Table 12.

Thermal degradation data of r-PP and r-PP biocomposites.

r-PP phase. As shown in Table 12, To increases between 34 and 60°C. Also, Tmax increases between 33 and 28°C in comparison to r-PP (as indicates in the orange area). This increment in the thermal stability of the biocomposites has been previously observed in different studies, indicating that the incorporation of fibers in the material induces spherulite nucleation points, increasing the crystallinity of the polymer and improving its thermal properties [64].

#### 3.2.3 Morphology

Figure 8a and b shows SEM images of the fractured surfaces of r-PP-CHF and r-PP-CCF, respectively. In these images, gaps between the fibers and the surrounding r-PP matrix can be clearly observed, which indicate a poor interfacial adhesion between the r-PP matrix and the natural fibers [65]. For Figure 9a and b, with the MAPP addition, gaps between natural fibers and r-PP were significantly reduced, and as a consequence, an improvement over the interface for the composite can be appreciated. This result confirms that MAPP addition improved the interfacial property of the hydrophobic PP matrix and the hydrophilic natural fibers. Also, this can be related with mechanical properties enhancement observed in the biocomposites after the MAPP addition.

#### 3.2.4 Environmental characterization of the materials

When assessing the carbon footprint of the material, the stages of the life cycle were limited to raw material acquisition, transport, and processing. Since the

Figure 8. SEM pictures for rPP-CHF and rPP-CCF biocomposites.

to the temperature of maximum weight loss rate (Tmax) of hemicellulose, while the second peaks located at 358°C and 328°C (for CHF and CCF) are related to the Tmax of α-cellulose. The residual weights of CHF and CCF have also been measured and are equal to 25 and 31% for CHF and CCF at 600°C. This results show that CHF

(a) TG and (b) DTG curves of r-PP and r-PP biocomposites at heating rates of 10°C/min.

TG and DTG curves for r-PP and r-PP biocomposites are shown in Figure 7. Also, main thermal parameters obtained from these curves are summarized in

Recycled PP degradation occurs in a single step process with an onset temperature (To) located at 368°C and a Tmax of 428°C. The residue after final degradation was 0.4%. Regarding biocomposites, TG and DTG show that the addition of coffee husk and coir coconut fibers produces an increase in the thermal stability of the

possesses a better thermal stability compared to CCF.

(a) TG and (b) DTG curves of CHF and CCF fibers at heating rates of 10°C/min.

Thermal degradation data of the fibers at 10°C/min in nitrogen atmosphere.

Sample Degradation stage To (°C) Tmax (°C) Residual Char (%)

2 336 358

2 314 328

Coffee husk fiber (CHF) 1 266 299 25

Coir coconut fiber (CCF) 1 245 284 31

Table 12.

100

Figure 7.

Figure 6.

Thermosoftening Plastics

Table 11.

Figure 9. SEM pictures for rPP-CHF-MAPP and rPP-CCF-MAPP biocomposites.

material was not transformed into a product, the functional unit was determined as the 1 kg of manufactured material and the carbon footprint was determined on a cradle to gate life cycle. The comparison was made between the biocomposite materials, recycled polypropylene, and neat polypropylene. Neat polypropylene was brought from Medellín 412 km away from the final user's location. Coffee husk was delivered from Tuluá (104 km) and coconut coir from Manizales (270 km). All the materials were transported on a diesel-powered truck to the final user location. Fibers were blended with the rPP matrix through an extrusion process and subsequentially pelletized with a 1.5 kW mill.

Emissions were determined through emission factors for every activity involved on the elaboration of the material using the Eq. (14). For each emission factor, there is one activity related in order to calculate the emissions for the product elaboration. The results of those emissions are listed for each biocomposite on Table 13.

$$Emission = Emission\,\,factor \,\*\, activity \tag{14}$$

3.3 Conclusions

Results of the emissions for the compared materials.

Table 13.

103

rPP-CHF Biocomposite

DOI: http://dx.doi.org/10.5772/intechopen.81635

Biocomposites based on recycled PP (r-PP) and two different natural fibers (coffee husk-CHF and coconut coir-CCF fibers) were prepared by a melt extrusion and injection processes. Proximate, elemental, and structural analysis performed to the natural fibers show that CHF contains a higher cellulose percentage and a higher ratio O/C in comparison to CCF. This condition makes CHF more attractive for biocomposites production. The effects of natural fibers and MAPP addition on the properties of the biocomposites were explored. Flexural characterization showed that MAPP incorporation induces a significant improvement of flexural properties

Stage Material Sub-stage Emission factor Activity Emission Raw material Coffee husk Production 0.52 kg CO2/kg [66] 3 kg 1,56 kg CO2

