Production and characterization of microfibrillated cellulose-reinforced thermoplastic starch composites

Preparation and characterization of Arenga pinnata thermoplastic starch/bacterial cellulose nanofiber biocomposites via in-situ twin screw extrusion

Thermoplastic starch (TPS) is considered as alternative material for substitute petroleum-based materials for single-use packaging material applications. The main weakness of TPS is sensitive to water and humidity which causes low mechanical properties and low thermal resistance. To address this limitation, one can enhance the strength is by incorporating cellulose nanofiber as a reinforcing agent. Cellulose nanofiber used in this study is bacterial cellulose, synthesized from tapioca liquid waste media, namely Nata de Cassava (NDCass). The effect of NDCass addition to TPS on chemical characteristics, physical properties, crystallinity, mechanical properties, and thermal properties was investigated. As the results, NDCass incorporation has no significant effect on the chemical structure and crystal structure of composites as observed by FTIR and XRD analysis. Incorporating of NDCass improved the mechanical properties by 37.3 %, the thermal stability, and the viscosity, however reduced the elongation at break by 65.6 %, the density, the melt flow and shear rate of TPS biocomposite. This study evidently that starch from Arenga pinnata trunk and bacterial cellulose from tapioca liquid waste can be manufactured into biocomposites using in-situ twin screw extrusion which beneficial for large-scale applications.

Biodegradable Nanocomposites Based on Blends of Poly(Butylene Adipate-Co-Terephthalate) (PBAT) and Thermoplastic Starch Filled with Montmorillonite (MMT): Physico-Mechanical Properties

Poly(butylene adipate-co-terephthalate) (PBAT) is widely used for production of biodegradable films due to its high elongation, excellent flexibility, and good processability properties. An effective way to develop more accessible PBAT-based bioplastics for wide application in packaging is blending of PBAT with thermoplastic starch (TPS) since PBAT is costly with prices approximately double or even triple the prices of traditional plastics like polyethylene. This study is focused on investigating the influence of TPS/PBAT blend ratio and montmorillonite (MMT) content on the physical and mechanical properties and molecular mobility of TPS-MMT/PBAT nanocomposites. Obtained TPS-MMT/PBAT nanocomposites through the melt blending process were characterized using tensile testing, dynamic mechanical thermal analysis (DMTA), and X-ray diffraction (XRD), as well as solid-state 1H and 13C NMR spectroscopy. Mechanical properties demonstrated that the addition of TPS to PBAT leads to a substantial decrease in the tensile strength as well as in the elongation at break, while Young's modulus is rising substantially, while the effect of the MMT addition is almost negligible on the tensile stress of the blends. DMTA results confirmed the formation of TPS domains in the PBAT matrix. With increasing TPS content, mobility of starch-rich regions of TPS domains slightly increases. However, molecular mobility in glycerol-rich regions of TPS domains in the blends was slightly restricted. Moreover, the data obtained from 13C CP/MAS NMR spectra indicated that the presence of TPS in the sample decreases the mobility of the PBAT chains, mainly those located at the TPS/PBAT interfaces.

Green composites based on thermoplastic starch reinforced with micro- and nano-cellulose by melt blending - A review

Starch is a biodegradable biopolymer, a sustainable material that can replace conventional petrochemical-based plastics. However, starch has some limitations, as it must be processed by heating and treated mechanically with a plasticizer to become thermoplastic starch (TPS). Different variables such as mixing speeds, amount, and kind of plasticizers play a vital role in preparing TPS by melting. Despite this, the properties of the TPS are not comparable with those of traditional plastics. To overcome this limitation, microcellulose or nanocellulose is added to TPS by melt mixing, including the extrusion and internal mixing process, which enables large-scale production. This review aims to compile several studies that evaluate the effect of plasticizers, as well as the relevance of incorporating different cellulosic fillers of different dimensions on the properties of TPS obtained by melt mixing. Potential applications of these materials in food packaging, biomedical applications, and other opportunities are also described.

