PVC windows offer a host of benefits making them a popular choice of window in the global markets. PVC-U windows and doors are tough, durable with a long life, low maintenance and come in a range of designs, colours and textures. They are long lasting and virtually maintenance free and therefore are the most cost-effective option. They are energy efficient, with simple recycling. PVC-U windows are made from sections of profile, which are cut and joined together to for the shape of the window. The windows are fabricated from pieces of profile that have been cut to the correct size, joined using either heat-fusion welding or T-joint connectors. Steel or aluminium reinforcement sections are fixed inside the PVC-U profiles to provide additional strength, where required. As per British Plastics Federation, PVC-U is based on the polyvinyl chloride polymer, however, in order to make the material suitable for use as a window, a number of different additives and stabilisers are used. Stabilisers often comprise a metallic component together with various organic compounds - the simple elemental form of a metal is never used. Several types of metal salts and soaps are used to stabilise PVC for window applications: • Lead : Elemental lead is not used as a PVC additive. Special compounds known as salts and soaps are used in PVC applications to give very good processing and weatherability characteristics. The presence of lead based stabilisers in PVC products does not represent any significant risk of damage to health. • Organotin Stabilisers: These stabiliser systems are now well established for use in PVC items, though their use in PVC-U window profile applications is limited. As with lead and cadmium based stabilisers, they remain firmly bound within the polymer matrix. The organotin compounds used as PVC stabilisers are safe to use • Calcium Organics: Are generally based on metal carboxylates and will sometimes incorporate other elements to boost performance such as aluminium or magnesium. This type of stabilising system can give products that have a high degree of clarity, good mechanical and electrical properties, excellent organoleptic properties and good outdoor weatherability. This stabilizer systems incorporating the proven range of co-stabilisers have low-toxicity and are often regarded as non-toxic. They have to meet the general requirements for dust emissions in the workplace although dust-free forms are readily available. The American Architectural Manufacturers Association (AAMA) is in the process of finalizing a Green Certification Criteria Matrix with stricter norms and regulations. Energy efficient PVC window will undergo design changes to make them more energy efficient. The first requirement has already been put into action by April 2010. Another change may come up in 2013. In addition to energy-efficient features, PVC window profile producers are working on enhancements of durability, weathering, higher strength, widening of processing window, higher throughput. Al l these parameters are driving the developments of additives. Some of the new notable developments are: • Paraloid KM X100 acrylic impact modifier from Dow provides higher impact strength, higher gloss and wider processing window. Paraloid KM 370 impact modifier from Dow to provide better gloss in mixed metal stabilization of PVC window profiles typically used in Europe. • Thermolite® 150 butyl tin stabilizer from Arkema provides higher thermal stability, and offers high output extrusion used in the manufacture of window profiles, as well as other demanding rigid PVC applications. It is a cost-effective, mid-range butyl stabilizer displaying good color hold with outstanding stability and weathering properties. It maintains excellent processing characteristics and may provide an added cost benefit because it can be used at similar use levels as higher-tin, higher-priced stabilizers. • Rohm and Haas’ range of Paraloid KM impact modifiers for extruded vinyl window profiles, optimizing different performance aspects of window profiles, enabling users to customize their PVC applications according to specific performance requirements. It allows lower use levels for cost reduction, provides a wider process window for lower melt temperatures, and also provides fast fusion for higher output rates. Use levels of 4 phr or less are said to provide excellent impact and gloss. • Arkema’s acrylic-based Durastrength® acrylic impact modifiers are free flowing powders designed to deliver optimum cost/performance in PVC profile, siding, fence, pipe and injection molding compounds. Durastrength® products offer superb weatherability, improved processing with better flow, more even pigment dispersion and heat stability, as well as greater impact strength even at low temperatures. They can be used as a high efficiency modifier system for siding, window profile and pipe fitting and conduit, and is suitable for all outdoor/weatherable PVC applications. • Arkema’s Clearstrength® 320 is an MBS impact modifier designed for use in clear packaging and profile applications where quick fusion, and added impact strength is desirable. Our patented manufacturing process ensures that Clearstrength® 320 excellent lot to lot consistency, uniform color hold, high impact strength and low gel levels. Clearstrength® 320 is formulated to provide optimum clarity to film and sheet. Improved additives available nowadays help PVC window profile producers meet requirements for increasing performance and for reducing manufacturing costs.