of mixtures (Figure 5).Figure 5: Oxygen Permeation of 0.35 Liter Jars from PET/PEN BlendsChemical ResistancePEN offers significant improvement in chemical,oxidative, and hydrolytic stability vs. PET . This has led to increased use of PEN in demanding engineering resin, fiber, film, and plastics applications and in returnable/refillable, pharmaceutical, and chemical packaging (Table 4).Table 4: Comparison of PET and PEN Chemical Resistance% Retention of Elongation at Break Chemical Agent PET PEN 1% hydrochloric acid 2 weeks 72855 weeks7410610% hydrochloric acid 2 weeks 4695 weeks0601% sodium hydroxide 2 weeks 769720 weeks6012610% sodium hydroxide 1 weeks 0702 weeks 050Ammonia gas 2 weeks 159310 weeks 096Thermal Aging2 weeks at 180°C, 0% RH 0802 weeks at 130°C, 100% RH2050PETWt % PENPENO x y g e n P e r m e a b i l i t y (c c /p a c k a g e /d a y )UV Absorption CharacteristicsNaphthalate-containing polyesters demonstrate a dramatically improved barrier to ultraviolet (UV)radiation. They also exhibit a greater retention of mechanical strength under external exposure or weathering conditions. This behavior is due to the fused aromatic structure of the naphthalate ring of NDC, which absorbs UV light at wavelengths as high as 370 nm. The benzene ring structure of DMT or PTA is essentially transparent at wavelengths above 310 nm. This UV absorption behavior is alsoexhibited in the corresponding polymers. (Figure 6and 7) Additional information can be found in the light absorbing properties bulletin. (N-10)Figure 6: UV Absorption Spectrum of NDC vs. DMTFigure 7: Relative UV Absorbance (300-400 nm)of PET, PEN and PET/NDA CopolymerNote: Spectra normalized to concentration and pathlength.The use of naphthalates, even at very low levels, can be a very effective UV barrier. This effectiveness,which is dependent upon both concentration and thickness of the absorbing layer, is illustrated in Figure 8.Even at concentrations of less than 1 mole %,naphthalate-containing polyesters can block >90%of the UV radiation in films < 2mm thick. This UV blocking behavior has practical benefits inprotection of light sensitive materials, such as foods and beverages.Figure 8: Effectiveness of Naphthalate UV BarrierNaphthalate content required to provide 99% extinction of UV light at 354 nm as function of thickness1020Wavelength (namometers)370330350390A b s o r b a n c ePENPET PET/10% NDA543102987610Thickness, mm0.30.40.10.20.5M o l e % N D C3000200010000Nanometers360380300320340400E x t i n c t i o n C o e f f i c i e n tNDCDMTMechanical Properties of Naphthalate Containing PolyestersIncorporation of naphthalates in polyesters also improves mechanical properties such as modulus and tensile strength. Like PET, PEN can be oriented uniaxially (fiber) or biaxially (film and bottle) and heat-treated in a variety of ways. Consequently, mechanical properties vary over a wide range depending upon the exact fabrication parameters used. Furthermore, in films, mechanical properties may differ between the machine (MD) and transverse (TD) directions; balanced films have very similar properties between the MD and the TD, whereas in tensilized films, the properties in MD and TD differ substantially. In general however, PEN bottle sidewalls, fibers, and films are capable of attaining tensile or flex modulus 1.5-3 times higher versus PET. Correspondingly, the elongation at break of PEN is generally lower vs. PET.Table 5 compares mechanical properties of PEN vs. PET in typical films and high-strength fibers.Table 5: Mechanical properties PEN and PET films and fibers50 Micron Films PEN PET Young’s Modulus, MPaMD50003800 TD53504200 Tensile Strength, MPaMD265190 TD150110 Stress at 5% Elongation, MPaMD80140 TD70100 Elongation at Break, %MD80140 TD70100 Thermal Shrinkage at 150°C, %MD0.6 1.3 TD0.4 1.3 High-Strength Industrial FibersTenacity, g/den109 Modulus, g/den360110 Elongation at Break, %814 Boiling Water Shrinkage, %15 Dry Heat Shrinkage at 177°C, %48ConclusionNaphthalate-based resins exhibit superior mechanical, thermal, chemical, barrier and UV properties versus standard polyester polymers. The use of naphthalates dramatically expands the performance capabilities of polyester enabling their increased use in more demanding packaging, film, fiber and engineering polymer applications.Regulatory InformationThe products and uses described herein may require global registrations for chemical inventory listings, or for use in food contact or medical devices. For further information, consult BP’s naphthalates “Regulatory Update” brochure, or send an e-mail to: bpcares@.Health and Safety InformationThe product described herein may require precautions in handling and use because of toxicity, flammability, or other considerations. The available product health safety information for NDC and NDA is contained in the Material Safety Data Sheet (MSDS) that may be obtained from your BP sales representative or by written request to the office address listed. Before using any material a customer is advised to consult the MSDS for the product under consideration for use.The Material Safety Data Sheet for this product includes the U.S. DOT 49, CANADIAN TDG, ADR/ RID, IATA/ICAO and IMO/IMDG shipping descriptions and should be consulted, before transportation, as a reference in determining the proper shipping description of this product.For additional information, on samples, pricing and availability, please contact:BPSales Administration and Customer Service150 West Warrenville Road, 605-CS 3Naperville, Illinois 60563-8460Toll-free: 877/701-2726Fax: 630/961-7700BPBuilding A, Chertsey RoadSunbury-on-ThamesMiddlesex TW16 7LLUnited KingdomTelephone: 44 (0) 1932 767627Fax: 44 (0) 1932 767914BPPetro House 3rd Floor4-5-21 KojimachiChiyoda-ku, Tokyo, Japan 102-0083Telephone: 81 (0) 3 3238 7319Fax: 81 (0) 3 3238 7343BP22nd Floor, Devon HouseTaikoo Place979 King’s RoadQuarry BayHong Kong, ChinaTelephone: 852 2586 8899Fax: 852 2827 1609BPPaseo de los Tamarindos 400Torre A Piso 1705120 Mexico, D.F.Telephone: 52 508 12100Fax: 52 508 12124Technical information contained herein is furnished without charge or obligation, and is given and accepted at recipient’s sole risk. Because conditions of use may vary and are beyond our control, BP makes no representation about, and is not responsible or liable for the accuracy or reliability of data, nor for toxicological effects or Industrial Hygiene requirements associated with particular uses of any product described herein. Nothing contained in this document shall be considered a recommendation for any use that may infringe patent rights, or an endorsement of any particular material, equipment, service, or other item not supplied by BP. “The Properties”and “Applications” listed in this document are not specifications. They are provided as information only and in no way modify, amend, enlarge, or create any specification or warranty, and ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE EXCLUDED.The letters bp and the Helios logo are trademarks of BP p.l.c.N-9, June, 2001© 2001 BP p.l.c.。