Hemp straw as filler/reinforcement for polypropylene composites

VALLEJOS, MARÍA E.; MÉNDEZ, JOSÉ A.; LÓPEZ, ÁNGEL; VILASECA, FABIOLA; CORRALES, FARMES; MUTJÉ, PERE

Viena, Austria

Otro; 5th European Meeting on Chemical Industry and Environmen - EMChIE 2006; 2006

Institute of Chemical Engineering - Austrian Chemical Society (GÖCH)

Due to the important overage of derivatives of the agricultural sector, the EU has promoted the culture of annual plants such as hemp (Cannabis Sativa) as alternative to the traditional cultures. Thus, these cultures contribute to keep the equilibrium in the country medium as well as they are accepted as an alternative with industrial high value. The stem of the hemp plant is based on two kind of fibrous materials. The inner part of the stem has the woody tissue formed by short fibres where the straw has the origin, whereas the outer part has the strands, industrially used. The more often yields that can be obtained in reference to the dry stem, are 50-55% of straw, 30-35% of strands and 10-15% of impurities. The hemp strands form the raw material for paper pulp production, fabrication of non-tailored tissues and for obtaining reinforced thermoforming plastic materials. The straw is a secondary product in the extraction of strands, which is used as bed for animals due to its good absorption character, easy manipulation and can be used as fertilizer after use. Just 5% of the production is destined for the building sector as material for isolation, boards or additives for brinks. In this work, the potential of the hemp straw as filler/reinforcement agent in composite materials has been studied by means of the modification of the polypropylene matrix. To achieve this purpose a maleic anhydride-modified polypropylene has been used (MAH-PP). Tensile, flexural and impact mechanical properties have been evaluated for reinforced composites materials with 20, 30 and 40% of straw and 6% wt of MAH-PP, in reference to the strand content, for compatibilize both phases. Observing the results it is possible to indicate that filler is the function of the straw in the polymer matrix, increasing the stiffness of the composite materials. The addition of MAH-PP to the reinforced composite materials with straw has improved lightly the UTS under tensile and flexural as well as the impact strength, whereas no significative influence on Young modulus has been observed. When the properties of the materials prepared in this work where compared with the properties of materials modified by plastic industry fillers such as CaCO3 and wood flour, the competitivity of the first materials, from a industrial point of view, was observed.