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1.
Effects of Starch Moisture on Properties of Wheat Starch/Poly(Lactic Acid) Blend Containing Methylenediphenyl Diisocyanate 总被引:2,自引:0,他引:2
Methylenediphenyl diisocyanate was found to improve the interfacial interaction between poly(lactic acid)(PLA) and granular starch. The objective of this research was to study the effect of starch moisture content on the interfacial interaction of an equal-weight blend of wheat starch and PLA containing 0.5% methylenediphenyl diisocyanate by weight. Starch moisture (10% to 20%) had a negative effect on the interfacial binding between starch and PLA. The tensile strength and elongation of the blend both decreased as starch moisture content increased. At 20% moisture level, the starch granules embedded in the PLA matrix were observed to be swollen, resulting in poor strength properties and high water absorption by the blend. 相似文献
2.
The influence of poly(dioxolane) (PDXL), a poly(ethylene oxide-alt-methylene oxide), as compatibilizer on poly(ɛ-caprolactone) (PCL)/tapioca starch (TS) blends was studied. In order to facilitate blending; PCL, PDXL and TS must be blended together directly; so that PDXL is partially adhered at the TS surface as shown by scanning electron microscopy. The molecular weight effect of PDXL on the PCL/TS blends showed that mechanical properties of PCL/TS/PDXL blends from low molecular weight (M
n=10,000) and high molecular weight (M
n=200,000) PDXL were rather dependent on TS content. The enzymatic degradability of PCL/TS/PDXL blends using α-amylase increased as the TS content increased but was independent on the dispersion of tapioca starch in the PCL matrix. 相似文献
3.
Worasak Phetwarotai Pranut Potiyaraj Duangdao Aht-Ong 《Journal of Polymers and the Environment》2013,21(1):95-107
The biodegradability of polylactide (PLA) and gelatinized starches (GS) blend films in the presence of compatibilizer was investigated under controlled soil burial conditions. Various contents (0–40 wt%) of corn and tapioca starches were added as fillers; whereas, different amounts of methylenediphenyl diisocyanate (MDI) (0–2.5 wt%) and 10 wt% based on PLA content of polyethylene glycol 400 (PEG400) were used as a compatibilizer and a plasticizer, respectively. The biodegradation process was followed by measuring changes in the physical appearance, weight loss, morphological studies, and tensile properties of the blend films. The results showed that the presence of small amount of MDI significantly increased the tensile properties of the blends compared with the uncompatibilized blends. This is attributed to an improvement of the interfacial interaction between PLA and GS phases, as evidenced by the morphological results. For soil burial testing, PLA/GS films with lower levels (1.25 wt%) of MDI had less degradation; in contrast, at high level of MDI, their changes of physical appearance and weight loss tended to increase. These effects are in agreement with their water absorption results. Furthermore, biodegradation rates of the films were enhanced with increasing starch contents, while mechanical performances were decreased. 相似文献
4.
Márcia Maria Favaro Ferrarezi Márcia de Oliveira Taipina Laura Caetano Escobar da Silva Maria do Carmo Gonçalves 《Journal of Polymers and the Environment》2013,21(1):151-159
A new route to prepare poly(lactic acid) (PLA)/thermoplastic starch (TPS) blends is described in this work using poly(ethylene glycol) (PEG), a non-toxic polymer, as a compatibilizer. The influence of PEG on the morphology and properties of PLA/TPS blends was studied. The blends were processed using a twin-screw micro-compounder and a micro-injector. The morphologies were analyzed by scanning and transmission electron microscopies and the material properties were evaluated by dynamic-mechanical, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. PLA/TPS blends presented large TPS phase size distribution and low adhesion between phases which was responsible for the lower elastic modulus of this blend when compared to pure PLA. The addition of PEG resulted in the increase of PLA crystallization, due to its plasticizing effect, and improvement of the interfacial interaction between TPS and PLA matrix. Results show that incorporation of PEG increased the impact strength of the ternary blend and that the elastic modulus remained similar to the PLA/TPS blend. 相似文献
5.