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological…

Processing Biocomposite Extrusion 0.374 KgCO2/kWh [67] 10.6 kWh 3.98 kg CO2

rPP-CCF Biocomposite Stage Material Sub-stage Emission factor Activity Emission Raw material Coconut coir Production 0.27 Kg CO2/kg [70] 3 kg 0.81 kg CO2

Processing Biocomposite Extrusion 0.374 kg CO2/kWh [67] 10.6 kWh 3.98 kg CO2

Recycled PP Stage Material Sub-stage Emission factor Activity Emission Raw material Recycled PP Process 0.38 kg CO2/kg [68] 10 kg 3.80 kg CO2

Neat PP Stage Material Sub-stage Emission factor Activity Emission Raw material Neat PP Process 1.86 kg CO2/kg [71] 10 kg 18.60 kg CO2

Grinding 0.374 kgCO2/kWh [67] 0.55 kWh 0.21 kg CO2 Transport 2.61 kgCO2/L [68] 36.4 L 95.01 kg CO2

Grinding 0.374 KgCO2/kWh [67] 1125 kWh 0.42 kg CO2

Grinding 0.374 KgCO2/kWh [67] 1.5 kWh 0.56 kg CO2

Grinding 0.374 kg CO2/kWh [67] 1.1 kWh 0.41 kg CO2 Transport 2.61 kg CO2/L [68] 94.7 L 246.65 kg CO2

Grinding 0.374 kg CO2/kWh [67] 1125 kWh 0.42 kg CO2

Grinding 0.374 kg CO2/kWh [67] 1.5 kWh 0.56 kg CO2

Grinding 0.374 kg CO2/kWh [67] 1.5 kWh 0.56 kg CO2

Transport 2.61 kg CO2/L [68] 146.95 L 382.76 kg CO2

Total 104.4 kg CO2

Total 255.49 kg CO2

Total 4.36 kg CO2

Total 401.36 kg CO2

Recycled PP Process 0.38 kg CO2/kg [69] 7 kg 2.66 kg CO2

Recycled PP Process 0.38 kg CO2/kg [69] 7 kg 2.66 kg CO2

From Figure 10 emission accounting for each category, it could be noted that transport is the largest contributor to the overall emissions. Emissions on this stage are directly proportional to the amount of fuel used to transport the materials, and so, the further away the place, the greater the associated emissions. In order to achieve a more sustainable product, materials should be taken from regional suppliers to lower the footprint from transporting activities. Since rPP is produced inside the processing site, there is no emission associated to the transport of this material as stated on the life cycle boundaries for this particular case. Regarding raw material acquisition, the incorporation of natural fiber seems to improve the impact of the material compared to neat PP and recycled PP. For the coffee husk composite case, the carbon footprint on this stage for the 10 kg of material corresponds to 4.84 kg CO2 eq, and for coconut coir biocomposite, it corresponds to 4.29 kg CO2 eq. When compared to neat PP, a reduction in terms of carbon emissions of 76.93 and 73.78%, respectively, for rPP-CFH and rPP-CCH biocomposites. Also when compared to recycled polypropylene, it could be noted that emissions of rPP-CHF composite were slightly lower, reducing emissions on a 1.98%. Nevertheless, for rPP-CCF composite, the emissions raised on this stage on an 11.26% compared to rPP. In order to elaborate the composite, the fibers had to be blended with the recycled material, and so an extra process is needed as mentioned before. This extrusion and grinding process generates emissions of 4.54 kg CO2 eq for both biocomposites, adding emissions to the overall score. For this scenario, the carbon footprint for the finished materials is shown on Table 14. This table shows the carbon footprint in terms of a functional unit defined as 1 kg of processed material.


Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological… DOI: http://dx.doi.org/10.5772/intechopen.81635

#### Table 13.

material was not transformed into a product, the functional unit was determined as the 1 kg of manufactured material and the carbon footprint was determined on a cradle to gate life cycle. The comparison was made between the biocomposite materials, recycled polypropylene, and neat polypropylene. Neat polypropylene was brought from Medellín 412 km away from the final user's location. Coffee husk was delivered from Tuluá (104 km) and coconut coir from Manizales (270 km). All the materials were transported on a diesel-powered truck to the final user location.

Emissions were determined through emission factors for every activity involved on the elaboration of the material using the Eq. (14). For each emission factor, there is one activity related in order to calculate the emissions for the product elaboration.

