Effects of plasticizer/cross-linker on the mechanical and thermal properties of starch/PVA blends

Biodegradable blends of potato starch and polyvinyl alcohol were prepared by solution casting method. Citric acid was employed to introduce the plasticizing effect into the starch materials. Glutaraldehyde as cross-linker was used to enhance the properties of the blend films. Cross-linking is a common method to improve the strength and stability of starch products. The effects of citric acid and glutaraldehyde on the mechanical properties, thermal properties and swelling degree were investigated. The prepared films were measured for their antibacterial activities and biodegradability. The blend samples were characterized by the thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and FTIR analysis techniques. From the mechanical properties study, it was analyzed that the blend films showed improvement in their tensile strength after cross-linking with glutaraldehyde. The SEM micrographs indicated that the blend films were smooth without any cracks, pores and were well cross-linked. The TGA curves showed that there was an increase in the thermal stability of the blend films after cross-linking as compared to uncross-linked blend films. The prepared films showed good antibacterial properties against Gam-positive and Gram-negative bacteria. The biodegradability of the blends was determined by placing the samples in compost soil for different time intervals and were found to be biodegradable in nature.     

Preparation and characterization of films based on crosslinked blends of gum acacia,polyvinylalcohol, and polyvinylpyrrolidone-iodine complex

In an attempt to develop iodine-release systems based on polymeric blend for biomedical applications, our research group prepared blends of gum acacia (GA), polyvinylalcohol (PVA), and polyvinylpyrrolidone-iodine (PVP-I) complex. The blends of GA/PVA and GA/PVA/PVP-I prepared from the aqueous solutions of the polymers were crosslinked with glutaraldehyde to increase the water resistance of the films and to improve their thermal and mechanical properties. The crosslinked GA/PVA and GA/PVA/PVP-I blend films were characterized by FTIR spectroscopy, DSC, and TGA. The swelling behavior of the prepared blends was investigated and crosslinked GA/PVA blend films were found to be pH sensitive. The properties of PVP-I containing blends differed from those prepared without it probably due to the formation of an intermolecular interaction between PVP-I and the hydroxy-polymers. The results indicated that after crosslinking the blends showed improvement in water resistance, thermal, and mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polyamide‐reinforced ethylene–propylene–diene rubber compatibilized with chlorinated polyethylene

Vulcanizates of blends of ethylene–propylene–diene rubber and polyamide copolymers were prepared by reactive compatibilization. A reactive route was employed for compatibilizing these blends with the addition of chlorinated polyethylene (CPE). The influence of the compatibilizers, crosslinking agents, blend compositions, and addition modes of the compatibilizers on the mechanical properties of the blends was investigated. The morphologies of the blends were determined with scanning electron microscopy. The addition of CPE was found to reduce the particle size of the dispersed phase remarkably. The stability of the blends with compatibilizers was measured by high‐temperature thermal aging. The mechanical properties were examined by stress–strain measurements and dynamic mechanical thermal measurements; the addition of polyamide copolymers caused significant improvements in the tensile properties of these blends.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1727–1736, 2003     

Binary mixtures of polyethylene and oxidized wax: Dependency of thermal and mechanical properties upon mixing procedure

The influence of the preparation procedure on the thermal and mechanical properties of linear low‐density polyethylene (LLDPE)– and LDPE–oxidized wax blends was investigated. It was found that mechanically mixed blends show reduced thermal stability as well as ultimate mechanical properties (stress and strain at break) compared to that of extrusion mixed blends. However, the structure of the blend and consequently its thermal and mechanical behavior also depend on the initial morphology of polyethylene. DSC measurements show miscibility up to high wax contents in both blend types, but increasing the amount of wax in LDPE blends induces increasing crystallinity. As a result, the LDPE/wax blends show improved thermal stability of between 20 and 50°C at low wax concentrations. Although the elasticity modulus of the blends increases, increasing the amount of wax generally degrades the mechanical properties. The main reason for this is the reduced number of tie chains. Changes in the average concentration of tie chains with increasing wax content were calculated and a correlation was made with the ultimate properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2446–2456, 2003     

