Fecha de vencimiento y amortización de los valores

The earliest reported comparative LCA study for automotive parts was performed between hemp/epoxy composites and acrylonitrile butadiene styrene (ABS) ma- terials for the production of automotive side panel component of passenger cars (Wötzel et al. 1999). Cradle-to-grave life cycle approach was implemented in this study to determine the environmental impact between both candidate materials. The study was aimed to support automotive engineers in the decision-making process by providing the data on the potential environmental benefits that can be gained through substituting ABS by hemp fibers in producing the component. The Eco-in- dicator 95 impact assessment method was applied in the assessment process due to its good handling and transparency with the assistance of Umberto LCA software. Lower total eco-indicator score has been achieved by using hemp/epoxy material compared to ABS. The cumulative energy demand results showed that natural fiber required lower energy (73 MJ) compared to ABS (132 MJ) for the production of a single basic component. Further ecological advantage is also provided due to lower component weight by using NFC compared to ABS especially during the use phase of the passenger car. Nevertheless, the substitution of hemp nearly doubles the eu- trophication effect compared to ABS which is caused by the use of fertilizer during hemp cultivation process and the score can be found higher if pesticides are also employed during the cultivation phase of the natural fiber crops.

An exhaustive LCA study of a whole vehicle was reported involving Mercedes- Benz S-class passenger vehicle model, which also included the application of coconut, wood, flax, and cotton fiber in combination with different polymers in the new component construction (Finkbeiner and Hoffmann 2006). Cradle-to-grave ap- proach was also selected for the LCA involving design, production, use, recycling, and disposal. In their report, results obtained from LCA which were analyzed using GaBi LCA software revealed that approximately 85 GJ reductions in the overall energy demand compared to the preceding model were achieved, corresponding to the energy content of approximately 2500 L of fuel. Over the life cycle, emissions of the carbon dioxide greenhouse gas also were predicted to reduce by 7 %, with a 14 % reduction in nitrogen oxide emissions compared to the previous S-class mod- el. In the analysis, the contributing factors to the improved environmental perfor- mance of the vehicle were found due to the new introduction of 27 components with a total weight of nearly 43 kg which were produced from NFC to the overall vehicle buildup. The total weight of components made from renewable raw materials also increased nearly 73 % compared to the previous model which also highlights the success of the design for environment (DfE) initiative taken for the vehicle design.

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The importance of renewable resources in technical applications especially in vehicle design was also reported through LCA by Mussig et al. (2006). Compara- tive LCA study was made using two types of matrix materials reinforced with hemp natural fibers, which are Polymer material made from Triglycerides and Polycarbon acid anhydrides (PTP) vegetable-based thermoset resin and polyester resin, while a bus body component produced from sheet-molding-compound (SMC) technol- ogy was selected as the reference component. For both materials, the cradle-to- grave LCA approach was implemented covering materials flow and energy usage across the entire life cycle. The Umberto LCA software was used as the tool for the modeling composites’ product system and environmental impact calculations. En- vironmental impact assessment results based on seven major indicators which are resources used, cumulative energy demand, human toxicity, eutrophication, acidi- fication, summer smog, and greenhouse effect show positive effect on the use of natural-based polyester resin for nearly all environmental impact categories expect eutrophication due to high agricultural prechain portion involving a vegetable- based thermoset resin at the raw material extraction phase in the product life cycle. In another report, Schmehl et al. (2008) published LCA results on the application of hemp natural fiber and PTP vegetable-based thermoset resin for passenger bus body component casing. Their work was an extension of the previous report on sim- ilar project reported by Mussig et al. (2006) but has been extended into more detail by comparing four different variants of the hemp/PTP composites to the glass fiber/ unsaturated polyester composites used in the existing component. Eco-indicator 99 and cumulative energy demand life impact assessment method were both employed for the analysis with the assistance of Umberto LCA software which covers the whole product life cycle starting with acquisition of raw materials, semifinished parts (prepregs) and body components’ production, the use phase, and finally end of life. In the results obtained, the material system using hemp/PTP composites at 66 wt% with optimized production conditions (natural fiber and vegetable-based thermoset resin (NFK) optimized) scored the lowest environmental impact based on the total eco-indicator method compared to other listed alternatives while the exist- ing synthetic-based glass fiber/unsaturated polyester composites scored the high- est environmental impact. Apart from that, similar environmental impact trend was also observed through the cumulative energy demand indicator whereby NFK op- timized composites required less energy throughout their total life cycle especially compared to glass fiber/unsaturated polyester composites. The performance of NFK optimized composites in their report was contributed by lower overall weight of the component which further brought benefits in eco-balancing through lower mate- rial input and emissions in the production phase as well as lower fuel consumption required in the product use phase.

