Sage Journals: Discover world-class research

Abstract

This work consists of preparation and characterization of composites produced from thermoplastic starch (TPS) and high impact polystyrene (HIPS). Due to the immiscibility of the system (TPS/HIPS), it was necessary to incorporate concentrations of 1, 2 and 3% of an organophilic montmorillonite (MMT) to improve the properties of the mixtures, in particular their rigidity. The composites thus prepared were characterized using XRD, FTIR, mechanical test, degree of swelling in water and biodegradability. The results show that the addition of MMT improves the mechanical properties of the mixtures such as the tensile strength and the Young’s modulus by 5% and 10%, respectively. In contrast, the resilience of the system has significantly decreased. Moreover, for 3% of MMT, the composites biodegradability is enhanced by 15% when compared to the TPS/HIPS mixture without MMT.

Keywords

High impact polystyrene thermoplastic starch montmorillonite biocomposite biodegradability

Introduction

Even though conventional plastics made from fossil fuels have attracted the market with their features such as low price and good mechanical characteristics, their resistance against biodegradation by microorganisms has caused many environmental problems. Hence, the researchers have started the discussion on their degradation methods in order to find out how to control the problems.¹ On the other side, biodegradable plastics gained a great attraction as a substitute for the conventional plastics, where the new polymer or polymer blends will provide similar properties and are convertible to non-toxic materials. To fulfil the criteria, biomaterials and their blends are most commonly used as biodegradable polymers.²

High impact polystyrene (HIPS) is abundantly used as matrix for biodegradable polymers. HIPS presents high impact strength due to the incorporation of polybutadiene (PB) rubber particles in the polystyrene (PS) rigid matrix. HIPS has the advantages of good impact resistance, low cost and easy processing and is commonly utilized in many applications, such as electrical appliances, automotive components, electronic instruments, packaging and building materials. However, it is degraded very slowly in the environment.³ Numerous biomaterials are blended with HIPS matrix to improve the mechanical properties and induce biodegradability.

Starch is the second largest bio-synthesized carbohydrate compound after cellulose and is the main source of energy for humans and animals.⁴ Starch is a mixture of two polysaccharides which are amylose and amylopectin. It is an inexpensive and renewable product that can be mixed with synthetic polymers to confer them a biodegradable character.⁵ When subjected to heat treatment and high shear in presence of suitable plasticizers, starch granules are disrupted to give thermoplastic starch (TPS) which could be transformed by conventional processes used for classic plastics such as extrusion and compression molding.⁶ However, TPS has poor mechanical properties making it necessary to modify in order to extend its fields of application via blending with other natural or synthetic polymers.

Many researchers have used glycerol as a plasticizer in HIPS/PS mixture preparation and found it very effective in improving the degradability of the mixture. Schlemmer et al.² prepared TPS/PS composites by solvent casting technique with buriti oil and glycerol as plasticizers. The results indicate that, when compared to buriti oil, glycerol tends to degrade very fast. In a similar study, Mihai et al.⁷ showed that glycerol content has a role in determining the viscosity of the composite. As the glycerol content increases, viscosity of TPS decreases and thus affects the overall TPS/PS blend viscosity and the ability to foam the material.

The overall studies suggest that blending HIPS and TPS reduces the mechanical properties when compared to the parent material. Thus, many researchers have tried different additives such as inorganic micro- or nano-particles to overcome this disagreement.⁸ Previous studies by Giannelis et al.⁹ suggested small amounts of clay (3–10%) can markedly increase many properties of the polymer matrix including the mechanical, thermal and barrier properties.⁹. A similar study was performed using titanium dioxide (TiO₂) in starch/polyvinyl alcohol (PVA) composites by Sreekumar et al.¹⁰

Bagcioglu et al.¹¹ used casting method to prepare HIPS/organophilic montmorillonite (MMT) nanocomposite and studied its properties. Morphological observations showed that clay layers were exfoliated and reduced rubber domains. Moreover, it reflected in increasing significantly the nanocomposites toughness. Furthermore, addition of MMT clay in 3 wt. % loading has produced composites with high tensile strength and toughness. Also, Abreu et al.¹² investigated the effect of adding 5% of nanoclay C30B on the rheological and physical properties of TPS mixtures with PP-g-MA according to the compositions (1:2, 1:1 and 2:1). Reactions between TPS and PP-g-MA groups allowed the synthesis at the interface of a TPS-g-PP copolymer consisting of an interpenetrating network capable of promoting the dispersion of the C30B nanofiller as confirmed from scanning electron microscopic observations which revealed remarkable homogenization of the blend.

