improved filling of
improved filling of longer cavities reduced part thickness reduced melt temperatures to fill the same cavity, enabling shorter molding cycle time gating simplification. Melt stability - mechanical properties Sorona EP exhibits good melt stability without significant change in mechanical properties up to a residence time of 10 minutes, when dried to below 0.02% moisture content and molded at a recommended melt temperature of 250°C. The melting point of Sorona EP is 227°C, close to PBT at 225°C. Melt stability - cylinder profile When molding semi-crystalline polymers such as PBT and Sorona EP PTT, the cylinder temperature profile should be adjusted as a function of residence time to minimize degradation, maintain stability, and achieve an optimum balance of homogeneity while maintaining the high molecular weight of the molten material. Effect of mold temperature on aesthetics Superior surface quality and a high gloss effect require a minimum temperature of 80°C in a polished mold. Increasing the mold temperature to 90°C will further improve the excellent scratch resistant properties of the DuPont PTT. This has been demonstrated in Erichsen scratch hardness testing showing that increasing the mold temperature from 70°C to 90°C increases the scratching force by up to 8N. Effect of mold temperature on shrinkage and warpage Shrinkage is caused by thermal contraction and crystallisation of the polymer during the hold pressure and cool down phase. Uneven wall thickness and anisotropic fillers will reinforce a tendency to deform. Non-reinforced Sorona EP exhibits approximately 0.4 to 0.5% lower shrinkage than standard PBT, while parts molded in glass-reinforced Sorona EP have shown less warpage versus standard glass-reinforced PBT. To produce molded parts of Sorona EP with optimum characteristics and low postshrinkage requires a sufficient degree of crystallization. This is influenced to a large extent by mold temperature. A mold temperature of 80°C is sufficient to produce parts with low postshrinkage. Higher mold temperatures (>85°C) contribute to reduced dimensional changes caused by post-crystallization (post-shrinkage). Meeting growing demand for bio-based polymers With Sorona EP, DuPont has developed a PTT polymer that meets the growing demand for a sustainable bio-based Photo 1: excellent high gloss finish of unreinforced Sorona EP pigmented using a masterbatch engineering plastic with in-use performance equivalent to, or better than, PBT, PET or PC/ABS polymers. It also exhibits a molding behavior similar to high-performance PBT in conventional injection molding equipment. Processing conditions are essentially the same with some minor adjustments, following DuPont processing recommendations. Compared to PBT, glass-fiber reinforced Sorona EP exhibits better mechanical properties at elevated temperatures including enhanced strength and dimensional stability, stiffness, lower warpage and shrinkage, and improved surface appearance. The new backbone chemistry of PTT provides new functionality to a PBT-like polymer. A skilled molder with PBT expertise should have no concerns about testing Sorona EP. The reward will be in the added value of higher quality finished components. www.dupont.com Diagram 5: Backbone chemistry of Sorona EP PTT Diagram 4: Shrinkage and post-shrinkage of Sorona EP PTT polymers Annealing conditions: 1 hour in an oven at 120°C HO C C C OH 1,3 Propanediol (PDO) + HO O C O C OH Terephthalic Acid O O O C O C C C C C C C O C O O O Polytrimenthylene terephtalate S hrinkage (%) 0.80 1.00 1.20 1.40 1.60 1.80 Standard PBT after annealing Standard PBT DuPont Sorona 3301 NC010 after annealing DuPont Sorona 3301 NC010 40 60 90 110 Melt Temperature (°C) 12 bioplastics MAGAZINE [03/14] Vol. 9
9th & 10th September 2014 Thon EU Hotel, Brussels Bioeconomy in Action – from Rhetoric to Reality e Bio-based Global Summit will inform decision akers from the Bio Chemical, Plastic, Polymer d Packaging markets of the real potential d viability of the Bio economy – in terms of emicals, plastics and fuels. Speaking at the Bio-based Global Summit will be: Maira Magnani, Ford Research & Advanced Engineering Europe esse Putzel, Senior Sustainability Manager, BAM (Packaging Design Agency) Dr John Williams, Group Technical Director, Sinvestec Rulande Henderson, PhD, Commercial Director, Econic Technologies and many more Book your place now delegates rates are: ore 23rd June 2014 – Early bird delegate rate of €895 elgian VAT or after 23rd June 2014 – Normal delegate rate of €1,000 elgian VAT can book online at: www.biobased-global-summit.com Organised by Supported by Media partners