Preparation and properties of foamed cellulose acetate/polylactic acid blends

In order to improve the foaming performance of pure cellulose acetate (CA), blends were prepared by mixing polylactic acid (PLA) in CA and foamed by supercritical CO₂ (ScCO₂) in this study. The effect of PLA content (percentage by mass of blend) on structure, thermal properties, rheological properties, foaming properties and mechanical properties of the blends was investigated. The results showed that the addition of PLA destroyed the original hydrogen bonds of CA, while the blends had good crystallization properties. At the same time, compared with pure CA, the glass transition temperature (T_g) of the blends decreased, and the initial decomposition temperature (T₀) was reduced from 349.41°C (pure CA) to 334.68°C (CA/20%PLA). In addition, the rheological properties of the blends were improved, and the viscosity was reduced, which was obviously beneficial to foaming process. The pore size and density of the foamed blends both reached the maximum value at 20%PLA. The presence of PLA could degrade the mechanical properties of the blends. However, the overall drop (1.01 KJ/m²) of impact strength of the blends after foaming is much smaller than that before foaming (12.11 KJ/m²), indicating that the improvement of foaming performance was beneficial to improve its impact strength.     

Miscibility, free volume behavior and properties of blends from cellulose acetate and castor oil-based polyurethane

A series of blend films from cellulose acetate (CA) and castor oil-based polyurethane (PU) were prepared. Morphology, miscibility, free volume behavior and properties of such blend films were investigated by wide-angle X-ray diffraction (WXRD), infrared, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS), thermogravimetric analysis and tensile test. The results indicated that lager free volume cavities did not form at the interface of two polymers although a certain degree of phase separation was found by the studies of SEM and DSC. Strong intermolecular hydrogen bonding interactions at the interface, which was proved by Fourier transform infrared spectroscopy, favors even better molecular packing, that is, PU dispersed in CA continuous phase to form fine microphase separation domain in the CA-rich blends. Due to such special interactions in the fine microphase separation domain structure, optimized properties of tensile strength, breaking elongation and cold-resistivity were obtained in the blend film with 75 wt% CA. The toughness of all the blend films was significantly higher than that of the film CA, owing to the plasticizing of PU elastomer in the blends.     

Poly(vinyl alcohol)-clay and poly(ethylene oxide)-clay blends prepared using water as solvent

Montmorillonite (MON) was solvent-cast blended with poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) using water as cosolvent. The structure and properties of the blend films have been investigated. From small- and wide-angle X-ray scattering measurements of the blends, the silicate layers of MON are found to be well dispersed individually in the PVA-MON blends, while the silicate layers in PEO-MON blends are found to exist in the form of a large clay tactoid. Furthermore, for both blends, it is found that the silicate layers are parallel to the film surface of the blends, and that preferred orientation of polymer crystallites is induced by the presence of MON. The effects of the MON content on the thermal behavior of the PVA- and PEO-MON blends have been studied with a differential scanning calorimeter. Furthermore, the effects of geometry of the silicate layers on dynamic behavior of the blends have been studied. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 573–581, 1997     

Physico-chemical characterization of compatibilized poly(propylene)/aromatic polyamide blends

Poly(propylene)/aromatic polyamide blends were prepared by melt mixing, without or with the addition of an interfacial modifier, viz. a poly(propylene) polymer grafted with 1 wt.-% of maleic anhydride. The characteristics of these polymer blends were investigated by differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy and surface tension measurements. The transport parameters of oxygen through films of such polymer blends were also determined by the differential permeation method. The new compatibilized blend materials, being transparent, sterilizable, dimensionally stable, and having very high barrier properties towards oxygen, are particularly suitable for packaging applications.     

Effects of a diisocyanate compatibilizer on the properties of citric acid modified thermoplastic starch/poly(lactic acid) blends

In this article, for the first time in the literature effects of phenylene diisocyanate (PDI)‐based compatibilizer on the physical and chemical properties of citric acid (CA) modified thermoplastic starch (TPS)/poly(lactic acid) (PLA) blends were investigated with respect to PDI and CA content and blend composition. The blends were prepared by melt compounding in a laboratory microcompounder. Fourier transformation infrared spectroscopy results showed that CA interacted with starch and PDI interacted by both starch and PLA through the hydroxyl groups. It was revealed from SEM micrographs that combinatorial usage of CA and PDI resulted in an improved, finer distribution of TPS in PLA matrix. This improvement affected the mechanical properties of blend, especially the toughness related properties such as impact strength and elongation at break. The thermal properties such as T_g and T_m revealed from differential scanning calorimeter analysis were in line with the morphological structure of the blends by suggesting the compatibilization phenomena in the presence of PDI and CA together. Thermogravimetric analysis showed that compatibilization of two phases improved the thermal stability of the blends. As a general conclusion, the combinatorial usage of PDI and CA can be utilized to obtain tougher PLA/TPS blends‐based materials to overcome the brittleness problem. POLYM. ENG. SCI., 53:2183–2193, 2013. © 2013 Society of Plastics Engineers     

