Thermoplastic starch films: DOE and O2PLS methodology for optimization and increased understanding of polymer processing

The combined effect of a plasticiser (glycerol) and a cross-linking agent (borax) on the mechanical properties of commercially extruded thermoplastic hydroxypropylated starch films was examined. The use of Design of Experiment (DOE) was demonstrated and used to predict and optimise formulations for a given set of material properties. As an extension to DOE, Orthogonal 2 Partial Least Squares (O2PLS) provided insight into joint correlations between the machine and transverse direction mechanical properties. Specific information regarding individual measurements or samples was also obtained with this analysis. O2PLS identified unique variables in individual compositions that were potentially incorrect measurements, or processing defects, which in turn can be used to aid quality control or processing optimisation with regards to DOE. Overall, DOE and O2PLS showed that within a starch borax-glycerol blend, borax increased mechanical strength and enhanced creep and recovery, whilst glycerol increased elongation and decreased modulus. There were competing interactions between the two dependent on concentration, and variation between machine and transverse properties was due to the extrusion induced molecular orientation of amylose. The optimum concentrations of borax and glycerol needed to achieve higher elongation, tensile strength, modulus and creep recovery than a control was found to be approximately 0.5% and 10%, respectively.     

Preparation of LDPE-acetylated/butyrylated starch blend blow films and characterization

Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution(DS) on properties of films.Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene(LDPE).Systematic studies were done to observe the effect of acyl groups,DS and starch concentration on the properties and biodegradability of the blend films.It was observed that blend films containing 5% acetylated and butyrylated starches of high DS(2.5,1.7) maintained 75% and 83% of tensile strength of LDPE films.Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 °C and 389 °C which were higher than the decomposition temperature of native starch film(349 °C).Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE.Water absorption capacity of high DS acetylated and butyrylated starch blend films(4.18% and 3.76%,respectively) was lower than that of native starch films(5%).This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.     

Oxygen Barrier LDPE/LLDPE/Organoclay Nano-Composite Films for Food Packaging

Summary: This study intends to replace polyethylene multi-layer films used in food packaging industry with single-layer polyethylene nanocomposites films. Nanocomposites of LDPE/LLDPE/ montmorillonite organoclay were prepared by melt compounding in a twin extruder and then film blown to prepare thin films. LLDPE-g-MA was used as compatibilizer to achieve better interaction between the blend and organoclay. Various compositions of organoclay and compatibilizer were prepared. The structure of nanocomposites was characterized by XRD and TEM. Permeability properties were measured using a permeability measuring set-up and aspect ratio of the particles was evaluated using permeability data. The results showed that addition of organoclay even at low level (below 5 phr) had significant effect on barrier properties of the nanocomposites. Oxygen permeability decreased by 50% by adding only 3 phr of nanoclay into the blend. Crystalline structure of the nanocomposites was studied by DSC. Addition of clay also led to increase in melting point and somewhat decrease in the crystalline level. Given the fact that crystals are effectively non-permeable, the concomitant reduction in crystallinity of the blend with decrease in permeability suggests that barrier properties arise from tortuousity of nanoparticles in the blend.     

Synergistic effect of polylactic acid(PLA) and Poly(butylene succinate-co-adipate) (PBSA) based sustainable,reactive, super toughened eco-composite blown films for flexible packaging applications

Polylactic acid (PLA)/poly (butylene succinate-co-adipate) (PBSA) based blend films at variable compositions and fixed weight percentage of Epoxy functionalized styrene acrylate (ESA) were prepared using a single step blending process, followed by blown film extrusion process. The morphological studies revealed proper interaction between polymers by the interaction of chain extender (ESA) subsequently improved the mechanical properties of the prepared blown films. Similarly, the blend films showed a decrease in oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) in the order of 60% and 14% as compared with VPLA film. The optical and antislip properties of the blend films also increased considerably. The thermal analysis of the blend films depicted marginal enhancement in the stability of PLA along with heterogeneous nucleation effect in PLA matrix due to the presence of ESA and PBSA.     

