Thermoplastic nanocomposites filled with wheat straw cellulose whiskers. Part I: Processing and mechanical behavior

Abstract

Cellulose microcrystals with dimensions of ∼5 nm × 150–300 nm were obtained from wheat straw. To evaluate the reinforcing effect of these fillers within a thermoplastic matrix, composites with a weight fraction of cellulose ranging from O to 30 wt% were processed by freeze‐drying and molding a mixture of aqueous suspensions of microcrystals and poly(styrene‐co‐butyl acrylate) latex. It was found that these microcrystals, or whiskers, bring a great reinforcing effect at temperatures higher than the glass transition temperature (Tg) of the matrix and improve the thermal stability of the composite. The relaxed modulus increased continuously with the filler content, and for a film containing 30 wt% of whiskers, it was more than a thousand times higher than that of the matrix. This effect is discussed with regard to theoretical calculations based on a mean field approach (Halpin‐Kardos model). It is concluded that the great reinforcement observed seems to be due not only to the geometry and stiffness of the straw cellulose whiskers but also to the interactions of the microcrystals, their topological arrangement, and the probable formation of whisker clusters within the thermoplastic matrix, the cellulose fillers probably being linked through hydrogen bonds.

Holocellulose Nanocrystals: Amphiphilicity, Oil/Water Emulsion, and Self-Assembly

“…5,6 CNCs have attracted tremendous interests due to its unique properties including high crystallinity of over 90%, 7,8 extraordinary elastic modulus of 110−220 GPa 4,9,10 and outstanding tensile strength of 2−6 GPa. 11 CNCs reported to date have focused primarily on those hydrolyzed from purified cellulose from sources such as bleached wood pulp, 5,12 bacteria, 13 cotton, 14,15 tunicate, 16,17 microcrystalline cellulose, 18 as well as agricultural residues, including rice straw 8,19 and husk, 20 grape pomace, 21 wheat straw, 22 tomato 23 and potato 24 peels, banana plants, 25 and so on. As cellulose microfibrils are tightly embedded in lignin and hemicellulose matrixes, 26,27 isolation of pure cellulose requires intensive chemical and energy input.…”

Effects of Silane Surface Treatment of Cellulose Nanocrystals on the Tensile Properties of Cellulose-Polyvinyl chloride Nanocomposite

“…Microcrystalline cellulose is a purified and partially depolymerized cellulose, which can be prepared from all forms of natural celluloses (Battista & Smith 1962). Many different sources have been used to prepare cellulose nanocrystals, such as tunicate (Favier et al 1995a(Favier et al , 1995b, wheat straw (Helbert et al 1996), cotton (Ebeling et al 1999), wood fibres (BeckCandanedo et al 2005), sisal (Garcia de Rodriguez et al 2006;Moran et al 2008), flax fiber (Cao et al 2007), ramie (Habibi et al 2008), mulberry (Li et al 2009), coconut husk fibres (Rosa et al 2010), pineapple leaves (Cherian et al 2010), bananas (Deepa et al 2011), kenaf bast fibers , rice husk (Johar et al 2012), rice straw (Lu & Hsieh 2012), mengkuang leaves (pandanus tectorius) ) and pandanus utilis (Chenampulli et al 2013).…”

Starch-based nanocomposites reinforced with flax cellulose nanocrystals

“…Natural polymers such as poly(β-hydroxyoctanoate) (PHO) [19], soy protein [20], silk fibroin [21] reinforced with cellulose whiskers were reported. Meanwhile, Poly-(styrene-co-butyl acrylate) (poly(S-co-BuA)) [22], poly(vinyl chloride) (PVC) [23], polypropylene [24], waterborne polyurethane [25], were also used as synthetic matrixes. The flax plant (Linum usitatissimum) is a member of the Linaceae family, which is an important crop in many regions of the world.…”