Fundamental studies on lignocellulose/polypropylene composites: Effects of wood treatment on the transcrystalline morphology and mechanical properties

Abstract

Effects of alkalization, esterification, and c-irradiation of wood on the transcrystalline morphology of wood/polypropylene composites were investigated using X-ray diffraction, hot stage optical microscopy, and scanning electron microscopy. The occurrence of transcrystallization in wood-polypropylene composites is strongly dependent on the type of chemical modification of lignocellulosic materials. A detailed analysis of the results obtained proved that the transcrystallization is strongly influenced by conditions of mercerization process of wood and kind of anhydrides. Moreover, it has been found that amount of cellulose in wood plays a key role in the development of transcrystallinity. The absence of cellulose in wood seems to be unfavorable for the growth of transcrystallinity. A relationship between mechanical properties of composites and the phenomena taking place at the polymer-filler interface, controlled by chemical modifications of lignocellulose components has been evaluated. It has been established that the mechanical properties of wood composites depend on the proper choice of a modifier and are obtained after optimization of the process of modification.

Supermolecular structure and nucleation ability of polylactide-based composites with silica/lignin hybrid fillers

“…The nucleation ability of certain fillers is extremely high so that subsequent crystal growth is normal to the surface of fillers until the growing front is impeded by the growth of spherulites nucleated in the bulk. The character of interfaces between the filler and the matrix in composite materials has been widely regarded as the most important factor determining their mechanical properties [38,39]. Figure 7 shows selected photographs taken at 138°C after 12 min.…”

“…Strong interphase surface transfers stresses appearing in the system and prevents the deterioration of its mechanical properties. Since lignocellulosic materials can heterogeneously nucleate crystallization along the interface with high density of nuclei, the resulting transcrystalline structures are believed to have a great influence on producing composites with good properties [37,38].…”

Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

“…It is also important that cellulose II is characterized with much lower degree of crystallinity than cellulose I. There are some papers in which the influence of cellulose type on nucleation and crystallization process of semicrystalline polymer matrices was reported as significant [25,26]. That diversity of crystalline structures of both celluloses may also have a great influence on hydrolysis of cellulose and effectiveness of nanometric cellulose production.…”

Influence of cellulose polymorphs on the polypropylene crystallization

“…It should be added that mercerization is also responsible for the formation of another polymorphic variety of cellulose (cellulose II), which has been described in [13][14][15][16][17][18][19]. Mercerization can have a beneficial effect on mechanical properties of polymer composites [20][21][22][23][24][25][26][27][28][29]. This fact has been explained by increased roughness of the lignocellulose filler as a result of removal of low-molecular components and fibrillation of the filler.…”