Comparison between pea and soy protein-based bioplastics obtained by injection molding

The elaboration of bioplastics from renewable polymers (e.g., proteins) is a field with great potential for industrial applications such as food packaging and agriculture. This study evaluates the development of bioplastic systems by injection molding using two different raw materials: soy protein isolate (SPI) and pea protein isolate (PPI). Both proteins are by-products, which lowers the price of processed bioplastics. However, it is necessary to control their properties during the manufacture processing, in order to ensure that they can replace conventional plastics. Therefore, the main objective of this work was to compare the properties of SPI and PPI bioplastics processed at different injection times (150, 300, and 450 s) and different mold temperatures (70 and 130°C). Thus, mechanical properties, water uptake capacity, and transparency were evaluated. The results show the potential of these raw materials to produce bioplastics that can replace conventional plastics, and that the processing conditions can be modified to obtain the desired final properties.     

Protein/glycerol blends and injection‐molded bioplastic matrices: Soybean versus egg albumen

Two well‐known proteins have been selected in order to produce bioplastics through injection molding: a soy protein isolate (SPI) and an egg white albumen concentrate (EW). Each of them has been thoroughly mixed with glycerol (40 wt %) and the blend then obtained have been characterized by means of rheological and thermomechanical techniques, which allowed the optimization of the processing moulding conditions (cylinder temperature, 60°C–65°C; mould temperature, 120°C; post‐injection pressure, 500–600 bars). Once bioplastics were obtained, their thermomechanical and tensile properties, as well as their water uptake capacity and transparency were evaluated. Bioplastics containing EW showed higher values in the elastic and loss moduli, E′ and E″, from ?30°C to 130°C, than the corresponding SPI bioplastic. However, they both showed qualitatively the same evolution with temperature, where E′ and E″ decreased up to a plateau at high temperatures. When examining their tensile and water uptake properties is found that SPI bioplastics are more ductile and present enhanced water uptake behavior over EW bioplastics, which on the other hand possess higher Young's modulus. SPI seems to provide tougher bioplastics, being an excellent option for potential superabsorbent applications, whereas EW would suit for those applications requiring higher mechanical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42980.     

Effect of plasticizer and storage conditions on thermomechanical properties of albumen/tragacanth based bioplastics

The effects of composition of the plasticizer fraction and storage conditions on the physical and thermomechanical properties of egg albumen/tragacanth gum based bioplastics were studied. Thus, glycerol (G) and water (W) were used as plasticizers at different G/W ratios (1:0, 3:1, 1:1, 1:3, 0:1), keeping the biopolymer fraction always at 60% (w/w). Tragacanth gum was included in the formulation for its well-known hydrophilic character, as possible future applications of these bioplastics may be moisture dependent (e.g. modified atmosphere packaging). Moreover, properties of bioplastics stored at room temperature under no control of relative humidity were different of those obtained when bioplastics were equilibrated a 53% relative humidity (RH) atmosphere. This is reflected in the DMTA and tensile tests results, for which water loss in the samples with the highest water contents (1:3, 0:1) involves very significant increases in viscoelastic moduli and tensile strength when equilibrated at 53% RH. Glycerol presence when no RH control was taken promotes water uptake, probably due to an interaction between both plasticizers, which eventually lead to a greater plastic region in the tensile tests.     

Surface and degradation properties of thermoplastic blends from albumin and zein‐based plastics

The use of traditional petroleum‐based thermoplastics in food packaging applications pose an environmental hazard, as their lack of biodegradability creates waste that environmental systems are unable to cope with. To address this issue, the investigation of surface, biodegradation, and water solubility properties of the albumin and zein thermoplastic blends plasticized with glycerol and mixed with varying amounts of low‐density polyethylene (LDPE) is conducted. When subjected to soil burial, albumin as a bioplastic completely biodegrades within two months, while a zein‐based bioplastic is more resilient to attacks from microbes within the soil (4.34% of intial mass remains). If albumin and zein proteins are used in the production of thermoplastics in tandem with LDPE, it could be possible to produce a plastic that will naturally biodegrade over time, decreasing the environmental impact of the use of thermoplastics in medical and food packaging applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44646.     

