Composites based on acylated cellulose fibers and low-density polyethylene: Effect of the fiber content, degree of substitution and fatty acid chain length on final properties

Abstract

a b s t r a c tLow-density polyethylene was filled with unmodified and fatty acid (hexanoic, dodecanoic, octadecanoic and docosanoic acids) esterified cellulose fibers. The thermal and mechanical properties, morphology and the water absorption behavior of the ensuing composites were investigated. The chemical modification of the cellulose fibers with fatty acids clearly improved the interfacial adhesion with the matrix and hence the mechanical properties of the composites and decreased their water uptake capacity. The performance of the composites was strongly affected by the degree of substitution (DS) and the fatty chain length as indicated by the fact that esterified cellulose fibers with low DS gave composites with better mechanical properties.

Transparent bionanocomposites with improved properties prepared from acetylated bacterial cellulose and poly(lactic acid) through a simple approach

“…This slight decrease in thermal stability is commonly found in surface-acetylated cellulose fibers. [26][27] In the present context, the main objective of the acetylation was the decrease in the fibers' hydrophilicity and polarity, aimed at increasing their adhesion to the PLA matrix. The surface energy of the BC and VC fibers before and after acetylation (Table 3) showed a considerable enhancement of the hydrophobic nature of the surface of the acetylated BC and VC fibers with a corresponding increase in the contact angle with polar liquids (water, formamide and ethylene glycol).…”

Nanocomposites in Food Packaging – A Review

“…Because of the hydrophilic cellulose surface, interactions between CNRs and hydrophilic matrices are usually satisfactory (Bondeson & Oksman, 2007). On the other hand, incorporation of cellulose nanoreinforcements to hydrophobic matrices results frequently in weak filler-matrix interactions (Hubbe et al, 2008) and filler aggregation by hydrogen bonding (Freire et al, 2008). Another limitation to the hydrophilic character of cellulose nanoreinforcements is the high water absorption capacity, which is undesirable in many potential applications (Hubbe et al, 2008).…”

“…The elongation was slightly impaired, but only at nanofiller concentrations above 10%. Several other studies have reported positive effects of CNRs on tensile properties -especially on modulus -of www.intechopen.com polymers Bhatnagar & Sain, 2005;Wu et al, 2007), although they tend to decrease elongation (Freire et al, 2008;Tang & Liu, 2008;Kim et al, 2009). According to Helbert et al (1996), the great effect of CNRs on modulus is ascribed not only to the geometry and stiffness of the fillers, but also to the formation of a fibrillar network within the polymer matrix, the CNRs being probably linked through hydrogen bonds.…”

“…Another limitation to the hydrophilic character of cellulose nanoreinforcements is the high water absorption capacity, which is undesirable in many potential applications (Hubbe et al, 2008). Such problems can be reduced by a variety of modifications (hydrophobization) on cellulose surfaces by several reactions involving hydroxyl groups, such as esterifications (Mohanty et al, 2001) and acylation with fatty acids (Freire et al, 2008).…”

Preparo e caracterização de filmes obtidos a partir de poli(ácido lático) e celulose microcristalina

“…O uso de celulose em materiais com matrizes hidrofóbicas como a de PLA resulta frequentemente em interações carga-matriz fracas [8] . A presença de celulose em matrizes apolares, em função da sua superfície altamente polar, pode conduzir a alguns problemas relativos à baixa compatibilidade interfacial, baixa resistência/barreira à água e a ocorrência de agregados de partículas pela formação de ligações de hidrogênio [9] . Essas ligações de hidrogênio são também responsáveis pela formação de uma estrutura fibrosa com cristalinidade elevada na celulose.…”