Characterisation of Hyaluronic Acid Blends Modified by Poly(N-Vinylpyrrolidone)

The viscosity behaviour and physical properties of blends containing hyaluronic acid (HA) and poly(N-vinylpyrrolidone) (PVP) were studied by the viscometric technique, steady shear tests, tensile tests and infrared spectroscopy. Viscometric and rheological measurements were carried out using blends of HA/PVP with different HA weight fractions (0, 0.2, 0.5, 0.8 and 1). The polymer films and HA/PVP blend films were prepared using the solution casting method. The study of HA blends by viscometry showed that HA/PVP was miscible with the exception of the blend with high HA content. HA and its blends showed a shear-thinning flow behaviour. The non-Newtonian indices (n) of HA/PVP blends were calculated by the Ostwald–de Waele equation, indicating a shear-thinning effect in which pseudoplasticity increased with increasing HA contents. Mechanical properties, such as tensile strength and elongation at the break, were higher for HA/PVP films with w_HA = 0.5 compared to those with higher HA contents. The elongation at the break of HA/PVP blend films displayed a pronounced increase compared to HA films. Moreover, infrared analysis confirmed the existence of interactions between HA and PVP. The blending of HA with PVP generated films with elasticity and better properties than homopolymer films.     

Properties stability and biodegradation behaviors of soy protein isolate/poly (vinyl alcohol) blend films

The objective of this work was to investigate the color, transparency, water sensitivity and mechanical properties stability in air under photo-oxidative degradation influencing consumer acceptance and biodegradation behaviors in soil of soy protein isolate (SPI)/poly (vinyl alcohol) (PVA) blend packaging films during 30 days. The results showed that PVA could dilute the yellow color and make the SPI-based films less darkness in application and the transparency of SPI/PVA films at various stages of degradation was improved. The addition of PVA decreased the ability of SPI protein molecules to absorb water and enhanced the mechanical properties of blend films comparing to pure SPI film in 30 days. Aerobic biodegradation of films in soil proved that the PVA compound interacting with protein imposed negative effects on biodegradation of blend films prolonging their decomposing time. The SPI/PVA blend films decomposed into small fragments of less complex molecules along with surface completely digested after 30 days.     

Preparation and properties of water‐soluble chitosan and polyvinyl alcohol blend films as potential bone tissue engineering matrix

The blend film was prepared by casting solutions of water‐soluble hydroxyethyacryl‐chitosan (HEA‐CS) and polyvinyl alcohol (PVA) and cross‐linked by glutaraldehyde. The structure and properties of the blend films were estimated by wide‐angle X‐ray diffraction (WXRD), contact angle measurements with water, and scanning electron microscopy (SEM). The tensile properties of the blend films were investigated and the tensile strength (TS) and the elongation increased with the increased amount of PVA. The thermal stability (thermogravimetric (TG) and derivative thermogravimetric (DTG)) was evaluated and HEA‐CS was more thermally‐stable than that of PVA. The water swelling properties analysis indicated that HEA‐CS in the blends promoted the water absorption owing to its porous structure and the antimicrobial ability of the blend films was retained. Indirect cytotoxicity assessment of the blend films with human bone sarcoma cell (SW1353) indicated that the biomaterials were non‐toxic and did not release substances harmful to living cells. Copyright © 2009 John Wiley & Sons, Ltd.     

Properties of water-soluble carboxymethyl chitosan film modified by hydrophobic poly(propylene glycol)

A series of water-soluble carboxymethyl chitosan (CMCS)/poly(propylene glycol) (PPG) blend films with various CMCS/PPG mole ratios were prepared by the solution casting method. Morphology of the CMCS/PPG blend films was investigated by scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of the CMCS/PPG blend films were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests, and contact angle tests. It was found that the introduction of PPG can markedly affect the morphology and the properties of CMCS films.     

