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The formulation of powder coatings using solid state shear extrusion
Author(s) -
Wojcik B.,
Teymour F.,
Arastoopour H.,
Mostovoy S.
Publication year - 2002
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11031
Subject(s) - materials science , extrusion , plastics extrusion , composite material , coating , ball mill , gel permeation chromatography , curing (chemistry) , extrusion moulding , agglomerate , polymer
The feasibility of producing homogeneous powder coating formulations without melting is investigated using Solid State Shear Extrusion (SSSE). A detailed comparison between conventional melt extrusion and SSSE processing conditions of identical formulations is accomplished by following the behavior and degree of polymerization during curing. Commercially available polyester and epoxide powder coating premix formulations were processed by SSSE using a Brabender® laboratory‐scale twin‐screw extruder and further pulverized in a ball mill. Calculations based on particle size before and after comminution in single batch ball mill studies indicate a reduction in energy requirements for SSSE during pulverization. Metal coupons were coated with dry pulverized formulations using an electrostatic fluidized bed coating system. The dynamics of curing were followed for a series of bake time exposures. The sol was separated from the gel using Soxhlet methods and characterized by gel permeation chromatography (GPC). A comparison of experimentally determined gel points and gelation dynamics showed general agreement between both processing methods. The critical yield stress, determined from preliminary mechanical testing of modified thick adherend specimens crack‐line‐loaded in compression, was also determined. Results showed the SSSE process to be equivalent to melt extrusion.