Enhancement of Mechanical and Thermal Properties of Oil Palm Empty Fruit Bunch Fiber Poly(butylene adipate-co-terephtalate) Biocomposites by Matrix Esterification Using Succinic Anhydride

Title

Article

Enhancement of Mechanical and Thermal Properties of Oil Palm Empty Fruit Bunch Fiber Poly(butylene adipate-co-terephtalate) Biocomposites by Matrix Esterification Using Succinic Anhydride

Author 

Samira Siyamak 1,* ,  Nor Azowa Ibrahim 1,* ,  Sanaz Abdolmohammadi 1

,Wan Md Zin Bin Wan Yunus 2

 and   Mohamad Zaki AB Rahman 1

1 Department of Chemistry, Faculty of Science, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

2 Department of Chemistry, Center for Defence Foundation Studies, National Defence University of Malaysia, 57000, Malaysia

* Authors to whom correspondence should be addressed. 

Received: 13 December 2011 / Revised: 2 February 2012 / Accepted: 3 February 2012 / Published: 16 February 2012

Abstract

In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (EcoflexTM), as a fully biodegradable thermoplastic polymer matrix. The aim of this research was to improve the new biocomposites’ performance by chemical modification using succinic anhydride (SAH) as a coupling agent in the presence and absence of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as initiators. For the composite preparation, several blends were prepared with varying ratios of filler and matrix using the melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 (wt %) and characterized. The effects of fiber loading and coupling agent loading on the thermal properties of biodegradable polymer composites were evaluated using thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical structure of the new biocomposites was also analyzed using the Fourier Transform Infrared (FTIR) spectroscopy technique. The PBAT biocomposite reinforced with 40 (wt %) of EFB fiber showed the best mechanical properties compared to the other PBAT/EFB fiber biocomposites. Biocomposite treatment with 4 (wt %) succinic anhydride (SAH) and 1 (wt %) dicumyl peroxide (DCP) improved both tensile and flexural strength as well as tensile and flexural modulus. The FTIR analyses proved the mechanical test results by presenting the evidence of successful esterification using SAH/DCP in the biocomposites’ spectra. The SEM micrograph of the tensile fractured surfaces showed the improvement of fiber-matrix adhesion after using SAH. The TGA results showed that chemical modification using SAH/DCP improved the thermal stability of the PBAT/EFB biocomposite.

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Preparation and Characterization of Poly(ethyl hydrazide) Grafted Oil Palm Empty Fruit Bunch for Removal of Ni(II) Ion in Aqueous Environment

Title

Article

Preparation and Characterization of Poly(ethyl hydrazide) Grafted Oil Palm Empty Fruit Bunch for Removal of Ni(II) Ion in Aqueous Environment

Author 

Ili Syazana bt Johari 1

,  Nor Azah Yusof 1,2,* ,  Md Jelas Haron 3

 and Siti Mariam Mohd Nor 1

1 Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang UPM 43400, Selangor, Malaysia

2 Institute of Advanced Technology, Universiti Putra Malaysia, Serdang UPM 43400, Selangor, Malaysia

3 Chemistry Unit, Centre of Foundation Studies for Agricultural Science, Universiti Putra Malaysia, Serdang UPM 43400, Selangor, Malaysia

* Author to whom correspondence should be addressed. 

Received: 22 May 2013 / Accepted: 2 July 2013 / Published: 25 July 2013

Abstract

Poly(ethyl hydrazide) grafted oil palm empty fruit bunch (peh-g-opefb) fiber has been successfully prepared by heating poly(methylacrylate)-g-opefb at 60 °C for 4 h in a solution of hydrazine hydrate in ethanol. The chelating ability of peh-g-opefb was evaluated based on removal of Ni(II) ions in aqueous solution. Adsorption of Ni(II) by peh-g-opefb was characterized based on effect of pH, isotherm, kinetic and thermodynamic study. This cheap sorbent based on oil palm empty fruit bunch fiber has a great future potential in water treatment industries based on high adsorption capacity, biodegradability and renewability.

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Higher Fungi of Northeast Langkawi

(Date created : 1/1/1970 07:30:00)

Title
Higher Fungi of Northeast Langkawi

Author 
Noorlidah Abdullah, Vikineswary, S., Yusoff, M., Desjardin, Dennis E.