Influence of recycling of poly(lactic acid) on packaging relevant properties

The most promising representative of biodegradable plastics in packaging applications is polylactide (PLA). Despite this, there is only a small market of PLA in Europe. Reasons for that are the high price of PLA raw material and the lack of knowledge of the behavior in packaging applications. It has a number of peculiarities so producers of plastics packaging hesitate to use it. Like other polyesters, it can degrade at increased temperatures in the presence of moisture by hydrolysis whereby it loses its physical and chemical properties. In all production processes, production waste is generated (i.e., stamping grids or edge trim). In most cases, this waste is used. It is not known in detail, how an internal recycling process will influence the final product properties. One problem is hydrolysis by which the production waste is partially degraded. Target of this study is to analyze the recycling process of PLA within the context of necessary process adaptions and the effects upon ecological efficiency. Films for packaging containing multiple types and amounts of production waste will be produced by extrusion and tested concerning their mechanical properties. The analysis of the recycling behavior showed that internal PLA production waste is well suitable for recycling. The influence of the recycling on the molecular weight is negligible. The effect on the viscosity and thus on the extrusion process is higher. Packaging relevant properties like mechanical or optical properties are hardly influenced. Especially recycling with a recycling quota of up to 50% has an insignificant effect on the film properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41532.     

Thermomechanical properties and water uptake capacity of soy protein‐based bioplastics processed by injection molding

The optimization of the processing conditions in the production of soy protein bioplastics by injection molding has been essential in order to develop materials with a great capacity to absorb water while displaying good mechanical properties. Using a 50/50 (wt/wt) soy protein/glycerol mixture, and 40 °C, 500 bar, and 70 °C as reference values for cylinder temperature, injection pressure, and mold temperature, respectively, the effect of those processing parameters over thermomechanical and hydrophilic properties was studied. Processing parameters did not show a great influence over the thermomechanical bending properties within temperatures ranging from ?30 to 130 °C, as most samples displayed a similar response, independently of the parameter studied. On the other hand, when studying tensile and hydrophilic properties, the main effect corresponded to the cylinder and mold temperature values, as pressure did not exert a clear influence when increased from 300 to 900 bar. Samples with a lower water uptake were obtained when processed at higher temperature, as a result of crosslinking promotion. Moreover, a greater extensibility was observed when bioplastics are processed at high mold temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43524.     

Green Preparation of Bioplastics Based on Degradation and Chemical Modification of Lignin Residue

Owing to its high abundance, high availability, and eco-friendly properties, lignin is currently considered a potential candidate for replacement of petroleum-based plastics. However, the direct incorporation of lignin in bioplastics is not highly efficient and is difficult to carry out due to the complex and heterogeneous structure of lignin. In order to utilize lignin in the production of value-added bioplastics, many processes have been investigated to modify lignin to obtain desired macromonomers possessing enhanced properties compared to lignin itself. In this review, depolymerization via liquefaction and chemical modification of lignin are discussed as two main approaches in order to evaluate the utilization of lignin in bioplastics applications. The optimal conditions for each process are discussed to provide a more detailed outlook. In addition, we also provide an overview of some common bioplastics as well as practical applications. Due to their high performance, these bioplastics are expected to be feasibly commercialized in the near future.     

Preparation,characterization, and antibacterial activities of quaternarized N‐halamine‐grafted cellulose fibers

A viable method for coating of cellulose fiber with quaternarized N‐halamine is reported in this article. The use of quaternary ammonium salt group in combination with N‐halamine group can reinforce the antibacterial activity. The chemical structure of as‐synthesized N‐halamine precursor 4‐(Bromo‐acetic acid methylester)‐4‐ethyl‐2‐ oxazolidinone (BEO) was characterized by ¹H‐NMR. The cellulose fibers were characterized by Fourier transform infrared spectra and X‐ray photoelectron spectra. The spectra data confirmed that the quaternarized N‐halamine‐grafted cellulose fibers were successfully obtained. The antibacterial properties of functional fibers were challenged with both Gram positive and Gram negative bacteria. The antibacterial tests and showed that the as‐prepared antibacterial cellulose fibers exhibited powerful and rapid bactericidal performance against both Gram negative E. coli and Gram positive S. aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42702.     

