Journal of Polymers and the Environment

, Volume 26, Issue 8, pp 3243–3249 | Cite as

Organically Modified Nanoclay and Aluminum Hydroxide Incorporated Bionanocomposites towards Enhancement of Physico-mechanical and Thermal Properties of Lignocellulosic Structural Reinforcement

  • Neetu Malik
  • Piyush Kumar
  • Subrata Bandhu Ghosh
  • Sharad Shrivastava
Original Paper


A range of bio-nanocomposites were prepared by incorporation of organo modified montmorillonite nanoclay (OMMT) with or without use of aluminum hydroxide (Al(OH)3) within polylactic acid (PLA) solution. Furthermore, the solution was employed for modification of ligno-cellulosic (jute) fabric structural reinforcements. The successful incorporation of nanofillers within the host polymer, polylactic acid (PLA) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). Water uptake and swelling behaviour studies revealed that the water uptake and swelling ratio of bio-composites reduced significantly as compared to pristine jute fabric, whereas upon incorporation of OMMT and Al(OH)3, the water barrier properties reduced even further in the developed bio-nanocomposites. The flexural strength of the bio-nanocomposites also showed improved mechanical and dimensional stability. Synergistic effects of OMMT and Al(OH)3 were observed in enhancing the aforementioned physico-mechanical properties. Scanning electron microscopy (SEM) studies revealed microstructural details of developed samples. Similarly, the thermo-gravimetric analysis and linear burning rate studies of Al(OH)treated bio-nanocomposite materials revealed enhanced thermal resistance and reduced flammability respectively compared to both pristine woven jute fabric and fabrics treated with PLA alone or those without Al(OH)3. From the above results it can safely be said that the bio-nanocomposite material can be a prospective candidate for development of flame retardant biopackaging.


Nanocomposites Flame retardant Biopolymer Organo modified montmorillonite nano clay 


Natural lignocellulosic fibres, such as jute, bamboo, ramie, flax and hemp have been attracted much attention as environment friendly substitutes for synthetic fibres such as glass fibres due to their unique property such as low cost, biodegradability, wide availability and virtual non-abrasiveness [1, 2, 3]. In this regard, the need for greener and more sustainable technologies has profound interest on the use of renewable and eco-friendly materials with high performance [4, 5, 6]. Hence, biopolymer-based materials can have a new direction in designing of greener materials and could widen the spectrum of applications in different sectors such as automobiles, furniture, drugs, carpet and fire protective suits and construction of industrial parts [7, 8, 9, 10, 11]. Out of various natural fibres, jute fibre has attracted much attention being less expensive and readily available worldwide [12, 13, 14]. In recent years, the focus of research regarding jute composites has been on the modification of flame retaerdance [15, 16, 17, 18, 19, 20]. It has been widely reported that improved properties can be achieved by using polymeric phase organic and inorganic filler [21, 22, 23]. In particular, polymer composites reinforced with inorganic fillers of magnitude in the nanometer range, known as nano-biocomposites, have engrossed great consequence from researchers, due to astonishing synergistic properties derived from the two components [24]. The most studied biopolymer nanocomposites are composed of a thermoplastic matrix, and organically modified montmorillonite (OMMT) [24, 25, 26, 27, 28, 29]. Besides, polymer/clay nanocomposites has found as an improved thermal, and fire retardant properties compared to either the matrix or to conventional composites, commonly called “particulate microcomposites” [30, 31, 32, 33], because of their unique phase morphology derived by layer intercalation or exfoliation, that maximizes interfacial contact between the organic and inorganic phases and thereby enhanced bulk properties [34].

Based on the above ideas and observations we intuited that the incorporation of nanoclay filler such as organo modified OMMT and Al(OH)3 within the poly lactic acid solution would modify the jute fabrics which can exhibit enhanced performance in terms of thermal resistance, improved mechanical strength and flame retardant properties [35, 36, 37, 38].

Materials and Methods

Materials Used

Plain woven jute fabrics were procured from local supplier having an areal density of 182 g/m2. OMMT clay surface modified with 15–35 wt% octadecylamine and 0.5–2 wt% amino propyl triethoxy silicone was purchased from Sigma-Aldrich, Ltd. PLA was purchased from 3DPrintronics, Greater Noida, chloroform (CHCl3) and other reagents were purchased from Avera Chemicals Pvt. Ltd.

Fabrication of Bio-composites and Bio-nanocomposites

Solution Casting

PLA/OMMT/FR bio-nanocomposite slurry was prepared by using chloroform as a common solvent. In brief, first 20% of PLA was allowed to dissolve in 80% of chloroform to prepare a homogeneous solution, followed by addition of suitable amount of OMMT and FR under continuous stirring for a period of 4 h. Thereafter, the composite slurry was transferred into a round bottom flask under vigorous stirring in an ambient temperature for 8 h followed by ultra-sonication for 120 min. Finally, this obtained viscous composite slurry was utilized for the modification of jute fabrics (structural reinforcements).