Phase separation,physical properties and melt rheology of a range of variously transesterified amorphous poly(ethylene terephthalate)–poly(ethylene naphthalate) blends

Amorphous, partially transesterified poly(ethylene terephthalate)/poly(ethylene naphthalate) (PET/PEN) blends of different levels of transesterification and blend composition were investigated in terms of resultant phase behavior, thermal transitions, and melt rheological properties. Intrinsic viscosities of the lowest transesterified material were found to be significantly below those of a physical blend of an identical composition, but at higher levels of transesterification, there was little difference. This was similarly found in melt rheometry measurements, where the zero‐shear rate viscosity of the low and highly transesterified mixtures were similar. Both solution and melt rheometry indicated that the molecular weight decreased by thermal degradation from processing. This is believed to play an important role in determining the final molecular architecture and properties. For similar levels of ester interchange, there was a minimum observed in zero shear melt viscosity at around 40 wt % PEN. This is likely due to competition between the slightly transesterified copolymer chains having poorer packing in the melt and reduced entanglement. Differential scanning calorimetry and dynamic mechanical thermal analysis were used to investigate the phase behavior of partially and fully transesterified blends. Results for the glass transition of the highly transesterified blends were compared with the theoretical values calculated from the Fox equation and were found to be close, although slightly lower. A correlation between the melting temperature of the blend and the degree of transesterification was shown to exist. This correlation can be used to estimate the degree of ester exchange reaction from these melting transitions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1556–1567, 2002     

Miscibility,thermal behaviour,morphology and mechanical properties of binary blends of poly[(R)‐3‐hydroxybutyrate] with poly(γ‐benzyl‐L‐glutamate)+

The miscibility, thermal behaviour, morphology and mechanical properties of poly[(R)‐3‐hydroxybutyrate] (PHB) with poly(γ‐benzyl‐L ‐glutamate) (PBLG) are investigated by means of differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests. The DSC results show that PHB and PBLG are immiscible in the melt state. Such immiscibility also exists in the amorphous state due to a clear two‐phase separated structure observed by SEM measurements. The blend samples with different thermal history, namely as original and melt samples separately, display differences in thermal behaviour such as the DSC scan profile, the crystallinity and the melting temperature of PHB. The crystallization of PHB both from the molten state and the amorphous state is retarded on addition of the second component. The SEM measurements reveal that a phase inversion occurs between the PHB/PBLG (60/40) and PHB/PBLG (40/60) blends. Except for the PHB/PBLG (40/60) blend, a microphase separated structure is observed for all blend compositions. The mechanical properties vary considerably with blend composition. Compared with pure components, the PHB/PBLG (20/80) blend shows a certain improvement in mechanical properties. © 2001 Society of Chemical Industry     

Polyimide nanocomposite with a hexadecylamine clay: Synthesis and characterization

A poly(amic acid) was prepared by the reaction of 3,3′‐dihydroxybenzidine and pyromellitic dianhydride in N,N‐dimethylacetamide. Hexadecylamine was used as an organophilic alkylamine in organoclay. Cast films were obtained from blend solutions of the precursor polymer and the organoclay. The cast film was heat treated at different temperatures to create polyimide (PI) hybrid films. We set out to clarify the intercalation of PI chains to hexadecylamine–montmorillonite (C₁₆–MMT) and to improve thermal and tensile properties and the gas barrier. It was found that the addition of only a small amount of organoclay was enough to improve both the thermal and the mechanical properties of PIs. Maximum enhancement in the ultimate tensile strength for PI hybrids was observed for the blends containing 4% C₁₆–MMT. The initial modulus monotonically increased with further increases in C₁₆–MMT content. Water vapor permeability was decreased with increasing clay loading from 1 to 8 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2294–2301, 2002     

