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Thermoplastic polymers can be divided into two categories based on their molecular structure: amorphous and semi-crystalline.  

Amorphous polymers have a randomly ordered molecular structure that lacks a sharp melting point. Instead, they soften gradually over a temperature range known as the glass transition temperature (Tg). Because these materials are isotropic in flow, they possess better dimensional stability than semi-crystalline plastics and are less likely to warp. Amorphous thermoplastics offer superior impact strength along with excellent resistance to hot water and steam, good chemical resistance, and good stiffness and strength. PPSU, PESU, PSU and PEI are good examples of amorphous thermoplastics offering these qualities. 

Semi-crystalline thermoplastics have a highly ordered molecular structure with both crystalline and amorphous regions. Due to the presence of crystals, they are generally opaque and have sharp melting points. Semi-crystalline polymers are anisotropic in flow, so they shrink more in the direction transverse to flow than they do along the direction of flow. This results in dimensional instability, compared to amorphous polymers. These materials have two different thermal transitions: the glass transition temperature (Tg), which corresponds to the softening of the amorphous phase, and the melting point (Tm), which corresponds to the melting of the different crystals and the flow of the material. The Tm is generally above that of the upper range of amorphous thermoplastics.


The performance of semi-crystalline polymers is directly related to the degree of crystallinity, i.e. the relative percentage of crystalline phase and amorphous phase and to the size of the crystalline domains. Those factors are intimately related to the polymer nature and to the parameters used for molding (applied shear, cooling rate, etc.).

In its natural state, Radel® PPSU is inherently transparent and light amber in color. Syensqo also offers 12 standard opaque and transparent colors that are ISO 10993 biocompatible and supported by extensive data in FDA Master Access Files. Custom colors are available through our partners.

Radel® PPSU is inherently flame retardant and has a V-0 rating down to a 0.8-mm thickness.

Most Radel® PPSU compounds comply with U.S. FDA and European Union (EU 10/2011 and 1183/2012) regulations for components having repeated contact with all types of foods. As regulatory action is an ongoing activity, please contact your Syensqo representative for the latest information regarding a specific application requiring agency approval or recognition.

Select Radel® PPSU compounds comply with all DW approvals required for components having continuous contact with drinking water and plumbing applications. As regulatory action is an ongoing activity, please contact your Syensqo representative for the latest information regarding a specific application requiring agency approval or recognition.

Radel® PPSU displays very good resistance to many chemicals, including aqueous systems, caustics, inorganic acids, aliphatic hydrocarbons, detergents and soaps, and certain alcohols.  Detailed chemical resistance data can be found in the Radel® PPSU design guide or by contacting your Syensqo representative.

Common solvents are generally ineffective due to the strong chemical resistance of Radel® PPSU. Chemicals used to dissolve PPSU include pyridine, dimethylformamide, aniline, N-methyl pyrrolidone or dimethylacetamide. Material Safety Datasheets should be read carefully prior to handling, as some solvents are toxic. Please contact your Syensqo representative for additional information.

As with most polymers, the UV resistance of Radel® PPSU depends strongly on the wavelength of the incident UV radiation and the exposure time. Long-term exposure of Radel® PPSU to direct sunlight significantly decreases the material’s ductility, and a decrease in tensile elongation at break and impact strength can be observed. Color change due to UV radiation occurs prior to loss of ductility. However, UV radiation does not affect other mechanical properties such as tensile strength or Young’s modulus.

Radel® PPSU can be sterilized using all commercial sterilization methods, including steam sterilization, EtO, gamma irradiation, and vaporized hydrogen peroxide. Radel® PPSU has the better retention of mechanical properties than PEI and all other amorphous polymers. Because it can withstand over 1,000 autoclave cycles without significant loss of properties, Radel® PPSU is widely used in medical device applications requiring repeated steam sterilization.

Pellets for molding trials and several shapes of molded articles are available for testing purposes. There is a wide range of products and sample types available. Stock shapes or other thick-walled semi-fabricates for machining prototypes are not offered due to the complexity of cooling parts fast enough to prevent the degradation of the inner core of thick sections. Please contact your Syensqo representative to request samples.

Most Radel® PPSU grades are fully characterized for FEA or rheological analysis. Data is available in most commercial rheological software, including Moldflow®, Moldex 3D, and CADFlow.