|
Polyphthalamide (aka. PPA, High Performance Polyamide) is a diverse subset of thermoplastic synthetic resins in the polyamide (nylon) family defined as when 60% or more moles of the carboxylic acid portion of the repeating unit in the polymer chain is composed of a combination of terephthalic (TPA) and isophthalic (IPA) acids.〔Cousin, Thibault, Jocelyne Galy, and Jerome Dupuy. "Molecular Modelling of Polyphthalamides Thermal Properties: Comparison between Modelling and Experimental Results." Elsevier 53.15 (2012): 3203-210. Web. 26 Nov. 2013. As a member of the nylon family, it is a semi-crystalline or amorphous material composed from a diacid and a diamine which means PPA is formed by the reaction of aromatic acids with aliphatic diamines. However, the diacid portion contains at least 55% terephthalic acid (TPA) or isophthalic acid (IPA).〔Lyons, J. S., Tinio, E. G. and Berry, S. F. (1995), Creep, stress rupture, and isothermal aging of reinforced polyphthalamide. J. Appl. Polym. Sci., 56: 1169–1177. doi: 10.1002/app.1995.07056091〕 TPA or IPA are aromatic components which serve to raise the melting point, glass transition temperature and generally improve chemical resistance vs. standard aliphatic nylon polymers and reduce water absorption.〔Harper, Charles A (2002-06-10). Handbook of plastics, elastomers, and composites. pp. 51–52. ISBN 978-0-07-138476-6.〕 If more than 55% of the acid part of a PPA is made out of IPA, then the copolymer is amorphous.〔Cousin, Thibault, Jocelyne Galy, and Jerome Dupuy. "Molecular Modelling of Polyphthalamides Thermal Properties: Comparison between Modelling and Experimental Results." Elsevier 53.15 (2012): 3203-210. Web. 26 Nov. 2013. Polyphthalamide with 6T-Segment Polyphthalamide with DT-Segment In recent years, polyphthalamides have been commercialized by several polymer resin manufacturers which are under the trade names Amodel, Grivory, Ultramid T, VESTAMID HTplus, Akromid T and Zytel HTN. ==Properties== Properties of polyphthalamide include: high heat resistance, high chemical resistance, abrasion/corrosion resistance, high tensile strength, high dimensional stability, direct bonding to many elastomers to give plastic-rubber composites, and is also approved for direct contact with drinking water and food.〔Evonik Industries, http://www.vestamid.com/product/vestamid/en/products-services/pages/default.aspx〕 PPA is more creep resistant and stiff compared to traditional polyamide nylons. Molar masses for PPA’s made with direct polycondensation techniques range between 12,000 and 16,000 g/mol. The glass transition temperature of PPA increases as the amount of TPA increases.〔Cousin, Thibault, Jocelyne Galy, and Jerome Dupuy. "Molecular Modelling of Polyphthalamides Thermal Properties: Comparison between Modelling and Experimental Results." Elsevier 53.15 (2012): 3203-210. Web. 26 Nov. 2013. PPA resin technology can produce both semi-crystalline and amorphous polymers. One of the major differences between amorphous and semi-crystalline polymers is the way their properties change in response to changes in temperature. At temperatures above the glass transition temperature the modulus decreases rapidly. Therefore, amorphous thermoplastics are rarely used at temperatures higher than their glass transition temperature.〔http://www.nevicolor.it/images/commercializzati/pdf/amodel/amodel_general_brochure.pdf〕 Like aliphatic nylons, PPAs can be modified with reinforcing agents, toughens stabilizers etc. for example 51% Glass/Mineral reinforced PTA is added by weight. Its flexural strength is 24 to 28.4 GPa. Its elongation at break is 1.9 to 2%, and specific gravity is 1.66 to 1.68.〔http://www.efunda.com/glossary/materials/polymers/polyphthalamide--51pct_glass_slash_mineral_reinforced--401.cfm〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「polyphthalamide」の詳細全文を読む スポンサード リンク
|