Effect of two different plasticizers on the properties of poly(3‐hydroxybutyrate) binary and ternary blends

Plasticized poly(3‐hydroxybutyrate) (PHB) films were obtained by solvent casting. The effects of two different additives on several properties of PHB have been examined, utilizing tributyrin and poly[di(ethyleneglycol) adipate] (A). Based on changes in the glass transition temperature (T_g) and cold crystallization temperature of host PHB, the two components are miscible with PHB and they can act as plasticizers. Binary and ternary blends were obtained by adding both plasticizers separately or together, respectively. The effect of plasticizer addition on the optical transparency, water vapor permeability, and tensile properties of the films was studied. It was found that the blends remain transparent and water vapor permeability was maintained constant until a 20 wt % of plasticizer content. Plasticizing effect was corroborated and it depended on the plasticizer percentage. Binary blends had an increased plasticity, in concordance with T_g diminution of PHB. Although ternary blends presented T_g diminution, mechanical properties were not improved probaby due to strong interactions between plasticizers. Finally, binary and ternary blends presented enhanced properties, causing an increment on processability. A correct knowledge between the formulation of the film and the role played by each component could allow getting custom films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46016.     

Edible films from mucilage of Cereus hildmannianus fruits: Development and characterization

Mucilages are heteropolysaccharides with rich monosaccharide composition. They are capable of forming films that are brittle and fragile, and in order to obtain flexible materials, plasticizers must be added. The present study aims to evaluate the physicochemical properties of mucilage‐based films produced with Cereus hildmannianus and different glycerol concentrations by the casting technique. Transparent and yellowish films were obtained by the addition of glycerol, which also improved handleability, evidenced by increased elongation, and reduced tensile strength and Young's modulus. Thermal gravimetric analysis and differential thermal analysis revealed that glycerol presence reduced the thermal stability, showing the influence of a plasticizer over the polymer structure. Water absorption capacity and contact angle were reduced with the increase of plasticizer concentration; on the other hand, the water vapor permeability increased, as expected, due to the hydrophilic nature of glycerol. The results indicated the potential application of C. hildmannianus mucilage as a promising material to produce edible films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45223.     

Films of chitosan and N‐carboxymethylchitosan. Part II: effect of plasticizers on their physiochemical properties

Chitosan (Ch) and N‐carboxymethylchitosan (N‐CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG‐400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1:1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG‐400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N‐CMCh. While the PEG‐400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG‐400 > unplasticized film; this was more pronounced in the N‐CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. Copyright © 2006 Society of Chemical Industry     

Mechanical properties and thermal aging behavior of styrene‐butadiene rubbers vulcanized using liquid diene polymers as the plasticizer

The mechanical properties of styrene‐butadiene rubber (SBR) vulcanizates prepared using various plasticizers including liquid polybutadiene and styrene‐butadiene copolymers were investigated. The effect of the liquid polymers as the plasticizers on the mechanical properties of the polymers, such as the hardness, tensile storage modulus, tanδ, and the modulus at 100% elongation values, were determined before and after the thermal aging. As a result, it was revealed that the use of these liquid polymers gave less amount of change in the measurement values for the mechanical properties during the aging. The crosslinking density and the amount of free polymers were also determined on the basis of the swelling and extraction data, respectively, using several organic solvents. These results support the fact that the added liquid polymers are fixed to the SBR networks. We revealed the superiority of the liquid styrene‐butadiene copolymers as the plasticizer, which provides sufficient mechanical properties after vulcanization and the excellent maintenance of the properties during the thermal aging process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Optimizing the mechanical and physical properties of thermoplastic starch via tuning the molecular microstructure through co‐plasticization by sorbitol and glycerol