Polyhydroxyalkanoates: Recent Advances in Their Synthesis and Applications

Polyhydroxyalkanoates (PHAs) are microbial biopolymers (polyesters) that have a wide range of functions and applications. They serve in nature mainly as carbon and energy storage materials for a variety of microorganisms. In past decades, their utilization has attracted much attention, from commodities and degradable plastics to specialty performance materials in medicine. PHA biosynthesis has been well understood, and it is now possible to design bacterial strands to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are very manifold: some are derived from food‐based carbon sources (e.g., fats and oils (triglycerids)), thus raising concerns with regard to the sustainability of their productions in terms of crop area and food. In addition, hemicellulose hydrolysates, crude glycerol, and methanol are very promising carbon sources for the sustainable production of PHAs. The integration of PHA production within a modern biorefinery is an important issue and can result in a simultaneous production of biofuels and bioplastics. Furthermore, many chemical‐synthetic procedures by means of efficient catalysts can give access to a variety of PHAs. This article summarizes recent developments in these fields and emphasizes the importance of a sustainable PHA‐based industry. Practical Applications: Practical applications of the microbial polyesters PHAs are, for example, a variety of sustainably produced commodities as well as special applications in (bio)medicine, for example, tissue engineering.     

Effect of coal filler on the properties of soy protein plastics

The influence of ultrafine coal filler (UFC) content on tensile properties, water absorption, and biodegradability of soy protein plastics were investigated. The addition of UFC in the soy protein plastics, with different content of glycerol as a plasticizer, was at different ratio varying from 10:0 to 6:4. Blend sheets of the soy protein composites were prepared by the compression molding processing. The results show that, with 23.08 wt % glycerol, the tensile strength and elongation at break for the soy protein sheet with coal filler (range from 5 to 30 parts) can be enhanced as compared with nonfilled soy protein plastics. Water resistance of the soy protein plastics improves with the increase in UFC content. The derivative thermogravimetry (DTG) curves indicate a double‐stage degradation process for defatted soy flour (SPF), while three‐stage degradation process for soy plastics and the soy protein composites. FT‐IR, XPS, and SEM were applied to study the interfacial interaction between coal macromolecules and soy protein molecules in UFC filled soy protein plastics. The results demonstrated that there is strong interfacial interaction in the soy protein plastics caused by the compression molding processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3134–3143, 2006     

Bring back the steel? The growth of plastics in automotive applications

The development of plastics has evolved from the use of natural materials to the use of chemically modified natural materials and, finally, to completely man-made molecules. Plastics continue to improve, to afford flexibility, high-impact, and strength. In automotive applications, plastics have increased in utilization to comprise approximately 10% of the total vehicle weight. They offer increased ductility, freedom from corrosion, and increased styling capability. Although plastics have had a remarkable impact on our culture, it is obvious that there is a price to be paid for their use. Plastics are almost too good, as they are durable when processed correctly, but easily damaged when utilized in the incorrect application. Plastics also degrade very slowly, making recycling mandatory. And finally, while plastics consume only 4% of the world’s oil production (petroleum is the raw material that is chemically altered to form commercial plastics), their cost hinges on the cost of petroleum. As petroleum prices increase, so too will the cost of plastic. In 2004, the higher price of plastic forced many plastic manufacturers out of business, and forced many automotive suppliers to look into alternative replacements. With publications such as USA Today reporting that current oil reserves will only last 40 years, scientists continue to seek cheaper alternatives to plastic. This article summarizes the history of commercial plastic development, with a focus on utilization of the materials in automotive applications. Damage criteria of plastic components, namely scratch, oxidative degradation, and impact, are discussed in relation to coatings and processing robustness. Environmental regulations, particularly in relation to recycling mandates, are explained. And finally, trends in alternative material development, including bioplastics, films, ceramic coatings, and nano-composites; are formulated. Presented at the 83rd Annual Meeting of the Federation of Societies for Coatings Technology, November 6–9, 2005 in Las Vegas, NV.     

