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.     

Effects of crosslinking on the mechanical properties and biodegradability of soybean protein‐based composites

A green composite with good mechanical properties and acceptable biodegradability was developed using wood flour and soybean protein that was modified by thermal‐caustic degradation and chemical crosslinking with glyoxal and polyisocyanate (PMDI). Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) in combination with the traditional evaluations were employed to investigate the structure, morphology, and properties of the crosslinked soybean protein and the crosslinking‐modified wood/soybean protein composites to understand the effects of the crosslinker species on the mechanical properties, water resistance, and microbial biodegradation of soybean protein‐wood flour composites. The results indicated that the chemical crosslinking modification could improve the mechanical properties and water resistance but decrease the biodegradability of the wood/protein composite to a certain extent. Both glyoxal and PMDI alone as crosslinkers could not perfectly modify the soybean protein because of the high reactivity of PMDI and low crosslinking reactivity of glyoxal. The incorporation of glyoxal with PMDI could result in the desired crosslinking efficiency and good interfacial adhesion by compromising the advantages and disadvantages of glyoxal or PMDI alone as crosslinkers, which balanced the performances of the wood flour/soybean protein composite. The preferable combination crosslinker was composed of 50 wt % glyoxal and 50 wt % PMDI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41387.     

Hybrid double‐network hydrogel based on poly(aspartic acid) and poly(acryl amide) with improved mechanical properties

Hydrogels usually have a smaller mechanical strength and toughness than generic polymeric materials. Therefore, many studies report improvements for mechanical properties of hydrogels by preparing double‐network hydrogels, nanocomposite hydrogels, and nanostructured hydrogels. In this study, interpenetrating‐type dually‐crosslinked hydrogels were prepared via free radical crosslinking polymerization of acrylamide monomers in the presence of poly(aspartic acid) and subsequent immersion in a metal ion containing aqueous solution to induce extra physical crosslinking through ionic or coordination bonding. Using this approach, the mechanical properties of inherently weak and brittle homopolymer gels could be improved via interpenetrating the double network formed by both covalent bonding and metal coordination‐assisted reversible physical crosslinks. The preparation, swelling behavior, morphology, and mechanical properties of these hydrogels are presented. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45925.     

Preparation and characterization of poly(vinyl alcohol) and 1,2,3‐propanetriol diglycidyl ether incorporated soy protein isolate‐based films

Novel biodegradable films were prepared from soy protein isolate (SPI), poly(vinyl alcohol) (PVA), glycerol, and 1,2,3‐propanetriol diglycidyl ether (PTGE). The mechanical, hydrophilic, and compatible properties of the films were investigated. The influence of PTGE as a crosslinker on the properties of the SPI/PVA/PTGE films was examined with Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), thermogravimetric analysis, mechanical analysis, contact angle measurements, and scanning electron microscopy. XRD and contact angle examination confirmed that the addition of PTGE altered the film microstructure to a crystalline one. The mechanical properties and water resistance of the SPI/PVA/PTGE films increased notably compared with those of the unmodified SPI films. All results indicate that the networks were formed between SPI and PTGE and played an important role in forming a homogeneous structure in the obtained films. The novel biodegradable films provide a convenient and promising way for preparing environmentally friendly film materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42578.     

Mechanical properties and morphology of polypropylene‐calcium carbonate nanocomposites prepared by dynamic packing injection molding

In this article, dynamic packing injection molding (DPIM) technology was used to prepare injection samples of Polypropylene‐Calcium Carbonate (PP/CaCO₃) nanocomposites. Through DPIM, the mechanical properties of PP/nano‐CaCO₃ samples were improved significantly. Compared with conventional injection molding (CIM), the enhancement of the tensile strength and impact strength of the samples molded by DPIM was 39 and 144%, respectively. In addition, the tensile strength and impact strength of the PP/nano‐CaCO₃ composites molded by DPIM increase by 21 and 514%, respectively compared with those of pure PP through CIM. According to the SEM, WAXD, DSC measurement, it could be found that a much better dispersion of nano‐CaCO₃ in samples was achieved by DPIM. Moreover, γcrystal is found in the shear layer of the DPIM samples. The crystallinity of PP matrix in DPIM sample increases by 22.76% compared with that of conventional sample. The improvement of mechanical properties of PP/nano‐CaCO₃ composites prepared by DPIM attributes to the even distribution of nano‐CaCO₃ particles and the morphology change of PP matrix under the influence of dynamic shear stress. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Formulation of a novel soybean protein‐based wood adhesive with desired water resistance and technological applicability

