Broom fibers as reinforcing materials for polypropylene-based composites

Abstract

Broom fibers have been used as reinforcement for the conventional polypropylene (iPP) and a maleate modified one (iPPMA). A conventional alkaline treatment and a steam explosion extraction process were applied to obtain the cellulosic material from broom branches. Composites were prepared by melt mixing materials with different weight percentages of broom fibers. Also ternary blends (iPPMA/iPP/broom fibers 5/45/50 wt) were obtained to examine the possibility of utilizing the maleate polypropylene as a compatibilizing agent. The fibers and the composites were thermally, morphologically, and mechanically characterized. Water absorption tests, to examine the behavior of these materials in wet conditions, were also performed. Particular attention was addressed to the study of the fiber/matrix interfacial adhesion. The results showed that the iPPMA-based composites, reinforced with alkaline extracted broom fibers, present specific mechanical properties competitive with those of the homologous polypropylene-based materials reinforced with short glass fibers. The ternary blends gave similar properties to those of the corresponding whole iPPMA-based composites. It is considered that the esteric linkage between the cellulose {OH, and the maleic anhydride groups grafted on the polypropylene backbone is greatly responsible for the similarity in the properties. In spite of better adhesion observed in the samples reinforced by the steam-exploded fibers, less improvement of the mechanical properties was observed, owing to significant damage of the structure of the fibers during the steam explosion process. A general decrease of mechanical properties is observed in normal polypropylene-based composites. The results are also supported by the water absorption tests: whereby the iPPMA-based composites showed good capability to return their dry properties when kept in an oven after wetting for many days.

Influence of cellulose polymorphs on the polypropylene crystallization

“…It can be found that the crystallinity index of fillers slightly decreases when the alkalization treatment is applied. A similar character of the dependence of cotton or ramie crystallinity during alkali treatment has been reported in recent works [51][52][53]. It is well known that the lignocellulosic fillers undergo three distinct process during mercerization [18,54,55]: fiber swelling, disruption of the crystalline areas and formation of new crystalline lattice after rinsing away the mercerization solution.…”

Distributed Physical and Molecular Separations for Selective Harvest of Higher Value Wheat Straw Components Project

“…It is expected that removal of hemicellulose will allow better resin penetration and adhesion, since similar results have been obtained using steam exploded broom fibers (Avella et al 1998). The fiber damage imparted by steam explosion would not be expected to be present in straw stems treated with fungi, especially by a fungus that does not degrade significant cellulose (Hadar et al 1993).…”

“…Indeed, steam explosion has been investigated to remove lignin and hemicellulose to allow better resin penetration and adhesion (Avella et al 1998). While significant improvement in interfacial adhesion was seen in steam exploded broom fibers, the extensive physical damage to the fibers imparted by the steam explosion process eliminated any mechanical property improvements.…”

Extraction Methods of Spanish Broom (Spartium Junceum L.)

“…During the past several years the number of scientifi c work related to the production of Spanish Broom as raw material in the manufacture of composite materials considerably increased (Avella et al, 1998; Angelini et al, 2000; Gabriele et al, 2010; Cerchiara et al, 2010 A). The advantage of Spanish Broom over fl ax and hemp is that it can grow in the most unfavorable limestone soil; it is resilient to draught; and once planted it can be used during a period of up to twenty years, whilst fl ax and hemp demand high quality soil each year.…”