Nowadays, environmental hazards caused by plastic wastes are a major concern in academia and industry. Utilization of biodegradable polymers derived from renewable sources for replacing common petroleum‐based plastics is a potential solution for reducing the problem. In this regard, starch has become one of the most promising alternatives to non‐biodegradable polymers for depleting plastic waste thanks to its low expense, abundance, renewability and biodegradability. However, the main drawbacks of starch are its poor processability, weak mechanical properties and severe hydrophilicity. In this work, thermoplastic starch (TPS) samples have been prepared using glycerol and sorbitol as co‐plasticizers in a laboratory co‐rotating twin screw extruder. Based on the mechanical test results, glycerol caused higher elongation to break but had lower tensile strength and elastic modulus compared to sorbitol plasticized starch. Fourier transform infrared spectroscopy and DSC results indicated that the hydrogen bond interaction between starch chains and plasticizers could be improved by replacing glycerol by sorbitol, which resulted in higher resistance against retrogradation proved by XRD results. TGA illustrated that the higher the sorbitol to glycerol ratio was, the more stable was the TPS. Using a proper amount of plasticizers (42 wt% total plasticizer, sorbitol to glycerol ratio 2:1) led to the preparation of a TPS sample with optimized properties including enhanced mechanical properties, high thermal stability, strong hydrogen bond formation and high resistance against retrogradation. © 2017 Society of Chemical Industry     

Preparation and characterization of starch‐based composite films reinforced by corn and wheat hulls

Biodegradable films, with starch as a matrix, were developed and reinforced with wheat and corn hulls. The effect of the particle size of the filler on the microstructure and mechanical and barrier properties of starch‐based films was investigated. We observed that the addition of hulls enhanced the modulus, tensile strength, and impact strength of the starch matrix at the expense of its elongation. The water‐vapor transmission rate results show that corn starch was more efficient in reducing the water‐vapor permeability than wheat hulls. Scanning electron microscopy observations indicated that the compatibility of both fillers with the matrix was quite good; this was expected because all of the components used in this study were hydrophilic and exhibited polar behavior. Optical microscopy and X‐ray diffraction observations indicated that the processing conditions did not affect the crystalline and geometric structures of the hulls. Because all of the components used in this study were from food resources, the films could also be used for edible packaging. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45159.     

Plasticized poly(3‐hydroxybutyrate) with improved melt processing and balanced properties

The widespread application of poly(3‐hydroxybutyrate) (PHB) in the food packaging and biomedical fields has been hindered by its high brittleness, slow crystallization, poor thermal stability, and narrow processing window. To overcome these limitations, a mixture of biodegradable and biocompatible plasticizers was used to modify PHB. Epoxidized soybean oil (ESO), acetyl tributyl citrate, poly(ethylene glycol) 4000 (PEG4000), and poly(ethylene glycol) 6000 (PEG6000) were tested to improve PHB melt processing and to achieve balanced thermal and mechanical properties. These plasticizers increased the flexibility and decreased the melt viscosity, improving the processability. The tensile strength was maintained within the limit of experimental error for ESO and decreased slightly (6–7%) for the other plasticizers. PEG6000 and ESO delayed the decomposition process of PHB. The plasticizers did not hinder the crystallization, and poly(ethylene glycol)s increased the crystallinity. The change in the interplanar distance and crystallite size, correlated with lamellar stack dimensions, gave more information on the plasticizers' effects in PHB. The blend with 5 wt % ESO was considered suitable for the fabrication of marketable PHB films. This study showed that it is possible to tailor the rheological, thermal, and mechanical behavior of a commercial PHB through the addition of a second plasticizer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44810.     

Electron‐beam processing of destructurized allylurea–starch blends: Immobilization of plasticizer by grafting

Allylurea (AU) was used as a reactive additive with poor aptitude to homopolymerization for obtaining grafted plasticized starch films with stabilized physical properties. Potato starch was mixed with AU (30–50 parts per hundred/pph) in a mixer operating at 125°C. Upon storage in well‐defined hygrothermal conditions, the resulting thermoplastic material shows strong plasticizer migration revealed by AU crystals blooming at the samples surface and exhibits strong opacity assigned to phase separation of the organic additive inside the material. Freshly prepared thermoplastic films of appropriate thickness were exposed to a 175‐kV electron beam (EB) radiation for inducing covalent grafting of AU by a free radical process. FTIR monitoring of the resulting chemical changes in thin films of AU–starch blends indicates unambiguously the transformation of AU allylic bond. High irradiation doses are required for achieving complete conversion of AU in the blend. However, no detectable AU migration was observed for intermediate AU conversion, probably as a consequence of higher plasticizer solubility in the grafted polysaccharide. Examination of the viscoelastic properties by dynamic mechanical thermal analysis shows that artificial aging by placing the films alternatively in high and low relative humidity (RH) atmosphere does not significantly alter the thermomechanical spectrum of the material reconditioned in a cell at 58% RH. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 409–417, 1999     