Even though MMT has proven to increase the mechanical properties of many polymer composites, the use of MMT in TPS/HIPS blends has not been investigated yet. Thus, in the current research, we focus on the development and characterization of composites based on styrene–ethylene/butylene–styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA) compatibilized (50/50) TPS/HIPS blend composite reinforced by an organophilic nanoclay. MMT is introduced into the blend matrix in different concentrations and is expected to induce improvements on the overall properties of the system, particularly the mechanical properties. The interest of the study consists in verifying the possibility of obtaining materials with attractive properties which can access applications, in particular rigid plastic packaging. The TPS/HIPS ratio was taken as 50/50 to provide the better balance between the mechanical properties and biodegradability aptitude of the mixture. At higher TPS concentrations, the material performances could be altered due to the pronounced hydrophilic nature of TPS. However, the mixture biodegradability could be affected also, if TPS is incorporated at lower concentrations.

Materials and methods

Materials

HIPS has a melt flow index (MFI) of 2.8 g/10 min at 200°C and under 5 kg and a density of 1.04 g/cm³. Corn starch consists of a powder having medium particles size in the range of 4–8 μm. The used plasticizer is glycerol which has a density of 1.25 g/cm³. The clay is known under the trade name Nanomer 1.34TCN synthesized by Nanocor. It is an organophilic montmorillonite modified by methyl dihydroxyethyl tallow ammonium. The compatibilizing agent SEBS-g-MA, containing 1.84% of maleic anhydride, is supplied by Shell Chemical Co. (USA) under the trade name of Kraton FG 1901X.

Processing

TPS was prepared according to an experimental protocol.^13,14 At first, starch is placed in an oven at 80°C for 3 h. Then, it is introduced into a mixer with an amount of glycerol equivalent to 30% and homogenized. Finally, the obtained mixture is placed into plastic bags and stored for 24 h. Afterwards, starch is mixed in a Brabender internal mixer to convert the powder into a translucent continuous mass which has been reduced into granules in Controlab pelletizer. In the next stage, the composites have been prepared by mixing HIPS/SEBS-g-MA/TPS (45/10/45) matrix with 1, 2 and 3% of MMT in a Brabender mixer at 200°C for 10 min. After processing, the formulations were pelletized for further characterization.

Characterization techniques

Fourier transform infrared (FTIR) spectroscopy

The spectral analysis was carried out using a Perkin Elmer 1000 infrared spectrophotometer with double beam. FTIR spectra were registered on thin films of 0.005 mm thickness, prepared by compression, and the transmittance was recorded for a wavelength sweep ranging between 500 and 4000 cm⁻¹.^15,16

X-Ray diffraction

X-ray diffraction measurements were performed on a XPert-Pro apparatus, using a Cu-Kα wavelength λ = 0.1540598 nm. The X-ray source is a ceramic tube fitted with a copper anode and powered by a current of 30 kV and an intensity of 25 mA. XRD studies were conducted for HIPS/TPS mixture, MMT and HIPS/TPS/MMT composites.

Melt flow index

The test was carried out using a Melt-Indexer model five which consists of a cylinder with a vertical axis placed in an oven ending with a standard die of length 8 mm and diameter 2.09 mm. The tests were carried out according to the standard ASTM D-1238, under a load of 5 kg and at a temperature of 190°C. The melt flow index was calculated using equation (1)⁸

MFI (g / 10 min) = \frac{m .600}{t}

(1)

m: average mass of the extrudate. t: time of extrudate.

Tensile test

Tensile test was conducted to evaluate the mechanical performance of HIPS and TPS/HIPS mixtures at different weight percentages of MMT. The test was carried out on three replicates at a speed of 6 mm/min on a Zwick Roell-Z050 universal testing machine. The samples were prepared by compression according to the ASTM standard D 638.^17–21 The gauge length (G), parallel length (L) and full length (L₀) were 50, 57 and 165 mm, respectively. The width at grip section (W₀), parallel section (W_c) and thickness (e) are 13, 19 and 7 mm, respectively. The distance between grips (D) is taken as 115 mm.