The blends of polylactide (PLA) and poly(ethylene glycol) (PEG) with different contents (0, 5, 10, 15, and 20 wt%) and molecular weights (\( \overline{M}_{w} \) 6000, 10,000 and 20,000, called respectively as PEG 6000, PEG 10,000, and PEG 20,000) were prepared by means of melt blending method. The effects of tensile speed, content and molecular weight of the PEG on the tensile properties of the PLA/PEG blends were investigated using a universal testing machine at 24 °C. With increasing tensile speed, the tensile modulus, strength and stress at break of the PLA/PEG blends marginally increased, while the tensile modulus and stress at break declined non-linearly, and the tensile strength dropped nearly linearly with increasing PEG 10,000 content. When the PEG 10,000 content was 5–15 wt%, the tensile strain at break of the PLA/PEG 10,000 blend markedly increased, and then decreased as the PEG 10,000 content exceeded 15 wt%. With increasing the molecular weight of PEG, tensile modulus and strength increased, whereas the tensile strain at break decreased. This showed that the application of right amount of lower molecular weight PEG was more conducive to improving the tensile toughness of the PLA/PEG blends, which was attributed to its better miscibility with PLA and increased mobility of PLA molecular chains. 相似文献
6.
As one of the biodegradable polymers, the blend of poly(butylene succinate) and poly(butylene terephthalate) is dealt with in this study. In our previous work, it was demonstrated that PBS and PBT are immiscible not only from the changes of T
g but also from logG–log G plots. It is expected that the biodegradability of the blends could be improved by enhancing the miscibility. We tried to induce the transesterification reaction between two polyesters with various time intervals to enhance the miscibility of the blends. The extent of transesterification reaction was examined by 1H-NMR. We utilized a dynamic mechanical thermal analyzer and a rotational rheometer to investigate the changes in miscibility. We also verified the biodegradability of PBS/PBT blends after the transesterification reaction by the composting method. 相似文献
7.
Gregory M. Glenn Artur K. Klamczynski Bor-Sen Chiou Delilah Wood William J. Orts Syed H. Imam 《Journal of Polymers and the Environment》2004,12(3):189-196
Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength. 相似文献
8.
Wannapa Chumeka Varaporn Tanrattanakul Jean-François Pilard Pamela Pasetto 《Journal of Polymers and the Environment》2013,21(2):450-460
Natural rubber grafted with poly(vinyl acetate) copolymer (NR-g-PVAc) was synthesized by emulsion polymerization. Three graft copolymers were prepared with different PVAc contents: 1 % (G1), 5 % (G5) and 12 % (G12). Poly(lactic acid) (PLA) was melt blended with natural rubber (NR) and/or NR-g-PVAc in a twin screw extruder. The blends contained 10–20 wt% rubber. The notched Izod impact strength and tensile properties were determined from the compression molded specimens. The effect of NR mastication on the mechanical properties of the PLA/NR/NR-g-PVAc blend was evaluated. Characterization by DMTA and DSC showed an enhancement in miscibility of the PLA/NR-g-PVAc blend. The temperature of the maximum tan δ of the PLA decreased with increasing PVAc content in the graft copolymer, i.e., from 71 °C (pure PLA) to 63 °C (the blend containing 10 % G12). The increase in miscibility brought about a reduction in the rubber particle diameter. These changes were attributed to the enhancement of toughness and ductility of PLA after blending with NR-g-PVAc. Therefore, NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. NR mastication was an efficient method for increasing the toughness and ductility of the blends which depended on the blend composition and the number of mastications. 相似文献
9.
