Preparation and characterization of modified starch‐based plastic film reinforced with short pulp fiber. I. Structural properties

Native corn starch‐ and hydroxypropylated starch (HPS‐) based plastic films were prepared using the short pulp fiber as the reinforcement and the glycerol as the plasticizer. Starch (or HPS) films showed different X‐ray diffraction patterns with the A‐type of native corn starch powder. The crystallinity of films increased with pulp content, but decreased with glycerol content and degree of substitution by hydroxypropylation. Also, the intensity of peaks at 2θ = 15.3 and 17.3° decreased with glycerol content and degree of substitution. The water uptake of films as a function of the relative humidity decreased with pulp content and degree of substitution by hydroxypropylation, but increased with glycerol content. Differential scanning calorimetry (DSC) thermograms showed that the glass transition temperature of films decreased and the endothermic peaks at the melting temperature broadened due to the plasticizing effect and the decrease of the crystallinity, which were caused by the addition of glycerol and the hydroxypropylation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2100–2107, 2003     

Influence of processing on the mechanical properties and morphology of starch-based blends for film applications

This article describes the effect of processing on the properties and morphology of thermoplastic starch (TPS) and poly(butylene adipate-co-terephthalate) (PBAT) blends and films with high starch content. Different process parameters were modified during compounding of blends and extrusion of blown films. Morphology was examined through scanning electron microscopy. Mechanical and optical characterization of films was carried out as well. Decreasing specific throughput during compounding led to an increase in strain at break of the blends from 66 to 497%. The tensile strength increased from 6 to 22 MPa as well. The highest elastic modulus and tear resistance were achieved at intermediate specific throughputs, whereas the maximum TPS particle size and the lowest color difference were obtained at high specific throughputs. A decrease of color difference from 6.4 to 2.2 was observed by reducing the temperature profile in 5 °C. In the case of blown film extrusion, increasing the temperature profile resulted in a reduction of color difference of the films from 7.9 to 4.2. In addition, tensile strength and strain at break slightly increased. Color difference decreased with decreasing screw speed as well. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47990.     

Effect of glycerol on thermal and mechanical properties of polyvinyl alcohol/starch blends

The paper reports the results of studies on the effect of glycerol content on thermal, mechanical, and dynamic mechanical properties of blends of starch and polyvinyl alcohol (PVA). Degree of crystallinity of the starch/PVA blends (4 g/4 g ratio) remains almost constant up to 3.78 g of glycerol as determined by differential scanning calorimetry (DSC) and x‐ray diffraction studies. At higher loading of glycerol the crystallinity decreases. DTG thermograms revealed occurring of one maximum degradation temperature closer to that of starch in blends containing up to 3.78 g of glycerol. At higher glycerol content there gradually occur two distinct peaks of maximum degradation temperature, one occurring close to that of starch and other occurring close to the PVA peak, indicating phase separation of the blend components. Results of stress–strain studies indicate lowering of tensile properties and energy at break particularly at higher glycerol content (beyond 3.78 g). Dynamic mechanical studies reveal a sharp drop in dynamic modulus at higher glycerol content at all temperatures. The blend with low glycerol content shows transitions of starch, while the blend containing high glycerol content beyond 3.78 g display the transitions due to both starch and PVA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of starch‐based plastic films by electron beam irradiation

Starch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007     

PBAT/热塑性玉米淀粉共混改性对结构和力学性能影响

采用价格低廉的玉米淀粉为填充剂来改性生物可降解聚己二酸?对苯二甲酸丁二酯（PBAT）,以降低PBAT价格,拓宽应用领域。首先采用丙三醇对玉米淀粉进行塑化,再采用双螺杆挤出机进行造粒获得热塑性淀粉（TPS）粒料,然后采用双螺杆挤出机和注塑机制备不同比例的PBAT/TPS样条,最后分析论文TPS含量对样条结构和力学性能的影响。结果表明,经丙三醇塑化后的淀粉含有大量的羟基,PBAT的结晶结构与PBT的相同,随着TPS含量的增加,PBAT的结晶完善程度逐渐降低,结晶温度向高温方向偏移,拉伸强度和断裂伸长率逐渐降低,而弹性模量有相反的趋势。     

Influence of glycerol and water content on the structure and properties of extruded starch plastic sheets during aging