A novel soybean protein‐based wood adhesive with good bond strength, excellent water resistance, and the desired technological applicability was formulated by combining thermal alkali degradation, thermal acid treatment, and crosslinking. The characterization results indicated that thermal alkali degradation could effectively improve the technological applicability, thermal acid treatment could positively improve the water resistance, and appropriate crosslinking modification could significantly enhance the bond strength and water resistance of the soybean protein adhesive. The crosslinker species, crosslinker level, and ratio of thermal alkali‐degraded soybean protein (DSP) to thermal acid‐treated soybean protein (TSP) had important effects on the primary properties of the soybean protein adhesives. The modified polyamide aqueous solution was the most preferable crosslinker because of its low viscosity, good crosslinking efficiency, and excellent miscibility with soybean protein solution. The optimal soybean protein adhesive that was formulated from 20 wt % modified polyamide as the crosslinker and a DSP/TSP ratio of 1:3 had a solid content of more than 35 wt %, suitable viscosity (～2180 mPa s), a long work life (>16 h), good dry bond strength (2.94 MPa), and 28 h of boiling–dry–boiling cycled wet strength (1.29 MPa) that met the required values for structural use according to JIS K6806‐2003 commercial standards. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43586.     

Influence of crosslinking methods toward poly(vinyl alcohol) properties: Microwave irradiation and conventional heating

In this study, crosslinking of poly(vinyl alcohol) (PVA) with tartaric acid, as crosslinker, is performed using microwave irradiation. A comparison between the properties of PVA crosslinked using microwave irradiation and conventional heating methods is also discussed. While the water absorption, tensile and thermal properties of PVA crosslinked by either of the methods are comparable, microwave irradiation took only one‐eighth (14 min) of the time compared to conventional heating. In comparison with PVA (42 MPa), the strength of PVA crosslinked with 35% TA increased to 145 and 153 MPa for conventional heating and microwave irradiation, respectively. Water absorption of crosslinked PVA film is successively reduced to less than 30% in comparison with PVA (～200%). Moreover, the crosslinked films are stable at higher temperatures in comparison with PVA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46125.     

Thermomechanical properties of alkali treated jute‐polyester/nanoclay biocomposites fabricated by VARTM process

A systematic study was carried out to investigate the effect of alkali treatment and nanoclay on thermomechanical properties of jute fabric reinforced polyester composites (JPC) fabricated by the vacuum‐assisted resin transfer molding (VARTM) process. Using mechanical mixing and sonication process, 1% and 2% by weight montmorillonite K10 nanoclay were dispersed into B‐440 premium polyester resin to fabricate jute fabric reinforced polyester nanocomposites. The average fiber volume was determined to be around 40% and void fraction was reduced due to the surface treatment as well as nanoclay infusion in these biocomposites. Dynamic mechanical analysis (DMA) revealed enhancement of dynamic elastic/plastic responses and glass transition temperature (T_g) in treated jute polyester composites (TJPC) and nanoclay infused TJPC compared with those of untreated jute polyester composites (UTJPC). Alkali treatment and nanoclay infusion also resulted in enhancement of mechanical properties of JPC. The maximum flexural, compression, and interlaminar shear strength (ILSS) properties were found in the 1 wt % nanoclay infused TJPC. Fourier transform‐infrared spectroscopy (FT‐IR) revealed strong interaction between the organoclay and polyester that resulted in enhanced thermomechanical properties in the composites. Lower water absorption was also observed due to surface treatment and nanoclay infusion in the TJPC. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effect of curing system on the properties of the thermoplastic elastomer foams of ethylene‐vinyl acetate copolymer and styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers

Thermoplastic elastomer (TPE) foams have important application in electrical, toys, and other industries. Several foams were prepared by ethylene‐vinyl acetate copolymer (EVA) lonely, and in combination with styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers (SBR and EPDM). The effects of crosslinking and foaming agents and EVA type on density and mechanical properties of the cured foams with two curing systems, peroxide and sulfur‐peroxide with potential use in automotive applications, were studied. The results showed that proposed compounds formulations were foamed properly. The viscosity of the EVA was a key factor for the density values of the formed foams. The densities of the cured foams with peroxide system with various SBR contents were higher when compared with cured foams with sulfur‐peroxide system. With increasing foaming agent, the densities of the foams were reduced for studied curing systems. The densities of the EVA–EPDM foams were lower than those of the EVA–SBR foams in the same studied conditions. Increasing rubber in foam formulation had adverse effect on tensile properties of the foams. The existence of the talc powder in foam formulation had important role on the shape and type of the formed cells and resulted in foams with mostly closed cells. The results of this study help the automotive article designer to produce suitable TPE foam. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45357.     

Effect of the nature and degree of crosslinking on the Rose Bengal uptake by DVB‐, NNMBA‐, HDODA‐, and TTEGDA‐crosslinked aminopolyacrylamides

Polyacrylamides with 2–20 mol % divinyl benzene (DVB), N,N′‐methylene‐bisacrylamide (NNMBA), 1,6‐hexanediol diacrylate (HDODA), and tetraethyleneglycol diacrylate (TTEGDA) crosslinking and without crosslinking were prepared by free radical solution polymerization. Amino functions were incorporated into these polymers by transamidation with excess ethylenediamine. The dye uptake of nonprotonated and protonated aminopolyacrylamides was followed by batch equilibration method towards Rose Bengal (RB), Methyl Orange (MO), Methyl Red (MR), and Methylene Blue (MB). RB uptake by the polyacrylamide‐supported systems is higher than other dyes. Generally the dye uptake by the protonated systems is higher than the nonprotonated systems. To optimize the conditions of dye uptake, the effect of the concentration of RB solutions, temperature, and pH were followed. Kinetic studies showed that the uptake of RB by both nonprotonated and protonated crosslinked aminopolyacrylamides is a phase boundary process followed by three‐dimensional diffusion. The extent of RB uptake by the various systems depends on the nature and degree of crosslinking, and the relative rigidity/flexibility ofthe polyacrylamide support. Thus, the dye uptake followed the order: linear > NNMBA‐ > DVB‐ > TTEGDA‐ > HDODA‐crosslinked system. The dye uptake followed the same trend as the variation of amino capacity with degree of crosslinking in the respective crosslinked system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The effect of vibration injection molding on mechanical properties of polyolefin parts

In this paper an experimental study of vibration field effect on molded polymers specimens is carried out. A self‐made vibration injection device is employed to mold the experiment samples. In the experiment some polyolefin materials are investigated, and property tests for the specimens are carried out. The results show that the tensile strength of high‐density polyethylene (HDPE) and polypropylene (PP) have an obvious increase, but polystyrene (PS) does not. The effect of vibration on the strength is related to the temperature, pressure, and gate. Lastly, the test results are analyzed and conclusions are presented. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1514–1518, 2004     

Effects of polyisocyanate on properties and pot life of epoxy resin cross‐linked soybean meal‐based bioadhesive

In this study, polyisocyanate (pMDI) was introduced into epoxy resin modified soybean meal‐based bioadhesive to address the issue of low dry bond strength. Specifically, we investigated the effects of adding pMDI in terms of amount and storage time on dry bond strength, water resistance, and pot life of adhesive. Factors examined included shear strength, apparent viscosity, chemical reaction, crystallinity, and morphology of modified adhesives. Results indicated that the dry bond strength and water resistance of the resultant plywood was respectively improved 29.5% and 39.7% by adding 2% pMDI. In addition, the pot life of modified adhesive reached in 4 h. Results also shown that the cross‐linking reactions between epoxy group and carbonyl as well as isocyano and amino increased the cross‐linking density and formed a denser cross‐linking network structure of cured adhesive. The composite cross‐linked soybean meal‐based adhesive is environmental‐friendly and high‐performance, which will promote the industrial application of the soy protein‐based adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43362.     