Coating of Woven Jute Fabrics

A range of square woven fabrics having average mass of 5.0 g/m2 were dried in a hot air oven at 40 °C for 24 h. The dried woven fabrics were then placed inside a square metal frame mold of 15 cm × 15 cm in dimensions and  different composite matrix/slurry was then poured over the woven jute fabrics. The assembly was kept at a room temperature for 24 h to evaporate the solvent. The solution cast samples of one layer woven fabric and PLA were subsequently hot pressed in compression molding machine fabricated in-house at 170 °C under 30 bar pressure for 30 min to get the bio-composite and bio-nanocomposite samples. The samples were taken out from hot press after cooling the upper and lower platens by circulating water through them. The thicknesses of the bio-composite and bio-nanocomposite of woven jute fabric, prepared by compression molding was 0.50 ± 0.05 mm. The composite samples, thus prepared, were designated as J, P, JP, JPC, JPF, and JPCF where J, P, C and F represent woven jute fabrics, PLA, OMMT clay and flame retardant, respectively. The jute fabric composites were allowed to fully cure at room temperature for 24 h and then in desiccator for further testing. The compositions are tabulated in Table 1.

Table 1

Chemical composition of bio-composite and bio-nanocomposite samples

Sl. no.


Jute fibres (wt%)

PLA (wt%)

OMMT clay (wt%)

FR (wt%)


































19. 5



























FT-IR Spectroscopy

The synthesized bio-composites, bio-nanocomposites, jute and PLA biopolymer were subjected to FT-IR characterization using a Perkin Elmer (USA) Spectrum One Spectrometer (Model: Frontier MIR93795) at room temperature. The wave number window employed was 400–4000 cm−1.

Water Uptake

A small piece from every PLA film, bio-composite along with bio-nanocomposite samples were first vacuum-dried, weighed and thereafter drenched into receptacles containing distilled water for legitimate soaking. Subsequent to leaving undisturbed for 42 h, individual cut piece of every specimen are taken out, trailed by wiping off the unabsorbed water. Water uptake of the prepared samples were ascertained according to Eq. 1:
$${\text{Moisture uptake values }}\left( \% \right)=\frac{{\left( {{{\text{W}}_{{\text{wet}}}} - {{\text{W}}_{{\text{dry}}}}} \right)\left( {100} \right)}}{{{{\text{W}}_{{\text{dry}}}}}}$$
where Wwet represents the weights of wet bio-composites and Wdry is the weight of the bone dry bio-composites at time.

Determination of Swelling Ratio

A piece was cut from every sample, having measurements of 2 × 2 cm2, and was first dried at 80 °C under vacuum. Their thicknesses were then measured by a thickness gauge, and they were along these lines drenched into receptacles containing distilled water for appropriate soaking. In the wake of leaving undisturbed for 24 h, individual cut piece of each specimen were taken out, and their thicknesses were measured with a specific end goal to decide their swelling degrees. Particular swelling ratio of the samples were calculated from the accompanying Eq. 2:
$${\text{Swelling ratio }}\left( \% \right)=\frac{{\left( {{{\text{T}}_{{\text{wet}}}} - {{\text{T}}_{{\text{dry}}}}} \right)}}{{{{\text{T}}_{{\text{dry}}}}}}$$
where Twet represents the thickness of wet composite and Tdry is the thickness of bone dry composite.

Thermo-gravimetric Analysis (TGA)

Thermo-gravimetric analysis (TGA) measurements were recorded using Perkin Elmer TGA-4000 thermo-gravimetric evaluator. Each sample was scanned from 25 to 800 °C at a heating rate of 10 °C/min in nitrogen (N2) atmosphere.

Mechanical Strength

The mechanical properties of PLA film, bio-composites and bio-nanocomposite samples were evaluated by using universal testing machine (UTM) (UNITEK9400), following standard procedure of ASTM D 638. The tensile tests were performed under a 500 N load cell at a crosshead speed of 5 mm/min. Three sets of tensile tests were conducted for each sample and then average value was considered.

Scanning Electronic Microscopy (SEM)

The microstructures of the PLA film, bio-composites and bio-nanocomposites were performed by SEM (LEO 435 VP). This method was used to observe the morphology of the samples. An accelerating voltage of 30 kVwas used. Samples were coated with a gold layer prior to analysis in order to increase their electrical conductivity by using a B7341 Agar automatic sputter coater BALZERS 5CD50 argon plasma model.

Flammability Test

The flammability of neat PLA, bio-composite and bio-nanocomposite samples were performed following the BS 3120 standard. LPG gas was used as a fuel to produce an unoxidized flame of height 38 mm. Height of the flame below the lower edge of the fabric was kept to be 19 mm. The samples were allowed to expose in flame for 12 s and then removed.

Results and Discussion

FT-IR Spectroscopy

Figure 1 shows the FTIR spectra of neat PLA, bio-composite and bio-nanocomposite samples. The peaks appeared between 3330 and 3346 cm−1 represents the hydroxyl group of PLA which was decreased or almost disappeared with the incorporation of OMMT/FR. The characteristic absorption peaks of C=O, C=C and CH2 stretching vibrations present in jute fabrics (J) and PLA (P) samples, can be observed within the range of 640–1800 cm−1. These peaks are present in all the bio-composite and bio-nano composite samples containing the J and P. The peak appeared at 1700–1750 cm−1 is due to C–H stretching vibration and C=O stretching vibration of OMMT and PLA, which was more prominent and sharper with increasing amount of OMMT and is due to strong interaction between them.

Wave number (cm−1)


3346 (1)

Stretching vibration mode of free hydroxyl (–OH) group of J

1145 (2)

Asymmetric stretching vibration modes of methylene group (–CH2) of long aliphatic tail of (CHCl3)

1750 (3)

Stretching vibration mode of carbonyl group (–CO) of (J, JP, JPC, JPF and JPCF)

1080 (4)

Stretching vibration of ether linkage (C–O–C) of P

1456 (5)

Asymmetric stretching vibration modes of methylene group –CH3 of CHCl3

759 (6)

Aromatic symmetric vibration stretching C–H group of (J, JP, JPC, JPF and JPCF)

Fig. 1

FTIR spectrum of bio-composite and bio-nanocomposite samples

Water Uptake and Swelling Ratio

The water uptake values of all the PLA film, bio-composite and bio-nanocomposite samples were calculated by using Eq. 1 and the results are plotted in Fig. 2. From the figure, it can be visually perceived that at 25 °C the water soaking values for samples J, P, JP, JPC-A, JPC-B, JPF-A, JPF-B, JPCF-A, JPCF-B and JPCF-C are 74, 45.8, 59.6, 54, 61, 43.3, 43.2, 34.4, 36 and 33% respectively. It is observed that the water absorption of all bio-composite and bio-nanocomposite samples reached the saturation stage at 7 days at a time when the composites achieved the equilibrium condition. The molecules on its surface by virtue of the prevailing vigorous interactions between its surface Al(OH)3 groups and di-hydrogen monoxide molecules via formation of vigorous H2 bonds. This, in turn, promotes the retention of di-hydrogen monoxide in PLA and jute with clay or FR agent. However, as can be visually perceived from Fig. 2, the samples JPCF and JPF exhibited a markedly decremented water soaking values at room temperature, compared to that obtained for J. This could be attributed to reaction of  Al(OH)3 which resulted in formation of adscititious aluminum cross-links within the composites structure leading to enhanced rigidity. In order to rationalize the water absorption results, the samples were subjected to swelling analysis. The corresponding swelling values were calculated using Eq. 2 and is also depicted in Fig. 2 alongside the water absorption plots. It can be realized that the swelling consequences followed the related trend as the decreasing trend in the swelling ratio due to the sample of JPCF and JPF holds the same reason as that of decrease in water soaking value in JPF. Nevertheless, the enhancements in both the parameters obtained for sample JPF shall provide a propitious condition for jute fabrics.

Fig. 2

Water uptake and swelling ratio of neat PLA, jute fabric, bio-composite and bio-nanocomposite samples

Thermo-gravimetric Analysis

Thermo-gravimetric analyses of PLA film, bio-composite and bio-nanocomposite samples were conducted under inert N2 atmosphere to determine the weight loss and to identify the decomposition of material at a certain temperature. From Fig. 3, it can be observed that initially all samples experienced one stage loss. In PLA, the initial weight loss occurred which correspond to removal of solvent from PLA film while at 310 °C major weight loss (93.04%) occurred due to degradation. The left over which remains after the degradation needs to be subjected to high temperature for further degradation. The results obtained by the process of TGA performed on jute and PLA polymer with OMMT clay bio-nanocomposites are illustrated in Fig. 3e. Again the weight loss occurred at 245 °C due to removal of solvent while, the degradation of bio-composites and bio-nanocomposites share the major weight loss (91%) at 310 °C. Thus this hybrid bio-nanocomposites demonstrated improved thermal stability. This results so obtained in bio-nanocomposite was different in samples reinforced with FR. The degradation shifted to higher temperature. This consequence of PLA and jute fabrics reinforced with FR/OMMT (JPCF) can be observed in Fig. 3f in that the samples (JPCF) revealed the first weight loss at 270 °C while major weight loss occurred (88.01%) at 303.18 °C. This enhanced temperature range proved the potency of the prospective bio-nanocomposite materials towards its thermal stability.

Fig. 3

TGA of jute, neat PLA and bio-nanocomposite samples

Analysis of Mechanical Strength

The flexural tests for all the neat PLA, bio-composite and bio-nanocomposite samples were performed at room temperature. Figure 4 reveals the flexural properties of jute fabrics, PLA, bio-composite and bio-nanocomposite samples. All the samples containing filler i.e. OMMT and FR exhibited lower flexural strength than the pristine PLA and jute fabrics. However, it is interesting to note that the sample containing both fillers i.e. OMMT and FR (JPCF-A, B and C) exhibited enhanced flexural strength in comparision with the corresponding sample JPC-A and B as well as JPF-A and B. This may be due to the strong interaction between OMMT clay–FR–PLA (as explained in earlier section), which indicates a good compatibility among them. Nevertheless, among all the bio-nanocomposite samples, the JPCF-A (having 1 wt% OMMT and FR) exhibited 117.4 MPa flexural strength and was comparable to corresponding Jute (J) sample.

Fig. 4

Flexural strength of bio-composite and bio-nanocomposite samples

Analysis of SEM Images

The microstructural details of neat PLA, bio-composites and bio-nanocomposites were analyzed by SEM and displayed in Fig. 5. The surfaces of the jute fabrics treated with bio-composite slurry solution differed clearly from those of the untreated matrix. As shown in untreated jute fabrics, there was unbound fibre pullout from the surface, but in treated jute bio-composites especially in JPF and JPCF, the fibres were well bound and shows good compatibility and exhibited compact structure. In addition, in case of jute fabrics treated with OMMT/Al(OH)3 (JPCF), the surfaces were found to be smoother compared to pristine jute fabrics (J) surface. Existence of Al(OH)3 and OMMT can only be found in some small particles. However OMMT and Al(OH)3 particles at higher concentrations showed additional continuous layers which accumulated on the inner surface of the cell wall.

Fig. 5

SEM micrographs of PLA, jute, bio-composites and bio-nanocomposites samples

Analysis of Flammability Test

The flammability tests for all PLA film, bio-composite and bio-nanocomposite samples were performed at ambient temperature and are depicted in Fig. 6. Flammability of both treated and untreated jute fabrics were analysed in respect of linear burning rate. The PLA/jute fabrics/Al(OH)3/OMMT bio-nanocomposites (JPCF) showed reduced char length as compared to PLA/jute fabrics/Al(OH)3 composite (JPF). No afterglow or afterflame was observed in both samples. The lower value of char lengths in case of bio-nanocomposite samples (JPC) indicate improved flame resistance due to high heat and flame resistant properties of bio-nanocomposites [39, 40]. Maximum flame resistance was however, oberved in case of Al(OH)3 treated bio-nanocomposite samples indicating a synergistic effect and revealed its potency towards the flame retardant applicability.

Fig. 6

Linear burning rate of neat PLA, jute, bio-composite and bio-nanocomposite samples


Environmental friendly bio-composites and bio-nano composites of jute fabrics were developed. These composites demonstrated enhanced water barrier, thermal and flame retardant properties based on the strong interactions between jute fabric and other ingredients. The inclusion of Al(OH)3 particles improved the thermal properties and decreased the flammability. The composites with 1% Al(OH)3 enhanced the modified physical properties in comparison to unfilled composites. The resulting thermal properties were enhanced even further when the OMMT nanoclay was incorporated. FT-IR study showed characteristic peaks and interactions between Al(OH)3, jute fabric and OMMT nanoclay. Scanning electron microscopy (SEM) studies revealed the distribution of Al(OH)3 particles and that of OMMT nanoclay particles and microstructural details in bio-composites and bio-nanocomposites. Water uptake and swelleing properties revealed enhanced water barrier properties which in turn could be attibuted to enhanced structural integrity. Composites containing 1% Al(OH)3 or 1% OMMT nanoclay recorded significant improvement in  thermal resistance and flame retardance properties; however, the bio-nanocomposite samples (JFPC) demonstrated futher enhancement, indicating a synergistic effect. The study could therefore, establish a potential route to develop bio-nanocomposites with enhanced moisture barrier, mechanical, thermal resistance and flame retardance properties, which in turn would be useful in developing new generation biopackaging.



The authors gratefully acknowledge Indian Institute of Technology Roorkee (IITR), Birla Institute of Technology & Science, Pilani (BITS, Pilani) for their support for my research work.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Centre for Materials Science and Technology, Mechanical Engineering DepartmentBirla Institute of Technology & SciencePilaniIndia
  2. 2.Department of Chemical EngineeringIndian Institute of TechnologyRoorkeeIndia
  3. 3.Mechanical Engineering DepartmentManipal University JaipurJaipurIndia

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