甲壳素/聚氨酯共混物膜结构与性能的研究

采用共混的方法分别制备了丁羟型和聚醚型聚氨酯／甲壳素共混膜(HPCT和PPCT系列),研究了甲壳素加入量对共混膜力学性能、热稳定性、溶胀性和吸湿性的影响,讨论了共混物膜在不同环境条件下的降解性能。结果表明随着甲壳素含量的增加共混材料对水的亲和力和热稳定性提高,当甲壳素质量分数分别为0．15和0．10时HPCT系列和PPCT系列具有较佳的力学性能,HPCT和PPCT系列分别在pH=7．0和pH=4．7的环境中具有良好的降解性能。     

Studies on the preparation of hydrolyzed starch-g-PAN (HSPAN)/PVA blend films--Effect of the reaction with epichlorohydrin

Absorbent hydrolyzed starch-g-PAN (HSPAN)/polyvinylalcohol (PVA) blend films crosslinked with epichlorohydrin (ECH) were prepared to overcome the phase separation and improve the mechanical properties of blend films. The absorbency of HSPAN/PVA blend films decreased with PVA contents due to the reduction of HSPAN contents which is known to play a major role in absorbing ability of the film. And also the absorbency decreased with the ECH contents due to the crosslinking reaction. As far as the solubility is concerned, it increased with PVA contents which is water soluble. But because of the crosslinking reaction between HSPAN and PVA by ECH, the solubility decreased with ECH contents. In the mechanical properties, the strength as well as the strain at break of the HSPAN/PVA blend films were improved very much if compared with HSPAN film, and those mechanical properties were improved even more by the reaction with ECH. The DSC thermograms of HSPAN films showed two major endothermic peaks at 32 and 128 °C, while those of PVA film showed two major endothermic peaks at 49 and 190 °C. In the non-crosslinked blend films, each four endothermic peak was apparent. But as the ECH content increased, both peaks at 128 and 190 °C disappeared and a new peak appeared at the intermediate temperature. In other words, the compatibility of blend films was increased by the reaction with ECH. Also, from the results of TGA, it was confirmed that the thermal degradation of blend films was decelerated by the crosslinking reaction.     

纤维素/甲壳素共混膜的结构表征与抗凝血性能

以 6wt %NaOH 4wt%尿素为纤维素的新溶剂 ,采用溶液共混法制备出纤维素 甲壳素共混膜 ,为甲壳素在碱性溶液中制膜提供了新的方法 .红外光谱、X 射线衍射、扫描电镜和力学性能、抗凝血性能测试结果表明 ,共混膜中甲壳素含量低于 4 0wt%时 ,纤维素与甲壳素分子间具有良好的相容性 ;在纤维素中引入适量甲壳素可提高共混膜的抗张强度 ,共混膜的干、湿态抗张强度在甲壳素含量 10wt%时最大 ,其值分别为 89 1MPa和 4 3 7MPa ,比纯态纤维素膜的干、湿态抗张强度分别提高了 6 7%和 11 5 % ;甲壳素的引入可明显降低血小板在共混膜表面的粘附、凝聚与变性 ,增大共混膜的抗凝血参数 ,甲壳素含量达到 5 0wt%时 ,该共混膜具有良好的抗凝血性能     

Surface characterization and liquid crystal alignment behavior of comb-like poly(oxyethylene)/poly(3-hexylthiophene) blend films

The blend surfaces of poly[oxy(n-decylsulfonylmethyl)ethylene] (CH(3)-10SE) and poly (3-hexylthiophene) (P3HT) with different weight ratios were prepared by spin coating the polymer solution mixtures. In this study, their surface properties such as surface morphology, chemical composition, molecular structure, and wettability were systematically studied and correlated with liquid crystal (LC) alignment behaviors on the blend films. Therefore, we found that CH(3)-10SE part with a well-ordered side chain structure predominantly affects the both of wettability and LC alignment behavior of the blend films while there was no clear association between the wettability and the LC alignment behavior.     