Methods to Increase or Decrease Resistance to Photodegradation and Biodegradation of Polyurethane/Polyisocyanurate (PU/PIR) Foams

Two series of rigid polyurethane-polyisocyanurate (PU/PIR) foams were obtained. They were modified using powder fillers, such as industrial food cocoa (K5-K15 foam) and instant freeze-dried coffee (KR-KR15) added in amounts of 5, 10 and 15 wt.%. W foam (reference) was obtained without filler. The foams were degraded in a climate chamber for 1 week, 2 weeks or 3 weeks. Appropriate temperature, humidity and UV radiation were set in the chamber, which did not change throughout the degradation process. The foams were also degraded in an oven for two days at 120 °C. The foam tests carried out indicated, among others, on the decrease in compressive strength along with the increase in the residence time of the samples in the chamber. Degraded foams also changed color. Foams containing 5% and 10% of industrial cocoa or freeze-dried coffee were more susceptible to degradation. The addition of 15% coffee or cocoa slows down the degradation process. In the present study, industrial food cocoa and instant freeze-dried coffee were used as modifiers of rigid PU/PIR foam. These fillers have two functions: they accelerate the biodegradation of foams and have antioxidant properties.

Effect of Polyethylene Glycol Methyl Ether Methacrylate on the Biodegradability of Polyvinyl Alcohol/Starch Blend Films

Blend copolymers (PVA/S) were grafted with polyethylene glycol methyl methacrylate (PEGMA) with different ratios. Potassium persulfate was used as an initiator. The blend copolymer (PVA/S) was created by combining poly(vinyl alcohol) (PVA) with starch (S) in various ratios. The main idea was to study the effect of different ratios of the used raw materials on the biodegradability of plastic films. The resulting polymers (PVA/S/PEGMA) were analyzed using FTIR spectroscopy to investigate the hydrogen bond interaction between PVA, S, and PEGMA in the mixtures. TGA and SEM analyses were used to characterize the polymers (PVA/S/AA). The biodegradability and mechanical properties of the PVA/S/PEGMA blend films were evaluated. The findings revealed that the mechanical properties of the blend films are highly influenced by PEGMA. The time of degradation of the films immersed in soil and Coca-Cola increases as the contents of PVA and S and the molecular weight (MW) of PEGMA increase in the terpolymer. The M8 sample (PVA/S/PEGMA in the ratio of 3:1:2, respectively) with a MW of 950 g/mol produced the lowest elongation at break (67.5%), whereas M1 (PVA/S/PEGMA in the ratio of 1:1:1, respectively) with a MW of 300 g/mol produced the most (150%). The film's tensile strength and elongation at break were improved by grafting PEGMA onto the blending polymer (PAV-b-S). Tg and Tm increased when the PEGMA MW increased from 300 to 950. Tg (48.4 °C) and Tm (190.9 °C) were the lowest in M1 (300), while Tg (84.8 °C) and Tm (190.9 °C) were greatest in M1 (950) at 209.3 °C. The increased chain and molecular weight of PEGMA account for the increase in Tg and Tm of the copolymers.

Mechanical, chemical, and bio-recycling of biodegradable plastics: A review

The extensive use of petroleum-based non-biodegradable plastics for various applications has led to global concerns regarding the severe environmental issues associated with them. However, biodegradable plastics are emerging as green alternatives to petroleum-based non-biodegradable plastics. Biodegradable plastics, which include bio-based and petroleum-based biodegradable polymers, exhibit advantageous properties such as renewability, biocompatibility, and non-toxicity. Furthermore, certain biodegradable plastics are compatible with existing recycling streams intended for conventional plastics and are biodegradable in controlled and/or predicted environments. Recycling biodegradable plastics before their end-of-life (EOL) degradation further enhances their sustainability and reduces their carbon footprint. Since the production of biodegradable plastic is increasing and these materials will coexist with conventional plastics for many years to come, it is essential to identify the optimal recycling options for each of the most prevalent biodegradable plastics. The substitution of virgin biodegradable plastics by their recyclates leads to higher savings in the primary energy demand and reduces global warming impact. This review covers the current state of the mechanical, chemical, and bio-recycling of post-industrial and post-consumer waste of biodegradable plastics and their related composites. The effects of recycling on the chemical structure and thermomechanical properties of biodegradable plastics are also reported. Additionally, the improvement of biodegradable plastics by blending them with other polymers and nanoparticles is comprehensively discussed. Finally, the status of bioplastic usage, life cycle assessment, EOL management, bioplastic market, and the challenges associated with the recyclability of biodegradable plastics are addressed. This review gives comprehensive insights into the recycling processes that may be employed for the recycling of biodegradable plastics.