Izod impact test

Unnotched specimens with dimensions (63 × 13 × 2) mm³ were subjected to Izod impact test at room temperature on a Ceast Resil impact pendulum, equipped with a hammer of 7.5 J. The impact strength (a_n) is evaluated using the following equation (2)

a_{n} = \frac{A_{n}}{b .e}

(2)

A_n and b are, respectively, the energy absorbed during the impact and the width of the test specimens.

Atomic force microscopy

Atomic force microscope (AFM) MFP 3D Original is a local probe microscope, and it is utilized to view the topography of the sample surface. The surface roughness was measured for HIPS/TPS/MMT composites at different concentration of MMT.

Degree of swelling in water

To conduct test for degree of swelling in water, films of (20 × 20) mm² were cut and weighed (m₀). After drying at 40°C, the specimens were kept in cold desiccators, then directly immersed in distilled water and kept there for 24 h. Then, the specimens were taken out of the container, wiped with absorbing paper, dried in the oven, and final weights were taken (m_f). Five specimens for each type were tested and average values were noted. The degree of swelling in water (W) was calculated using the equation (3)²²

W (%) = [\frac{m_{f} {- m}_{0}}{m_{0}}] \times 100

(3)

Biodegradation

To carry out biodegradation test, (40 × 40) mm² films with an average thickness of 0.05 mm and an initial mass (m₀) were buried in a mixture consisting of 70% of soil, 10% of sawdust and 20% of sand; then, the residual masse (m_r) was measured after 2 months. To measure the biodegradation, the variations in the residual mass percentage (Rw) were measured in terms of weight variation, using the following equation (4)²²

R w (%) = \frac{m_{0} - m_{r}}{m_{0}} \times 100

(4)

Results and Discussion

Structural analysis

Fourier transform infrared spectroscopy was conducted for raw materials, TPS/HIPS mixture and its 3% clay composite. Figure 1 and Table 1 show FTIR spectra of raw and plasticized starches. After starch treatment with glycerol, the FTIR spectrum shows a remarkable intensification of the hydroxyl group characteristic band due to the presence of the plasticizer. The hydroxyls of glycerol moieties could be linked to each other and/or to those present in starch by hydrogen bonds. The spectrum of TPS reveals also adsorbed water hydroxyls as detected by the valence vibration of the O-H bond of the H-O-H group observed around 1640 cm⁻¹.^23,24

Figure 1.

FTIR spectra of raw starch and TPS. Note: TPS: thermoplastic starch; FTIR: Fourier transform infrared.

Table 1.

FTIR results of starch and TPS compared with the data in literature.

Attributes	Current work (cm⁻¹)	Silverstein et al.²³ (cm⁻¹)	Amir et al.²⁴ (cm⁻¹)
Hydroxyl groups	3800 and 3100	Between 2700 and 3800	3000 and 3600
C-H elongation in –CH₂	Between 2970 and 2840	2853	2800 and 3000
C-H deformation in –CH₂	1425	1467	1550 to 1570
O-H elongation in H-O-H group	1630	—	1640
C-O-C stretching	1200 and 980	1224	Between 937–1156

Note: FTIR: Fourier transform infrared; TPS: thermoplastic starch.

Figure 2 depicts the IR spectra of HIPS, TPS and their mixture. Table 2 compares the obtained FTIR attributions of HIPS spectra with the data in the literature. The spectrum of (50/50) (TPS/HIPS) mixture assembles the components spectra and shows a broad hydroxyl band which is exclusively induced by the higher hydroxyl groups concentration after starch plasticization by glycerol. Also, the strong bands around 753 and 690 cm⁻¹ are due to the deformations of C-H of the monosubstituted aromatic cycle.²⁵

Figure 2.

FTIR spectra of HIPS, TPS and (50/50) TPS/HIPS mixture. Note: HIPS: high impact polystyrene; TPS: thermoplastic starch; FTIR: Fourier transform infrared.

Table 2.

FTIR attributions of HIPS spectra compared with the data in the literature.

Attributions	Hu et al.²⁶ (cm⁻¹)	Silverstein et al.²³ (cm⁻¹)	Current work (cm⁻¹)
C-H bond elongation in benzene ring	3081and 3024	3080–3010	3090 and 3000
C=C elongation in benzene ring	1600	1600	1660
C-H elongation in vinyl group	2920	2840 and 3000	2920 and 2850
Out of plane C-H bending in vinyl group	991 and 907	900 and 675	950 and 975

Note: FTIR: Fourier transform infrared; HIPS: high impact polystyrene.