Preparation of chitin‐CdTe quantum dots films and antibacterial effect on Staphylococcus aureus and Pseudomonas aeruginosa

Novel chitin–cadmium‐tellurium quantum dot (Chitin‐CdTeQD) hybrid films combining chitin and CdTe quantum dots (CdTeQDs) were prepared via a facile aqueous synthesis route at room temperature. Films were characterized by high‐resolution field emission scanning electron microscopy (HR‐FESEM) and energy dispersive X‐ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and X‐ray diffraction analysis (XRD). Antibacterial activity was studied on both Gram‐positive (Staphylococcus aureus) and Gram‐negative (Pseudomonas aeruginosa) bacteria. Antibacterial properties were investigated with agar diffusion testing assay and with confocal laser scanning microscopic image analysis. Chitin–CdTeQD films exhibited an excellent antibacterial activity against both Gram‐positive and Gram‐negative bacteria. Chitin–CdTeQD films might be a desirable antibacterial material for wide range of biomedical applications including wound dressing, burn treatment, drug delivery systems, packaging, ophthalmology, and implants. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44904.     

Preparation and properties of transparent,waterproof, and antibacterial composite film materials

Transparent polymer materials, such as plastics, have become widely used in the packaging industry due to their excellent properties. However, their nondegradability has led to a significant environmental issue known as “white pollution.” To address this issue, a transparent antibacterial film material was prepared using carboxymethyl cellulose and carboxymethyl chitosan as raw materials through an acid-assisted freeze–thaw strategy. The material exhibits optical transmittance exceeding 90% and a tensile strength of up to 124.1 MPa. Meanwhile, this material demonstrated excellent waterproof performance as well as antibacterial activity to Staphylococcus aureus and Escherichia coli. Therefore, this film material holds promising potential for development in antibacterial food packaging.     

Correlation between viscoelasticity,microstructure, and molecular properties of zein and pennisetin melts

Cereals are a large source of biopolymers, where mainly the starch is used for food and feed. A rapidly growing cereal application is the production of biofuel, mainly produced from corn in the US. The starch is fermented to ethanol leaving spent grain rich in cereal proteins as a by-product. The corn protein zein is currently extracted on a large scale and used in, for example, material applications. Similarly, pennisetin can be extracted from pearl millet, a crop critical for food security in sub-Saharan Africa. The formation of viscoelastic melts is crucial for (bio)plastics production and the viscoelasticity, microstructure, and molecular properties of zein and pennisetin melts were determined here. The proteins were mixed with plasticizers (polyethyleneglycol or glycerol/citric acid) to form melts. The melts displayed a phase separated microstructure with protein-rich and plasticizer-rich regions with distinctly separate T_gs. The pennisetin melts formed cross-links at temperatures above 60°C, which could be related to the high content of cysteine and methionine, as compared to zein. As a consequence, pennisetin melts showed a more thermocomplex behavior than zein melts. For zein melts, the mixture of glycerol and citric acid interacted with protein in addition to being a plasticizer causing a high-molecular weight shoulder in the molecular weight distribution. The study showed that, although both zein and pennisetin form viscoelastic melts, the choice of plasticizer strongly affects both melt structure and physical properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of the injection moulding processing conditions on the development of pea protein‐based bioplastics

Bioplastic materials from renewable polymers, like proteins, constitute a highly interesting field for important industrial applications such as packaging, agriculture, etc., in which thermo‐mechanical techniques are increasingly being used. Pea protein‐based bioplastics can be made through a mixing process followed by an injection moulding. The objective of this study was to investigate the influence of different injection parameters (moulding time and injection pressure) on the properties exhibited by the final bioplastics obtained. A dynamic mechanical analysis and tensile strength measurements were performed, along with water absorption capacity and transparency tests. The results indicated that the major differences between bioplastics obtained at different moulding times are in transparency and in the Young's Moduli, exhibiting lower values as moulding time increases. On the other hand, modifying the injection pressure lead to more consistent bioplastics which differed mainly in the elastic component (E′ profiles) and in the strain at break. Furthermore, the water uptake was more than 100% in almost all the different bioplastics processed because of its hydrophilic character, so they could be considered as potential sources for absorbent material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43306.     