Effect of LDPE on the thermomechanical properties of LLDPE‐based films

The present study compares the properties of five films: one film of low‐density polyethylene (LDPE), two films of linear low density polyethylenes (1‐octene comonomer)—one made by metalllocene catalyst (mLLDPE) and the other by Ziegler–Natta (zLLDPE)—and two blend films, one of mLLDPE/LDPE (film A) and the other of zLLDPE/LDPE (film B). The effect of LDPE (22% by weight) on the thermomechanical properties of LLDPE‐based films is investigated by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and stress‐strain in the yield region measurements. The mechanical, dynamic, and thermal properties of film A are quite similar to a single component system (mLLDPE). The addition of this amount of LDPE does not affect the melting temperature of mLLDPE but it enhances its crystallinity. Film B is a rather inhomogeneous material, as opposed to film A, and its properties seem to be dependent on stretching conditions. Furthermore, the thermally activated rate process (Eyring's theory) is applied to analyze the yielding behavior of the two blend films. Double yielding manifested by film B is described with two thermally activated processes, while film A is satisfactorily described by a single process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1712–1727, 2005     

Stereocomplexation and Mechanical Properties of Polylactide-b-poly(propylene glycol)-b-polylactide Blend Films: Effects of Polylactide Block Length and Blend Ratio

In the present work, poly(propylene glycol)(PPG) was block copolymerized to form polylactide-poly(propylene glycol)-polylactide(PL-PPG-PL) triblock copolymers for preparing flexible stereocomplex PL(sc PL) blend films. The sc PL blend films were prepared by solution blending of poly(L-lactide)-PPG-poly(L-lactide)(PLL-PPG-PLL) and poly(D-lactide)-PPG-poly(D-lactide)(PDL-PPG-PDL) triblock copolymers before film casting. The influences of PL end-block lengths(2×10~4 and 4×10~4 g/mol) and blend ratios(75/25, 50/50 and 25/75 W/W) on the stereocomplexation and mechanical properties of the blend films were evaluated. From DSC and WAXD results, the 50/50 blend films had complete stereocomplexation. Phase separation between the sc PL and PPG phases was not observed from their SEM images. The tensile stress and elongation at break increased with the sterecomplex crystallinities and PL end-block lengths. The PPG middle-blocks enhanced elongation at break of the sc PL films. The results showed that the PL-PPG-PL triblock structures did not affect stereocomplexation of the PLL/PDL block blending. In conclusion, the phase compatibility and flexibility of the sc PL films were improved by PPG block copolymerization.     

Breakthrough in the preparation of irradiated sodium alginate/polyethylene oxide blend films using methacrylate monomer

The present work is an attempt to prepare biodegradable films of sodium alginate (SA)/polyethylene oxide (PEO) blend tailored by methacrylate (MA) and γ irradiation following casting method. The effects of SA/PEO composition, glycerol as a plasticizer, methacrylate as a monomer, and radiation dose were investigated and it was found that the mechanical properties of the films strongly depend on the film-forming parameters. The incorporation of glycerol in the blend is crucial as it creates a suitable environment for monomer addition and points out that tensile strength of the films decreased, while the elongation at break increased. Moreover, it was found that the tensile properties were improved by the application of γ radiation as well as monomer treatment. The mechanical properties of the blend films integrated with MA monomer were higher than that without monomer at the analogous conditions. The structural and morphological features of the films were examined by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.     

Preparation of gelatin/poly(vinyl alcohol) film modified by methyl methacrylate and gamma irradiation

The properties of gelatin–polyvinyl alcohol (G–PVA) blend films were improved by methyl methacrylate (MMA) and γ irradiation for a practical viewpoint. The films were prepared by the casting method, modified by glycerol and MMA monomer, and their mechanical properties were also studied. The gelatin-based films were successfully prepared using γ irradiation (3.1 kGy) and gelatin: PVA = 97:3 (w/w) as optimized. Tensile properties of the films were studied and thermal properties of the films were characterized by thermogravimetric analysis and dynamic mechanical analysis pointed out that MMA treated both gelatin films, and G–PVA blend films showed less thermal degradation than untreated films. In addition, structural and morphological features of the gelatin-based films were examined by Fourier transform infrared and scanning electron microscopy, respectively. The ultimate results of the present study showed remarkable enhancement in tensile properties (> 40%) and a reduction in elongation at break of the films, thanks to the MMA addition and γ irradiation.     