FTIR spectra of MMT, (50/50) TPS/HIPS mixture and its 3% MMT composite are displayed in Figure 3. For MMT, the characteristic elongation band of OH is found around 3400 and 3100 cm⁻¹, whereas the asymmetric and symmetric bands of CH₃ and CH₂ group of the methyl dihydroxyethyl tallow ammonium modifier are detected at 2920 and 2850 cm⁻¹. The absorption band at 1620 cm⁻¹ corresponds to the elongation of the O-H bond in the H-O-H group due to water adsorbed on the surface of the hydrophilic clay. At 1470 cm⁻¹ is observed the asymmetric deformation in plane characteristic of the C-H in CH₃ group.^26,27 The FTIR spectrum of the TPS/HIPS/MMT composite consists essentially of the vibration bands of all the constituents of the material.

Figure 3.

FTIR spectra of MMT, (50/50) TPS/HIPS mixture and its composite with 3% MMT. Note: HIPS: high impact polystyrene; TPS: thermoplastic starch; FTIR: Fourier transform infrared; MMT: montmorillonite.

Microstructure analysis

Figure 4 shows X-ray diffractograms of the raw and plasticized starch. The diffraction diagram of the used raw starch shows that it presents an A-type crystalline structure, which is usually encountered for cereal starches like corn, with characteristic peaks for 2θ angles of 15.33°; 17.43°; 18.13°; 20.12° and 23.22°.²⁸

Figure 4.

X-ray diffractograms of raw starch and thermoplastic starch.

Furthermore, the diffractogram for plasticized starch shows that significant changes have been caused to the starch crystalline structure after the plasticization process. It can be noted that due to the diffusion of glycerol and to heating, the starch granules burst to release amylose, which increases the amorphous fraction and justifies the reduced crystallinity of TPS. Also, new diffraction peaks appeared resulting from the retrogradation process which induces the reconstitution of a new crystalline form and opacity of TPS after cooling. In this context, the diffraction peaks observed at 2θ of 14.23° and 22.52° are assigned to V_A-type crystalline structure attributed to the crystallization of a single amylose helix. Also, the diffraction peak noted around 2θ of 19.83° is due to a V_H- crystalline structure caused by an induced crystallization of the amylose helix during the transformation of the starch in presence of a sufficient amount of plasticizer.²⁸ Finally, the peak noted around 2θ of 17.03° could be assigned to the residual A-type structure of the starch and confirms that the plasticization was not complete and that a fraction of raw starch granules have not been disrupted.

HIPS X-ray diffractogram, given in Figure 5, shows two diffraction peaks at 2θ values of 14.88° and 19.53°. The non-crystalline part seems quite large due to the amorphous structure of the butadiene phase. Furthermore, the diffractogram of the (50/50) TPS/HIPS mixture exhibits essentially the diffraction peaks owing to the TPS phase, thus pointing out the fact that the mixing process has not affected the crystalline structure of TPS due to the immiscibility of the blend, even though the presence of the compatibilizer.

Figure 5.

XRD patterns of TPS, HIPS and (50/50) TPS/HIPS mixture. Note: XRD: X-Ray diffraction; HIPS: high impact polystyrene; TPS: thermoplastic starch.

The X-ray diffractogram of the organophilic montmorillonite is shown in Figure 6. It exhibits the diffraction peaks characterized by the following 2θ values: 4.74°; 19.71° and 35.01°. The diffraction peak located at 4.74° is attributed to the reticular plane (001) characteristic of the basal spacing of the clay organically modified by the surfactant methyl dihydroxyethyl tallow ammonium. The XRD diagram of the TPS/HIPS mixture at 3% of MMT also reveals the diffraction peak of MMT at the same position as for organo-treated clay. This testifies to the dispersion of the nanocharge in the form of aggregates and supports the microcomposite structure of the material.

Figure 6.

XRD patterns of MMT, (50/50) TPS/HIPS blend and its 3% MMT composite. Note: XRD: X-Rray diffraction; HIPS: high impact polystyrene; TPS: thermoplastic starch; MMT: montmorillonite.

