*Article* **Hazardous Waste Management of Bu**ffi**ng Dust Collagen**

### **Miroslawa Prochon \*, Anna Marzec and Oleksandra Dzeikala**

Institute of Polymer and Dye Technology, Faculty of Chemistry, Lodz University of Technology, Stefanowskiego 12/16, 90-924 Lodz, Poland; anna.marzec@p.lodz.pl (A.M.); dzeikala.sandra@gmail.com (O.D.)

**\*** Correspondence: miroslawa.prochon@p.lodz.pl

Received: 24 February 2020; Accepted: 23 March 2020; Published: 25 March 2020

**Abstract:** Buffing Dust Collagen (BDC) is a hazardous waste product of chromium tanning bovine hides. The aim of this study was to investigate whether BDC has the desirable properties required of modern fillers. The microstructural properties of BDC were characterized by elemental analysis (N, Cr2O3) of dry residue and scanning electron microscopy (SEM). The BDC was applied (5 to 30 parts by weight) to styrene butadiene rubber (SBR), obtaining SBR-BDC composites. The physicochemical properties of the SBR-BDC composites were examined by Fourier transform infrared analysis, SEM, UV–Vis spectroscopy, swelling tests, mechanical tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The biodegradability of the SBR-BDC composites and their thermo-oxidative aging were also investigated. The filler contributed to increase the cross-link density in the elastomer structure, as evidenced by enhanced mechanical strength. The introduction of a filler into the elastomer structure resulted in an increase in the efficiency of polymer bonding, which was manifested by more favorable rheological and mechanical parameters. It also influenced the formation of stable interfacial bonds between the individual components in the polymer matrix, which in turn reduced the release of compact chromium in the BDC filler. This was shown by the absorption bands for polar groups in the infrared analysis and by imaging of the vulcanization process.

**Keywords:** buffing dust collagen (BDC); styrene–butadiene rubber (SBR); polymer composites; biodegradation