The morphology,rheological, and mechanical properties of wood flour/starch/poly(lactic acid) blends

An entirely biosourced blend composed of poly(lactic acid) (PLA), starch, and wood flour (WF) was prepared by a co‐extruder with glycerol as a plasticizer. The morphology, rheological properties, and mechanical properties of the WF/starch/PLA blends were comprehensively analyzed. The results showed that with the decrease of the starch/WF ratio, the morphology experienced a large transformation, and the compatibility of the blends was found to be superior to other blends, with a starch/wood flour ratio of 7/3. The dynamic mechanical thermal analysis (DMA) results demonstrated the incompatibility of the components in WF/starch/PLA blends. Following the decrease of the starch/WF ratio, the storage modulus (G″) and the complex viscosity (η*) of the blends increased. The mechanical strength first increased, and then decreased with the increase of the WF concentration. The water absorption results showed that the water resistance of the blends was reduced with the lower starch/WF ratio. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44743.     

Effect of five saturated fatty acids on the properties of sweet‐potato‐starch‐based films

To fully explore the influences of saturated fatty acids (SFAs) on the properties of sweet‐potato‐starch (SPS)‐based films, five SFAs were chosen to add to SPS. The SPS‐based films were prepared by casting. The microstructure, mechanical, optical, water vapor barrier, and thermal properties of the films were investigated. The 2.0% (w/w, on the basis of starch) SFA significantly changed the SPS pasting characteristics in the peak viscosity, breakdown, and other feature point viscosity values as determined by a Rapid Visco Analyser. The amylose molecular weights decreased as measured by high‐performance size exclusion chromatography. A thermal study with differential scanning calorimetry suggested that the addition of SFA increased the onset temperature and peak temperature. Scanning electronic microscope (SEM) images showed a continuous and uniform structure in the films with SFA. The SPS–SFA composite films showed lower light transmission and elongation at break than the control. Compared with the control films, the addition of SFA increased the tensile strength and decreased the water vapor permeability of the films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41380.     

Structure and properties of a compatible starch‐PCL composite using p‐phthaloyl chloride‐based prepolymer

Biodegradable composites from starch and hydrophobic polymer usually show poor compatibility. A novel p‐phthaloyl chloride‐based prepolymer (PCP) compatibilizer based on p‐phthaloyl chloride and polycaprolactone (PCL) diol (2000) was synthesized successfully and the chemical structure was characterized by Fourier transform infrared spectra and ¹H nuclear magnetic resonance (NMR). The PCP compatiblizer was mixed with starch granules to form a coating layer, and then the coated starch granules were melt‐compounded with PCL plastic to prepare compatible starch‐PCL composites with enhanced properties. The structural, mechanical, thermal properties, and water absorption of the composites were then investigated. It was found that the composites containing the PCP compatibilizer showed better interfacial interaction and compatibility between starch and PCL domains compared to the pure starch‐PCL composite, which led to the improved mechanical properties of the composites. The results were attributed to the ester linkage between the PCP compatibilizer and starch as well as the strong physical crosslinking between the PCP compatibilizer and PCL plastic through PCL‐PCL crystallinity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45400.     

Oxygen barrier materials from renewable sources: Material properties of softwood hemicellulose‐based films

The aim of this study was to investigate the film‐forming ability of the hemicellulose O‐acetyl‐galactoglucomannan (AcGGM) and to evaluate its potential as a barrier material. The polymer film was evaluated by measurement of its oxygen permeability (Ox‐Tran® Mocon), thermal properties (differential scanning calorimetry), and dynamic mechanical properties under a humidity scan (humidity‐scan DMA). The AcGGM was isolated from industrial process water obtained from mechanical wood pulping. The self‐supporting films were formed by solution‐casting from water. As expected, a plasticizer was needed to avoid brittleness, and glycerol, sorbitol, and xylitol were compared. However, these additives resulted in higher sensitivity to moisture, which might be less beneficial for some applications. Interesting oxygen barrier and mechanical strength properties were achieved in a film obtained from a physical blend of AcGGM and either alginate or carboxymethylcellulose, both having a substantially higher molecular weight than AcGGM. No phase separation was observed, since all the components used were rich in hydroxyl functionalities. When a plasticizer was also added to the binary mixture, a compromise between (1) low O₂ permeability, (2) high mechanical toughness, and (3) flexibility of an AcGGM‐based film was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2985–2991, 2006     

Effects of vanillin and plasticizer on properties of chitosan‐methyl cellulose based film

Chitosan‐methyl cellulose based films which incorporatate vanillin as an antimicrobial agent and polyethylene glycol 400 (PEG) as a plasticizer were developed in this study. The effects of vanillin and plasticizer concentration on mechanical, barrier, optical, and thermal properties of chitosan‐methyl cellulose film were evaluated. When the vanillin concentration was increased at a given PEG level, film flexibility decreased while tensile strength increased slightly. Vanillin increased the barrier to oxygen but not water vapor. Increasing vanillin content resulted in less transparency and a more yellowish tint. The bulky nature of vanillin reduced film crystallization. When PEG concentration was increased at a given vanillin level, it resulted in greater film flexibility but reduced film strength. Water vapor permeability (WVP) and oxygen permeability (OP) increased with increase in PEG content. PEG contributed less to the opacity, yellowness, and crystallization of the film than did vanillin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dialkyl furan‐2,5‐dicarboxylates,epoxidized fatty acid esters and their mixtures as bio‐based plasticizers for poly(VInylchloride)

Dialkyl furan‐2,5‐dicarboxylates and epoxidized fatty acid esters (EFAE) of varying molecular weights and volatilities, as well as their mixtures, were investigated as alternative plasticizers for poly(vinylchloride) (PVC). The EFAE utilized were epoxidized soybean oil (ESO) and epoxidized fatty acid methyl ester (e‐FAME). All plasticizers were compatible with PVC, with plasticization efficiencies usually increasing with decreasing molecular weights of the plasticizers (except in the case of ESO, which was remarkably effective at plasticizing PVC, in spite of its relatively high molecular weight). In comparison with phthalate and trimellitate plasticizers, the alternatives generally yielded improved balance of flexibility and retention of mechanical properties after heat aging, with particularly outstanding results obtained using 30?50 wt % e‐FAME in mixtures with diisotridecyl 2,5‐furandicarboxylate. Although heat aging characteristics of the plasticized polymer were often related to plasticizer volatilities, e‐FAME performed better than bis(2‐ethylhexyl) 2,5‐furandicarboxylate, and bis(2‐ethylhexyl) phthalate of comparatively higher molecular weights. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42382.     

Preparation and characterization of nano‐SiO2 reinforced alginate‐based nanocomposite films (II)

Crosslinked alginate‐based nanocomposites at different SiO₂ contents were prepared successfully by blending the nano‐SiO₂ solution into low concentration alginate solution (0.5 wt %), with the alginate concentration increased step by step to the resulted concentration, in this course glycerol was used as plasticizer and 5 wt % CaCl₂ as crosslinker. The combined effect of SiO₂ content (1.5–8 wt %) on the microstructural, physical, mechanical, and optical properties of the nanocomposite films were investigated. The results showed that tensile strength and elongation was improved by about 40.33% and 89%, respectively, upon increasing the SiO₂ content to 4.5 wt %. In addition, water vapor permeability and swelling degree decreased by 19% and 16% with increasing SiO₂ content up to 8 and 4.5 wt %, respectively with respect to pure crosslinked alginate film. Thermogravimetric analysis also revealed that nano‐SiO₂ can improve the thermal stability of sodium alginate films produced by this method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45286.     

Mixture design applied for the development of films based on starch,polyvinyl alcohol,and glycerol

Starch and polyvinyl alcohol (PVA) are biodegradable materials with potentiality to replace the conventional polymers in some applications. The aim of this work was to produce biodegradable films of PVA, cassava starch, and glycerol by thermoplastic extrusion using a mixture design to evaluate the effects of each component in the blend properties. Six formulations were prepared using a twin‐screw extruder coupled with a calender. All the materials were visually homogeneous and presented good processability. Mechanical properties were dependent on both the relative humidity conditioning and the formulation; higher relative humidities detracted the mechanical properties, which was associated to plasticizer effect of the water. Furthermore, the mechanical properties were better when higher concentrations of PVA were used, resulting in films with lower opacity, lower water vapor permeability, and higher thermal stability, according to TGA. Biodegradable materials based on starch, PVA, and glycerol have adequate mechanical and processing properties for commercial production. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42697.     

Poly(citrate glyceride): a hyperbranched polyester for starch plasticization

Hyperbranched polyesters (HBPETs), terminated with either hydroxyl or carboxyl groups, were prepared from citric acid and glycerol in simple one‐step syntheses. The HBPET structure and degree of branching were investigated using Fourier transform infrared and ¹H NMR spectroscopies and gel permeation chromatography. The HBPET plasticizers were combined with a maize starch via cooking and film formation. The mechanical, thermal, paste and structural properties of the plasticized starch composites were studied in detail using differential scanning calorimetry, thermogravimetric analysis, rapid viscosity analysis and X‐ray diffraction. The HBPETs reduced the pasting viscosity but slightly increased the pasting temperature of the starch. The smaller breakdown and setback values of the plasticized starch pastes relative to those of native starch suggested weaker retrogradation. Compared with glycerol/starch plasticized films, HBPET/starch composite films had lower crystallinity, lower glass transition temperature and better mechanical and thermal properties. The properties of the plasticized starch samples strongly depended on the terminal groups and the molecular weight of the HBPET plasticizers. © 2017 Society of Chemical Industry     

Bioplastic based on 1,8‐octanediol‐plasticized feather keratin: A material for food packaging and biomedical applications

Keratin without plasticizer produces fragile films. 1,8‐Octanediol (OD) was used as a plasticizer to modify keratin films in this study. Two keratins with different structures were extracted from duck feather, including reduced keratin (RK) and native keratin (NK). Formaldehyde was used as the crosslinking agent for RK to prepare crosslinked keratin (CK) films. The addition of OD toughened the CK and RK films. In particular, the plasticized CK films demonstrated good mechanical properties and had satisfactory water resistance. The water vapor permeability varied between 0.106 and 0.808 g/(m s Pa) for CK films without OD and with 0.30 g OD/g keratin, respectively, and the tensile strength decreased from 12.1 to 8.0 MPa and the elongation at break increased from 2.3% to 11.6%. Cell culture experiments suggest that OD‐plasticized NK films are biocompatible. In general, OD‐plasticized keratin films can find applications in food packaging and biomedical materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46516.     

Addition of 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl) imide to improve the thermal stability of regenerated cellulose

This article reports the influence of 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl) imide (BMITFSI) addition on the thermal and mechanical properties of regenerated cellulose. Scanning electron microscopy, Young's modulus values, thermogravimetric analysis, glass‐transition temperature values, and ultraviolet–visible spectroscopy were used to assess the effect of BMITFSI addition on the properties of regenerated cellulose. The addition of a room‐temperature ionic liquid, BMITFSI, during the dissolution of cellulose was found to enhance the thermal stability of regenerated cellulose. Compared to other reported plasticizers for regenerated cellulose, such as glycerol, glycols, water, mineral oil, and α‐monoglycerides, the low vapor pressure of BMITFSI led to a long performance with the least evaporation or leaching. In addition, the immiscible nature of BMITFSI in water and its stability against moisture made BMITFSI an effective plasticizer for regenerated cellulose over a broad range of surrounding humidities and temperature conditions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cassava starch‐based nanocomposites reinforced with cellulose nanofibers extracted from sisal

Cellulose nanofibers were extracted from sisal and incorporated at different concentrations (0–5%) into cassava starch to produce nanocomposites. Films' morphology, thickness, transparency, swelling degree in water, water vapor permeability (WVP) as well as thermal and mechanical properties were studied. Cellulose nanofiber addition affected neither thickness (56.637 ± 2.939 µm) nor transparency (2.97 ± 1.07 mm^?1). WVP was reduced until a cellulose nanofiber content of 3.44%. Tensile force was increased up to a nanocellulose concentration of 3.25%. Elongation was decreased linearly upon cellulose nanofiber addition. Among all films, the greatest Young's modulus was 2.2 GPa. Cellulose nanofibers were found to reduce the onset temperature of thermal degradation, although melting temperature and enthalpy were higher for the nanocomposites. Because cellulose nanofibers were able to improve key properties of the films, the results obtained here can pave the route for the development and large‐scale production of novel biodegradable packaging materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44637.