From Figure 10 emission accounting for each category, it could be noted that transport is the largest contributor to the overall emissions. Emissions on this stage are directly proportional to the amount of fuel used to transport the materials, and so, the further away the place, the greater the associated emissions. In order to achieve a more sustainable product, materials should be taken from regional suppliers to lower the footprint from transporting activities. Since rPP is produced inside the processing site, there is no emission associated to the transport of this material as stated on the life cycle boundaries for this particular case. Regarding raw material acquisition, the incorporation of natural fiber seems to improve the impact of the material compared to neat PP and recycled PP. For the coffee husk composite case, the carbon footprint on this stage for the 10 kg of material corresponds to 4.84 kg CO2 eq, and for coconut coir biocomposite, it corresponds to 4.29 kg CO2 eq. When compared to neat PP, a reduction in terms of carbon emissions of 76.93 and 73.78%, respectively, for rPP-CFH and rPP-CCH biocomposites. Also when compared to recycled polypropylene, it could be noted that emissions of rPP-CHF composite were slightly lower, reducing emissions on a 1.98%. Nevertheless, for rPP-CCF composite, the emissions raised on this stage on an 11.26% compared to rPP. In order to elaborate the composite, the fibers had to be blended with the recycled material, and so an extra process is needed as mentioned before. This extrusion and grinding process generates emissions of 4.54 kg CO2 eq for both biocomposites, adding emissions to the overall score. For this scenario, the carbon footprint for the finished materials is shown on Table 14. This table shows the carbon footprint in terms of a functional unit defined as 1 kg of processed material.

Emission ¼ Emission factor ∗ activity (14)

Fibers were blended with the rPP matrix through an extrusion process and

The results of those emissions are listed for each biocomposite on Table 13.

subsequentially pelletized with a 1.5 kW mill.

SEM pictures for rPP-CHF-MAPP and rPP-CCF-MAPP biocomposites.

Figure 9.

Thermosoftening Plastics

102

Results of the emissions for the compared materials.

## 3.3 Conclusions

Biocomposites based on recycled PP (r-PP) and two different natural fibers (coffee husk-CHF and coconut coir-CCF fibers) were prepared by a melt extrusion and injection processes. Proximate, elemental, and structural analysis performed to the natural fibers show that CHF contains a higher cellulose percentage and a higher ratio O/C in comparison to CCF. This condition makes CHF more attractive for biocomposites production. The effects of natural fibers and MAPP addition on the properties of the biocomposites were explored. Flexural characterization showed that MAPP incorporation induces a significant improvement of flexural properties

Acknowledgements

Conflict of interest

Author details

105

Miguel Ángel Hidalgo-Salazar<sup>1</sup>

Andrés Felipe Rojas-González<sup>2</sup>

de Occidente, Cali, Colombia

Colombia, Manizales, Colombia

provided the original work is properly cited.

Juan Manuel Montalvo-Navarrete<sup>1</sup>

technical and financial support.

DOI: http://dx.doi.org/10.5772/intechopen.81635

The authors acknowledge to the Universidad Autónoma de Occidente, Cali-Colombia and Universidad Nacional de Colombia, Manizales-Colombia for the

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological…

The authors of this manuscript declare that do not hold any conflicts of interest that might have any bearing on research reported in their submitted manuscript.

\*, Juan Pablo Correa-Aguirre<sup>1</sup>

1 Research Group for Manufacturing Technologies GITEM, Universidad Autónoma

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

2 Investigation Group on Waste Recovery GIAR, Universidad Nacional de

\*Address all correspondence to: mahidalgo@uao.edu.co

,

, Diego Fernando Lopez-Rodriguez<sup>2</sup> and

#### Figure 10.

Carbon emissions comparison for neat PP, r-PP, and r-PP biocomposites.


#### Table 14.

Carbon footprint of the compared materials.

of r-PP biocomposites. Also, the impact tests showed that the addition of MAPP increases the capacity of r-PP biocomposites to absorb energy. Thermal studies show that CHF and CCF fibers addition did not disturb the melting process and improves the thermal stability of the PP matrix. Despite that for this case scenario, the values of the carbon footprint for both biocomposites is considerably high compared to the recycled polypropylene, it is important to keep in mind that the evaluation was made on a cradle to gate analysis, this means that the benefits of the mechanical and thermal enhancements are not taken into account on this evaluation among the use and operational phases. Depending on the application, the use of these biocomposites has the potential to reduce the carbon footprint over the lifespan of a product made with it, saving emissions derived from usage and disposal. Regarding the performance of both biocomposites, it can be noted that rPP-CHF has a better operation regarding environmental issues due to the saved emissions from raw material transportation. This means that in order to elaborate more sustainable biocomposites, raw material should be delivered on a local extent. Also in order to lower the environmental impacts of the material, the fiber fraction is an important issue due to the replacement of polymer fraction over the composite and thus saving emissions from polymer primary elaboration process.

Recycled Polypropylene-Coffee Husk and Coir Coconut Biocomposites: Morphological… DOI: http://dx.doi.org/10.5772/intechopen.81635
