Properties and biodegradability of chitosan/nylon 11 blending films

Different ratios of nylon 11/chitosan blending films were prepared by solution casting method. The strength of the hydrogen bond in the blending films is weakened after addition of chitosan and spherulite growth is restricted as the ratio of chitosan increases. Sea-island morphology could be observed once the concentration of chitosan in the blends was more than 50%. Blending films are characterized by FTIR (Fourier transform infrared spectroscopy), X-ray, and scanning electron microscopy (SEM) and the biodegradability is also investigated. The extent of biodegradability for nylon 11/chitosan blending films is strongly affected by the addition percentage of chitosan.     

Biodegradability of conventional and bio-based plastics and natural fiber composites during composting,anaerobic digestion and long-term soil incubation

Plastics are a major constituent of municipal solid waste that pose a growing disposal and environmental pollution problem due to their recalcitrant nature. To reduce their environmental impacts and allow them to be transformed during organic waste recycling processes, various materials have recently been introduced to improve the biodegradability of plastics. These include conventional plastics amended with additives that are meant to enhance their biodegradability, bio-based plastics and natural fiber composites. In this study, the rate and extent of mineralization of a wide range of commercially available plastic alternative materials were determined during composting, anaerobic digestion and soil incubation. The biodegradability was assessed by measuring the amount of carbon mineralized from these materials during incubation under conditions that simulate these three environments and by examination of the materials by scanning electron micrography (SEM). The results showed that during a 660 day soil incubation, substantial mineralization was observed for polyhydroxyalkanoate plastics, starch-based plastics and for materials made from compost. However, only a polyhydroxyalkanoate-based plastic biodegraded at a rate similar to the positive control (cellulose). No significant degradation was observed for polyethylene or polypropylene plastics or the same plastics amended with commercial additives meant to confer biodegradability. During anaerobic digestion for 50 days, 20–25% of the bio-based materials but less than 2% of the additive containing plastics were converted to biogas (CH₄ + CO₂). After 115 days of composting, 0.6% of an additive amended polypropylene, 50% of a plastarch material and 12% of a soy wax permeated paper pulp was converted to carbon dioxide. SEM analysis showed substantial disintegration of polyhydroxyalkanoate-based plastic, some surface changes for other bio-based plastics and coconut coir materials but no evidence of degradation of polypropylene or polypropylene containing additives. Although certain bio-based plastics and natural fibers biodegraded to an appreciable extent in the three environments, only a polyhydroxyalkanoate-based resin biodegraded to significant extents during the time scale of composting and anaerobic digestion processes used for solid waste management.     

Formulation selection of aliphatic aromatic biodegradable polyester film exposed to UV/solar radiation

Aliphatic aromatic copolyester films, poly(butylene adipate-co-terephthalate) or PBAT, are susceptible to photodegradation, leading to main chain scission and crosslinking. The presence of crosslinked structures not only decreased the mechanical properties of the film due to embrittlement, but also hindered the biodegradation process by limiting access of water and microorganisms to the polymer chains. This has limited the use of PBAT for outdoor applications, such as mulch films. In this study, response surface methodology (RSM) was used to determine the optimal concentrations of carbon black (CB) and the chain breaking antioxidant butylated hydroxytoluene (BHT) for the design of mulch films that can prevent the formation of crosslinked structures from recombination of free radicals. An overlaid contour plot of suitable concentrations of CB and BHT for the formulation of mulch film for crop production in Michigan or regions with similar solar radiation was established using selection criteria of light transmission of less than 20%, final tensile strength of at least 6.35 MPa, maximum gel fraction of 0.30, and positive number average molecular weight reduction sensitivity in the early stage of degradation.     

Synthesis, characterization and degradability of the novel aliphatic polyester bearing pendant N-isopropylamide functional groups

The synthesis, characterization, and degradability of the novel aliphatic polyester bearing pendant N-isopropylamide functional group are reported for the first time. 2-(N-Isopropyl-2-carbamoylethyl)cyclohexanone (CCH) was first synthesized by the Michael reaction of N-isopropylacrylamide with cyclohexanone and was subsequently converted into 6-(N-isopropyl-2-carbamoylethyl)-?-caprolactone (CCL) by the Baeyer-Villiger oxidation reaction using 3-chloroperoxybenzoic acid (mCPBA) as the oxidant. Finally, the novel functionalized poly(?-caprolactone) bearing the pendant N-isopropylamide functional groups, poly(6-(N-isopropyl-2-carbamoylethyl)-?-caprolactone-co-?-caprolactone)s (poly(CCL-co-CL)), were carried out successfully by bulk ring-opening polymerization of CCL and ?-CL initiated by Sn(Oct)₂. Poly(CCL-co-CL) were characterized by ¹H NMR, ¹³C NMR, SEC and DSC. The copolymer containing 9.1 mol% CCL formed flexible films and was used to study its degradability. A phosphate buffer (pH = 7.4) with temperature 37 °C was adopted to proceed the degrading study all through. Compared with poly(?-caprolactone), the hydrolytic degradation of poly(CCL-co-CL) was much faster, which is confirmed by the weight loss and change of intrinsic viscosity.     