Properties of poly(lactic acid-co-glycolic acid) film modified by blending with polyurethane

A number of poly(lactic acid-co-glycolic acid)/polyurethane (PLGA/PU) blend films with various PU mole contents were prepared by casting the polymer blend solution in chloroform. The surface morphologies of the PLGA/PU blend films were studied by scanning electron microscopy (SEM). The thermal, mechanical and chemical properties of the PLGA/PU blend films were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests and surface contact angle tests. The results revealed that the introduction of PU could markedly modify the properties of PLGA films.     

Crystallization behavior and electroactive properties of PVDF,P(VDF-TrFE) and their blend films

PVDF, poly(vinylidene fluoride), as a semi-crystalline polymer, has interesting electroactive properties but usual melt and solution processing techniques result in its thermodynamically favored non-polar α-phase. By comparison, poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE), PT for short, directly crystallizes in the polar β-phase under the same conditions as PVDF. In this study, blend thin films comprising PVDF and P(VDF-TrFE) were prepared by solvent casting method. The difference in the crystallization behavior is comprehensively investigated between the polymers: PVDF, P(VDF-TrFE), and the resulting blend films. It is found that replacement of the fluoride atom in TrFE monomer induces a strong steric hindrance that may alter the crystallization process to become more favorable for nucleation of the PVDF β-phase. To figure out the effect of TrFE content on the crystallization behavior and electroactive properties, films with different blend ratios of PVDF and P(VDF-TrFE) were prepared. We found that the PVDF films exhibit higher crystallization activation energy (ΔE) as PT content increases. The atomic force microscopy (AFM) in the piezoresponse force microscopy (PFM) mode illustrated that P5T5 films with equal contents of PVDF and P(VDF-TrFE) induced the highest d₃₃ values.     

Cellulose acetate blends with acrylonitrile/N-phenyl maleimide copolymers morphological and thermal properties

Cellulose acetate (CA) was blended in different compositions with various acrylonitrile-N-halo phenyl maleimide (AN-XPhM) copolymers to improve the thermal and mechanical properties of cellulose acetate. The structure, morphology, thermal stability, and crystallinity of the blend films were characterized by infrared spectroscopy, scanning electron micrographs, thermogravimetry/differential thermal analysis, differential scanning calorimetry, and X-ray diffraction. The results revealed that the thermal stability was improved by the increase in AN-XPhM content, irrespective of the type of the N-halo phenyl maleimide. The CA/AN-4BrPhM blend films possessed the highest thermal stability compared to the other CA/AN-XPhM blend films. Blending CA with AN-4BrPhM yielded the most homogeneous blend films, irrespective of the composition ratio. The mechanical properties of various compositions of the CA/AN-4BrPhM blend films were also discussed.     

Phase separation morphology of thin films of polystyrene/polyisoprene blends

We present the results of a study of the morphology of phase separation in a thin film blend of polystyrene (PS) and polyisoprene (PI) in a common solvent of toluene. The blend is quenched by rapid solvent evaporation using a spincoating technique rather than a temperature quench. The mass fraction of polystyrene is varied to determine the effect of the substrate on thin film phase separation morphology. We compare the phase separation morphology for very thin films of the PS/PI blend cast onto three different substrates: Si(001) with a native oxide layer (Si (SINGLEBOND) SiO_x), Si(001) etched in hydrofluoric acid (Si-H), and a Au/Pd alloy sputtered onto Si(001). We observe large differences between the morphologies of 1000 Å thick blend films on the Si(SINGLEBOND) SiO_x and Si-H substrates as the mass fraction is varied due to the difference in the wetting properties of PS on the two substrates. Smaller differences are observed between the films on the Si(SINGLEBOND) SiO_x and Au/Pd substrates only for film thicknesses h < 600 Å. © 1996 John Wiley & Sons, Inc.