Effect of lignin removal on mechanical, thermal, and morphological properties of polylactide/starch/rice husk blend used in food packaging

Abstract

The aim of this work was to investigate the possibility of using cost‐effective natural filler in a biodegradable polymer and find new set of materials for green biocomposites to be used in food packaging. In this regard, rice husk (RH) and bleached rice husk (BRH) have been used in the form of powder and the effect of lignin removal on mechanical and thermal properties of prepared composites with poly(l‐lactide) and starch were studied. Using FTIR technique, the lignin removal from RH has been approved. The tensile, charpy impact, and hardness tests were implemented to investigate the mechanical properties. It was concluded that filler caused increase both in the toughness and the Young modulus of samples. It was also found that the lack of lignin in BRH samples improves the mechanical properties. It was clearly observed that the BRH samples show larger modulus, charpy impact strength, and hardness compared to those filled with RH. Despite larger values for the elongations at break of RH samples, the mechanical properties showed a significant improvement (between 25 and 50% improvements) on lignin removal. The differential scanning calorimetry thermograms revealed an improvement in crystallization behavior and reduction of Tg from 47 to 31°C in the case of BRH‐filled samples. Finally, due to the removal of toxic lignin in the samples and modification of mechanical properties by this method, the BRH could have the ability of wide use in the bioplastics and food packaging industries. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41095.

Investigating the Effect of Treated Rice Straw in PLLA/Starch Composite: Mechanical, Thermal, Rheological, and Morphological Study

“…After washing the supplied material with hot water, it was washed with distilled water at 25°C and finally dried in an oven for 48 h at 110°C. 25 The holocellulose and lignin content of all treated RSs including HWRS are obtained according to our previous study 9 and are reported in Table I.…”

“…Therefore, it is required to be blended with other polymers, 8 specially poly(lactic acid) (PLA). 9 PLA is the most famous biodegradable polymer implementing starch as main part of structure. PLA is also a biodegradable polymer with a natural base that is synthesized from lactic acid and widely used in polymer industries for food packaging and medical applications.…”

“…PLA is also a biodegradable polymer with a natural base that is synthesized from lactic acid and widely used in polymer industries for food packaging and medical applications. [9][10][11][12][13] In our recent study, the effects of lignin removal from filler on mechanical, thermal, and morphological properties of the PLA/starch/rice husk composite were investigated. 9 The lignocellulosic additives such as rice husk, rice straw (RS), rice bran, wheat straw, saw dust, and bagasse have been shown to be effective on the polymer mechanical and thermal properties.…”

“…9 These materials have been used in both biodegradable and nonbiodegradable polymers and many studies demonstrated their ability to make several polymers stronger. [15][16][17] The lignocellulosic biomasses are mainly composed of cellulose, hemicellulose, and lignin.…”

“…21 Lignin is a phenolic polymer with a complex structure that acts as a paste in lignocellulosic materials and make the material stronger against mechanical strength, while it can act as plasticizer that leads the materials chains to more freedom of motion. 9,22 In the present study, PLA/starch composite was selected as a base matrix, and RS was added to this composite as filler in different amounts. The RS was treated by different methods such as the hot water treatment (hot water treated rice straw, HWRS), alkali treatment (alkali-treated rice straw, ARS), bleaching (bleached rice straw, BRS), and alkali bleaching treatment (alkali-bleached rice straw, ABRS).…”