Plasma Surface Engineering of Natural and Sustainable Polymeric Derivatives and Their Potential Applications

Recently, natural as well as synthetic polymers have been receiving significant attention as candidates to replace non-renewable materials. With the exponential developments in the world each day, the collateral damage to the environment is incessant. Increased demands for reducing pollution and energy consumption are the driving force behind the research related to surface-modified natural fibers (NFs), polymers, and various derivatives of them such as natural-fiber-reinforced polymer composites. Natural fibers have received special attention for industrial applications due to their favorable characteristics, such as low cost, abundance, light weight, and biodegradable nature. Even though NFs offer many potential applications, they still face some challenges in terms of durability, strength, and processing. Many of these have been addressed by various surface modification methodologies and compositing with polymers. Among different surface treatment strategies, low-temperature plasma (LTP) surface treatment has recently received special attention for tailoring surface properties of different materials, including NFs and synthetic polymers, without affecting any of the bulk properties of these materials. Hence, it is very important to get an overview of the latest developments in this field. The present article attempts to give an overview of different materials such as NFs, synthetic polymers, and composites. Special attention was placed on the low-temperature plasma-based surface engineering of these materials for diverse applications, which include but are not limited to environmental remediation, packaging, biomedical devices, and sensor development.

Novel In Situ Modification for Thermoplastic Starch Preparation based on Arenga pinnata Palm Starch

Thermoplastic starch (TPS) has three main disadvantages, i.e., poor mechanical properties, low thermal stability and water sensibility. To overcome these disadvantages, TPS properties can be improved by starch modification, adding reinforcements and blending with other polymers. In this research, to prepare modified TPS, starch modification was carried out by in situ modification. The modified TPS was prepared by adding Arenga pinnata palm starch (APPS), glycerol and benzoyl peroxide simultaneously in the twin-screw extruder. Morphology analysis of TPS revealed that the starch granules were damaged and gelatinized in the extrusion process. No phase separation is observed in TPS, which exhibits that starch granules with and without benzoyl peroxide were uniformly dispersed in the matrix. The addition of benzoyl peroxide resulted in increased density of TPS from 1.37 to 1.39 g·cm^-3, tensile strength from 7.19 to 8.61 MPa and viscosity from 2482.19 to 2604.60 Pa.s. However, it decreased the elongation at break of TPS from 33.95 to 30.16%, melt flow rate from 7.13 to 5.73 gr/10 min and glass transition temperature from 65 to 52 °C. In addition, the thermal analysis showed that the addition of benzoyl peroxide increased the thermal stability of TPS and extended the temperature range of thermal degradation.

A simple preparation of low water-soluble crosslinking starch-based foam containing palm oil: Thermo-physicochemical properties

A simple preparation method was established for a low water-soluble citric acid crosslinking starch-based foam containing palm oil. The method was performed by pouring the boiling citric acid solution into the starch compound unlike the citric acid starch crosslinking by conventional solution casting. Thermo-physicochemical properties of the starch-based foams were examined. The I3300/I1149 intensity ratio of non-citric acid-containing foam was higher, suggesting greater amounts of the available -OH groups. The addition of citric acid into the starch matrix exhibited weaker thermal stability that was attributed to the lower thermal stability of the substituted ester bonds. The increment of citric acid concentration increased thermoplastic starch foams densities as well as their cell wall thickness. No differences in moisture absorption behavior were observed after soaking in water, the non-citric acid-filled foam exhibited dissolution and changed from its original shape upon drying. Experimental results showed a promising alternative methodology to prepare low water-soluble citric acid crosslinked starch-based foam to replace conventional solution casting.

Overview of Nanocellulose in Food Packaging

BACKGROUND

The rising concern with environmental preservation has led to increasing interest in biodegradable polymer composites from renewable sources, such as cellulose and its derivatives. The use of nanocellulose is an innovative food packaging trend.

DISCUSSION

This paper presents an overview and discusses the state of the art of different nanocellulose materials used in food and food packaging, and identifies important patents related to them. It is important to consider that before marketing, new products must be proven safe for consumers and the environment.

CONCLUSION

Several packaging materials using nanocellulose have been developed and shown to be promising for use as active and intelligent materials for food packaging. Other nanocellulose products are under investigation for packaging and may enter the market in the near future. Many countries have been adjusting their regulatory frameworks to deal with nanotechnologies, including nanocellulose packaging.

