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1.
Wenxiang Zhu Xi Huang Chuncheng Li Yaonan Xiao Dong Zhang Guohu Guan 《Polymer International》2011,60(7):1060-1067
Aliphatic polycarbonates (APCs) synthesized by polycondensation of dialkyl carbonates and aliphatic diols have often been used as precursors for the preparation of novel polyurethanes. However, they could not be applied in plastics directly because of poor mechanical properties caused by low molecular weight. In the work reported in this paper, three kinds of fairly high molecular weight (Mw ≥ 166 000 g mol?1) APCs with narrow dispersity ( ) were successfully synthesized via a successive two‐step polycondensation of dimethyl carbonate and diols, using a novel TiO2/SiO2‐based catalyst. This process gave a high yield of above 85%. 1H NMR spectra indicated that there was no detectable decarboxylation happening during polycondensation at high temperature. The effects of molecular weight on the mechanical properties of the APCs are discussed. APCs with Mw greater than 70 000 g mol?1 showed useful mechanical properties. Especially, poly(butylene carbonate) and poly(hexamethylene carbonate) exhibited excellent tensile strengths of 34.1 and 40.0 MPa, respectively, when their Mw was ca 170 000 g mol?1. All the APCs showed appreciable biodegradability under enzymatic degradation. Copyright © 2011 Society of Chemical Industry 相似文献
2.
Environmental factors such as oxygen, temperature, and microbial species may have significant effects on decomposition of biodegradable polymers. A representative biodegradable, thermoplastic polymer, poly(3‐hydroxybutyrate‐co‐hydroxyvalerate) (PHBV), was decomposed in an aqueous medium under controlled laboratory conditions by soil microbes for the intrinsic degradation kinetics and the effects of the environmental factors on polymer biodegradation. The amount of proteins, including the PHBV depolymerases, that attached to the polymer surfaces was quite constant during the period of significant mass loss of the polymer specimens. The microbial polymer degradation followed a zero‐order rate model, so the residual mass fraction of PHBV films declined linearly with time. The mixed aerobic microbial organisms from fertile soil showed a higher activity of polymer degradation than an aerobic PHBV‐producing bacterium and the mixed anaerobes in the same soil. The mixed anaerobic microorganisms from barren soil decomposed the polymer at a slower rate than the anaerobes from fertile soil, and this was attributed to fewer microbial cells in the barren soil instead of the difference in the microbial species. The temperature effect on PHBV degradation can be described with an Arrhenius equation, and the activation energy is around 16 kcal/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 205–213, 2003 相似文献
3.
Aleksandra Buzarovska Anita Grozdanov M. Avella G. Gentile M. Errico 《应用聚合物科学杂志》2009,114(5):3118-3124
Nanocomposites, based on a poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) matrix and titanium dioxide (TiO2) nanoparticles and fabricated with a solvent‐casting technique, were characterized with differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. The content of TiO2 nanoparticles varied between 0.5 and 10 wt %. Degradation studies, including hydrolytic degradation in a strong base medium (1N NaOH) and degradation under ultraviolet light at 365 nm, were performed. It was confirmed that the inorganic filler had no great influence on thermal properties such as the melting and crystallization temperatures. Improved degradation temperatures were also confirmed with the increase in the filler content. Degradation observations confirmed significant increases in hydrolytic erosion with the filler content increasing in comparison with the degradation of a pure PHBV film. Also, the photocatalytic activity of the inorganic filler TiO2 in all investigated composites [irradiated at λ = 365 nm and immersed in a liquid medium (H2O)] was evaluated. The degraded samples were analyzed with Fourier transform infrared spectroscopy, which confirmed their increased crystallinity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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Heng Zheng Zhenyu Dai Jie Wei Lin Li Haitao Peng Aiping Yang Hong Li Guoyu Lv 《应用聚合物科学杂志》2021,138(5):49751
Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants. 相似文献
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Electrospinning of biodegradable poly(3‐hydroxybutyrate) (PHB)/magnetite and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)/magnetite composites in 2,2,2‐trifluoroethanol (TFE) and chloroform are investigated to develop nonwoven nanofibrous structure. Ultrafine PHB/magnetite fibers are obtained and the resulting fiber diameters are in the range of 690–710 nm and 8.0–8.4 µm for the polymer dissolved in TFE and chloroform. The surface of PHB composites fiber fabricated in chloroform contains porous structures, which are not observed for the sample of PHB composites fiber dissolved in TFE. The fiber diameters for PHBV5/magnetite composites are in the range of 500–540 nm and 2.3–2.5 µm, depending on the use of TFE and chloroform. The average diameters of PHBV5/magnetite composite fibers are smaller than those of PHB/magnetite composites fiber. All electrospun PHB/magnetite and composite fibers are superparamagnetic. The degradation behaviors of PHB/magnetite and PHBV5/magnetite composite fibers were investigated using Caldimonas manganoxidans. For the fabricated composite fibers, it is found that the degradation rate increased with the increasing loading of magnetite nanoparticles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41070. 相似文献
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Poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s were successfully synthesized by the ring‐opening copolymerization of p‐dioxanone and ethyl ethylene phosphate with triisobutyl aluminum as an initiator; this was confirmed by 1H‐NMR and infrared spectra. The effects of the reaction conditions, such as the feeding ratio of the monomers and the reaction temperature and time, on the molecular weight of the copolymers were also studied. The in vitro degradation results showed that the introduction of phosphate segments into the backbone chains of the copolymers led to an enhancement of the degradation rate of the copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5507–5511, 2006 相似文献
7.
In this study, the durability of poly(butylene succinate) (PBS), poly(butylene adipate‐co‐terephthalate) (PBAT), and PBS/PBAT blend was assessed by exposure to 50°C and 90% relative humidity for a duration of up to 30 days. Due to the easy hydrolysis of esters, the mechanical properties of PBS and PBAT were significantly affected with increasing conditioning time. The PBS, PBAT, and PBS/PBAT showed an increase in modulus as well as a decrease in tensile strength and elongation at break with increased exposure time. Furthermore, the impact strength of PBAT remains unaffected up to 30 days of exposure. However, it was clearly observed that the fracture mode of PBS/PBAT changed from ductile to brittle after being exposed to high heat and humid conditions. This may be attributed to the hydrolysis products of PBS accelerating the degradation of PBAT in the PBS/PBAT blend. The differential scanning calorimetry results suggested that the crystallinity of the samples increased after being exposed to elevated temperature and humidity. This phenomenon was attributed to the induced crystallization from low molecular weight polymer chains that occurred during hydrolysis. Therefore, low molecular weight polymer chains are often favored to the crystallinity enhancement. The increase in crystallinity eventually increased the modulus of the conditioned samples. The enhanced crystallinity was further confirmed by polarizing optical microscopy analysis. Moreover, the hydrolysis of the polyesters was evaluated by scanning electron microscopy, rheology, and Fourier transform infrared spectroscopy analysis. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42189. 相似文献
8.
Larissa Stieven Montagna Maria Madalena de Camargo Forte Ruth Marlene Campomanes Santana 《应用聚合物科学杂志》2014,131(22)
In order to reduce the environmental impact of the accumulation of synthetic polymer waste, especially in the case of products with a short shelf life, such as disposable diapers and sanitary napkins, this study evaluated the biodegradation of samples of polypropylene (PP) modified with an organic additive free of transition metals. The samples were prepared using a single‐screw extruder, then ground with liquid nitrogen and processed by thermal compression molding into the form of plates. They were then submitted to a respirometric test involving biodegradation carried out at 58°C for 120 days. The samples were characterized according to their physical, thermal, and morphological properties. The results verified that the modified PP showed evidence of enhanced degradation through increased CO2 generation and weight loss during incubation. The thermal analysis revealed an increase in the degree of crystallinity and a decrease in the melt temperature. SEM micrographs showed exfoliation, the appearance of holes, and surface deterioration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41054. 相似文献
9.
The synthesis of a series of poly(ester amide)s constituted by glycolic acid, adipic acid, and different ratios of 1,3‐pentanediamine and 1,5‐pentanediamine units was studied and the derived copolymers were characterized. Thermal polycondensation between the potassium adipate salt and the appropriate ratio of N,N′‐bis(chloroacetyl)‐1,3‐pentanediamine and N,N′‐bis(chloroacetyl)‐1,5‐pentanediamine was proved to be effective, proceeded with high yield, and rendered samples with moderate molecular weight for carefully controlled competitive thermal degradation reactions. Physical properties were highly dependent on the final composition. In particular, crystallinity and thermal stability decreased with 1,3‐pentanediamine unit content, that is, with the incorporation of lateral ethyl groups into the main chain. The presence of these units also changed solubility in solvents like methanol and degradability in a protease K enzymatic medium. Specifically, incorporation of 1,3‐pentanediamine units led to a gradual increase in degradability. All poly(ester amide)s were able to establish intermolecular hydrogen bonding interactions, which in semicrystalline samples pointed to typical sheet structures of polyamides according to X‐ray diffraction and infrared spectroscopic data. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40102. 相似文献
10.
Horacio Vieyra Eduardo San Martín‐Martínez Esmeralda Juárez Ulises Figueroa‐López Miguel A. Aguilar‐Méndez 《应用聚合物科学杂志》2015,132(29)
Starch‐based biodegradable polymers are obtained by incorporating plant‐derived polymers into plastics. This blending allows for a reduction in the polymer's resistance to microbial degradation. Assessing biodegradability is a key step in the characterization of newly designed polymers. Composting has been taken into consideration in waste management strategies as an alternative technology for plastic disposal. This study analyzed the biodegradability of an injection‐molded plastic material in which thermoplastic unripe banana flour (TPF) acts as a matrix (70%) and metallocene catalyzed polyethylene acts as a reinforcing filler (30%). This plastic was termed 70 TPF, and the structural, physical, and mechanical changes associated with its degradation were analyzed. The characterization of the microorganism that contributes to 70 TPF biodegradation was also performed. After composting, 70 TPF decreased in tensile strength and the TPF moiety in the blend was lost, greatly affecting the microstructure of the sample. Based on these indicators of degradation, this study identified the fungus Mortierella elongata as the microorganism responsible for the degradation of the plastic, a finding that supports the role of fungal communities in the biodegradation of designed materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42258. 相似文献
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双酚A型聚碳酸酯性能优异,应用广泛。但在户外使用时,由于光、一氧和湿度等环境因素的作用,导致聚碳酸酯力学强度和外观发生变化。为提高PC的抗老化性能,必须通过研究。充分认识聚碳酸酯的老化反应和老化进程。综述了近年来聚碳酸酯老化行为的研究,并提出存在的问题和今后研究的方向。 相似文献
13.
X.-W. Wang G.-X. Wang D. Huang B. Lu Z.-C. Zhen Y. Ding Z.-L. Ren P.-L. Wang W. Zhang J.-H. Ji 《应用聚合物科学杂志》2019,136(2):46916
We investigated the degradation behavior of biodegradable poly(butylene adipate terephthalate) (PBAT) and its composites containing starch (PBAT–starch) and calcium carbonate (PBAT–CaCO3). The test splines were immersed in six different water bodies with various microbial compositions and salt concentrations for a 56 week period to obtain consistent experimental data. The results show that the pure PBAT degraded very slowly in the six water bodies, with a maximum weight loss of only 4.7% over the 56 week study period. Strips of the PBAT–starch composite showed a significantly accelerated biodegradation in microbe-containing water; the degree of degradation depended largely on the type and abundance of microorganisms in the water bodies. Conversely, compared with the pure PBAT strips, PBAT–CaCO3 showed less degradation in the various water bodies. A comparison of degradability between the strips immersed in sterilized distilled water and sterilized seawater indicated that inorganic salts did not significantly affect the degradation of PBAT. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46916. 相似文献
14.
The methanolysis of poly(lactic acid) (PLA) was studied by using acidic ionic liquids (ILs) as catalyst in detail. The results showed that HSO3‐functionalized ILs exhibited higher catalytic activity than non‐functionalized ILs and traditional acid catalyst such as H2SO4. The influences of experimental parameters, such as the amount of catalyst, reaction temperature, methanolysis time, and dosages of methanol on the conversion of PLA, yield of methyl lactate were investigated. Under the optimal conditions, using 1‐methyl‐3‐(3‐sulfopropyl)‐immidazolium hydrogen sulfate ([HSO3‐pmim][HSO4]) as catalyst, the IL could be reused up to six times without apparent decrease in the conversion of PLA and yield of methyl lactate. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA in [HSO3‐pmim][HSO4] was a first‐order kinetic reaction with activation energy of 47.01 kJ/mol and Arrhenius constant of 2.7 × 107 min?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40817. 相似文献
15.
The objective of this article is to assess the mechanical performance of PLA‐based materials under exposure of an organic liquid. In evaluating new opportunities of PLA‐based material, it is important to understand not only the chemical resistance of the material but also the potential route for degradation, which affect the mechanical behavior of the product during its service time. Degradation of PLA material with amount of sorption should be carefully controlled in order to maintain its mechanical performance in response to various loading condition. Distribution of the absorbed liquid within the package is firstly evaluated by identifying the characteristics of the mass transport. Gravimetric analysis is employed to investigate the liquid sorption mechanism and the induced expansion over a particular period. The profile of absorbed liquid content is numerically obtained and verified with the analytic solution. The changes in mechanical performances were investigated by measuring the properties of specimens containing saturated liquid content. It is found that at low temperature, the kinetics of liquid sorption follows the Fick's law but at higher temperature, it showed a deviation from the Fickian curve. The experiment results also confirm progressive decrease of the modulus and strength by increasing of fluid content inside the material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43250. 相似文献
16.
Xian Jun Loh 《应用聚合物科学杂志》2013,127(3):2046-2056
The in‐vitro hydrolytic behavior of diblock copolymer films consisting of poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) was studied at pH 7.4 and pH 9.5 at 37°C. The degradation of these films was characterized at various time intervals by mass loss measurements, GPC, 1H‐NMR, DSC, FTIR, XRD, and SEM. A faster rate of degradation took place at pH 9.5 than at pH 7.4. Analysis of the molecular weight profile during the course of degradation revealed that random chain scission of the ester bonds in PCL predominates at the initial induction phase of polymer degradation. There was also an insignificant mass loss of the films observed. Mass spectroscopy was used to determine the nature of the water soluble products of degradation. At pH 7.4, a variety of oligomers with different numbers of repeating units were present whereas the harsher degradation conditions at pH 9.5 resulted in the formation of dimers. From the results, it can be proposed that a more complete understanding of the degradation behavior of the PCL‐b‐PEG copolymer can be monitored using a combination of physiological and accelerated hydrolytic degradation conditions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
17.
Wood flour reinforced poly(propylene carbonate) (PPC) composites were prepared by melt blending followed by compression molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal properties of PPC/wood flour composites were investigated. In terms of mechanical properties, wood flour had the significant effect of improving tensile strength and stiffness. Scanning electron microscopic examination revealed good dispersion of wood flour (especially at lower content) in the PPC matrix. Moreover, experimental results indicated that the wood flour addition led to an obvious improvement in the thermal stability of the composites. This paper demonstrates that the incorporation of low‐cost and biodegradable wood flour into PPC provides a practical way to produce completely biodegradable and cost‐competitive composites with good mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 782–787, 2006 相似文献
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Nathalia S. Q. S. Amorin Gabriela Rosa Jefferson Fernandes Alves Suely P. C. Gonçalves Sandra M. M. Franchetti Guilhermino J. M. Fechine 《应用聚合物科学杂志》2014,131(6)
The thermomechanical degradation and thermostabilization of poly(lactic acid) (PLA) have been studied using subsequent extrusion cycles under different temperature profiles. Primary and secondary antioxidants were used to avoid degradation process during extrusion. Melt flow index (MFI), size exclusion chromatography (SEC), and infrared spectroscopy (FTIR) analysis were used to evaluate the degradation and stabilization of PLA. The MFI and SEC analysis show that the main thermodegradation mechanism of PLA is governed by scission reactions. FTIR analysis confirmed the SEC results and showed that the synergetic effect between primary and secondary antioxidant is a suitable way to thermostabilize the PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40023. 相似文献
20.
Novel synthetic biodegradable methacrylated anhydride oligomers (MAOs) based on methacrylated alaninyl maleamic acid (MAMA) and methacrylated aminocaproyl maleamic acid (MACMA) were synthesized and characterized. Injectable and in situ crosslinkable polymer networks were formulated by the copolymerization of MAOs with triethylene glycol dimethacrylate (TEGDMA). Furthermore, composites composed of MAOs, TEGDMA, and β‐tricalcium phosphate were prepared. The networks and composites were initiated by photopolymerization and redox polymerization, respectively. The initial compressive strength (CS) and diametral tensile strength (DTS) of these materials were determined and used to evaluate the effects of the MAO/TEGDMA ratios on the degradation behavior of the materials. The MAMA‐based composites had initial DTS values of 5.7–17.1 MPa and CS values of 30.7–114.2 MPa. The MACMA‐based composites had initial DTS values of 2.8–20.8 MPa and CS values of 19.1–119.5 MPa. During the course of degradation, the neat polymer resins lost 97 and 87% of their initial CS values after 6 months with 50/50 MAMA/TEGDMA and MACMA/TEGDMA ratios, respectively. The composite with a 25/75 MACMA/TEGDMA ratio showed a significant increase in CS after an initial decrease for 7 days and then lost 57% of its initial CS value after 3 months. The composite composed of 100% methacrylated anhydride oligomer (MAOs) showed complete degradation after 21 days. The degrees of conversion of the neat resins were 60–77%. Both the neat resins and the composites had low polymerization shrinkage ranging from 3.8 to 5.6%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1979–1984, 2005 相似文献