Composites rheology

Table 3 reports the variations in the melt flow index of the TPS/HIPS/MMT composites as a function of the MMT rate. A decrease in the fluidity index is noted when MMT is added. Also, the higher the rate of MMT, the lower the melt flow index of the composites. The results shows that the interactions of the clay hydroxyls with the TPS phase via hydrogen bonding and their effective chemical reaction with the anhydride group of compatibilizer whose chains are at the same entangled with the HIPS phase ones seem to be responsible of hindering greatly the chains sliding through the die. Additionally, association of clay particles into aggregates appears to oppose resistance to the free flow of chains of the two polymers.

Table 3.

Variation of melt flow index, degree of swelling and residual mass percentage for TPS/HIPS/MMT composites as a function of MMT rate.

Sample	MFI (g/10 min)	W (%)	Rw (%)
50/50/0	12.5	5	48
50/50/1	7	3	41
50/50/2	3	1.5	34
50/50/3	2	0.3	35

Note: HIPS: high impact polystyrene; MMT: montmorillonite; TPS: thermoplastic starch.

Mechanical properties

The tensile properties of TPS/HIPS/MMT composites were investigated and the obtained stress–strain plots are represented in Figure 1S in supplementary file. Also, the calculated mechanical properties for HIPS and its composites are shown in Table 4. It can be observed that the HIPS follows a typical thermoplastic polymer behaviour. At first, the linear elastic region of stress-strain graph is seen to extend up to 11 MPa. After reaching the elastic limit, a negative slope is formed confirming the start of nicking. The recorded strain at break was 12.1. Also, pure HIPS shows a tensile strength (TS) of 9.7 MPa with a tensile modulus (TM) of 1500 MPa and an impact strength (IS) of 45 KJ/m². Similar behaviour can be noticed in other thermoplastic polymers.^29–33

Table 4.

Mechanical properties of HIPS and TPS/HIPS/MMT composites.

Sample	Tensile strength (MPa)	Tensile modulus (MPa)	Strain at break (%)	Impact strength. (KJ/m²)
HIPS	9.7 (±0.9)	1500 (±24)	12.1 (±1)	45 (±1.2)
50/50/0	8.2 (±0.8)	600 (±11)	1.8 (±0.08)	7 (±0.5)
50/50/1	8.5 (±0.8)	640 (±12)	1.6 (±0.08)	9 (±0.6)
50/50/2	8.7 (±0.8)	650 (±12)	2 (±0.08)	10 (±0.9)
50/50/3	8.6 (±0.8)	660 (±13)	1.8 (±0.08)	12 (±1)

Note: HIPS: high impact polystyrene; MMT: montmorillonite; TPS: thermoplastic starch.

As expected, incorporation of TPS into HIPS resulted in substantial decrease in mechanical properties of the blend. The plastic region of (50/50) TPS/HIPS is very short, and the sample tends to fail very quickly. Also, the mixture has recorded 8.2 MPa of tensile strength, 15% less than pure HIPS. It shows that the components are immiscible and there is formation of two differentiated phases with poor interfacial adhesion.

After the incorporation of MMT, there is a marginal increase observed on the tensile strength of the blend and it tends to increase with the increase in MMT percentage. This indicates that the surface area of the nano-reinforcement has contributed to the stress transfer along the matrix by the filler at the interfaces.³⁴ Similar trends were observed for TM and IS of the composites. However, there is a slight reduction in strain at break observed for composite loaded with 3% MMT. This can be due to agglomeration of the clay particles at the interface, which affects chains extension ability.³⁵

Figure 2S (supplementary file) illustrates the variations in the tensile properties and Izod impact resistance of (50/50) TPS/HIPS mixture after the addition of increasing concentrations of MMT. It can be observed that the composites tensile strength and elastic modulus increase slightly relatively to the matrix which supports the stiffening of the mixtures after adding the clay. However, this increase in rigidity is not significant because the dispersion of the clay in the TPS/HIPS matrix resulted in a microcomposite structure. Consequently, the evolution of the strain at break as a function of the MMT rate is slight. It appears that incompatibility prevails on the compatibilizer effect. So, despite eventual interfacial interactions due to the reaction of TPS hydroxyls with SEBS-g-MA anhydride groups and the possibility of HIPS chains anchoring with styrene phase in the compatibilizer, these seem to be insufficient to promote the elongation at break. Furthermore, the Izod impact resistance of the material tends to increase with the percentage of incorporated MMT. This also can be related to the effective distribution of load by MMT into the blend matrix. These results seem also to be related to a somewhat competing effect between the stiffening effect induced by the rigid clay particles and the plasticizing effect engendered by the long chains tallow brought by the surfactant inserted into the basal spacing of the clay. Similar behaviour is observed by different nanomaterials in polymer and fibre reinforced polymer matrices.^36–39

