III MATERIALS AND METHODS
• Recycled EPDM rubber powder was used.
• Low density polyethylene, FA3220, was provided by Borealis A/S (detailed data sheet is listed in appendix A).
• Optene, Ethylene methylacrylate copolymer, was manufactured by Borealis, Finland (detailed data sheet is listed in appendix B
1); this kind of commodity we can buy today is Dupont Elvaloy 1126 AC (detailed data sheet is listed in appendix B 2).
• Ethylene based octene Plastomer, EXACT 0210, was manufactured by DEXPlastomer V.O.F, The Netherlands (detailed data sheet is listed in appendix C).
• Phenolic resins SP-1045 and HRJ-10518 were supplied by SI Group- Bethune SASFrance (Appendix D).
• Zinc oxide extra pure was provided by Sigma-Aldrich, Germany.
• Tin chloride 98% was provided by Sigma-Aldrich, Germany.
III.2.1.1. Raw materials preparation
30 grams of blend containing different percentage of recycled rubber, EMA or LDPE, compatibilizer and additives was used for each batch (Appendix D).
When unvulcanized rubber was used (Section IV.4), unvulcanized rubber was added first and then the recycled rubber was added in the chamber.
III.2.1.2. Specimen preparation
The mixing machine Plasti-Corder® PLE 650, Brabender was heated to 140oC and kept constant before used. The rotating speed was maintained at 70 rpm.EMA or LDPE was first introduced into the mixing chamber. When it was totally melted, compatibilizer and rubber were added consecutively. In case of reactive compatibilization, reactive compatibilizers and other chemicals (Table 1) were incorporated into the mixing chamber as the mixing schedule shown in Table 2. The blend, then, was mixed in 10 minutes and compression molded using at 150oC, 25 MPa in 5 minutes into sheets approximately 1.5 mm thick with hot pressing equipment (FW-2200 type from P.h.i Pasadena Hydraulics, Inc, USA). Finally, the resulting sheet was cooled down quickly by cold water to ambient temperature.
III.2.2. Mechanical testing procedures
III.2.2.1. Tensile strength testing
The produced sheet was cut into desired specimens under ASTM- D412-06a standard using standard dumbbell die C (Fig.3.1). Specimens, then, were mounted on Instron® 4411 tensile testing equipment between two mechanic grips. The initial distance between the two grips was 70 mm. The testing standard was ASTM-D412-06a using the load cell of 500 N and loading speed of 500 mm/min.
During the test, the room temperature and humidity were in the range of 210-230C and 27%-35% respectively.
Tensile data were averaged over at least five specimens.
Compounding formulation used to prepare rubber/thermoplastics blends
Rubber 55 wt% - 85 wt%
EMA/LDPE 5 wt% - 15 wt%
Compatibilizer 5 wt% - 25wt%
ZnO (for reactive compatibilization only) 3 phr
SnCl2 (for reactive compatibilization only) 1.5 phr