The replacement of these long-distance connections with short distance connections, multiplied over millions of bonds are responsible for the overall shrinkage in the material when it changes from a liquid to a solid plastic. Shrinkage of acrylates and methacrylates occurs during polymerization and is caused by the replacement of long-distance connections via Van der Waals force by strong and short covalent bonds between the carbon atoms of different monomer units. One of the challenges is the shrinkage of acrylate resins. The different polymerization chemistry brings some advantages and disadvantages. Desktop and mid-sized printers are often equipped with 385 to 405nm LED’s and work perfectly with acrylate and methacrylate chemistry. For desktop and mid-sized printers, this technology is not feasible due to its required wavelength. These printers are equipped with 355nm lasers to activate the epoxide part of the resin properly. These materials cure by a mechanism of ring-opening-polymerization which limits the shrinkage which is beneficial when printing extremely big parts. ![]() In large scale SLA 3D-printers like from UnionTech, 3DSystems, Raplas, RPS, EnvisionTEC and others, epoxy resins are the standard. ![]() One based on acrylates and the other one based on epoxides. In the field of resin 3D-printing there are two mainstream resin technologies.
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