Processing and properties of phthalic anhydride modified soy protein/glycerol plasticized soy protein composite films

Phthalic anhydride modified soy protein (PAS)/glycerol plasticized soy protein (GPS) composite films were fabricated by using extrusion and compression‐molding. Modified with phthalic anhydride, the soy protein lost its thermoplastic ability and was used as a filler to reinforce the GPS matrix. Fourier transform infrared spectra, optical transmittance, scanning electron microscope, mechanical tests, water resistance tests, as well as thermo‐gravimetric analysis were carried out to investigate the structure and properties of PAS and the plastic composites. The similar chemical structure of PAS and GPS led to compatibility of the two components resulting in high transparency and enhanced tensile properties of the composites. The water resistance of GPS was also improved by the incorporation of PAS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42221.     

Fabrication of κ-carrageenan and whey protein isolate-based films reinforced with nanocellulose: optimization via RSM

The aim of this study was to prepare nanocomposite films composed of whey protein isolate (W) and carrageenan (C) with nanocellulose (N) for food packaging applications. Response surface methodology was applied to investigate the effect of W concentration (v/v, 0–100%), glycerol/sorbitol (G/S) ratio (0–1), and N concentration (w/w, 0–5%) on the physicomechanical properties of film samples. Higher W and N contents and lower G/S ratios showed positive effect on rigidity of film samples, while introducing high concentration of N increased the water vapor permeability values with increasing plasticizer and C concentration. The highest water uptake values were observed in C based films, while a higher C content resulted in lower opacity values. The addition of nanocellulose into whey protein and carrageenan blend films in the presence of a plasticizer mixture improved the suitability of selected biopolymers for food packaging applications when compared to their neat films. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48902.     

Structure and properties of soy protein films plasticized with hydroxyamine

Two kinds of transparent films of soy protein were successfully prepared by plasticizing with diethanolamine (DEA) and triethanolamin (TEA). The films were hot pressed at 140°C and 20 MPa, and characterized with Fourier transform infrared spectroscopy, scanning electron microscope, ultraviolet–visible spectrometer, differential scanning calorimetry (DSC), thermogravimetric analysis, and tensile testing. The results indicated that films with triethanolamine plasticizers possessed better optical transmittance (more than 80% at 800 nm) than those with diethanolamine and glycerol. All of the sheets exhibited only one T_g in DSC curves. Moreover, the soy protein plastics with TEA had higher thermal stability and mechanical properties, as well as lower water uptake than those with DEA and glycerol, as a result of the strong interaction between TEA and protein molecules. The soy protein materials will be promising for the application in the fields of package and container, substituting for the nongreen polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

硬脂酸对大豆蛋白质塑料性能的影响

对水的敏感性是阻碍大豆蛋白质降解塑料广泛应用的不利因素,为了克服这一缺点,实验固定甘油和大豆蛋白质的比例,通过添加硬脂酸与大豆蛋白质共混,研究了其添加量对机械性能和吸水率的影响。同时拉伸和红外、扫描电镜等实验表明甘油、硬脂酸对膜的力学性能、吸水率、断面形态、红外图谱均有影响。     

An overview on properties and applications of poly(butylene adipate‐co‐terephthalate)–PBAT based composites

There is growing interest in biodegradable polymers (BP), in particular poly(butylene adipate‐co‐terephthalate) (PBAT), due to environmental problems associated with the disposal of non‐biodegradable polymers into the environment. However, high production cost and low thermo‐mechanical properties restrict the use of this sustainable material, making its biodegradability advantageous only when it is decisively required. The addition of different compositions of monomers and selective addition of natural fillers have been reported as alternatives to develop more accessible PBAT‐based bioplastics with performance that could match or even exceed that of the most widely used commodity plastics. This review explores the recent progress of the applications and biodegradation of PBAT. The addition of natural fillers and its effect on the final performance of the PBAT‐based composites is also reported with respect to improving the properties of composites. The advance of polymerization reaction engineering combined with sustainable trend offers great opportunities for innovative green chemical manufacturing. POLYM. ENG. SCI., 59:E7–E15, 2019. © 2017 Society of Plastics Engineers