Biodegradable Blends Based on Starch and Poly(Lactic Acid): Comparison of Different Strategies and Estimate of Compatibilization 总被引:1,自引:0,他引:1
Emmanuelle Schwach Jean-Luc Six Luc Avérous 《Journal of Polymers and the Environment》2008,16(4):286-297
Finding plastic substitutes based on sustainability, especially for short-term packaging and disposable applications has aroused
scientific interest for many years. Starch may be a substitute for petroleum based plastics but it shows severe limitations
due to its water sensitivity and rather low mechanical properties. To overcome these weaknesses and to maintain the material
biodegradability, one option is to blend plasticized starch with another biodegradable polymer. To improve both the compatibility
between the main phases and the performance of the final blend, different compatibilization strategies are reported in literature.
However, the relative efficiency of each strategy is not widely reported. This paper presents three different strategies:
in situ (i) formation of urethane linkages; (ii) coupling with peroxide between starch and PLA, and (iiii) the addition of
PLA-grafted amylose (A-g-PLA) which has been elaborated ex situ and carefully analyzed before blending. This study compares
the effect of each compatibilization strategy by investigating mechanical and thermal properties of each blend. Compatibilizing
behavior of the A-g-PLA is demonstrated, with a significant increase (up to 60%) in tensile strength of starch/PLA blend with
no decrease in elongation at failure. 相似文献
10.
Naiwen Zhang Chao Zeng Liang Wang Jie Ren 《Journal of Polymers and the Environment》2013,21(1):286-292
Poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) are biodegradable polyesters and can be blended by twin-screw extrusion. Epoxy-functional styrene acrylic copolymer (ESA) was used as reactive agent for PLA/PBAT blends and the mechanical properties, phase morphology, thermal properties, melt properties, and melt rheological behaviors of the blends were investigated. During thermal extrusion, ESA was mainly a chain extender for the PLA matrix but had no evident reaction with PBAT. The great improvement in the toughness of PLA based blends was achieved by the addition of PBAT of no less than 15 wt% and that of ESA of no more than 0.5 wt%. Although SEM micrographs and the reduced deviation of the terminal slope of G′ and G″ indicated better compatibility and adhesion between the two phases, the blend with ESA was still a two-phase system as indicated in DSC curves. Rheological results reveal that the addition of ESA increased the storage modulus (G′), loss modulus (G″) and complex viscosity of the blend at nearly all frequencies. The melt strength and melt elasticity of the blend are improved by addition of ESA. 相似文献
11.
Photodegradation and Biodegradation Study of a Starch and Poly(Lactic Acid) Coextruded Material 总被引:1,自引:0,他引:1
Alain Copinet Céline Bertrand Antoine Longieras Veronique Coma Yves Couturier 《Journal of Polymers and the Environment》2003,11(4):169-179
To simulate the behavior of agricultural mulch coextruded poly(lactic acid)(PLA)/starch films, two stages were carried out. The first was an ultraviolet treatment (UV) at 315 nm, during which glass transition temperature Tg, weight, and molecular weight (MW) decreased and a separation between PLA and starch phase was observed. For the second stage, the mineralization of the carbon of the material was followed using the ASTM (D 5209–92 and 5338–92) and ISO/CEN (14852 and 14855) standard procedures. To measure the biodegradability of polymer material, the assessment of the carbon balance allowed determination of the distribution between the carbon rate used to the biomass synthesis or the respiration process (released CO2), as well as the dissolved organic carbon into the culture medium and the carbon in the residual insoluble material. The influence of the nature of the medium and the standardized procedures on the final rate of biodegradation was investigated. Whatever the standardized method, the biodegradation percentage was significantly stronger in liquid medium (92.4–93.4) than on inert medium (80–83%). In the case of the compost process, only released CO2 was measured and corresponded to 79.1–80.3%. 相似文献
12.