Morphology observation

To characterize the surface topography of the materials, atomic force microscopy images were taken and analysed. Figure 7 shows the AFM image of (50/50) TPS/HIPS matrix and (50/50/3) TPS/HIPS/MMT composite. It is clear from the images that the incorporation of 3% of MMT in TPS/HIPS system has significantly enhanced the roughness of the mixture from 40.46 nm to 42 nm. Moreover, in Figure 7(b), the agglomeration of the clay particles is visible which contributed to the increased surface roughness and concomitantly the stiffness of the material. The observations in the AFM micrographs are supportive to the mechanical performance of the composites.

Figure 7.

AFM micrographs of (a) (50/50) TPS/HIPS blend and (b) its 3% MMT composite. Note: AFM: atomic force microscope; HIPS: high impact polystyrene; TPS: thermoplastic starch.

Degree of swelling in water

The degree of swelling in water is calculated using equation (3) for all composites and results are reported in Table 3. It can be observed that water content decreases with the concentration of MMT into the composites. As previously described, FTIR studies has shown that there is a reduction in the hydroxyl groups rate after the incorporation of MMT. So, the reduction in degree of swelling is expected to be due to the reduction in concentration of hydroxyl groups resulting from the interactions of TPS/HIPS system with MMT via hydrogen bonding at the interface TPS/MMT and their reaction with anhydride groups of SEBS-g-MA. Thus, the decrease in hydroxyl groups, susceptible of attracting water molecules, contributes in depressing the composites aptitude to absorb water, which is obviously an additional advantage since water uptake is considered as the major bottleneck towards the application of TPS blends and composites in various applications. Similar trend was noticed by Tang et al.⁴⁰ for nanosilica-reinforced starch/poly (vinyl alcohol) (PVA) composites and palm date flour–reinforced PP/TPS blends.

Biodegradation

Biodegradation of the blends was evaluated using the equation (4). The variations in the mass loss for TPS/HIPS/MMT composites as a function of the MMT concentration after a period of 3 months of burial in the soil is tabulated in Table 3. MMT has a well-known catalytic effect with regard to biodegradation, due to its mineral origin which promotes the bio-assimilation of composites by bacteria present in the soil.⁴¹ However, the results show that up to 2% of MMT, mass loss of TPS/HIPS mixture decreases in the presence of MMT, undoubtedly due to the fact that water uptake prevails over biodegradation effect. However, for 3% MMT, the catalytic activity is achieved, and the biodegradability is enhanced. This could be explained by the higher concentration of the nanoclay which could have accelerated the biodegradation process; at this content, the fragmentation of the sample is promoted, thus increasing its contact area with the degrading medium containing microorganisms and enhancing its bio-assimilation aptitude.^41–43 Even though the addition of HIPS affects TPS biodegradability, but on the other side, the application of TPS alone presents many disadvantages, particularly its pronounced hydrophilic character. So, even though blending decreases the mixture biodegradability, it allows surmounting TPS shortcomings and inducing many improvements on the mixture properties, thus enlarging its application possibilities.

Conclusion

In this work, biodegradable composites based on thermoplastic starch and high impact polystyrene were successfully prepared by incorporating different percentages of montmorillonite clay. XRD results confirm the formation of microcomposite structure with the incorporation of 3% MMT into the TPS/HIPS mixture. The addition of MMT improves the mechanical properties of the mixtures such as the tensile strength and the Young’s modulus. However, the resilience of the system is significantly decreased. Moreover, the degree of swelling got reduced with increasing the percentage of MMT, whereas biodegradability is enhanced when compared to the TPS/HIPS blend.

Supplemental Material

sj-pdf-1-ppc-10.1177_09673911211046803 – Supplemental Material for Investigation of mechanical properties and biodegradability of compatibilized thermoplastic starch/ high impact polystyrene blends reinforced by organophilic montmorillonite

Supplemental Material, sj-pdf-1-ppc-10.1177_09673911211046803 for Investigation of mechanical properties and biodegradability of compatibilized thermoplastic starch/ high impact polystyrene blends reinforced by organophilic montmorillonite by Nour El Houda Aouadi, Abdelhak Hellati, Nizamudeen Cherupurakal, Melia Guessoum and Abdel-Hamid I Mourad in Polymers and Polymer Composites

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Abdel-Hamid I Mourad

Supplemental material

Supplemental material for this article is available online.