Zah et al. (2007) investigated the use of curaua-reinforced polypropylene (PP) NFC for automotive interior component production compared to glass fiber-rein- forced PP composites in terms of their environmental impacts using LCA. CML impact assessment method was applied to analyze the related ecological impact of both composite materials based on the cradle-to-grave approach for a better overview of the component performance. Final results show that overall, lower environmental impact performance was obtained by using curaua/PP composites compared to glass fiber/PP composites. Apart from that, results from the exercise

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also highlight that lower fuel consumption obtained through lightweight curaua composites significantly affect the environmental impact for the component. On the other hand, they also stated from the economical and sociological point of view, that the use of curaua composites over glass fiber composites will be able to present further positive advantages such as low cost, amplifying more agricultural business, and eco-marketing works as well as increasing jobs for less developing countries and reducing health risks during the component manufacturing process.

Alves et al. (2010) performed LCA on buggy enclosure component made from three types of jute fiber composites which are produced in dried, untreated, and dried and bleached-treated conditions. In their study, the jute fiber composite (JFRP) alternative materials are also compared with glass fiber composites (GFRP) to determine the difference in environmental performance for the same application. Cradle-to-grave approach and Eco-indicator 99 LCIA method were both chosen in the analysis and the LCA modeling was made using SimaPro software whereby for the end-of-life phase, three types of disposal methods were also included in the investigation namely recycling, incineration, and landfilling. Results for overall life cycle show that GFRP produced higher environmental damage compared to JFRP, caused by heavier GFRP weight which further caused higher fuel consumption for the vehicle. Besides that, similar high-fuel consumption which relied on nonrenew- able fossil fuel resource was also the reason found to cause the use phase of the product to create highest environmental damage compared to the other life cycle stages, and they suggested that future improvement actions should be focused on the use stage to minimize the environmental damage. On the other hand, for com- ponents made from three types of jute fiber composites (untreated, dried, and dried/ bleached-treated conditions), results also show that treated jute bonnet composites are more pollutant compared to nontreated jute bonnets until the production phase. They also added that through qualitative analysis made on the social and economic impacts of using jute composites compared to glass fiber composites, they found that jute fiber composites performed better in both categories compared to glass fiber composites despite their lower technical performance.

In another automotive application, Luz et al. (2010) studied the environmental performance of an aesthetic covering component of a vehicle made from hybrid sugarcane/bagasse-reinforced PP composites using LCA. The environmental per- formance of hybrid NFC was also compared with talc-reinforced PP composites for similar application. The study was focused on a Brazilian setting which included data gathering and component usage. Cradle-to-grave approach was adapted in de- fining the LCA boundary condition and modeling of the system was made using GaBi LCA software. Apart from that, three different product end-of-life methods were also investigated in the study to simulate and compare their effect on the envi- ronmental performance and results obtained showed that recycling disposal method caused the lowest environmental damage compared to incineration and landfilling methods. From the comparative LCA analysis results, it was observed that hybrid sugarcane/bagasse composites produced lower environmental damage compared to talc-reinforced PP composites throughout the component life cycle, with added advantage of comparable mechanical properties between both composite materials

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for the intended application. They also concluded that lower hybrid sugarcane/ba- gasse composites environmental damage was influenced by several factors such as lower global warming impact especially during cultivation stage of the raw materi- als, cleaner raw material production process, lower materials weight which causes lower-fuel consumption during use stage of the component, and the availability of implementing recycling method to dispose the material at the end-of-life stage.