Nugraha E. Suyatma Alain Copinet Lan Tighzert Veronique Coma 《Journal of Polymers and the Environment》2004,12(1):1-6
Biodegradable film blends of chitosan with poly(lactic acid) (PLA) were prepared by solution mixing and film casting. The main goal of these blends is to improve the water vapor barrier of chitosan by blending it with a hydrophobic biodegradable polymer from renewable resources. Mechanical properties of obtained films were assessed by tensile test. Thermal properties, water barrier properties, and water sensitivity were studied by differential scanning calorimeter analysis, water vapor permeability measurements, and surface-angle contact tests, respectively. The incorporation of PLA to chitosan improved the water barrier properties and decreased the water sensitivity of chitosan film. However, the tensile strength and elastic modulus of chitosan decreased with the addition of PLA. Mechanical and thermal properties revealed that chitosan and PLA blends are incompatible, consistent with the results of Fourier transform infrared (FTIR) analysis that showed the absence of specific interaction between chitosan and PLA. 相似文献
13.
The rheological behavior of biodegradable blends of starch and poly(vinyl alcohol) (PVOH) was measured as a function of temperature, shear rate, and moisture content using a capillary rheometer. An excellent correlation was found with a rheological model which was used as a means to characterize the influence of starch/PVOH content as well as a qualification of the viscosity for simulation studies. This model consisted of a power law dependence on shear rate, an Arrhenius dependence on temperature, and an exponential dependence on moisture.Paper presented at the Biodegradable Materials and Packaging Conference, September 22–23, 1993, Natick, Massachusetts.Guest Editor: Dr. Randall Shogren, USDA. 相似文献
14.
Extruded Cornstarch-Glycerol-Polyvinyl Alcohol Blends: Mechanical Properties, Morphology, and Biodegradability 总被引:3,自引:0,他引:3
Lijun Mao Syed Imam Sherald Gordon Patrizia Cinelli Emo Chiellini 《Journal of Polymers and the Environment》2000,8(4):205-211
Elongation properties of extruded cornstarch were improved by blending with glycerol. Further blending of starch-glycerol with polyvinyl alcohol (PVOH) resulted in significant improvements in both tensile strength (TS) and elongation at break. Samples of starch-glycerol without PVOH equilibrated at 50% relative humidity had a TS of 1.8 MPa and elongation of 113%, whereas those containing PVOH had a TS and elongation of 4 MPa and 150%, respectively. Dynamic mechanical analysis (DMA) of starch-glycerol-PVOH blends showed that decreases in glass transition temperatures (T
g values) were proportional to glycerol content. Scanning electron microscopy (SEM) of fractured surfaces revealed numerous cracks in starch-glycerol (80:20) samples. Cracks were absent in starch-glycerol (70:30) samples. In both blends, many starch granules were exposed at the surface. No exposed starch granules were visible in blends with added PVOH. Starch-glycerol samples incubated in compost lost up to 70% of their dry weight within 22 days. Addition of PVOH lowered both the rate and extent of biodegradation. 相似文献
15.
Effect of Nucleating Agents on Physical Properties of Poly(lactic acid) and Its Blend with Natural Rubber 总被引:1,自引:0,他引:1
Poly(lactic acid) (PLA) presents high strength and modulus, but very low toughness as well as slow crystallization. Natural
rubber (NR) was blended to enhance the toughness and nucleating agent was added to improve the crystallization. Cyclodextrin
(CD), considered as a green compound, as well as calcium carbonate (CaCO3) and talc were used as nucleating agents. Effects of these nucleating agents on crystallization, mechanical properties and
morphology of neat PLA and PLA/NR blend were investigated. It was found that the addition of talc and CD decreased cold crystallization
temperature (Tcc) of the PLA. Same result was obtained in PLA/NR blend containing talc. All nucleating agents increased the degree of crystallinity
(ΧC) of PLA, whereas only talc and CaCO3 increased ΧC of PLA in PLA/NR blends. The enhanced toughness of PLA by the addition of nucleating agent was attributed to its increased
crystallinity, as well as decreased spherulite size. For PLA/NR blends, the increase in toughness was mainly contributed by
the presence of the rubber. 相似文献
16.