References

Ammala

Bateman

Dean

, et al. An overview of degradable and biodegradable polyolefins. Prog Polym Sci 2011; 36: 1015–1049.

Schlemmer

De Oliveira

Araújo Sales

. Polystyrene/thermoplastic starch blends with different plasticizers. J Therm Anal Calorim 2007; 87: 635–638.

Zhang

Wang

, et al. Preparation and performance of high-impact polystyrene (HIPS)/nano-TiO₂ nanocomposites. J Appl Polym Sci 2003; 87: 381–385.

Cerclé

Sarazin

Favis

. High performance polyethylene/thermoplastic starch blends through controlled emulsification phenomena. Carbohydr Polym 2013; 92: 138–148.

Roy

Ramaraj

Shit

, et al. Polypropylene and potato starch biocomposites: physicomechanical and thermal properties. J Appl Polym Sci 2011; 120: 3078–3086.

Battegazzore

Bocchini

Nicola

, et al. Isosorbide, a green plasticizer for thermoplastic starch that does not retrogradate. Carbohydr Polym 2015; 119: 78–84.

Mihai

Huneault

Favis

. Foaming of polystyrene/thermoplastic starch blends. J Cell Plastics 2007; 43: 215–236.

Naffakh

Díez-Pascual

. Thermoplastic polymer nanocomposites based on inorganic fullerene-like nanoparticles and inorganic nanotubes. Inorganics 2014; 2: 291–312.

Giannelis

. Polymer layered silicate nanocomposites. Adv Mater 1996; 8: 29–35.

10.

Sreekumar

Al-Harthi

. Reinforcement of starch/polyvinyl alcohol blend using nano‐titanium dioxide. J Compos Mater 2012; 46: 3181–3187.

11.

Bagcioglu

Sen

Yagci

, et al. Preparation of super HIPS via nanocomposite assemblies in the presence of toughener-intercalant. European Polymer Federatio, 8.

12.

Abreu

Oliveira

Machado

. Effect of clay mineral addition on properties of bio-based polymer blends. Appl Clay Sci 2015; 104: 277–285.

13.

As’habi

Jafari

Khonakdar

, et al. Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence. Express Polym Lett; 7.

14.

Waryat

Romli

Suryani

, et al. Using of compatibilizer for improve morphological physical and mechanical properties of biodegradable plastic from thermoplastic-strach-polyetylene blends. Indones J Mater Sci 2013; 14: 131218.

15.

Babaghayou

Mourad

A-HI

Ochoa

, et al. Study on the thermal stability of stabilized and unstabilized low-density polyethylene films. Polym Bull 2020: 1–17.

16.

Benabid

Kharchi

Zouai

, et al. Impact of co-mixing technique and surface modification of ZnO nanoparticles using stearic acid on their dispersion into HDPE to produce HDPE/ZnO nanocomposites. Polym Polym Compos 2019; 27: 389–399.

17.

Mourad

A-HI

Abdel-Magid

El-Maaddawy

, et al. Effect of seawater and warm environment on glass/epoxy and glass/polyurethane composites. Appl Compos Mater 2010; 17: 557–573.

18.

Christy

Arunachalam

Mourad

A-HI

, et al. Processing, properties, and microstructure of recycled aluminum alloy composites produced through an optimized stir and squeeze casting processes. J Manuf Process 2020; 59: 287–301.

19.

Mourad

A-HI

Bekheet

El-Butch

, et al. The effects of process parameters on the mechanical properties of die drawn polypropylene. Polym Test 2005; 24: 169–180.

20.

Mourad

A-HI

Idrisi

Wrage

, et al. Long-term durability of thermoset composites in seawater environment. Compos B: Eng 2019; 168: 243–253.

21.

Ismail Mourad

A-H

Idrisi

Christy

, et al. Mechanical performance assessment of internally-defected materials manufactured using additive manufacturing technology. J Manuf Mater Process 2019; 3: 74.

22.

Roz

Carvalho

Gandini

, et al. The effect of plasticizers on thermoplastic starch compositions obtained by melt processing. Carbohydr Polym 2006; 63: 417–424.

23.