Soluble soybean polysaccharide/nano zinc oxide antimicrobial nanocomposite films reinforced with microfibrillated cellulose

Nanocomposite films of soluble soybean polysaccharide (SSPS)/nano zinc oxide (nZnO) reinforced with microfibrillated cellulose (MFC) were developed by solvent casting method. The structure, optical, barrier, thermal, surface wettability, mechanical properties and antimicrobial activity of the SSPS/MFC, SSPS/nZnO and SSPS/nZnO/MFC nanocomposite films were evaluated. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra indicated interactions between SSPS and the nano-fillers. The nanocomposite films containing MFC showed improved tensile strength, stiffness, ultraviolet (UV) light barrier property, thermal stability and water resistance when compared with the neat SSPS film. The nZnO-incorporated nanocomposite films exhibited good antimicrobial activity against E. coli and B. subtlis. Overall, the MFC-reinforced SSPS/nZnO nanocomposite films possessed desirable characteristics to be considered as potential candidates for antimicrobial packaging and biomedical applications.

Cellulose Nanofibrils Filled Poly(Lactic Acid) Biocomposite Filament for FDM 3D Printing

As direct digital manufacturing, 3D printing (3DP) technology provides new development directions and opportunities for the high-value utilization of a wide range of biological materials. Cellulose nanofibrils (CNF) and polylactic acid (PLA) biocomposite filaments for fused deposition modeling (FDM) 3DP were developed in this study. Firstly, CNF was isolated by enzymatic hydrolysis combined with high-pressure homogenization. CNF/PLA filaments were then prepared by melt-extrusion of PLA as the matrix and CNF as the filler. Thermal stability, mechanical performance, and water absorption property of biocomposite filaments and 3D-printed objects were analyzed. Findings showed that CNF increased the thermal stability of the PLA/PEG600/CNF composite. Compared to unfilled PLA FDM filaments, the CNF filled PLA biocomposite filament showed an increase of 33% in tensile strength and 19% in elongation at break, suggesting better compatibility for desktop FDM 3DP. This study provided a new potential for the high-value utilization of CNF in 3DP in consumer product applications.

Characterization and properties of cellulose microfibers from water hyacinth filled sago starch biocomposites

The cellulose microfibers (CMF) from water hyacinth (WH) fiber as a filler in sago starch (SS) biocomposites was investigated. The CMF was isolated by pulping, bleaching and acid hydrolysis methods. The addition of CMF in sago matrix was varied i.e. 0, 5, 10, 15 and 20 wt%. Biocomposites were made by using solution casting and glycerol as a plasticizer. The biocomposites were also determined by tensile test, FTIR, X-Ray, thermogravimetric, SEM, and soil burial tests. The results show that the SS15CMF sample has the highest tensile strength of 10.23 MPa than those other samples. Scanning Electron Microscope (SEM) images show that the strong interaction was formed between CMF WH and matrix. Fourier Transform Infra-red (FTIR) indicated that the functional group of biocomposites was a hydrophilic cluster. The addition of CMF WH in sago starch biocomposites lead to the moisture barrier, crystallinity, and thermal stability increased; it is due to the pure sago starch film was more rapidly degraded than its biocomposites.

Study of green nanocomposites based on corn starch and cellulose nanofibrils from Agave tequilana Weber

Global environmental pollution issues caused by synthetic materials and the lack of practical utilization of the local industrial lignocellulosic waste, force Mexican researchers to produce new biobased sustainable materials that use industrial waste as a source of components. Herein, we show the preparation and characterization of environmentally friendly starch-based nanocomposites reinforced with cellulose nanofibrils (CNF) extracted from Agave tequilana Weber. Tensile, bending and impact mechanical properties of dried and hydrated nanocomposites were studied. Moreover, the water absorption capacity of the nanocomposites were measured and evaluated. The mechanical properties improved because of the presence of a small amount of CNF (1 wt%). This work demonstrates the importance of the addition of a natural biomodifier in a starch matrix to achieve better mechanical properties. Most importantly, this study highlights that lignocellulosic waste from the tequila industry can have a practical application, which is being a source of natural nanoreinforcements for preparation of all-biobased sustainable materials.