# Utilization of Polymeric Materials toward Sustainable Biodiesel Industry: A Recent Review
## 4 Cold-Flow Improvers
### Polymeric CFIs for Pure Biodiesel  
Different polymeric materials have been used as CFIs for biodiesel. [PERSON] et al. [102] used commercial polyolefins CFI to enhance cold-flow properties of biodiesel synthesized from waste cooking oil. The findings proved the capability of 0.04 wt% T803 polyolefins to reduce CP and CFPP 1 \({}^{\circ}\)C. Similarly, [PERSON] and [PERSON] [27] used multiple industrial polyolefins in a unified concentration 0.1 wt% on waste cooking oil biodiesel. The reduction was 2-3 \({}^{\circ}\)C in CFPP depending on the industrial polyolefins type. Beside polyolefins, ethylene/vinyl acetate (EVA) copolymers proved better progress as CFIs for biodiesel fuel. [PERSON] et al. [102] could reduce CFPP and PP of waste cooking oil biodiesel by 2 and 6 \({}^{\circ}\)C, respectively, once they used 0.02-0.08 wt% of EVA. The same concentration of EVA with same biodiesel feedstock was used by [PERSON] et al. [103]. However, PP was lowered 3 \({}^{\circ}\)C. In addition, EVA was used as CFIs for soybean biodiesel in a concentration of 0.01 wt%. The PP was reduced 2 \({}^{\circ}\)C [104]. The remarkable PP reduction was achieved by [PERSON] [105] once EVA was used with a concentration of 1 wt% on canola biodiesel to reduce PP 11 \({}^{\circ}\)C. In addition, blended biodiesel of rapeseed and soybean oils were subjected to 0.3 wt% Keroflux (BASF), EVA as CFIs. Here, 2 and 9 \({}^{\circ}\)C were the reduced values of CP and CFPP, respectively [28]. Two types of polyacrylates and related, copolymers poly(dodecyl methacrylate) and poly(hexadecyl methacrylate), have been tested as CFIs for canola biodiesel with a concentration of 1 wt%. Both of them recorded successful reduction in PP to \(-\)46 and \(-\)20 \({}^{\circ}\)C, respectively [105]. Moreover, 0.02-0.08 wt% of polymethyl acrylate have been tested on waste cooking oil biodiesel by [PERSON] et al. [102] which lowered 8 \({}^{\circ}\)C in PP. The last group is maleic anhydride copolymers and their derivatives, from which two types poly(MA-alt-1-octadecene) and octadecyl vinyl ether were tested. The first one was tested on palm oil biodiesel [106] and tobacco seed biodiesel [107]. The results were a reduction of 6 \({}^{\circ}\)C in PP for palm oil biodiesel and 7 \({}^{\circ}\)C in CFPP for tobacco seeds biodiesel with concentrations of 2 and 1 wt%, respectively. The other one succeeded to reduce 3 \({}^{\circ}\)C in PP once it was tested on canola biodiesel with a concentration of 1 wt% [105]. Table 7 explores more details regarding polymeric CFIs for pure biodiesel.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Polymeric CFIs**} & \multirow{2}{*}{**Biodiesel**} & \multirow{2}{*}{**Concentration** **(wt\%)**} & \multicolumn{3}{c}{**The Effect**} \\ \cline{3-5}  & & & **Property** & **Reduced Value (\({}^{\circ}\)C)** & **Reference** \\ \hline \hline \multirow{5}{*}{Polyolefins} & T803 & Waste & 0.04 & CP & 1 \\ \cline{2-5}  & T803 & cooking oil & 0.04 & CFPP & 1 \\ \cline{2-5}  & P388 & & 0.1 & CFPP & 2 \\ \cline{2-5}  & A134 & & 0.1 & CFPP & 2 \\ \cline{2-5}  & T803 & & 0.1 & CFPP & 2 \\ \cline{2-5}  & DX-248 & & 0.1 & CFPP & 3 \\ \cline{2-5}  & LZ-7749 & & 0.1 & CFPP & 2 \\ \cline{2-5}  & CS-1 & & 0.1 & CFPP & 2 \\ \cline{2-5}  & V-385 & & 0.1 & CFPP & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Some polymeric CFIs for pure biodiesel.