*Article* **Limonene Derivative of Spherosilicate as a Polylactide Modifier for Applications in 3D Printing Technology**

**Dariusz Brz ˛akalski 1, Bogna Sztorch 2, Miłosz Frydrych 1, Daria Pakuła 1, Kamil Dydek 3, Rafał Kozera 4, Anna Boczkowska 3, Bogdan Marciniec 1,2,\* and Robert E. Przekop 2,\***


Academic Editors: Sławomir Rubinsztajn, Marek Cypryk and Wlodzimierz Stanczyk Received: 26 November 2020; Accepted: 10 December 2020; Published: 12 December 2020

**Abstract:** The first report of using limonene derivative of a spherosilicate as a modifier of polylactide used for 3D printing and injection moulding is presented. The paper presents the use of limonene-functionalized spherosilicate derivative as a functional additive. The study compared the material characteristics of polylactide modified with SS-Limonene (0.25–5.0% *w*/*w*) processed with traditional injection moulding and 3D printing (FFF, FDM). A significant improvement in the processing properties concerning rheology, inter-layer adhesion, and mechanical properties was achieved, which translated into the quality of the print and reduction of waste production. Moreover, the paper describes the elementary stages of thermal transformations of the obtained hybrid systems.

**Keywords:** spherosilicate; limonene; hydrosilylation; polylactide; 3D printing; FDM; FFF; injection moulding; rheology; thermal analysis