The properties of starch plastic sheets were investigated by stress—strain measurements in relation with starch crystallinity. Granular potato starch was plasticized with different amounts of glycerol and water by extrusion. The materials were amorphous directly after processing. During aging above the glass transition temperature at various humidities single helical (V and E-type) and double helical (B-type) crystallinity was formed. The rate of crystallization is a function of water and glycerol content. The amorphous rubbery materials were soft and weak with high elongations. During aging the materials became less flexible with higher elastic modulus and tensile stress. The changes are related to changes in water content and glass transition temperature and to changes in B-type crystallinity. The changes in stress—strain properties are explained by the formation of helical structures and crystals, which results in a reinforcement of the starch network by physical crosslinking. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1411–1422, 1997     

Synthesis and properties of composites of starch and chemically modified natural rubber

A means is developed for forming polysaccharide-based composites with useful material properties through use of unmodified and chemically modified natural rubber latex (NRL). Starch was used as a model for polysaccharides. The NRL was modified by grafting with dimethylaminoethyl methacrylate (DMAEMA) to form a latex with cationic water-soluble polymeric ‘hairs’ of polyDMAEMA, which should form hydrogen bonds with starch. Starch solutions, containing 20% glycerol as a film-forming aid, and the modified NRL were mixed and films allowed to form. The unmodified latex acted only as filler in the starch films, but with modified NRL, the mechanical properties of the films were significantly altered. The elastic modulus was greatly decreased and strain at break greatly increased. The glass transition temperature increased from −48 °C to −32 °C, suggesting significant compatibilization. Freeze-fracture TEM micrographs indicate strong interactions between the surface of the modified NRL and starch. The polyDMAEMA chains are more hydrophilic than the starch, and the addition of grafted latex results in a 20° drop of the water contact angle of the formed film, and a 25% increase of the water absorption compared to the native starch; with unmodified NRL, the opposite effect was observed.     

On-Line Rheological Measurements and Mechanical Properties of Acrylonitrile-Butadiene-styrene/Corn Starch Composite

In this work, rheological and mechanical properties of acrylonitrile–butadiene–styrene/corn starch composites (ABS/starch) were studied. The composites were prepared using a laboratory-scale, single-screw extruder. Rheological properties were determined using the single-screw extruder, apparent shear rate (γ _a ), apparent shear stress (τ _a ), apparent viscosity (η _a ), non-Newtonian index (n), and flow activation energy at a constant shear rate (E _γ) and constant shear stress (E _τ). Mechanical properties in terms of tensile tests were performed using Testometric M350-10KN, stress at break, strain at break, and Young's modulus were determined. Rheological results showed that the composites are pseudo plastic in behavior, and the apparent viscosity of the composites increases with increasing starch content above the additive rule, which indicates a partial compatibility in the composite. It was also found that the flow activation energy of the composite increases with increasing starch content. The mechanical results showed that the strain at break of the composite decreases sharply by the presence of starch, whereas the Young's modulus increases with increasing starch content.     

碳纤维改性HA/PMMA生物复合材料力学性能的研究

采用原位合成与溶液共混相结合的方法,制备了短切碳纤维增强纳米羟基磷灰石(HA)/聚甲基丙烯酸甲酯(PMMA)生物复合材料。研究了碳纤维的含量和长度对HA/PMMA复合材料结构和力学性能的影响。采用万能材料试验机和扫描电子显微镜对复合材料的力学性能及断面的微观形貌进行了测试和表征。结果表明:碳纤维在HA/PMMA复合材料中分布均匀,有效提高了复合材料的力学性能;碳纤维含量为4%时,复合材料的拉伸强度、弯曲强度、压缩强度和弹性模量等均达到最大值;复合材料的断裂伸长率随碳纤维含量的增加而减小;当碳纤维含量一定时,随其长度的增加,复合材料的拉伸强度、弯曲强度和弹性模量均增加,但断裂伸长率降低。     

Thermal and mechanical properties of hybrid carbon/oxidized polyacrylonitrile fibers‐epoxy composites

Nowadays, hybrid composites are one of the important materials in industry due to their special properties. In this research, hybrid oxidized polyacrylonitrile (PAN) and carbon fibers reinforcement were used in epoxy matrix. The hybrid composites were fabricated using the hand lay‐up technique by placing the reinforcements in different layering sequences. Thermal and mechanical properties of these hybrid composites were investigated by thermal analysis, horizontal burning, tensile and bending tests. The tensile test results indicated that increasing oxidized polyacrylonitrile fibers (OPFs) to carbon fibers ratio decreased tensile strength and elastic modulus but increased failure strain. Hybrid oxidized PAN and carbon fibers reinforcement in composites led to decreasing flexural stress and modulus, and increasing flame retardancy. Thermal analysis results also showed that the maximum rate of mass loss in all composites was 370.6°C. It was also found that the maximum and minimum amounts of char residue at 900°C were related to the composites with four layers of carbon and OPFs, respectively. POLYM. COMPOS., 38:1412–1417, 2017. © 2015 Society of Plastics Engineers     