Effects of Modified Starch and Different Molecular Weight Polyvinyl Alcohols on Biodegradable Characteristics of Polyvinyl Alcohol/Starch Blends 总被引:1,自引:0,他引:1
Wan-Lan Chai Jing-Dong Chow Chien-Chung Chen 《Journal of Polymers and the Environment》2012,20(2):550-564
The common biodegradable properties of polymer make them an excellent pair for blending, and the water solubility of polyvinyl alcohol (PVA) makes it easy to mix evenly with the starch. In this study, PVAs with different molecular weights were blended with various compositions of cross-linked starch (CLS) to explore the effects of molecular weight of PVA on the biodegradable characteristics of the PVA/starch blends. Comparing the biodegradability of all the various PVA/starch blends, a PVA was singled out from the PVA/starch blends of higher biodegradability. Further, the chosen PVA was then blended with the acid-modified starch (AMS) to systematically investigate the effects of the modified processing of starch on the biodegradable characteristics of the PVA/starch blends. Differential scanning calorimetry (DSC) analysis of PVA and PVA/starch specimens reveal that the Tm values of PVA/starch specimens reduce gradually as their CLS or AMS contents increase. After the CLS is blended in PVAs of different molecular weights, the tensile strength (??f) and elongation at break (??f) values of (P100S0)G20M1 specimen increase and simultaneously reduce, respectively, as their molecular weights of PVA increase from about 80,000 (PVABF-17) to 120,000 (PVABF-26). The ??f and ??f values of the PVA/modified-starch blends decrease with an increase in the modified starch contents. The ??f values of the PVA/AMS specimens decrease with an increase in the concentrations of hydrochloric acid. Comparing the ??f values of the PVA/CLS specimens with those of the PVA/AMS specimens, the ??f values of the PVA/CLS specimens are better than those of the PVA/AMS specimens. On the contrary, the ??f values of the PVA/AMS specimens are better than those of the PVA/CLS specimens. According to the biodegradability of all the PVA/starch blends, PVA with higher molecular weights displays higher biodegradability. The biodegradability of the PVA/modified-starch blends increase as the modified starch contents of the PVA/modified-starch blends increase. As evidenced by the results of the biodegradability test, the biodegradability of the PVA/modified-starch blends, therein PVA is blended with 1N AMS, shows better biodegradability. The result of bio-reaction kinetics experiment can evaluate the decomposition tendency of the PVA/starch blends up to any biodegradable rate under ambient environment. Using the kinetic model of the first order reaction, it is estimated that 16.20?years and 12.47?years will be needed for the PVABF-17/starch blends, containing 20 and 40% of CLS respectively, to be degraded up to 70% under ambient environment. In addition, it is 1.68?years for the PVABF-26 blends with the 40% 2N AMS under decomposition environment while it is 1.94?years for the 40% 1N AMS. Overall, the decomposition potential of PVA/AMS specimens is better than PVA/CLS specimens. Furthermore, the 1N(26P60AS40)100G20M1 specimen is coincidence the biodegradable material criteria of Environmental Protection Administration (EPA) of Taiwan. 相似文献
17.
Effect of Glycerin and Starch Crosslinking on Molecular Compatibility of Biodegradable Poly(lactic acid)-Starch Composites 总被引:1,自引:0,他引:1
Xue Shen Wu 《Journal of Polymers and the Environment》2011,19(4):912-917
Poly(lactic acid) (PLA) is a biodegradable material. However, PLA is relatively cost effective. Blending starch with PLA is
one of the promising efforts because starch is a widely distributed and inexpensive product. PLA and starch were blended using
a rheometer to form composites in this report. Glycerin was added into the blends to make the mixture molecular compatible
and more homogeneous. The starch was crosslinked using epichlorohydrin to improve the compatibility of starch with PLA. Two
series of composite were fabricated. One was PLA and the crosslinked starch containing 32 wt% glycerin. In this group, the
crosslinking degree of the modified starch was varied. The second group was PLA and non-crosslinked starch with varied amount
of glycerin added. Micro-structure of the blending composites was observed using a SEM to view the homogeneity of the mixture.
