Biodegradability of photodegraded polymers. I. Development of experimental procedures (original) (raw)

A Review on Biodegradations of Polymers and its Effect on Environment

Journal of Composites and Biodegradable Polymers, 2016

Biodegradation refers to the chemical dissolution of materials by microorganisms or other biological means. Biodegradability of a material refers to the ability of that material to be decomposed by biological agents, especially bacteria. Carbon dioxide and water are produced during aerobic biodegradation and carbon-dioxide, water and methane are produced during anaerobic biodegradation. The process of degradation induces changes in polymer properties resulting in bond scission, chemical transformation and formation of new functional groups. Most of the polymers are non-degradable and some are degraded after longtime and causes environmental pollution. Biodegradation of polymers have both positive and negative impact on environment but the negative impacts are more remarkable. Because some polymeric materials take about million year to degrade in environment. Disposal problem will be introduced from these materials and finally destroy our ecological balance. To protect the environmen...

Biodegradation of Organic Compounds and Plastics: A Review

Biodegradation is defined as the biologically catalyzed reduction in complexity of chemical compounds. Indeed, biodegradation is the process by which organic substances are broken down into smaller compounds by living microbial organisms. When biodegradation is complete, the process is called "mineralization". However, in most cases the term biodegradation is generally used to describe almost any biologically mediated change in a substrate. So, understanding the process of biodegradation requires an understanding of the microorganisms that make the process work. The microbial organisms transform the substance through metabolic or enzymatic processes. It is based on two processes: growth and cometabolism. In growth, an organic pollutant is used as sole source of carbon and energy. This process results in a complete degradation (mineralization) of organic pollutants. Cometabolism is defined as the metabolism of an organic compound in the presence of a growth substrate that is used as the primary carbon and energy source. Several microorganisms, including fungi, bacteria and yeasts are involved in biodegradation process. Algae and protozoa reports are scanty regarding their involvement in biodegradation. Biodegradation processes vary greatly, but frequently the final product of the degradation is carbon dioxide. Organic material can be degraded aerobically, with oxygen, or anaerobically, without oxygen.

Evaluation of the rate of abiotic and biotic degradation of oxo-degradable polyethylene

Polymer Testing, 2016

The recent introduction of oxo-degradable additive in the Argentinean market has motivated the study of the effect of abiotic (temperature and ultraviolet (UV) radiation) and biotic (aerobic in compost) degradation on the structure and mechanical behavior of films of polyethylene (PE) and oxo-degradable polyethylene (PEþAD). Physico-chemical tests show that the failure strain and the carbonyl index of degraded PE and PEþAD samples depend on the UV irradiation dose. Furthermore, the additive plays a crucial role in the degradation and subsequent decay of the molecular weight. It was observed that, for the same dose, the most deteriorated material was the one exposed to the lowest irradiance, emphasizing the importance of the time of exposure to UV radiation. The ratio between the irradiance and the critical dose, is a characteristic time associated to the sharp decay on the failure strain. The critical dose decreases significantly when increasing the temperature of the photodegradation assay. PE is more susceptible to thermal degradation than PEþAD; the latter only degrades under thermal aging at the highest temperature. Initially biotic degradation in compost showed an increasing production of carbon dioxide for both previously UV-degraded and untreated PEþAD. It is also remarkable that UV-degraded samples of PE and PEþAD with differences in their abiotic degradation level, reached the same final biotic degradation level. It was observed that although the additive increased the abiotic photodegradation, the molecular weight reduction in compost was not enough to reach the maximum biotic degradation level established by international standards for biodegradable materials.

Bio-Based Plastics and Their Degradation by Soil Microbes

Bio-based plastics, which are degradable polymer-blends from renewable agricultural products had been investigated as good substitute for non-degradable petroleum-based plastics. The attempt is to modify the non-biodegradability, strong carbon-carbon bonds, hydrophobicity, and durability properties of conventional thermoplastics, to ensure their natural decomposition by soil microorganisms. The surface topography of the corn-starch/plastic blended-sheets were taken using a scanning electronic microscope (PPSK)SEM, model, before subjecting them to soil burial biodegradation process. The major bacteria species identified from the soil after culturing, incubation, and biochemical identifications were Staphylococus aureus, E. Coli, Samonella Sp., Bacillus Sp., Pseudomanas Sp., Lactobacillus Sp. etc. The mechanical properties, percentage weight-loss, reduction in tensile properties, water absorption properties, appearance of remarkable voids, and cracks on the plastic surfaces, as compared to the pure plastic samples, confirmed the extend of biodegradation.

Research of the biodegradability of degradable/biodegradable plastic material in various types of environments

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

Research was carried out in order to assess biodegradability of degradable/biodegradable materials made of HDPE and mixed with totally degradable plastic additive (TDPA additive) or made of polyethylene (PE) with the addition of pro-oxidant additive (d2w additive), advertised as 100% degradable or certifi ed as compostable within various types of environments. Research conditions were: (i) controlled composting environment – laboratory-scale, (ii) real composting conditions – domestic compost bin, (iii) real composting conditions – industrial composting plant and (iv) landfill conditions. The results demonstrate that the materials made of HDPE and mixed with totally degradable plastic additive (TDPA additive) or made of polyethylene (PE) with the addition of pro-oxidant additive (d2w additive) or advertised as 100% degradable did not biodegrade in any of the above-described conditions and remained completely intact at the end of the tests. Biodegradation of the certified compostable...

Biodegradability of degradable plastic waste

Waste Management & Research, 2005

Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60°C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.

AND BIODEGRADATION RATES OF DEGRADABLE/BIODEGRADABLE PLASTICS WITHIN SIMULATED ENVIRONMENT Summary

2016

The objective of this study was to evaluate and compare the biodegradabi-lity and biodegradation rates of ‘single-use ’ plastic bags available on the market and labeled as degradable/biodegradable. The test was carried out under both ae-robic and anaerobic conditions. The project length was 20 months. The biodegra-dation results in the laboratory conditions demonstrate that none of the degrada-ble/biodegradable bags showed visual changes and/or were broken into pieces and none of them experienced any disintegration or degradation. The cellulose filter paper (CFP) completely degraded after 10 days in the aerobic conditions and after 5 month in the anaerobic conditions, implying that the conditions required for biodegradation to occur in a sampling environment were present.