Basics PTT by Michael
Basics PTT by Michael Thielen PTT (Polytrimethylene terephthalate) is a semicrystalline polyester, closely related to the more common thermoplastic polyesters, PET (Polyethylene Terephthalate) and PBT (polybutylene terephthalate) but typically less expensive [1]. Toyota launched the ‘Prius a‘ with interior components made of Sorona EP in Japan in May 2011. The parts are used on the instrument-panel air-conditioning system outlet. (Photo: Toyota) The aromatic polyester is generally prepared by a polycondensation reaction of terephthalic acid (C 6 H 4 (COOH) 2 ) with 1,3-propanediol (HO(CH 2 ) 3 OH)) compared to PET (polyethylene terephthalate, which is made with ethylene glycol as opposed to 1,3-propanediol) and to PBT (polybutylene terephthalate, which is made with 1 ,4-butane diol as opposed to 1,3-propanediol). PTT was first synthesized by Whinfield and Dickson in 1941 [3]. Further commercialization was slowed by a lack of readily available, inexpensive 1,3-propanediol [4]. Today the 1,3-propanediol (PDO) component can be derived from renewable resources such as technical starch in a fermentation process and is marketed as Bio-PDO [5, 6]. When eventually a biobased terephthalic acid becomes available, even 100% biobased PTT seems viable. PTT was first launched onto the market mainly in the form of spun fibres and textiles. Because they are particularly soft and yet can bear heavy wear the principal area of application was for domestic carpets and carpets for the automobile industry [7]. The New generation SIM-Drive SIM-WIL electric vehicle features features interior components made from Sorona. Photographs are not yet available (Picture: SIM-Drive Corporation ). PTT can be injection molded and extruded, it shows performance such as a very good surface finishing, better mechanical properties at elevated temperatures, low warpage and good dimensional stability. The material is very attractive in a range of uses for, electrical and electronic components such as connectors, switches, plugs and housings (appliances, audio equipment, lighting systems, business machines), snapfit parts for automobiles or computers, knobs, and keyboards or instrument-panel air-conditioning system outlet [7, 8, 9, 10, 14]. Key markets include existing PBT (or PET) resin and alloy applications where aesthetics, cost, and/or performance are insufficient [10]. DuPont is one of the companies offering PTT in a broad range of products. DuPontSorona ® EP thermoplastic polymers contain between 20% to 37% (by weight) renewably sourced Susterra 46 bioplastics MAGAZINE [01/13] Vol. 8
Basics C 6 H 4 (COOH) 2 + HO(CH 2 ) 3 OH terephthalic acid + 1,3 propanediol → [O 2 CC 6 H 4 CO 2 (CH 2 ) 3 )] n + 2 H 2 O → PTT (polytrimethylene terephthalate) + water O O O n O Polycondensation of PTT Tensile/Flex Modulus, MPa 12000 10000 8000 6000 Sorona ® Polymer 15-30% Glass 4000 PLA 2000 Starch Based Bio-Polymer 0 0 20 40 60 80 100 120 140 160 180 Tensile Strength, MPa Source: [13] 1,3 propanediol (bio-PDO) produced by DuPont/Tate&Lyle currently derived from technical starch. Sorona EP thermoplastic polymer starts with the basic Sorona polymer (fibre) chemistry and then uses a proprietary formulation technology to create high-performance engineering polymer resins. Compared to PBT, Sorona EP filled with glass fibers shows better mechanical properties such as strengtht and stiffnes, improves the surface appearance, provides lower warpage and good dimensional stability. Sorona EP exhibits performance and molding characteristics similar to highperformance PBT, it can be moulded using conventional injection moulding machines. DuPont offer different types of Sorona from fibre/fabric grades through 15 and 30% glass fibre reinforced grades to food contact compliant types with 15% glass fibre reinforcement. When extruded as a fibre, Sorona holds an odd cross section – necessary for moisture management – better than traditional polyester – so moisture is transported away from the body efficiently and effectively in activewear. Since fibres and fabrics made with the new polymer are fade resistant, activewear colors remain bold and vivid through many workouts and adventures, not to mention washings. Most agree that the comfort stretch and full recovery of fabrics made with Sorona also lead to freedom of movement – a necessity in activewear. Fleece reaches new levels of softness. With fibres from Sorona microdenier softness is achieved at larger deniers making processing easier. When blended with other fibres, Sorona continues to offer valuable attributes. Blended with wool it offers softness and drape along with resistance to wrinkles – perfect for the business traveler who goes from plane to meeting. Cotton / Sorona blends offer softness and a comfort stretch and recovery to provide freedom of movement through the shoulders and elbows where consumers need it most. In other words, Sorona blends easily with other fibres – both synthetic and natural - to enhance and maximize both performance and style. Fabrics with Sorona can be dyed at a lower temperature and maintain their color fastness. With Sorona, black underclothes stay a lush, rich black while white intimates hold their crisp, fresh white. Colors are vibrant, saturated, and remarkably fade resistant. Sorona intimate apparel is bleachable. Unlike other intimate apparel textiles, PPT fabrics require no special delicate clothes dryer settings or hand washing. With Sorona, denim and jeans manufacturers can deliver stretch denim fabric, which provides freedom of movement. Most importantly, the PTT fabric retains both the individual shape and personalized fit of denim garments even after frequent washes. Apparel made from Sorona PTT fibres (photos: DuPont) bioplastics MAGAZINE [01/13] Vol. 8 47