Biaxially self‐reinforced high‐density polyethylene prepared by dynamic packing injection molding. I. Processing parameters and mechanical properties

Uniaxial oscillating stress field by dynamic packing injection molding (DPIM) is well established as a means of producing uniaxially self‐reinforced polyethylene and polypropylene. Here, the effects on the mechanical properties of high‐density polyethylene (HDPE) in both flow direction (MD) and transverse direction (TD) of packing modules and processing parameters in DPIM are described. Both biaxially and uniaxially self‐reinforced HDPE samples are obtained by uniaxial shear injection molding. The most remarkable biaxially self‐reinforced HDPE specimens show a 42% increase of the tensile strength in both MD and TD. The difference of stress–strain behavior and impact strength between MD and TD for the DPIM moldings indicates the asymmetry of microstructure in the two directions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1584–1590, 2004     

Improved mechanical properties and structure of PP/nano‐CaCO3 blends prepared by low‐frequency vibration injection molding

BACKGROUD: Melt vibration technology was used to prepare injection samples of polypropylene (PP)/nano‐CaCO₃ blends. It is well known that nano‐CaCO₃ particles are easy to agglomerate owing to their large surface energy. Improving the distribution of nano‐CaCO₃ particles in PP/nano‐CaCO₃ blends is very important for enhancing the mechanical properties. In this work, low‐frequency vibration was imposed on the process of injection molding of PP/nano‐CaCO₃ blends. The aim of importing a vibration field was to change the crystal structure of PP as we studied previously and improve the distribution of nano‐CaCO₃ particles. Furthermore, the mechanical properties were improved. RESULTS: Through melt vibration, the mechanical properties of PP/nano‐CaCO₃ samples were improved significantly. Compared with conventional injection molding, the enhancement of the tensile strength and impact strength of the samples molded by vibration injection molding was 17.68 and 175.96%, respectively. According to scanning electron microscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry measurements, it was found that a much better dispersion of nano‐CaCO₃ in samples was achieved by vibration injection molding. Moreover, the crystal structure of PP in PP/CaCO₃ vibration samples changed. The γ crystal form was achieved at the shear layer of vibration samples. Moreover, the degree of crystallinity of PP in vibration samples increased 6% compared with conventional samples. CONCLUSION: Concerning the microstructure, melt vibration could effectively change the crystal structure and increase the degree of crystallinity of PP besides improving the distribution of nano‐CaCO₃ particles. Concerning the macrostructure, melt vibration could enhance the mechanical properties. The improvement of mechanical properties of PP/nano‐CaCO₃ blends prepared by low‐frequency vibration injection molding should be attributed to the even distribution of nano‐CaCO₃ particles and the formation of γ‐PP and the increase of the degree of cystallinity. Copyright © 2007 Society of Chemical Industry     

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.     

Mechanical properties and morphological behavior of calcium carbonate‐filled polypropylene in dynamic injection molding

A custom‐made electromagnetic dynamic injection molding machine was adopted to study the mechanical properties and morphological behavior of calcium carbonate‐filled polypropylene (PP) in a dynamic injection molding process. The influence of vibration amplitude and frequency on the mechanical properties and morphological behavior of samples was investigated using tensile tests, notched Izod impact tests, differential scanning calorimetry, and scanning electronic microscopy. The tensile stress and the impact stress for all samples investigated were found to increase in a nonlinear manner with increasing vibration amplitude and frequency. The tensile stress reached a maximum value at about 8 Hz and 0.15 mm for neat PP and PP filled with 3, 20, and 30 wt% CaCO₃. For PP filled with 40 wt% CaCO₃, the tensile stress reached a maximum value at about 12 Hz and 0.2 mm. The impact stress reached a maximum value at about 12 Hz. From DSC experiments it was shown that the melting temperature slightly increased, but no new polymeric crystalline peak appeared under the vibration force field. The CaCO₃ particles were diffused easily and distributed evenly in the PP melt under the vibration force field, so it is very useful in improving the quality of injection products. Copyright © 2006 Society of Chemical Industry     

Physical–mechanical properties and morphological study on nylon‐6 recycling by injection molding

The effect of the multiple recycling of nylon‐6 by injection molding on its physical–mechanical properties and morphology was studied after each cycle of injection. These studies were made in order to know how many times it is possible to recycle the nylon‐6 without significant loss of the physical–mechanical properties. Optical and electronic microscopy were used to evaluated the morphology. Molecular weight changes were determinated by gel permeation chromatography (GPC). The nylon‐6 was recycled 10 times, until the eighth cycle the properties of the material did not suffered any change. Changes of 10–15% in the properties between nylon‐6 with 10 cycles of injection and virgin material were observed. An exception was the percentage of elongation that decreased 70% gradually until in the tenth cycle of injection. The results from GPC show that the molecular weight of nylon‐6 increased with recycling (M_w = 17% and M_n = 14%). With the reprocess was also observed the presence of gels. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 851–858, 2000     

Foaming of EPDM with water as blowing agent in injection molding

Chemical foaming of elastomers is state of the art and preferred to the more complex systems engineering of physical foaming, yet, many commonly used chemical blowing agents often are hazardous. In current investigations, we introduced water bound to carrying substances (silica, carbon black) into elastomer compounds. A stable, reproducible foaming process can be implemented using water as physical blowing agent. In first tests, the average cell diameters in injection molded elastomer parts exceed the average cell diameters of chemically foamed parts. Yet, varied amounts of blowing agent can reduce the cell diameters. Furthermore, nucleating agents and water carriers are being examined to reduce cell diameters and reach cellular structures and mechanical properties of chemically foamed parts. In conclusion, foaming of elastomers with water is a promising. Yet, further examinations have to cover the effect mechanism of foaming and vulcanization as well as continuous processing and compounding. Rear end of an EPDM part foamed with water carried on silica in injection molding process (mold temperature 195 °C, breathing mold opening 2 mm) © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43613.     

Effect of injection molding on structure and properties of poly(styrene-ethylene-butylene-styrene) and its nanocomposite with functionalized montmorillonite

In this paper, the effects of injection molding on structure and properties of poly(styrene-ethylene-butylene-styrene) (SEBS) and its nanocomposite with a functionalized montmorillonite (FMMT) were illustrated by comparison with the results of hot pressing. The injection-molded SEBS and its FMMT nanocomposite have a skin-core morphology with FMMT platelets more preferentially aligned along the sample plane, while hot-pressed samples not. The injection-molded samples also have a dense structure, and a less extent of microphase separation. In the injection molding process, the high shear flow coupled with solidification in presence of temperature gradient and high pressure in the closed cavity greatly affect the morphology and structure of the SEBS and its nanocomposites. The results also indicate attractive interaction between the soft segments of SEBS and the long alkyl silane chain grafted to FMMT, which allows FMMT to form a macroscopic network structure after the high-speed and high-pressure injection molding. The SEBS/FMMT-injected nanocomposite have the highest tensile strength and the best corrosion resistance, which can be attributed to the dense skin-core structure, stronger SEBS/FMMT interaction and the preferentially aligned FMMT platelets.     

Smart carboxymethylchitosan hydrogels that have thermo‐ and pH‐responsive properties

Thermo‐responsive poly(N‐isopropylacrylamide) (poly(NIPAAm)) and pH‐responsive poly(N,N′‐diethylaminoethyl methacrylate) (poly(DEAEMA)) polymers were grafted to carboxymethylchitosan (CMC) via radical polymerization to form highly water swellable hydrogels with dual responsive properties. Ratios of CMC, NIPAAm to DEAEMA used in the reactions were finely adjusted such that the thermo and pH responsiveness of the hydrogels was retained. Scanning electron microscopy (SEM) indicated the formation of an internal porous structure for the swollen CMC hydrogels upon incorporation of poly(NIPAAm) and poly(DEAEMA). Effect of temperature and pH changes on water swelling properties of the hydrogels was investigated. It was found that the water swelling of the hydrogels was enhanced when the solution pH was under basic conditions (pH 11) or the temperature was below its lower critical solution temperature (LCST). These responsive properties can be used to regulate releasing rate of an entrapped drug from the hydrogels, a model drug, indomethacin was used to demonstrate the release. These smart and nontoxic CMC‐based hydrogels show great potential for use in controlled drug release applications with controllable on‐off switch properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41505.