Abstract

The North-East Langkawi is unique with different ecosystems and diverse forest types which are relatively undisturbed. A total of 212 specimens were collected from eight localities in the North-East Langkawi during two sampling periods from 10 - 19 April 2003 and 4 - 9 April 2004. The highest number of macrofungi collected was from Gunung Raya and Sungai Sireh Forest Reserves which are richly forested with predominantly dipterocarp trees. Twenty-two specimens were identified to species and 153 specimens were identified to genus. Macrofungi from the Division Ascomycota and Subdivision Ascomycotina recorded were Xylaria spp. (4 specimens) from Xylariaceae and Phillipsia sp. (1 specimen) from Sarcoscyphaceae. Further, 71 genera of Basidiomycotina belonging to 8 orders and 25 families were among the identified specimens. The Agaricales was the dominant order documented with 42 genera from eleven families recorded. The frequently recorded genera were Marasmius (29 specimens) followed by Lentinus (13 specimens) and Gymnopus and Polyporus (9 specimens each). The Marasmius specimens belonged to Marasmius sect. Marasmius (15 specimens), Marasmius sect. Sicci (6 specimens), Marasmius sect. Globulares (1 specimen) and seven unknown.

Keywords : Macrofungi, biodiversity, checklist, mycobiota, Langkawi

References

1. Kuthubutheen, A.J. (1981). Notes on the Macrofungi of Langkawi. Malayan Nature Journal 34(3) : 123 - 13. 2. Singer, R. (1962). The Agaricales in Modem Taxonomy, Second edition, 915 pp. Hajner Publishing Co. New York. 3. Corner, E.J.H. (1966). A Monograph of Cantharelloid Fungi, 255 pp. Oxford University Press. 4. Corner, E.J.H. (1972). Boletus in Malaysia, 263 pp. Botanic Garden, Singapore, Lim Bian Han, Government printing. 5. Pegler, D.N. (1983). The Genus Lentinus. A World Monograph, 281 pp. New Bulletin additional series X. 6. Largent, D.L. (1986). How to Identify Mushrooms to Genus I: Macroscopic Features, 166 pp. Mad River Press, Inc., Eureka Printing Co. 7. Lessoe, T. and A. Del Conte. (1996). The Mushroom Book, 255 pp. Dorling Kindersley. London. 8. Ruksawong, P. and T.W. Flegel. (2001). Thai Mushrooms and Other Fungi, 268 pp. Biotec, Thailand. 9. Hemmes, D.E. and D.E. Desjardin. (2002). Mushrooms of Hawaii, 211 pp. Ten Speed Press. Berkeley/Toronto. 10. Kirk, P.M., P.F. Cannon, J.C. David and J.A. Stalpers. (2001). Ainsworth and Bisby's Dictionary of the Fungi, Ninth Edition, 655 pp. CABI Publishing. 11. Watling R. (1994). Taxonomic and floristic notes on some Malaysian Larger fungi - I. Malayan Nature Journal 48 : 67 - 78. 12. Ujang S. and Thillainathan, P. (1998). Some common macrofungi in Malaysia. FRIM Technical Information 64: 1-4. 13. Ujang, S. and Jones, E.B.G. (2001). Occurrence of wood-inhabiting fungi in forests of Peninsular Malaysia. Journal of Tropical Forest Science 13 : 237 - 245. 14. Watling R. and Lee S.S. (1995). Ectomychorrhizal fungi associated with members of the Dipterocarpaceae in Peninsular Malaysia - I. Journal of Tropical Forest Science 7(4) : 657 - 669. 15. Watling R. and Lee S.S. (1998). Ectomychorrhizal fungi associated with members of the Dipterocarpaceae in Peninsular Malaysia - II. Journal of Tropical Forest Science 10(4) : 421 - 430. 16. Lee Su See, Watling R. and Noraini Y.S. (2002). Ectomycorrhizal basidiomycota fruiting in lowland rain forests of Peninsular Malaysia. Bois Et Forets Des Tropiques 274(4) : 33-43. 17. Wilson, A., D.E. Desjardin and E. Horak. (2004). The genus Gymnopus from Java and Bali. Sydowia 55 (2) : in press. 18. Corner, E.J.H. (1935). The seasonal fruiting of agarics in Malaya. Gardens Bulletin Straits Settlement 9 : 79-88.


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The Benefit of Cinnamon Leaves

The leaves of cinnamon trees, called cinnamomum verum or true cinnamon, contain phytonutrients that may provide nutritional benefits. Cinnamon powder is extracted from the bark of the tree and is not a major component of its leaves. The leaf of the cinnamon tree contains vitamins and minerals that can either be extracted and placed in a nutritional supplement in the form of an oil or capsule, or the entire leaf itself can be used as a hot water tea ingredient so that its contents can be extracted into the tea and orally ingested. As with any herbal supplement, consult your physician before using a supplement or tea containing cinnamon or cinnamon leaf extract due to the potential risk of side effects.

Cinnamon leaves are common ingredients in teas and herbal remedies. Photo Credit Jupiterimages/Pixland/Getty Images.

Anti-bacterial

The oil contained within cinnamon leaves may have anti-bacterial properties Cinnamon leaf oil contains compounds that promote the growth of healthy bacteria in your upper gastrointestinal tract that aid in digestion, as well as strengthens your immune system to fight against potentially harmful bacteria in your blood stream that may cause sickness or infection. For this reason, cinnamon leaf oil has sometimes been used as a remedy for the common cold or flu.

