Pulverisette 5 classic line planetary ball mill

Polymer: Natural rubber (NR) RSS I was provided by Torimex-Chemicals Ltd. Sp. z o.o (Konstatntynów Łódzki, Poland). Crosslinking agent: Rubber mixtures were vulcanized with sulfuric crosslinking system consisting of sulfur (Siarkopol, Poland); mercaptobenzothiazole (Sigma-Aldrich, Schnelldorf, Germany); micro-sized zinc oxide (Huta Będzin, Poland); and stearin (SA, Avantor Performance Materials, Gliwice, Poland). Fillers: Cereal straw (several different types of straw mixed together: rye, wheat, triticale and oat) was collected from local farms. Dried straw was crushed using a Pulverisette 5 classic line planetary ball mill (Fritsch, Idar-Oberstein, Germany), grinding time 2 h, speed 300 rpm; chalk–Socal 31 (Solvay GmbH, Hannover, Germany). Talc–Naintsch A-20 (Luzenac Group, Toulouse, France); carbon black–N774 carbon black (MAKROchem S.A, Lublin, Poland); silica – AEROSIL^® A380 (Evonik Degussa GmbH, Essen, Germany).
Composition of typical elastomer mixture: NR rubber (100 phr–parts per hundred rubber), sulfur (2 phr), mercaptobenzothiazole (2 phr), zinc oxide (5 phr), stearin (1 phr), and fillers (0 phr for reference sample or 10, 20, and 30 phr for other composites).

The lignocellulose filler in the form of beech wood, straw, and Miscanthus were obtained from a sawmill and local farms, respectively. Miscanthus is a perennial grass that is a mixture of Chinese Miscanthus (Miscanthus sinensis) and sugar (Miscanthus sacchariflorus). After drying in a laboratory dryer (70 °C, 24 h), filler in the form of beech wood, straw, or Miscanthus was ground into a fine powder using a ball mill Pulverisette 5 Classic Line planetary ball mill (Fritsch, Idar-Oberstein, Germany) for 3 h.
Natural rubber (Torimex-Chemiclas Ltd., Lodz, Poland) (NR) in the form of ribbed smoke sheets (RSS1) was used as the elastomer matrix. The elastomeric composites were cross-linked with the use of sulphur (Siarkopol, Poland) (S, in the quantity of 2 phr per 100 phr of rubber) in the presence of mercaptobenzothiazole (Saint Louis, MO, USA) (MBT, in the amount of 2 phr per 100 phr of rubber), stearic acid (Avantor Performance Materials, Gliwice Poland) (SA, in the quantity of 1 phr per 100 phr of rubber), and zinc oxide (Huta Będzin, Poland) (ZnO, in the quantity of 5 phr per 100 phr of rubber). The compositions of the elastomer mixtures are presented in Table 1.
Carbon black, HAF 330 (CB) (Makrochem, Poland) was used as a black filler.
Melamine polyphosphate (MPP) (Everkem, Italy) was used as a flame retardant.