LCA analysis related to the application of NFC in packaging for transportation application was also investigated by Duigou et al. (2011). They performed simpli- fied LCA of flax mat/poly-L-lactic acid (PLLA) biocomposites and flax mat/PLLA/ balsa bio-sandwich composites and later compared the environmental performance to synthetic-based glass mat/unsaturated polyester composites and glass mat/unsat- urated polyester/balsa sandwich composites. Cradle-to-gate approach was selected for their study which covers raw material extraction up to composites’ production stages. The CML 2000 and cumulative energy demand impact assessment methods were applied to quantify the environmental effect of the composite materials using SimaPro LCA software. From the analysis, results show that lower environmental damage can be achieved using NFC (flax/PLLA composites and flax/PLLA/balsa bio-sandwich composites) instead of synthetic glass fiber/polyester composites. Furthermore, they also found that a larger weight of flax NFC is required compared to glass fiber/polyester composites in order to provide comparable mechanical per- formance for the intended application which influenced the overall environmental performance. Thus, they suggested that weight reduction initiatives to be taken to reduce the effect especially towards the intended application.

LCA study was also made to investigate the environmental impact of using natu- ral fiber as alternative materials in paper pulp production (González-García et al.

2010). Two different types of natural fibers, namely, flax and hemp, were chosen as the candidate materials and LCA analysis was carried out to predict and com- pare the environmental impact associated with the use of both natural fibers. In their study, cradle-to-gate approach was selected in the study which covers the raw material cultivation up to the production of the paper pulp product (pulp mill gate). SimaPro LCA software was also used in the LCA modeling based on CML base- line 2000 LCIA method. The environmental impact obtained by the use of natural fibers was later categorized in terms of global warming potential, acidification, eu- trophication, photochemical oxidant formation, energy usage, and pesticide usage. Overall results gained from the analysis showed that the potential use of flax fiber as a raw material for the paper pulp production is more environmentally friendly compared to hemp fiber. Despite the overall environmental advantage, flax fiber however showed lack in irrigation and pesticide use environmental performance compared to flax fiber and future improvement were later suggested to be focus in both of the identified areas to further strengthened the final decision in applying hemp fiber as the new raw materials for paper pulp product.

LCA was also implemented in determining the building materials’ environmen- tal impact performance involving the use of kenaf-reinforced polyester composites for thermal insulation board component (Ardente et al. 2008). A cradle-to-grave approach was selected for the LCA analysis which included kenaf raw material

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cultivation, transportation, manufacturing, use, and disposal stages of the prod- uct. The environmental impacts were assessed in three major categories which are energy consumption, waste product, and environmental impact indexes such as global warming potential and water consumption. The analysis results showed that significant reduction of the environmental impact was obtained through the use of NFC compared to synthetic composites for the insulation board application while maintaining the required thermophysical and noise-abatement properties. The com- parative LCA results involving six other alternative candidate materials for thermal insulation board component, namely, polyurethane, glass wool, flax rolls, stone wool, mineral wool, and paper wool with kenaf composites, showed that highest environ- mental impact was contributed by synthetic materials and improved environmental impact score was due to mineral wools. It was shown that kenaf-based composites’ environmental impact performance is situated between both material categories and its performance can be further improved by adopting other disposal scenario in the end-of-life stage of the product such as through the use of incineration method with energy recovery and energy production. Elsewhere, LCA results also point out that the use of kenaf-based composites as thermal insulation materials will be able to provide higher energy, saving gain during the whole building operation time com- pared to the material calculated total energy consumption throughout its life cycle which further highlights the advantage of using NFC for the intended application.