Mental Health

Cinnamon leaf oil may improve the balance of chemicals and neurotransmitters in your brain, according to the book, "Today's Herbal Health: The Essential Reference Guide." By balancing brain chemicals and promoting the production of neurotransmitters, such as dopamine and serotonin, cinnamon leaf oil may reduce the symptoms associated with some mental conditions, such as depression, anxiety, nervousness and mental tension. Dopamine in particular is recognized as a mood-enhancing hormone and is directly related to positive thoughts, reducing the effects of depression and anxiety.

Other Benefits

Cinnamon leaf oil contains eugenol, which may reduce symptoms of gastrointestinal distress such as upset stomach, nausea, and diarrhea. Cinnamon leaf oil also contains high concentrations of a chemical compound called cinnameldehyde, which is a natural pain reliever that also has anti-inflammatory properties which can reduce the painful effects of arthritis, or swelling in your body's joints. Cinnameldehyde may also have a positive effect on the metabolism of glucose, which may increase insulin sensitivity and decrease the risk of developing type 2 diabetes.

Aphrodesiac

Cinnamon leaf oil is sometimes used in aromatherapy as an aphrodisiac for its potential ability to increase sexual function. According to the book, "Aromatherapy: An A-Z," cinnamon leaf oil has a warming, spicy scent that is used to relieve impotence and increase sexual potency in both men and women. Cinnamon leaf oil in aromatherapy is most often mixed with other therapeutic oils, burned in an oil bowl and inhaled for its potential benefits.

www.livestrong.com

Biodegradable foams based on starch, polyvinyl alcohol, chitosan and sugarcane fibers obtained by extrusion

Title
Biodegradable foams based on starch, polyvinyl alcohol, chitosan and sugarcane fibers obtained by extrusion

Directory of Open Access Journals (Sweden)

Author
Flávia Debiagi^I; Suzana Mali^I, *; Maria Victória Eiras Grossmann^II; Fábio Yamashita^II
IDepartamento de Bioquímica e Biotecnologia; Centro de Ciências Exatas; Universidade Estadual de Londrina; C. P.: 6001; 86051-990; Londrina - PR - Brasil 
^IIDepartamento de Ciência e Tecnologia de Alimentos; Centro de Ciências Agrárias; Universidade Estadual de Londrina; C. P.: 6001, 86051-990, Londrina - PR - Brasil

Published Date 
2011-10-01


ABSTRACT

Biodegradable foams made from cassava starch, polyvinyl alcohol (PVA), sugarcane bagasse fibers and chitosan were obtained by extrusion. The composites were prepared with formulations determined by a constrained ternary mixtures experimental design, using as variables: (X₁) starch / PVA (100 - 70%), (X₂) chitosan (0 - 2%) and (X₃) fibers from sugar cane (0 - 28%). The effects of varying proportions of these three components on foam properties were studied, as well the relationship between their properties and foam microstructure. The addition of starch/PVA in high proportions increased the expansion index and mechanical resistance of studied foams. Fibers addition improved the expansion and mechanical properties of the foams. There was a trend of red and yellow colors when the composites were produced with the highest proportions of fibers and chitosan, respectively. All the formulations were resistant to moisture content increase until 75% relative humidity of storage.

Key words: cassava starch, mechanical properties, microstructure and expansion

INTRODUCTION

In recent years, much progress has been achieved in the development of biodegradable products using agricultural material as basis. Various approaches have used starch for the production of different functional materials (Soykeabkaew et al., 2004). Considerable effort has been made to develop starch foams as alternative to expanded polystyrene (EPS) for loosefill packaging application. Starch foams with insulating properties that are similar to polystyrene foam have been industrially developed by extrusion. Extrusion technology is a high-temperature, short-duration process with the advantage of high versatility and absence of effluents (Bastioli et al., 1994, 1998a; Bhatnagar and Hanna, 1995, Cha et al., 2001; Fang and Hanna, 2001; Lacourse and Altieri, 1989, 1991; Willett and Shogren, 2002; Chiellini et al., 2009).

Starch foams can be employed to substitute the polystyrene products, but it is known that thermoplastic starch composites have weak mechanical properties, such as poor water resistance (Guan and Hanna, 2004). Bio-based materials, such as cellulose, and other biodegradable polymers are being used as ingredients to improve the moisture sensitivity and mechanical properties of starch-based foams (Lawton et al., 2004; Guan and Hanna, 2006; Salgado et al., 2008; Lee et al., 2009). Some authors have also reported that the resistance of starch foams to the direct contact with water showed an improvement by the addition of a high proportion of polyvinyl alcohol (Shogren et al., 1998; Shogren and Lawton, 1998). Polyvinyl alcohol (PVA) is a particularly well-suited synthetic polymer for the formulation of blends with natural polymers, as it is highly polar and can also be manipulated in water solutions, and depending upon its grade, in functional organic solvents as well (Chiellini et al., 2001).