抗静电木粉/聚丙烯复合材料的研究

为了提高木粉/聚丙烯复合材料的抗静电性能,通过高速混合、挤出造粒以及热压成型的方式制备了4种抗静电木粉/聚丙烯复合材料,并比较了它们的体积电阻率和拉伸强度,结果表明:在4种抗静电复合材料中加入炭黑的复合材料体积电阻率最小,拉伸强度最大。探讨了炭黑用量对木粉/聚丙烯复合材料抗静电性能和力学性能的影响,结果表明:当炭黑用量增加时,复合材料的体积电阻率明显降低,拉伸强度和弯曲强度出现最大值,弹性模量和断裂伸长率呈下降趋势。     

MC尼龙／Sm2O3纳米复合材料的制备及性能研究

用原位分散聚合法制备了一系列MC尼龙/Sm2O3纳米复合材料,并对其结构和力学性能进行了表征.结果表明,纳米Sm2O3使MC尼龙晶格尺寸发生了一定程度的改变;纳米Sm2O3的加入可以明显改善MC尼龙的力学性能,对MC尼龙同时具有增强和增韧双重效果;MC尼龙/Sm2O3纳米复合材料的力学性能随着纳米Sm2O3用量的增加呈先升高后降低的趋势.当纳米Sm2O3的质量分数为0.5%时,复合材料的拉伸强度和断裂伸长率达到最大值,分别比MC尼龙提高了18.8%和91.5%,当纳米Sm2O3的质量分数为1.0%时,复合材料的缺口冲击强度、穹曲强度和弯曲弹性模量达到最大值,分别比MC尼龙基体提高了36.6%、11.2%和11.5%.     

Mechanical property characterization of a 9 mol% Ce-TZP ceramic material — I. Flexural response

Investigations were carried out on four tetragonal zirconia polycrystalline (TZP) ceramics of differing grain size containing 9 mol% CeO₂. Precision flexural tests on these materials were conducted to determine the elastic modulus, the non-linear deflection and the associated acoustic emission during such testing. The deformation was characterized in terms of the number and size of the transformation bands that developed during the non-linear response. The finest grained material initially exhibited permanent set without the presence of such bands, whereas all the coarser grained materials showed a linear relationship between the summation of the band widths and the residual deflection. The acoustic emission and plastic strain behaviour are discussed in terms of the number and size of the stress induced phase transformation bands.     

Preparation and studying properties of polybutene‐1/thermoplastic starch blends

Starch as an inexpensive and renewable source has been used as a filler for environmental friendly plastics for about two decades. In this study, glycerol was used as a plasticizer for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/polybutene‐1(PB‐1) blend. PB‐1 was melt blended with TPS using a single screw extrusion process and molded using injection molding process to investigate the rheological and mechanical properties of these blends. Rheological properties were studied using a capillary rheometer, and the Bagley's correction was performed. Mechanical analysis (stress–strain curves) was performed using Testometric M350‐10 kN. The rheological properties showed that the melt viscosity of the blend is less than that of PB‐1, and the flow activation energy at a constant shear stress of the blend increases with increasing glycerol content in the blend. The mechanical experiments showed that both stress and strain at break of the blends are less than that of PB‐1, whereas the Young's modulus of the most blends is higher than that of PB‐1 which confirms the filling role of TPS in the blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Water resistance,mechanical properties,and biodegradability of poly(3‐hydroxybutyrate)/starch composites

Composites of poly(3‐hydroxybutyrate), P(3HB), and starch were prepared by solution casting technique. To improve adhesion of starch to P(3HB), stearic acid was added as a compatibilizer and glycerol as a plasticizer. The water resistance, mechanical, and biodegradable properties of the P(3HB)/starch composites were studied. Diffusion and penetration coefficients of water increased with increasing starch content in the composites. The results showed that the elastic modulus and strain at rupture of the P(3HB)/starch composites were enhanced by increasing starch content upto 10 wt % and the tensile strength increased from 21.2 to 93.9 MPa. The presence of starch content higher than 10 wt % had an adverse effect on the mechanical properties of the investigated composites. The biodegradation rate using Actinomycetes increased proportionally to the starch content in the composite and accelerated in a culture medium of pH ≈ 7.0 at 30°C. Enzymatic degradation experiments showed that lipase produced by Streptomyces albidoflavus didnot degrade P(3HB)/starch composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical Properties, Biodegradation and Water Vapor Permeability of Blend Films of Soy Protein Isolate and Poly (vinyl alcohol) Compatibilized by Glycerol

Summary Novel blend films of soy protein isolate (SPI) and poly(vinyl alcohol) (PVA) compatibilized by glycerol were fabricated by preparing a solution, and then casting it on a Teflon-coated metal sheet. Mechanical, biodegradation and water vapor permeability of the blend properties were systematically investigated with various methods. SEM analysis results release that the SPI/PVA/glycerol film degrades at a slower rate than pure SPI. The mechanical test showed that the stress at yield point, stress at break point and Young’s modulus were decreased and percentage elongation at yield point and percentage elongation at break point and of SPI/PVA were increased obviously than pure SPI films. The blend plastics were softened and became semi-rigid contributing to the plasticization of glycerol and the crystalline partion of PVA was destroyed by glycerol. Water vapor permeability of SPI/PVA/glycerol showed the minimum at the component of SPI/PVA (100/35) compatibilized by 3.5% of glycerol.     

Natural weathering of polypropylene films. I. Exposure time and yield properties

The yield properties of about 500 h of outdoor weathering (in the rainy season) of polypropylene (PP) films have been studied. The yield strain, plastic strain, and initial modulus, work of yield attained local maxima at 48- and 240-h exposure time; elastic strain attained near double maxima at these times. The yield stress reached a local minimum for the 144-h exposed film before increasing with further exposure hours. The increase in yield strain, plastic strain, and initial modulus were explained in terms of crosslinking chemocrystallization; decreases were due to chain scission and leaching. Critical dissolution time data, interpreted in proportion to density, crystallite thickness, and percent crystallinity, increased with PP exposure time, reaching a maximum at 48 h before decreasing to values even lower than that of unexposed film from the 120-h exposure. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 667–673, 1998     

Mechanical Properties of Sputter-Deposited Titanium-Silicon-Carbon Films

The effect of SiC additions on the mechanical properties of TiC films was investigated. Ti-Si-C films with varying SiC content were deposited using dual-cathode radio-frequency magnetron sputtering. The nanoindentation hardness of these films increased with SiC content to a maximum of 20–22 GPa for films in the range of 15–30 at.% SiC. The elastic modulus was also measured, and the hardness to modulus ratio ( H / E ) increased with SiC content, indicating that hardness increases were due to microstructural effects. The residual stress was measured in several films, but was low in magnitude, indicating that hardness measurements were not influenced by residual stress. TEM examination of several films revealed that the SiC additions altered the film microstructure in a manner that could account for the observed hardness increases.     

PP/Rosin Blends: Mechanical and Rheological Properties

Abstract

Melting mixtures of polypropylene (PP) and glycerol ester of hydrogenated rosin (ester gum) were prepared under select conditions using up to 50% of rosin. The addition of modified rosin on PP increased the elastic modulus which maximum value was observed in the 70/30 PP/ROSIN blend. The stress dropped monotonically with rosin content. Above 10% rosin, the elongation at yield diminished and reached a constant value. The elongation at break dropped abruptly above 10% of rosin. The density and hardness of blends increased with amount of rosin. The melt flow index of blends increased exponentially with the rosin content while the torque decreased monotonically with the composition and the processability was improved.     

周期性孪晶结构碳化硅纳米线改性环氧树脂的性能

通过超声分散和模具浇注成型法制备了周期性孪晶结构碳化硅(SiC)纳米线改性环氧树脂,探讨了SiC纳米线的周期性孪晶结构及含量对环氧树脂复合材料力学性能的影响。结果表明,周期性孪晶结构SiC纳米线的加入明显改善了环氧树脂基体的力学性能,孪晶结构有助于提高SiC纳米线与基体树脂之间的相互结合程度。随着孪晶SiC纳米线含量的增加,复合材料的拉伸性能和弯曲性能都呈现出先增加后减小的趋势。当SiC纳米线的含量为2%时,复合材料的拉伸强度、拉伸弹性模量、断裂伸长率、弯曲强度和弯曲弹性模量均达到最大值,相比于纯环氧树脂分别提高了90.6%,37.8%,38.3%,53.4%和24.5%。当SiC纳米线含量为3%时,弯曲应变达到最大值(6.72%),相比于环氧树脂提高了32.0%。