Silverstein

Webster

Kiemle

. Identification spectrométrique de composés organiques, de boeck, 27. Boeck Univ Bruxelles, 2007.

24.

Amir

Anjum

Khan

, et al. Application of fourier transform infrared (FTIR) spectroscopy for the identification of wheat varieties. J Food Sci Tech 2013; 50: 1018–1023.

25.

Kiemle

Silverstein

Webster

. Identification spectrométrique de composés organiques-3ème édition. De Boeck Superieur, 2016.

26.

Cui

Z-K

Yuan

, et al. Synthesis, structure, and properties of high-impact polystyrene/octavinyl polyhedral oligomeric silsesquioxane nanocomposites. Polym Compos 2016; 37: 1049–1055.

27.

Bahrani

. Modification des propriétés physico-chimiques de l’amidon par procédés hydrothermiques: Contribution à l’étude des transferts couplés chaleur-masse. Theses. Français: Université de La Rochelle, 2012.

28.

Teyssandier

. Formulation et morphologies de mélanges de polymères thermoplastiques à base d’amidon. Theses. Français: INSA de Lyon, 2011.

29.

Babaghayou

Mourad

A-HI

Cherunurakal

. Anisotropy evaluation of LDPE/LLDPE/PIB trilayer films. Advances in science and engineering technology international conferences (ASET). Dubai, United Arab Emirates: IEEE, 2020, pp. 1–3.

30.

Babaghayou

Mourad

A-HI

Lorenzo

, et al. Photodegradation characterization and heterogeneity evaluation of the exposed and unexposed faces of stabilized and unstabilized LDPE films. Mater Des 2016; 111: 279–290.

31.

Mejia

Al-Maqdi

Alkaabi

, et al. Upcycling of HDPE waste using additive manufacturing: feasibility and challenges. Advances in science and engineering technology international conferences (ASET). IEEE, 2020, pp. 1–6.

32.

Mozumder

Mourad

A-HI

Mairpady

, et al. Effect of TiO2 nanofiller concentration on the mechanical, thermal and biological properties of HDPE/TiO2 nanocomposites. J Mater Eng Perform 2018; 27: 2166–2181.

33.

Babaghayou

Mourad

A-HI

Lorenzo

, et al. Anisotropy evolution of low density polyethylene greenhouse covering films during their service life. Polym Test 2018; 66: 146–154.

34.

Santana

RMC

Manrich

. Studies on morphology and mechanical properties of PP/HIPS blends from postconsumer plastic waste. J Appl Polym Sci 2003; 87: 747–751.

35.

Ray

Bousmina

. Role of organically modified layered silicate both as an active interfacial modifier and nanofiller for immiscible polymer blends. Polymer 2004; 45: 8403–8413.

36.

Mourad

A-H

Zaaroura

Cherupurakal

. Wet lay-up technique for manufacturing of advanced laminated composites. Karbala Int J Mod Sci 2019; 5: 5.

37.

Mourad

A-HI

Zaaroura

. Impact of nanofillers incorporation on laminated nanocomposites performance. J Mater Eng Perform 2018; 27: 4453–4461.

38.

Derradji

Ramdani

Zhang

, et al. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles. Mater Des 2015; 71: 48–55.

39.

Ciecierska

Boczkowska

Kurzydlowski

, et al. The effect of carbon nanotubes on epoxy matrix nanocomposites. J Therm Anal Calorim 2013; 111: 1019–1024.

40.

Tang

Xiong

Tang

, et al. A starch-based biodegradable film modified by nano silicon dioxide. J Appl Polym Sci 2009; 113: 34–40.

41.

Toumi

Guessoum

Nekkaa

. Biocomposites based on date palm flour reinforced (70/30) polypropylene/thermoplastic starch blend: Effects of flour treatment and selective dispersion. J Adhes Sci Tech 2019; 33: 2071–2092.

42.

Medjdoub

Guessoum

Fois

. Viscoelastic, thermal and environmental characteristics of poly(lactic acid), linear low-density polyethylene and low-density polyethylene ternary blends and composites. J Adhes Sci Techol 2017; 31: 787–805.

43.

Bouzidi

Guessoum

Fois

, et al. Viscoelastic, thermo-mechanical and environmental properties of composites based on polypropylene/poly(lactic acid) blend and copper modified nanoclay. J Adhes Sci Technol 2018; 32: 496–515.