Another biopolymer used in combination with starch to produce the biodegradable foams is chitosan, a cationic polymer produced by alkaline N-deacetylation of chitin, which is the main component of the shells of crab, shrimp, and krill (Nakamasu et al., 2006; Wang et al., 2006). Nakamasu et al. (2006) reported that chitosan and starch could be used to produce the porous structures. According to Wang et al. (2006), chitosan/PVA foams demonstrated interconnected and open-cell structures with large pore size.

In this work, sugarcane bagasse fiber, an under-utilized waste residue from sugar and alcohol industries was evaluated as filler for starch foams to reduce the moisture sensitivity. Brazil is the largest worldwide producer of ethanol from sugarcane, and large amounts of fibers is left as a by-product, which is cheap, non-toxic, easily recyclable and its use contributes to environmental protection (Ruggiero et al, 2006). During the biodegradation process, the presence of fibers induced a faster breaking in pieces of the samples due to the action of microorganism attracted by the lignocellulosic components (Chiellini et al., 2009).
Thus, the objectives of this work were to evaluate the effects of cassava starch, polyvinyl alcohol, sugarcane bagasse fibers and chitosan on microstructure, density, expansion index, color, water adsorption and mechanical properties of extruded foams using a mixture design methodology.

MATERIALS AND METHODS

Materials
Cassava starch (19% amylose) was provided by Hiraki Industry (São Paulo, Brazil). Sugarcane fiber was provided by the regional ethanol producers, which was milled and sieved through mesh N-50 obtaining a product with a size between 290 - 297 μm and before use, it was dried. PVA (ACS degree, molecular weight 72,000 and degree of hydrolysis of 86.5 - 89.5%) was purchased from Reagen (Quimibrás Industrias Química, Rio de Janeiro, Brazil), chitosan was obtained from Sigma Aldrich (EUA) and glycerol from Synth (Labsynth, São Paulo, Brazil).

Foams production by extrusion
A three-component constrained simplex mixture design (Cornell, 1990) was used to study the effects of cassava starch/PVA (X₁), chitosan (X₂) and fibers (X₃) on the properties of the extruded foams. The range selected for each component was based on previous experience and ranged from 70 to 100% for starch/PVA, 0 to 2 % for chitosan and 0 to 28% for sugarcane fibers. The starch/PVA employed proportion was 60/40.  Table 1 shows the nine employed formulations and two replications at center point in terms of its original components and pseudo-components (a set of components that took on the values from 0 to 1 over the feasible region). The pseudo-components were calculated as follows: X´_I = (X_i - L_i)/(1-ΣL_i), here, X'_i was the i'th pseudo-component, X_i was the original component value, L_i was the lower constraint (limit) for the i'th component, ΣL_i was the sum of all lower constraints (limits) for all the components in the design and this transformation made the coefficients for different factors comparable in size (Cornell, 1990).

To prepare each formulation, the indicated proportions of starch/PVA, chitosan and sugarcane fibers (Table 1), glycerol (20 % w/w) and water (sufficient to produce the samples with 18% of moisture content before extrusion) were mixed during 5 min at 780 rpm (Arno - Brasil). The extrusion of the samples was performed in a single-screw extruder (BGM EL-25, São Paulo, Brasil) with a barrel (700 mm in length and 25 mm in diameter). Temperatures from the feeding to die zone were maintained at 120ºC and two 2.8 mm die nozzles were employed to produce the cylindrical foams extrudates. The screw speed was maintained at 70 rpm. The extrudates were cut into 100 mm samples with a rotary cutter operating at 20 rpm.

Foams characterization
Density
Density was calculated as the ratio between the weight and volume (Shogren et al., 1998). The reported values were the averages of ten determinations of each formulation.

Expansion index
The expansion index (EI) was measured dividing the extrudates diameter by die orifice diameter (Gujska and Khan, 1991). Reported values were the averages of twenty determinations of each formulation.

Scanning electron microscopy (SEM)
SEM analyses were performed with a FEI Quanta 200 microscope (Oregon, USA). Foams pieces were mounted on the bronze stubs using a double-sided tape and then coated with a layer of gold (40-50 nm), allowing surface and cross-section visualization. To obtain the cross-section, the samples were prepared by immersion into liquid nitrogen in order to avoid the deformation during the fracture. All the samples were examined using an accelerating voltage of 20 kV.

Adsorption isotherms
Starch foams specimens were pre-dried for 14 days over phosphorous pentoxide (P₂O₇) and then were placed at 25ºC over saturated salt solutions in separated desiccators having desired water activities (0.11, 0.32, 0.43, 0.58, 0.75 and 0.90) (Rockland, 1960). Each foam specimen was weighed at regular intervals (minimum 6 h and maximum 12 h), and when two consecutive weights were equal, it was assumed that an equilibrium condition was reached. Under the above conditions, an equilibrium period of seven days was sufficient to establish the moisture equilibrium in all the samples. Equilibrium moisture content was calculated from the increase in the mass of the dried sample after equilibration at a given RH. All the tests were conducted in triplicate.

Color
Foams color was determined using a colorimeter (CR 10, Minolta Chroma Co., Osaka, Japan). The color parameters range from L = 0 (black) to L = 100 (white), - a (greenness) to +a (redness), and -b (blueness) to +b (yellowness). The instrument was calibrated using a set of three Minolta calibration plates. Reported values were the averages of five determinations of each formulation.

Mechanical properties
A texture analyzer model TA.XT2i (SMS, Surrey, UK) with a 25 N load cell was used to determine the compression strength of samples. The 10 mm long extrudates were placed on a flat plate with carefully aligned cut surfaces so that the edges were perpendicular to the axis of the sample (direction of extrusion). Then, each foam was compressed once to 80% of its original diameter at a loading rate of 5.0 mm/s using a Knife probe. The force (N) was reported as compression strength. Reported values were the averages of fifteen determinations of each formulation.

Statistical data analysis
Experiments were design and analysed using Statistica software version 6.0 (Statsoft - Oklahoma). Linear models (equation 2) for three components were fitted to the experimental data:
Y = β₁X´₁ + β₂X´₂ + β₃X´₃ (2)
where Y was a predictive dependent variable; β₁, β₂ and β₃ were the corresponding parameter estimates for each linear term produced for the prediction models for cassava starch/PVA (X`₁), chitosan (X´₂) and sugarcane fibers (X´₃), respectively. The pseudo-components were employed to fit the models and to construct the surface contour plots.

RESULTS AND DISCUSSION

The results (Table 2) were statistically evaluated. Thecalculated regression coefficients of the equations and the analysis of variance (ANOVA) are shown in Table 3. All the models were statistically significant (p < 0.05) and able to explain 80-98% of the variation (R²). No significant lack of fit (p > 0.05) was observed, showing the good correlation between the models and the experimental data. The different proportions between starch/PVA (X´₁) and fibers (X´₃) caused significant alteration in all the measurements (p < 0.05), except for a* parameter of color, for which only the fibers proportions (X₃) was significant. The chitosan (X´₂) proportion was significant only for the density and b* parameter of color (Table 3).

Density is an important physical property of extruded foams and low density is a desirable attribute for these products because of reduction in the material cost (Lee et al., 2009). In this work, density was positively influenced by the effects of starch/PVA (X´₁), chitosan (X´₂) and fibers (X´₃) proportions (Table 3). When the content of these three components increased, density increased; however, the effects of chitosan and fiber proportions on the density were higher than the effect of starch/PVA (Table 3). Figure 1 shows a decreasing trend for the density with increasing of starch/PVA and decreasing of fiber proportions.This occurred because the shear generated inside the extruder barrel was not enough to form the starch-fiber network required for expansion. These results agreed with some data reported by other authors. According to Guan and Hanna (2004) and Salgado et al. (2008), the density of starch foams increased with the increase in fiber content. Carvalho et al. (2003) and Jin et al. (1995) reported that an increase in fiber content appeared to increase the starch chain degradation during extrusion because it caused an increase in the product temperature, extruder torque, die pressure and axial expansion of the extrudate. Thus, the increase in density could be explained due to the breakage of the starch glycosidic linkages during the extrusion to form the molecules of small molecular weight, which decreased the wall extensibility of the cells and caused the rupture of the macrostructure of the product (Lee et al., 2009). Besides, Funabashi and Kunioka (2005) found that the existence of fibers during the extrusion caused a decrease in the density due to the fiber trapping air inside the foam which increased the expansion.

In this work, density of starch foams ranged from 0.20 to 0.34 g/cm³ (Table 2), which was higher than the values of expanded polystyrene, close to 0.06 g/cm³ (Glenn et al., 2001; Shey et al., 2006). They were also higher than the values (0.067 to 0.106 g/cm³) reported by other authors for the foams made with high amylose starch (Miladinov and Hanna, 2001) and high amylose maize starch, which ranged from 0.048 to 0.091 g/cm³ (Guan and Hanna, 1994). However, these values were lower than those reported by Salgado et al. (2008) for the foams made of cassava starch, cellulose fibers, and sunflower protein isolate, which ranged from 0.456 to 0.587 g/cm³. Tartaka and Cunninghan (1998) attributed the higher density of starch-based foams compared to the expanded polystyrene ones to the open cells of starch foams, which prevented the material from continuing to expand.

EI is an important property to define the foam production cost. In general, extruded foams with lower densities have higher EI (Rhee et al., 1999; Xu et al., 2005). The EI of starch foams was influenced positively by the linear effects of starch/PVA (X´₁) and fibers (X´₃) proportions. The starch/PVA effect was more important for the increase of this property (Table 3). Figure 2 shows the increase of EI with the increase in starch/PVA proportion and decrease in fiber and chitosan proportions. The lowest EI value (Table 2) were obtained for the formulations produced with the maximum of fiber (28%) and chitosan (2%) proportions, and a proportion of starch/PVA of 70% (run 3 of the experimental design - Table 1). These results agreed with the density values discussed above and could be explained as the same way. Besides, according to other authors (Carr et al., 2006; Cinelli et al., 2006), some vegetable fibers act as a reinforcing material only at low concentration levels, and the increase in fiber content results in the foams with higher densities and lower EI. The presence of fibers in the foam formulation is responsible for an increase in the viscosity of this mixture, which causes a less expandable material, a smaller average cell size, a thicker cell wall, and higher density (Shogren and Lawton, 1998).

Figure 3 shows some SEM micrographs of the produced foams. Foams produced exclusively with starch/PVA (run 1 of experimental design - Table 1) resulted in a material with good expansion, which was observed by the opened cell structure when compared to the foams produced with low starch/PVA (70%) and high chitosan (2%) and fiber (28%) proportions, as run 3 of experimental design (Table 1), which showed closed cell structure. Fiber accumulation was observed (arrow 1), resulting in a non-homogeneous structure (Fig. 3), as also reported by Carr et al. (2006), who related this non-homogeneity to a decrease in the compression strength of the foams, as discussed below. According to others researchers (Moraru and Kokini, 2003; Preechawong et al., 2004), the opened cell structure of foams was a result of the venting of large amount of water molecules when the starchy polymer emerged from the extruder die.
The effect of starch/PVA on homogeneity and expansion of produced foams could be explained by the high compatibility between the starch and PVA, which contributed to the formation of less rigid and more expandable foam matrices with less starch-starch interaction, resulting in the materials with good expansion properties (Cinelli et al., 2006; Lui and Peng, 2005).

Starch/PVA (X´₁) and sugarcane fibers (X´₃) positively affected the compression strength (force) of the samples (Table 3). The starch/PVA effect, however, was more significant (Table 3), as higher values were obtained at higher starch/PVA proportions (Fig. 4). According to Cinelli et al. (2006), the addition of PVA to starch foams led to the formation of structures which were more resistant (less rigid) to compression, possibly due to the break of hydrogen bonds of starch and the PVA content in the foam formulation. According to Carr et al. (2006), starch foams had their compression strength improved by the fiber addition until its content reached around 15%. The foams containing around 30% fibers had lower strength, probably due to uneven fiber distribution. Lee et al. (2009) reported that the presence of fibers resulted in good bonding with the starch matrix which can form a stronger matrix, thereby increasing the compressive strength of the foam. Lawton and Shogren (2002) found that the addition of 5-10% fiber clearly produced higher strength foams because the fibers adhered well to the starch matrix, and thus acted as reinforcement. This could be observed in this work; the foams with the highest fibers proportions had their compression strength decreased (Table 2) compared with those formulated with the intermediary levels, probably because of the formation of a non-homogeneous structure, as observed by SEM (Fig. 2).

The color parameters of the foams are shown in  Table 2. Luminosity (L*) was positively influenced by the linear effects of starch/PVA (X´₁) and sugarcane fibres (X´₃); the effect of starch/PVA on L* (Table 3) was higher than the effects of the other components (Table 3). Figure 5a showed that the luminosity increased with increasing starch/PVA content in the studied experimental region.
According to ANOVA (Table 3), parameter b* was influenced bythe linear effects of starch/PVA (X´₁), chitosan (X´₂) and sugarcane fibers (X´₃) proportions, but the most important effect was exerted by chitosan addition (Table 3). Figure 5b showed the increase in parameter b* when high proportions of chitosan were used in foam formulations. Pranoto et al. (2005) reported that chitosan biodegradable packaging had a yellowish aspect.
The foam redness observed with the parameter a* increase was significantly influenced only by the linear effect of fibers proportion (X´₃). When the fibers proportion increased, the redness increased (Fig. 5c). According to Famá et al. (2009), color parameters of starchy biocomposites increased significantly with fiber addition, which limited the use of this reinforcing agent in food applications.
The moisture sorption isotherms of starch foams are shown in Figure 6. The foams presented similar isotherm patterns, and in general, the equilibrium moisture content of the samples increased with the increase in water activity, but the increase in the equilibrium moisture was more pronounced when the samples were stored in RH above 75%. This behavior was interesting considering that in these materials the main problem was the sensitivity to moisture (Salgado et al., 2008; Mali et al., 2006), and the produced foams in this work were relatively stable to moisture increase with increasing water activity (Relative Humidity /100).

CONCLUSIONS

In this work, biodegradable foams were produced by extrusion of raw materials that were economically important in South America, such as cassava starch and sugarcane bagasse fiber. The introduction of sugarcane fibers could help in improving the properties of starch composites, but in controlled proportions so as not to affect their expansion and color. The studied proportions of chitosan did not improve the properties of the foams. All the formulations were resistant to different environmental conditions until 75% relative humidity of storage. The produced materials need further development to get the best results of expansion. oever, This study could be the key step in the production of composites at industrial scale.

ACKNOWLEDGEMENTS

The authors wish to thank the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq-No. 577146/2008-4 and 478109/2008-3) of Brazil for the financial support.

REFERENCES

Bastioli, C.; Bellotti, V.; Del Giudice, L.; Lombi, R.; Rallis A. (1984), Expanded articles of biodegradable plastic materials. US Patent 5.360.830.         [ Links ]
Bastioli, C.; Bellotti, V.; Del Tredici, G.; Montino, A.; Ponti, R. (1988), Biodegradable foamed plastic materials. US Patent 5.736.586.         [ Links ]
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Anaerobic digestion of starch-polyvinyl alcohol biopolymer packaging: biodegradability and environmental impact assessment.

Title
Anaerobic digestion of starch-polyvinyl alcohol biopolymer packaging: biodegradability and environmental impact assessment.

Science.gov (United States)

Author 
Guo, M; Trzcinski, A P; Stuckey, D C; Murphy, R J

Published Date 
2011-12-01

Abstract 

The digestibility of a starch-polyvinyl alcohol (PVOH) biopolymer insulated cardboard coolbox was investigated under a defined anaerobic digestion (AD) system with key parameters characterized. Laboratory results were combined with industrial operational data to develop a site-specific life cycle assessment (LCA) model. Inoculated with active bacterial trophic groups, the anaerobic biodegradability of three starch-PVOH biopolymers achieved 58-62%. The LCA modeling showed that the environmental burdens of the starch-PVOH biopolymer packaging under AD conditions on acidification, eutrophication, global warming and photochemical oxidation potential were dominated by atmospheric emissions released from substrate degradation and fuel combustion, whereas energy consumption and infrastructure requirements were the causes of abiotic depletion, ozone depletion and toxic impacts. Nevertheless, for this bio-packaging, AD of the starch-PVOH biopolymer combined with recycling of the cardboard emerged as the environmentally superior option and optimization of the energy utilization system could bring further environmental benefits to the AD process.

 PMID:22001054

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Polyvinyl alcohol/starch composite nanofibers by bubble electrospinning

Title
Polyvinyl alcohol/starch composite nanofibers by bubble electrospinning

Author

Liu Zhi

Published Date 

2014-01-01

Abstract 

Full Text Available Bubble electrospinning exhibits profound prospect of industrialization of macro/ nano materials. Starch is the most abundant and inexpensive biopolymer. With the drawbacks of poor strength, water resistibility, thermal stability and processability of pure starch, some biodegradable synthetic polymers such as poly (lactic acid, polyvinyl alcohol were composited to electrospinning. To the best of our knowledge, composite nanofibers of polyvinyl alcohol/starch from bubble electrospinning have never been investigated. In the present study, nanofibers of polyvinyl alcohol/starch were prepared from bubble electrospinning. The processability and the morphology were affected by the weight ratio of polyvinyl alcohol and starchy. The rheological studies were in agreement with the spinnability of the electrospinning solutions.

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Mixture design to develop biodegradable sheets with high levels of starch and polyvinyl alcohol

Published Date
First published: 3 September 2015

DOI: 10.1002/star.201500094

Author
Juliano Zanela, Marianne Ayumi Shirai, Mônica Oliveira Reis, Suzana Mali, Maria Victória Eiras Grossmann, Fabio Yamashita


Title
Mixture design to develop biodegradable sheets with high levels of starch and polyvinyl alcohol

Abstract

A mixture design was used to analyse the effects of polyvinyl alcohol (PVA) on glycerol-plasticised cassava starch sheets obtained by flat extrusion from a twin-screw extruder. PVA was the main component that improved the properties of the sheets, and glycerol presented the opposite effect. The properties ranging: tensile strength (0.22–1.5 MPa), Young's modulus (0.45–7.29 MPa), elongation at break (59–111%), puncture resistance (10–107 N/mm), puncture elongation (5.64–10.13 mm), crystallinity index (17–21%) and water vapour permeability (3.39–7.40 × 10−5 g m−1 day−1 kPa−1) for the sheets. Scanning electron microscopy showed good compatibility between the components of the blend because the resultant materials were continuous and cohesive and did not exhibit phase separation. The sheets were not significantly different from others, based on XRD and FTIR analyses, consistent with the literature. PVA was able to improve the mechanical and barrier properties of starch-based sheets.

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Physicochemical properties of glutinous rice in the presence of alkali and borax

Published Date
First published: 18 June 2015

DOI: 10.1002/star.201500103

Title
Physicochemical properties of glutinous rice in the presence of alkali and borax

AuthorsSukanya AnupapsamosAbstract

Author 

Sukanya Anupapsamosorn, 

Sanguansri Charoenrein

Abstract 

The influences of alkali, represented by sodium hydroxide (NaOH), and sodium tetraborate (borax) on the physicochemical properties of glutinous rice (RD6 cultivar) were investigated. The results showed that NaOH and borax treatment differently influenced the properties of glutinous rice. NaOH-treated flour (NTF) had the highest pH value, followed by borax-treated flour (BTF), and the control sample, respectively. NaOH caused a significant decrease in the protein content while borax had no effect. These results related to scanning electron micrographs of NTF which showed a smoother surface than that of the others. The BTF had the highest peak and final viscosity, possibly due to cross-linkages between borate ions and hydroxyl pairs on the polysaccharide chains. The results of pasting properties were in line with the hardness of the flour paste. Gelatinization temperature of both NTF and BTF was significantly higher than in the control, but enthalpy was not significantly different. This information provides a greater understanding of the behavior of NaOH and borax on glutinous rice and is useful for applications of NaOH and borax in food and non-food products. It is also important to understand borax's effect on starch and to find a suitable substitute.

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Published Date
First published: 22 June 2015

DOI: 10.1002/star.201500011

Author 
Osamah A. Bin-Dahman, Jobin Jose, Mamdouh A. Al-H

Title 

Compatibility of poly(acrylic acid)/starch blends

Abstract

Compatibility of poly(acrylic acid) (PAA) and corn starch blends was studied by various techniques. Blends were prepared by using solution mixing and casting method with the aid of glycerol as a plasticizer. The molecular level interactions between the blend components were analyzed with Fourier transform infrared spectroscopy (FTIR). Dynamic mechanical analysis (DMA) showed that the introduction of starch into PAA matrix contributed substantially to the increase of the storage modulus. Differential scanning calorimetry (DSC) studies revealed that the PAA/starch blends were partially miscible and had an amorphous structure. The thermal gravimetric analysis (TGA) confirmed that the blends had higher thermal stability than the individual polymers. Water uptake experiments showed that the degree of swelling was mainly dependent on the PAA content in the blend. X-ray diffraction (XRD) studies showed that the incorporation of the PAA into starch destructed its crystalline structure. The morphology of the blends was changed by varying the composition. Scanning electron microscopic (SEM) analysis showed that at higher loads of starch, the PAA was formed as layers around starch granules. Blends containing higher amount of starch showed more homogenous and compatible behaviors relative to those with lower starch contents.



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Effects of various nanomaterials on the properties of starch/poly(vinyl alcohol) composite films formed by blow extrusion process

Published Date

August 2015, Volume 24, Issue 8, pp 687-696

First online: 07 July 2015

Title 

Effects of various nanomaterials on the properties of starch/poly(vinyl alcohol) composite films formed by blow extrusion process

• Author 

• Wentao Wang
• , Hui Zhang
• , Yangyong Dai
• , Hanxue Hou
• , Haizhou Dong

Cover Date

2015-08


DOI
10.1007/s13726-015-0359-7


Print ISSN
1026-1265


Online ISSN
1735-5265


Publisher
Springer Berlin Heidelberg


Author Affiliations

• 1. Department of Food Science and Engineering, Shandong Agricultural University, Tai’an, 271018, People’s Republic of China

Abstract

Effects of various nanomaterials on the physical and mechanical properties of hydroxypropyl distarch phosphate/poly(vinyl alcohol) (starch/PVA) composite films fabricated by blow extrusion were investigated. The starch/PVA nanocomposite films were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA/DTG), FTIR, and scanning electron microscope (SEM). The nanocomposite films containing nano-CaCO3 and organically modified montmorillonite (OMMT) showed the lowest and highest tensile strengths of 3.72 and 7.04 MPa, respectively. The film containing natural montmorillonite (MMT) exhibited the lowest elongation-at-break of 118.73 %. The film with OMMT exhibited the lowest water vapor permeability of 4.12 × 10−10 g m−1 s−1 Pa−1. Addition of nano-TiO2 to starch/PVA films resulted in a significant decrease in ∆E*(increased clearness). Differential scanning calorimetry (DSC) indicated that the nanocomposite films exhibited higher glass transition temperatures (T g) and lower melting enthalpy compared to the control film. Adding MMT and OMMT to starch/PVA blends increased the thermal stabilities of the films according to the TGA/DTG analysis. Agglomeration of particles was observed in the starch/PVA composite films containing nano-CaCO3 and nano-TiO2while nano-SiO2 and MMT dispersed well in the matrix. On the whole, OMMT was more compatible with starch/PVA blends and served as a better nanomaterial to prepare starch/PVA nanocomposite films which was superior to that of the other four nanomaterials.

Keywords

Starch Poly(vinyl alcohol) Nanocomposite Film blowing Properties

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