Sustainable polymeric materials put emphasis on mastering the whole life-cycle of polymeric materials. This includes the choice of raw materials, selection of synthesis and processing, environmental impact during long-term use followed by detailed knowledge about recycling and waste management.  Within this large efforts are put in the design and development of new biocomposites using renewable fibres instead of inert ones. The thesis deals with surface modifications of agricultural fibres and the design of biocomposites with optimal long-term properties balancing the potential risk for biodegradation.  The first part of this thesis involved surface modifications of oil palm fibres and production of biocomposites with PP as matrix. The chemical surface modifications of oil palm fibres explored propionylation, PPgMA grafting via solution modification and reactive blending and vinyltrimethoxy silanization as methods. All modified fibre/PP biocomposites showed improvements in the mechanical properties followed also by an improvement of water resistance. In comparison with unmodificed fibres/PP matrix the highest water resistance after the surface modifications of oil palm fibres were observed for silanization followed by PPgMA modified,  PPgMA blending and  propionylation. The second part aimed at producing fully biodegradable biocomposites and analysing the resulting properties with respect to potential risk for biodegradation. Sisal fibres were incorporated in PLA and PHBV and the resulting risk for biodegradation using a fungus, Aspergillus niger, monitored. Neat PLA and PHBV were compared with the corresponding biocomposites and already without fibres both polymers were notably biodegraded by Aspergillus niger. The degree of biodegradation of PLA and PHBV matrices was related to the extent of the growth on the material surfaces. Adding sisal fibres gave a substantial increase in the growth on the surfaces of the biocomposites. Correlating the type of surface modification of sisal fibres with degree of biodegradation, it was demonstrated that all chemically modified sisal/PLA biocomposites were less biodegraded than unmodified sisal biocomposites.  Propionylated sisal/PLA demonstrated the best resistance to biodegradation of all biocomposites while sisal/CA/PLA demonstrated high level of biodegradation after severe invasion by Aspergillus niger. In general, the biodegradation correlated strongly with the degree of water absorption and surface modifications that increase the hydrophobicity is a route to improve the resistance to biodegradation. Designing new biocomposites using renewable fibres and non-renewable and renewable matrices involve the balancing of the increase in mechanical properties, after improved adhesion between fibres and the polymer matrix, with the potential risk for biodegradation. / <p>QC 20130325</p>

This study has its background in the EU directive, the ‘Single-Use Plastics Directive’. The directive was initiated due to the environmental impacts that the oceans suffer due to plastic waste. The directive presents the most common single-use products found as waste in the oceans, including wipes and cloths. In collaboration with Essity, a global hygiene and health company, this study aims to find a replacement fibre for the currently used polyester fibre in Essity’s industrial cleaning cloths. To this end, we have evaluated the applicability of an agricultural fibre in the aspects of processability and sustainability. A theoretical part including a literature study of agricultural fibres is combined with a practical experimental part to evaluate a manufactured prototype. The theoretical part includes a compilation of the relevant parameters per fibre and the experimental part consists of laboratory tests and a panel test. On this basis, it was concluded that the first agricultural fibre, hemp, did not function adequately in the process due to the variations in fibre length and coarseness. A solution to this problem may be pre-treatments of the fibres. The second fibre, flax, functioned well in the process and may then be considered applicable in the aspect of process. The applicability of an agricultural fibre is possible in industrial cleaning cloths, but the geographical location of cultivation, transport, the chemicals used and irrigation should also be taken into account in the aspects of sustainability. / Bakgrunden till denna studie är EU-direktivet, ‘Single-Use Plastics Directive’. Direktivet har sitt ursprung i de miljöproblem som våra hav lider av på grund av nedskräpningen medplastavfall. Direktivet redovisar de engångsartiklar som återfinns allra mest i haven idag, däribland rengöringsdukar. På förekommen anledningen ska därför denna studie i samarbete med Essity, ett globalt hygien- och hälsoföretag, undersöka möjligheten att ersätta den befintliga polyesterfibern i deras industriella rengöringsdukar. Studien har utvärderat möjligheten att använda en naturlig fiber med avseende på tillverkningsprocess och hållbarhet. För att möjliggöra en utvärdering av en tillverkad prototyp, så har en teoretisk del med en litteraturstudie i kombination med en praktisk experimentell del genomförts. Den teoretiska delen består av en sammanställning av relevanta parametrar för varje fiber och den experimentella delen består av laboratorietester och ett paneltest. Slutsatserna från ett förstaförsök var att hampafibrer inte fungerade i processen på grund av variationer i hampansfiberlängd och grovlek. Att göra en förbehandling skulle kunna vara lösningen. I det andraförsöket med linfibrer, visade det sig att linfibrer fungerar i processen och därför kan vara applicerbar med avseende på tillverkningsprocess. En naturlig fiber kan användas i industriella rengöringsdukar, ur ett hållbarhetsperspektiv är det viktigt att beakta den geografiska platsen för odling, transporter, användning av kemikalier och konstbevattning.