Xu et al. (2008) also studied environmental performance of NFC particularly involving the use of wood fiber-reinforced PP composites for the production of preforms which are intermediate materials for producing other final composite products. In the study, wood polymer composites were compared with PP mate- rial for the production of preforms product and Eco-indicator 99 impact assess- ment method was employed to determine the materials environmental burden based on cradle-to-gate approach by assuming that the production phase dominates the environmental standing of the product throughout its total life cycle stages. The processes involved in the analysis using SimaPro LCA software were limited from raw material extraction up to the product production. Analysis results showed that the use of wood fiber-reinforced PP composites was able to contribute to lower environmental impact compared to PP materials for the production of preforms and the environmental performance is directly linked to the amount of wood fiber used as the reinforcement. Moreover, at similar volume conditions, preforms made from wood fiber-reinforced PP composites also possessed better environmental standing due to lower density, and subsequently better lightweight property of the composite material compared to PP material. Apart from that, in terms of material’s service density index which was also proposed in their study to determine the equivalent materials strength required to withstand the operational load, the environmental performance of wood fiber-reinforced PP composites was also found to be consis- tent with the previous results in comparison with PP materials due to less volume of material required by wood fiber-reinforced PP composites. This is contributed by the higher wood fiber tensile strength compared to PP.

Vidal et al. (2009) studied environmental burden of NFC made from cotton linters and rice husks as the reinforcement materials and aggregated in recycled

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thermoplastic PP and high-density polyethylene (HDPE) matrices. The cotton liner/PP composites, rice husks/PP composites, and cotton liner/HDPE composites environmental impacts were later compared to virgin PP and virgin HDPE resins based on a similar functional unit. Cradle-to-grave life cycle approach was selected in their analysis and the results were displayed in four main categories, namely, greenhouse effect, nonrenewable energy depletion, eutrophication, and acidifica- tion which were all simulated using SimaPro LCA software. Apart from that, two disposal scenarios were also studied for the selected materials which are incinera- tion and landfilling. For all impact categories, LCA results show that NFCs were able to reduce the environmental burden compared to virgin thermoplastics. More- over, for both incineration and landfilling disposal process, all NFC also yielded lower greenhouse gas effect impact as high as 40 % lower for cotton linters/HDPE compared to virgin thermoplastic. Another interesting finding was also observed between the simulated disposal scenarios whereby disposal of NFC through land- filling process was able to provide higher greenhouse gas savings compared to incineration process, thus providing a useful insight for selection of disposal meth- od involving NFC.

Corbière-Nicollier et al. (2001) studied comparative LCA of transport pallet product made by using China reed biofibers and glass fibers, both reinforced in PP matrix. Their study used the cradle-to-grave approach where the life cycle of product was assessed from the raw material production, transport, use, and disposal stages. For natural fiber production, it also includes the plant cultivation stages up to fiber processing. Critical surface-time method (CST95) was employed as the impact assessment method due to its ability to include the effect of heavy metals in the soil, and the final results were later checked for reliability using CML 95 and Eco-indicator 99 methods. Apart from that, during the functional unit definition process, due to lack of actual data, rules of mixture composites’ micromechanical model were employed to determine the China reed composite’s fiber weight frac- tion information. LCA results showed that the use of China reed composites for the production of transport pallet product is more environmental-friendly compared to glass fiber composites for minimum pallet service time of 3 years. Moreover, life cycle emissions (air, water, and soil emissions) and primary nonrenewable energy usage are both higher using glass fiber compared to China reed fiber, while natural fiber lacks in terms of higher land-use requirement for China reed pallet production. In addition, they also stated that the potential of natural fiber to be implemented in product design application is greater compared to biofuel production and direct biomass heat production.

Apart from single system composites, LCA was also utilized in the environ-