Polysiloxane improved resist properties

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

The evolution of HALS technology to meet the requirements of emerging polyolefin markets and applications is a story of continuous improvement and structure/property optimisation [19-21], Current trends in the industry are toward low-volatility, extraction-resistant, hindered phenolic AOs, such as oligomeric polysiloxane based, high-MW antioxidants... 

Exfoliating layered particles such as the clays, mica, or graphite is being used to provide very effective reinforcement of polymers at loading levels much smaller than in the case of solid particles such as carbon black and silica.77 81 Other properties can also be substantially improved, including increased resistance to solvents, and reduced permeability and flammability. A number of such studies specifically address the effects of introducing layered fillers into polysiloxanes 42,82 88... 

Another important class of linear polysiloxanes are the siloxane copolymers. The replacement of methyl groups by other organic groups improves the specific physicochemical properties of PDMS, and one such improvement is in the area of resistance to thermal degradation, e.g., phenyl-containing polysiloxanes have superior thermal stability compared to PDMS. 

Chem. Descrip. Methylalkyl polysiloxane sol n. in naphtha Uses Defoamer for org. systems improves mar resistance and leveling in air-dry and baking enamels, acid-curing systems, polyurethane and nitrocellulose lacquers, solv.-based industrial paints Properties Sp.gr. 0.87-0.90 g/cc dens. 7.36 Ib/gal flash pt. (Seta) 45 C ... 

Polycarbonate homopolymer when exposed to heat and humidity, under some eonditions may suffer a reduction in the meehanical properties. This paper discusses significantly improved heat and hydrolytie resistance of eopolymers of Polycarbonate with Polysiloxane. Retention of transparenQr conpled with good mechanieal properties upon heat and hydrolytie aging makes these new materials excellent candidates for hot and hnmid engineering thermoplastic apphcations. 

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