Since DDGS sells for around $0.03 to $0.05/lb. and PINEW flour sells for $0.08 to $0.22/lb. there appears to be a case for combining the two ingredients to obtain a “mixed” DDGS composite and accessing the mechanical properties of the resulting PINEW/DDGS composites. Therefore, it is the contention of this study to mix these two chemically dissimilar fillers (DDGS and PINEW) together in order to deter­mine if an enhancement of the lower-grade filler (i. e., DDGS) can be achieve by the partial mixing with higher-grade filler (PINEW). Pine wood flour was selected to be employed as the wood of choice in the DDGS mixture filler study due to its common usage in WPC.81163 PINEW formulations (HDPE-25PINEW and HDPE-25PINEW — MAPE) exhibits mechanical properties comparable or better to neat HDPE values except for %El values (Table 13.2 and 13.3; Fig. 13.4). For example, the HDPE — 25PINEW formulation exhibited oU, E, and %El values that were -9, +141 and -74%, respectively, that of neat HDPE. Similarly, the HDPE-25PINEW-MAPE for­mulation exhibited oU, E, and %El values that were +8, +98 and -65%, respectively, that of neat HDPE (Table 13.2). Similarly, the flexural and impact strength proper­ties of PINEW formulations were comparable or superior to neat HDPE except for impact strength values. For example, the HDPE-25PINEW formulation exhibited ofm Eb and impact strength values that were +9, +68 and -88%, respectively, that of neat HDPE. The HDPE-25PINEW-MAPE formulation exhibited o„ E and im-

fm, b

pact strength values that were +18, +52 and -89%, respectively, that of neat HDPE (Table 13.3). The mechanical properties of DDGS formulations have been discussed previously. The PINEW formulations were superior to the DDGS formulations in several mechanical properties.

Mixing PINEW and STDDGS fillers in equal proportions resulted in a “combi­nation” composite that manifested somewhat different tensile, flexural and impact strength properties than that of composites composed of the individual ingredi­ent fillers. Refer to Tables 13.2 and 13.3 and Fig. 13.4. For example, the HDPE — 12.5STDDGS/12.5PINEW formulation exhibits oU values that were significantly less than in HDPE-25PINEW but slightly higher than in HDPE-25STDDGS. The E values of HDPE-12.5STDDGS/12.5PINEW were significantly higher than HDPE-25STDDGS but less than HDPE-25PINEW. Percent elongation values of the HDPE-12.5STDDGS/12.5PINEW formulation were significantly lower than either of the single filler composite formulations. The flexural values, ofm and E of HDPE-12.5 STDDGS/12.5PINEW were lower than HDPE-25PINEW

b,

but higher than the HDPE-STDDGS composites. The impact strength of HDPE —

12.5STDDGS/12.5PINEW composite was significantly higher than the HDPE — 25PINEW but likewise was significantly lower than the HDPE-25STDDGS composites. These trends were mimicked when the “mixed” composites con­tained MAPE. See Tables 13.2 and 13.3, and Fig. 13.4. Interestingly, the HDPE — 12.5STDDGS/12.5PINEW-MAPE composite exhibited higher impact strength values than in the HDPE-25STDDGS-MAPE composites. Inclusion of MAPE in the “mixed” composite formulation caused a decrease in impact strength com­pared to composite formulations without MAPE. Obviously, some benefits and drawbacks in terms of the mechanical properties of the “mixture” composite was obtained by mixing STDDGS with PINEW over that of composites containing a single filler ingredient. To summarize, comparing the HDPE-25STDDG to HDPE — 12.5STDDGS/12.5PINEW for oU E, %El, o^ Eb, and impact strength values the following changes occurred: +5, +65, -49, +7, +15, and -40%, respectively. When comparing the HDPE-STDDG-MAPE to the HDPE-12.5STDDGS/12.5PINEW- MAPE for oU, E, %El, ofm, Eb, and impact strength values the following changes occurred: +16, +15, -28, +6, +13, and -43%, respectively.

When comparing the two 40% filler composites, HDPE-40PINEW and HDPE- 10STDDGS/30PINEW, dissimilar mechanical and flexural properties also occurred between them. Refer to Tables 13.2 and 13.3, and Fig. 13.4. The difference between the HDPE-10STDDGS/30PINEW to the HDPE-40PINEW for n E, %El, E, and impact strength values were +24, -11, +60, +6, -18, and +16%, respectively. Obviously, some benefits and drawbacks were obtained comparing these “mixed” formulations. These results suggest that further work needs to be conducted to iden­tify and maximize the merits of mixing fillers from dissimilar sources in order to obtain novel composites. This report is a preliminary evaluation employing this line of research but suggests that a useful inexpensive LPC composed of mixing DDGS and WF is feasible.