## 2 Materials and Methods
### Materials
#### 2.1.3 Manufacturing Process of Modifier Pellets  
A V-cone mixer was used operating at 24 rpm for four minutes to mix the Ken-React(r) CAPS(r) L2(l) 12/L and LLDPE pellets. The modifier pellets were prepared using extrusion equipment in the Chemical Engineering Department at Michigan Technological University. An American Leistritz Extruder Corporation, model ZSE 27 has a 27 mm co-rotating intermeshing twin-screw extruder with ten heating zones, a length/diameter ratio of 40 and two stuffers was used to produce the modifier pellets. Two Schenck AccuRate gravimetric feeders were used to accurately control the amount of LLDPE, CaCO\({}_{3}\) and the coupling agent supplied into the extruder. Figure 3 illustrates the screw design that used during manufacturing of pellet modifiers [33]. The LLDPE and LLDPE/Ken-React(r) CAPS(r) L2(l) 12/L coupling agent was added to zone 1. Meanwhile, CaCO\({}_{3}\) was added in Zone 5.  
After passing through the extruder, the polymer strands (3 mm in diameter) enter a 3 m long water bath (Sterling Blower model WT-1008-10) and then a pelletizer (Accu-grind Conair Model 304) produced nominally 3 mm diameter by 3 mm long pellets. The final product of the manufacturing process is shown in Figure 4. After compounding, the pelletized composite resin was dried in an indirect heated dehumidifying oven (Bry Air RD-20) at 60 \({}^{\circ}\)C for 7 h. It was then stored in sealed moisture barrier bags prior to mixing with asphalt binder [34].  
The extrusion conditions for different modifiers are shown in Table 1. Three different formulations were extruded. The first was called PECC, which contained 70 wt % LLDPE and 30 wt % CaCO\({}_{3}\). The second was called PECC-1 CA, which contained 69.3 wt % LLDPE, 29.7 wt % CaCO\({}_{3}\), and 1 wt % Ken-React(r) CAPS(r) L2(l) L coupling agent. The third was called PECC-2 CA, which contained 29.4 wt % CaCO\({}_{3}\), 68.6 wt % LLDPE, and 2 wt % Ken-React(r) CAPS(r) L2(l) L coupling agent.  
Figure 1: Chemical structure of Ken-React® LICA® 12 (20% active portion of CAPS® L® 12/L).  
Figure 2: Titanate coupling agent (shown in red circle) mixed with LLDPE pellets.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material Number** & **PECC** & **PECC-1 CA** & **PECC-2 CA** \\ \hline Extrusion Date & March 12 2013 & March 12 2013 & March 12 2013 \\ Extruder, rpm & 250 & 250 & 250 \\ Motor Average, \% & 27 & 27 & 27 \\ Melt Temperature, \({}^{\circ}\)C & 244 & 244 & 244 \\ Melt Pressure, psig & 80 & 80 & 80 \\ \#2 Feeder Setting, lb/h & 6.0 & 6.0 & 6.0 \\ Material in Feeder \#2 & CaCO\({}_{3}\) & CaCO\({}_{3}\) & CaCO\({}_{3}\) \\ \#3 Feeder Setting, lb/h & 14 & 14 & 14 \\ Material in Feeder \#3 & LLDPE & LLDPE + CAPS & LLDPE + CAPS \\ Vacuum Port & 1 atm & 1 atm & 1 atm \\ Zone 5 Side Stuffer Setting, rpm & 300 & 300 & 300 \\ Feeder at Zone 5 & CaCO\({}_{3}\) & CaCO\({}_{3}\) & CaCO\({}_{3}\) \\ Zone 7 Side Stuffer setting, rpm & 300 & 300 & 300 \\ Feeder at Zone 7 & none & none & none \\ Feed Section Temperature & H\({}_{2}\)O Cooled & H\({}_{2}\)O Cooled & H\({}_{2}\)O Cooled \\ Zone 1 Temperature, \({}^{\circ}\)C & 175 & 175 & 175 \\ Zone 2 Temperature, \({}^{\circ}\)C & 195 & 195 & 195 \\ Zone 3 Temperature, \({}^{\circ}\)C & 210 & 210 & 210 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Extrusion conditions.  
Figure 4: Final product of manufactured pellets.  
Figure 3: Extruder screw design.