The effect of poly(butylene succinate) content on the structure and thermal and mechanical properties of its blends with polylactide

Poly(butylene succinate) (PBS) and polylactide (PLA) were blended in a co‐rotating twin‐screw extruder with various contents of PBS from 0 to 100 wt%. The effect of PBS content on the thermal and mechanical properties of PBS/PLA blends was investigated by using DSC, softening point measurements, a Charpy impact test and tensile testing. The Fourier transform infrared spectra showed that the polymers are immiscible, but the addition of PBS could modify the PLA structure in PBS/PLA blends by changing the content of amorphous and crystalline phases. In addition, the cold crystallization temperature of PLA in blends decreases in comparison with pure PLA, which shows that PBS could have a plasticizing effect on PLA. This is confirmed by the results of DSC analysis. The mechanical properties of the blends depend on the percentage of PBS addition. Typically, the mechanical properties of PBS/PLA blends are intermediate between the properties of the polyesters from which they are obtained. However, in some cases unexpected changes in mechanical properties of the blends were observed. For example, the elongation at break for a PBS/PLA blend containing 10 wt% PLA is higher than for pure PBS. © 2019 Society of Chemical Industry     

Improvement of physical properties of crosslinked alginate and carboxymethyl konjac glucomannan blend films

Blend films from carboxymethyl konjac glucomannan and sodium alginate in different ratios were prepared by blending 4 wt % sodium alginate aqueous solution with 2 wt % konjac glucomannan aqueous solution. After crosslinking with 5 wt % calcium chloride aqueous solution, the blend films formed a structure of semi‐interpenetrating networks. The structure and physical properties of both uncrosslinked and crosslinked films were characterized by Fourier transformed infrared spectra (FTIR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests. The results indicated that the mechanical properties and the thermal stability of the films were improved by blending sodium alginate with carboxymethyl konjac glucomannan due to the intermolecular hydrogen bonds between sodium alginate and carboxymethyl konjac glucomannan. The crosslinked blend films with Ca²⁺, compared with uncrosslinked blend films, exhibited further improved physical properties due to the formation of a semi‐IPN structure. Furthermore, the degree of swelling of the crosslinked films was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2554–2560, 2002     

Acrylic rubber‐fluorocarbon rubber miscible blends: Effect of curatives and fillers on cure,mechanical, aging,and swelling properties

The cure characteristics and mechanical properties of gum and filled acrylic rubber (ACM), fluorocarbon rubber (FKM), and their blends of varying compositions were studied both under unaged and aged conditions. The rheometric study showed that optimum cure properties were obtained using a mixed curing system of blocked diamine, hexamethylenediamine carbamate (Diak #1), and ammonium benzoate. From varying the curing agents, the optimum levels of Diak #1 and ammonium benzoate were found to be 1.5 and 2.5 phr, respectively. The addition of different fillers and their loading influenced the cure properties, with increased torque and reduced scorch safety. The gum and filled 50:50 (w/w) ACM‐FKM showed overall performance in strength properties. Postcuring improved the strength of all the systems, especially the systems with a higher proportion of FKM. None of the properties changed significantly during aging of the blends. FKM and the blends containing a higher proportion of FKM were affected least by aging. Swelling of the blends was reduced by the addition of fillers. Dynamic mechanical thermal analysis showed a single tan δ peak corresponding to a single phase transition for both cured and filled blends. The storage modulus of the blend increased from the gum blend to the filled blend, indicating the presence of polymer‐filler interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1442–1452, 2003     

Electrical and mechanical properties of ethylene propylene diene monomer–chloroprene rubber blend loaded with white and black fillers