Biodegradation of chemically modified wheat gluten-based natural polymer materials

Biodegradation of a series of chemically modified thermally processed wheat gluten (WG)-based natural polymers were examined according to Australian Standard (AS ISO 14855). Most of these materials reached 93-100% biodegradation within 22 days of composting, and the growth of fungi and significant phase deformation were observed during the process. Chemical crosslinking did slow down the rate or reduce the degree of the biodegradation with different behaviours for different modified systems. The segments containing structures derived from the reactions with additives such as tannin or epoxidised soybean oil remained in the degradation residues while the glycidoxypropyl trimethoxysilane agent produced ∼20% un-degraded residues containing silicon-crosslinking structures. The biodegradation rate of each component of the materials was also different with the protein and starch components degraded fast but lipid degraded relatively slowly.     

Fire retardancy and biodegradability of poly(methyl methacrylate)/montmorillonite nanocomposite

The poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposite was prepared by emulsifier-free emulsion technique and its structure and properties were characterized with infra red, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, and cone calorimetry. The highly exfoliated MMT layers with dimension 1-2 nm in thickness were randomly dispersed in the polymer matrix containing MMT lower than 5% w/v, whereas the intercalated structure was predominant with MMT content higher than 5% w/v. Consequently, the fine dispersion of the MMT and the strong interactions between PMMA and MMT created significant improvement of the thermo-stability and fire retardancy of the nanocomposite. The combustion behavior has been evaluated using oxygen consumption cone calorimetry. In addition, a scheme was proposed to describe fire retardancy of PMMA and MMT as well as the correlation between the interaction and structure in polymer/clay systems. The biodegradability of the nanocomposite fire-retardant was tested for its better commercialization.     

Chromatographic investigations on biodegraded crude oils

Summary Microorganisms have been isolated from a biodegraded crude oil from the Gifhorn trough, Lower Saxony. A non-degraded crude oil, related to the same source rock as the biodegraded one, was inoculated with the microorganisms found and the course of biodegradation thus initiated was followed by gas and liquid chromatographic techniques. The influence of biodegradation on commonly used oil-to-oil correlation parameters was investigated in detail.Originally presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984.     

植物单宁的生物降解

植物单宁的生物降解对于拓展这类天然产物的应用领域，使其获得高附加值利用有重要的意义。本文较全面的综述了这一研究领域的发展现状和趋势，并根据笔者的研究体会，对技术方法和学术观点进行了一些规律性的总结和归纳。     

FTIR and NMR study of poly(lactide-co-glycolide) and hydroxyapatite implant degradation under in vivo conditions

The influence of hydroxyapatite (HAP) addition on the rate and mechanism of lactide-co-glycolide copolymer (PGLA) degradation after implantation (in vivo study) was analyzed and compared with the process taking place during in vitro studies. Structural and phase changes of poly(lactide-co-glycolide) and its composite with hydroxyapatite were determined using IR and NMR spectroscopy.Degradation of PGLA and PGLA + HAP composite in biological environment proceeds faster than under in vitro condition. Concentration of glycolidyl units in the copolymer chain decreases and that of lactidyl units increases during in vivo degradation both, in PGLA and in PGLA + HAP composite. However, in the case of the composite the decrease of glycolidyl units concentration is slower and after 6 weeks of degradation the contents of lactidyl and glycolidyl units remain stable. On the other hand, PGLA + HAP composite degrades faster than pure PGLA. The addition of HAP nanoparticles distinctly accelerates degradation of PGLA copolymer which is probably connected with the increase of hydrophilicity of the composite and inhibition of semi-crystalline lactidyl domains formation during the degradation process. Observation of the bone tissue after implantation of PGLA + HAP allows to conclude that the degradation of the composite occurs simultaneously with the implant replacement by the bone cells.