The SEM pictures indicated that the compatibility of PLA and starch molecules was poor. The addition of glycerin can change
the compatibility of PLA and starch. The higher the glycerin content in the composites, the better the compatibility between
PLA and starch. Furthermore, when the starch was crosslinked by epichlorohydrin, the compatibility of PLA and starch can be
greatly improved. The compatibility increases with the increase of crosslinking degree. This is due to the change of hydrophilicity
of starch because the hydroxyl groups on the starch molecules were crosslinked into ether groups by the epichlorohydrin molecules. 相似文献
18.
Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends 总被引:2,自引:0,他引:2
In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated
for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry
(DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the
DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that
adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight
increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially
oriented films showed an increase in tensile strength, modulus, and strain-at-break. 相似文献
19.
Physical properties and biodegradability of blends containing poly(ε-caprolactone) and tropical starches 总被引:1,自引:0,他引:1
Hardaning Pranamuda Yutaka Tokiwa Hideo Tanaka 《Journal of Polymers and the Environment》1996,4(1):1-7
In order to assess feasibility of tropical starches (sago and cassava starches) as biodegradable plastic materials, blending with poly(-caprolactone) (PCL), a biodegradable polymer, was carried out. It was confirmed that the physical properties (tensile strength and elongation) of PCL/sago and PCL/cassava blends were similar to those of PCL/corn blend, suggesting that sago and cassava starches can also be blended with PCL for production of biodegradable plastic. However, the properties of all PCL/starch blends were still low compared with those of polyethylene. Enzymatic degradability evaluation showed that lipase degradation of PCL and-amylase degradation of starch increased as the starch content in the blend increased. Burial test of the blends for 1, 3, and 5 months was carried out and the rate of degradation of the PCL/sago blend was confirmed to be slower than those of PCL/corn and PCL/cassava blends. Observation of the film blends structure by scanning electron microscope revealed that the starch was dispersed in a PCL continuous phase. Furthermore, changes in the film surface before and after enyzme treatments were observed. 相似文献
20.
Study on the Effect of Dicumyl Peroxide on Structure and Properties of Poly(Lactic Acid)/Natural Rubber Blend 总被引:1,自引:0,他引:1
Yun Huang Chunmei Zhang Yonghao Pan Weiwei Wang Long Jiang Yi Dan 《Journal of Polymers and the Environment》2013,21(2):375-387
In attempt to enhance the compatibility of NR in PLA matrix, and furthermore to enhance mechanical properties of PLA, PLA/NR blends with strong interaction were prepared in Haake internal mixer, using dicumyl peroxide (DCP) as cross-linker. The effects of dicumyl peroxide on morphology, thermal properties, mechanical properties and rheological properties of PLA and PLA/NR blends were studied. The results indicated that dicumyl peroxide could increase the compatibility of poly(lactic acid) and natural rubber. With small amount of dicumyl peroxide, the effect on NR toughening PLA was enhanced and the tensile toughness of PLA/NR blends was improved. When the DCP content was up to 0.2 wt%, the PLA/NR blend reached the maximum elongation at break (26.21 %) which was 2.5 times of that of neat PLA (the elongation at break of neat PLA was 10.7 %). Meanwhile, with introducing 2 wt% DCP into PLA/NR blend, the maximum Charpy impact strength (7.36 kJ/m2) could be achieved which was 1.8 times of that of neat PLA (4.18 kJ/m2). Moreover, adding adequate amount of DCP could improve the processing properties of blends: the viscosity of PLA/NR blend decreased significantly and the lowest viscosity of the blends could be achieved when the DCP content was 0.5 wt%. 相似文献