The permittivity ε′ and dielectric loss ε" for different ratios of an ethylene propylene diene monomer (EPDM)–chloroprene rubber (CR) blend ranging from 0 to 100 phr were measured over a frequency range from 400 Hz to 60 kHz. The measurements were carried out at room temperature (25°C). The values of ε′ and ε" were found to decrease with increasing EPDM content in the EPDM–CR blend. The sample which possesses the best mechanical and electrical properties was a 50 EPDM–50 CR blend. This sample was chosen to be loaded with 40 phr of some white fillers, namely, calcium carbonate, silica, silitan z, and talc. From the electrical and mechanical investigations, it was found that the use of silica and calcium carbonate in these blends could improve these properties. The electrical and mechanical properties were also studied for the investigated blends loaded with both silica and calcium carbonate with different contents (10–40 phr). It was found that 20 phr is the most promising concentration which can possess better properties. The same trend was obtained by the addition of 20 phr SRF black in addition to the white fillers to the above blends. On the other hand, from the compatibility study between both investigated rubber, it is found that both types are incompatible, in which some improvement may occur by the addition of PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2061–2068, 1998     

Study on physical properties of blend films from gelatin and polyacrylamide solutions

Blend films of gelatin and polyacrylamide (PAAm) were prepared by casting the mixed aqueous solutions of both samples in different ratios. All blend films obtained are optically clear to the naked eye. The structure and physical properties of the films were studied by FT‐infrared (FTIR), wide‐angle X‐ray diffraction (WAXD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The experimental results show that the blend films exhibit the higher thermal stability and improved mechanical properties of both tensile strength and elongation at break in dry states, which suggests the occurrence of interaction detected by FTIR between gelatin, PAAm, and water molecules in the films. The morphological transition of the blend films from gelatin‐like to PAAm‐like was observed by SEM. Furthermore, moisture content and water swelling property of the blend films were also investigated, which was consistent with the results from SEM. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 949–955, 2002     

Mechanical and thermal properties of poly(vinyl chloride)/α‐methyl‐styrene‐acrylonitrile blends prepared by melt extrusion

In this article, we have examined the physical and mechanical properties of poly(vinyl chloride) (PVC)/α‐methyl‐styrene‐acrylonitrile (αMSAN; 31 wt % AN concentrations) blends with different blend ratios. And, we also examined the effect of the molecular weights of PVC on the miscibility and material properties of the blends prepared by melt extrusion blending. Our results showed that the PVC/αMSAN blends have good processing properties and good miscibility over all blend ratios because of the strong interaction between PVC and αMSAN. And, the blends showed enhanced mechanical and thermal properties. In addition, high molecular weight PVC showed reasonable processability when melt blended with αMSAN, which resulted in enhanced mechanical and physical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Novel Poly(3-hydroxyoctanoate)/Poly(3-hydroxybutyrate) blends for medical applications

Novel Poly(3-hydroxybutyrate)/Poly(3-hydroxyoctanoate) blends were developed with varying amounts of Poly(3-hydroxyoctanoate), P(3HO) and Poly(3-hydroxybutyrate), P(3HB) for their potential use in various medical applications. These blend films exhibited higher tensile strength and Young’s modulus values compared to neat P(3HO). The overall protein adsorption and % cell viability was also found to be significantly higher in the blend films than the neat P(3HO) film. Hydrolytic degradation was faster in the blend films and the degradation rate could potentially be tailored to achieve the optimum rate required for a particular medical application. Hence, these novel blends were found to be highly biocompatible with surface, mechanical and thermal properties suitable for a range of potential medical applications, a great step forward in the area of medical materials.     

Thermal and mechanical properties of electron beam irradiated poly(vinyl chloride)/polystyrene blends

The effect of electron beam irradiation on the thermal and mechanical properties of poly(vinyl chloride)/polystyrene (PVC/PS) blends and PVC/PS blends containing epoxidized natural rubber (ENR) was studied. The thermogravimetric analysis study showed that the thermal decomposition of the plasticized PVC individual polymer goes through two stages, whereas PS decomposes through one stage. However, the temperature of the maximum rate of reaction (T_max) of PS is much higher than that for PVC and their blends. Meanwhile, the T_max was found to increase with increasing PS ratios in the blend. The thermal stability of PVC/PS blends was greatly increased after electron beam irradiation in comparison with unirradiated blends. Moreover, the addition of ENR to PVC/PS increased the thermal stability. On the other hand, the mechanical properties in terms of tensile strength and elongation at break of PVC/PS blends are lower than pure PVC polymer because of the immiscibility. However, the addition of ENR to the PVC/PS (80/20) blend increased the elongation at break from 114 to 321% associated with a small effect on the tensile properties. These behaviors were supported by structure morphology studies observations, which indicate an improvement in the interfacial adhesion between the phases. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers