Manjusri Misra

Effect of chemical modifications of the pineapple leaf fiber surfaces on the interfacial and mechanical properties of laminated biocomposites

Natural fiber reinforced renewable resource based laminated composites were prepared from biodegradable poly(lactic acid) (PLA) and untreated or surface-treated pineapple leaf fibers (PALF) by compression molding using the film stacking method. The objective of this study was to determine the effects of surface treatment of PALF on the performance of the fiber-reinforced composites. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to aid in the analysis. The mechanical properties of the PLA laminated composites were improved significantly after chemical treatment. It was found that both silane- and alkali-treated fiber reinforced composites offered superior mechanical properties compared to untreated fiber reinforced composites. The effects of temperature on the viscoelastic properties of composites were studied by dynamic mechanical analysis (DMA). From the DMA results, incorporation of the PALF fibers resulted in a considerable increase of the storage modulus (stiffness) values. The heat defection temperature (HDT) of the PALF fiber reinforced PLA laminated composites was significantly higher than the HDT of the neat PLA resin. The differential scanning calorimeter (DSC) results suggest that surface treatment of PALF affects the crystallization properties of the PLA matrix. Additionally, scanning electron microscopy (SEM) was used to investigate the distribution of PLA within the fiber network. SEM photographs of fiber surface and fracture surfaces of composites clearly indicated the extent of fiber–matrix interface adhesion. It was found that the interfacial properties between the reinforcing PALF fibers and the surrounding matrix of the laminated composite are very important to the performance of the composite materials and PALF fibers are good candidates for the reinforcement fiber of high performance laminated biodegradable biocomposites.

Nanocomposites from biobased epoxy and single-wall carbon nanotubes: synthesis, and mechanical and thermophysical properties evaluation

The synthesis, and thermophysical and mechanical properties of anhydride-cured biobased epoxy containing diglycidyl ether of bisphenol F (DGEBF) epoxy and epoxidized linseed oil (ELO) reinforced with fluorinated single-wall carbon nanotubes (FSWCNT) are reported. Sonication was used to disperse FSWCNT in the biobased glassy epoxy network, resulting in great improvement of the modulus of nanocomposites containing extremely small amounts of FSWCNT. The glass transition temperature of the obtained nanocomposites decreased by approximately 30 °C after the addition of 0.20 wt% (0.16 vol%) FSWCNT, without adjusting the amount of the anhydride curing agent. This was because of the non-stoichiometry of the epoxy matrix, caused by the fluorine on the single wall carbon nanotubes. The adequate amount of the anhydride curing agent needed to achieve stoichiometry was experimentally determined by dynamic mechanical analysis (DMA). The storage modulus of the epoxy at room temperature, which is below the glass transition temperature of the nanocomposites, increased up to 0.44 GPa with the addition of only 0.24 wt% (0.20 vol%) of FSWCNT, representing an up to 14% improvement from the modulus of the biobased ELO neat epoxies. The fracture toughness of the neat biobased ELO epoxies was also improved by approximately 43% upon addition of FSWCNT. The excellent improvement of the modulus was achieved without sacrificing the fracture toughness.

A Preliminary Study on Antimicrobial Edible Films from Pectin and Other Food Hydrocolloids by Extrusion Method

ABSTRACT Antimicrobial edible films were prepared from natural fiber of pectin and other food hydrocolloids for food packaging or wrapping by extrusion followed by compression or blown film method. Microscopic analysis revealed a well-mixed integrated structure of extruded pellets and an even distribution of the synthetic hydrocolloid in the biopolymers. The resultant composite films possess mechanical properties that are comparable to films cast from most natural hydrocolloids that are consumed as foods or components in processed foods. The inclusion of poly(ethylene oxide) alters the textures of the resultant composite films and therefore demonstrates a new technique for the modification of film properties. The composite films were produced in mild processing conditions, thus the films are able to protect the bioactivity of the incorporated nisin, as shown by the inhibition of Listeria monocytogenes bacterial growth by a liquid incubation method.

Exploring the Effect of Poly(propylene carbonate) Polyol in a Biobased Epoxy Interpenetrating Network

Poly(propylene carbonate) (PPC) polyol derived from carbon dioxide has been used to make a tough biobased interpenetrating polymer network (IPN). PPC polyol (10, 20, and 30 phr) was added to an epoxy/poly(furfuryl alcohol) IPN, and the effect of PPC polyol on the tensile modulus, tensile strength, tensile toughness, and notched Izod impact strength was determined. Dynamic mechanical analysis (DMA) was used to investigate the effect of PPC polyol on the glass-transition temperature. Loss area (LA) as a characteristic of IPN damping properties was evaluated using DMA. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to obtain more information on the morphology of IPNs on the micro- and nanoscale. It was found that the incorporation of PPC polyol improved the notched Izod impact strength and tensile toughness up to 190 and 220%, respectively. The damping factor peak was broadened with the addition of PPC polyol, and the glass-transition temperature was decreased as the amount of PPC polyol increased. The IPN with 20 phr PPC polyol exhibited better damping properties than neat epoxy and the epoxy/PFA IPN. SEM and AFM images revealed that PPC polyol domains were dispersed in the epoxy phase with an average diameter of around 280 nm.

The effect of particle size on the rheological properties of polyamide 6/biochar composites

To assess the potential of biochar as filler for thermoplastic materials and to optimize its processing conditions, composites of polyamide 6 and biochar were produced by extrusion followed by injection moulding. Biochar was prepared by grinding and ball-milling, respectively before addition to the polymer. The different biochar treatments resulted in strong differences in the mean particle size as well as the particle size distribution. The size of the filler particle significantly influences the flow behaviour of the melt.

Miscibility and Performance Evaluation of Biocomposites Made from Polypropylene/Poly(lactic acid)/Poly(hydroxybutyrate-co-hydroxyvalerate) with a Sustainable Biocarbon Filler

The incorporation of poly(lactic acid) (PLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) as a partial biobased polymer substitute for polypropylene (PP) was investigated. The ternary blends were prepared through melt compounding extrusion followed by injection molding techniques with a constant biopolymer ratio of 30 wt %. Further addition of pyrolyzed miscanthus-based carbon was carried out to establish a contrast between talc-filled PP. When the morphology of the biopolymer minor phase was analyzed theoretically using contact angle for interfacial tension and spreading coefficient values along with solubility parameter calculations and via scanning electron microscopy imaging, the core–shell architecture was found with the PHBV encasing the PLA phase. Mechanical testing of the materials showed that only the tensile properties were reduced for all samples, whereas the impact strength was increased above the neat PP. With inclusion of the biobased carbon filler into the blend system, the thermomechanical properties were elevated above that of the PP matrix. The final properties of the multiphase polymeric composites are found to be related to the morphology obtained and inherent properties of the individual constituents.

Characterization of electrospun lignin based carbon fibers

The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 – 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Dif...

Effect of maleated polypropylene emulsion on the mechanical and thermal properties of lignin-polypropylene blends

The increasing oil rates and environmental concerns of the use of synthetic or petroleum-based polymers has newly led to a growing attention in eco-friendly materials. Lignin has received much attention as a novel eco-friendly material due to its abundant availability and its potential as a low-cost filler. Biobased blends from polypropylene (PP) and lignin were fabricated by extrusion followed by injection moulding. In order to improve the compatibility of the polar lignin and the non-polar matrix PP, three different maleated PP emulsions, namely ME91735 (nonionic PP emulsion), ME42035 (cationic water based emulsion of polyolefin waxes) and PP286 (containing 1-5% N,N-ethylethanolamine) were used as coupling agents. The mechanical properties such as tensile and flexural strength as well as tensile and flexural modulus of the blends were improved by using lignin treated with 2.5 wt.% of the emulsions. However, the elongation at break decreased in the case of the lignin treated with ME91735 and ME42035 as c...

An in-depth analysis of the physico-mechanical properties imparted by agricultural fibers and food processing residues in polypropylene biocomposites

The use of agricultural and food processing residues as potential reinforcements in plastics has been extensively studied. However, there is a large variation in the mechanical performance of agricultural fiber-based biocomposites due to different processing materials and parameters. An in-depth comparison of the resulting effect of the agricultural filler on the matrix is often not possible given the discrepancy in processing conditions. This study seeks to determine the intrinsic properties of agricultural fibers and food processing residues for their use in polypropylene biocomposites based on a standardization of experimental design. The effect of 25wt% loading of miscanthus, fall-and spring-harvest switchgrass, wheat straw, oat hull, soy hull, soy stalk, hemp and flax on the physico-mechanical properties of polypropylene biocomposites was investigated. The addition of fiber led to an improvement in flexural strength, flexural modulus, and tensile modulus, and a general decrease in tensile strength at...

Binary blends of poly(butylene adipate-co-terephthalate) and poly(butylene succinate): A new matrix for biocomposites applications

In this study, biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) binary blends were melt compounded. The mechanical, thermal and morphological properties of the PBAT/PBS blends were investigated. The melt compounded binary PBAT/PBS blends showed balanced mechanical properties (especially in tensile strength and elongation) compared to neat components. The obtained melt flow index (MFI) value of the blends is much higher than PBAT. This may be attributed to PBS phase residual catalyst that can induce thermal degradation of the polymers at higher temperature. The toughness of the PBAT is not significantly affected with addition of 40 wt% PBS in the PBAT/PBS blend. This could be the reason of good compatibility achieved between the PBAT and PBS phase in the blends. The phase morphology and spherulite morphology were also correlated with compatibility between the PBAT and PBS in the blends.