Photo-oxidation and biodegradation of Polyethylene nanocomposites

Polyethylene (PE) is widely used in packaging and agricultural industries because of its low cost and unique combination of properties such as high strength, light weight, water resistance, high stability and ease of fabrication. Each year a considerable amount of PE waste accumulates at landfill sites, and it takes a very long time to biodegrade. Since PE waste is not always retained in the upper level of a landfill for a long time, it can undergo very limited oxidation. In an attempt to solve the polymer degradation problem, researchers have identified a simple and inexpensive method that involves blending PE with pro-oxidants, which enhances oxidation significantly. The PE-pro-oxidant blend, known as oxo-biodegradable polyethylene, has been found to undergo oxidation rapidly but experiences very little biodegradation. This work aims to evaluate the suitability of polyethylene-layered silicate nanocomposites as a biodegradable polymer that can degrade through the oxo-biodegradation process. One of the main objectives of the thesis is to investigate the combined effect of nanoclay and a commercial pro-oxidant on the photo-degradation and biodegradation of PE. This study also investigates whether the roles of nanoclay and pro-oxidant in biodegradation can be achieved by using modified nanoclay that has been prepared by synthesising a pro-oxidant on the surface of unmodified MMT. In conclusion, nanoclay in oxo-biodegradable PE nanocomposites enhances both the photo-oxidation and biodegradation of polyethylene. However, the oxo-biodegradable PE nanocomposite that contains Co2+- PEG monolaurate pro-oxidant is the most efficient because it provides a low-cost solution to reduce PE wast

Species diversity and forage value of herbage in a neglected coconut land proposed for livestock integration

The proposed coconut land is situated in the southern province. belongs to the land suitability class S4which is moderately suitable for coconut. Therefore, managing coconut as rnonoculture is unprofitableand steps have been taken to optimize the land use through livestock integration. Therefore, objectiveof this study was to investigate the species diversity and forage value of understory vegetation in thecoconut land before introducing cattle. Stratified quadrate sampling technique was adopted and 4samples each from 6 paddocks (approx 0.4 ha) were randomly taken. Each stratum contained morethan 80% of edible species while the non edible species found in all strata were common uplandweeds Axonopus affinus (carpet grass), Axonopus compressus (narrow carpet grass) andDesmodium trifolium were dominant prostate grass and legume species found in 0-5 em strataabove ground level. In addition to above species Pueraria phasioloides (Centro) was found to bedominant in 5-15 em strata. Crysopogen ariculatus and Pueraria phasioloides were dominant in15-25 cm strata while Seteria anceps (fox tail grass) found to be dominant above 25 em height. Thecommon non-edible species found in the lower two strata's were Urena lobota, Hemidcsmus indicumand Ocimum tenuiflorum while Lantana camara and Ocimum tenuiflorum were dominant in uppertwo strata's. The dry matter (DM) and crude protein (CP) content of edible herbage increased frombottom to top layers ranged from 390 gkg' to 480 gkg' and 75 gkg' to 100 gkg' respectively.The results of this study reveal that the species diversity and forage value are in an acceptablestandard to initiate cattle grazing. However, crop and cattle management strategies are important inorder to improve coconut and livestock performance.

Accelerating effect of montmorillonite on oxidative degradation of polyethylene nanocomposites

Polyethylene, one of the most widely used packaging materials, can be made biodegradable by blending it with biopolymers such as starch and/or pro-oxidants which are metal complexes (e.g. cobalt stearate, cerium stearate). Recent studies on polyethylene degradation have found that addition of nanoclay, which is used as a filler in polymer composites mainly to enhance their mechanical properties, also increases their photo-oxidative degradation. The present study aims to investigate the degradation of low density polyethylene (LDPE) formulated with nanoclay and evaluate the effect of nanoclay compositions on the overall photo-oxidation process. Photo-oxidative aging of polyethylene and its nanocomposites were carried out in a QUV weathering tester for a maximum period of two weeks. The degradation progress was followed by monitoring the chemical changes of the samples using Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The results indicate that the incorporation of nanoclay significantly enhances the degradation of polyethylene

The effect of nanoclay on photo-oxidation of polyethylene

Increasing environmental concerns about plastic waste in the community has led to the development of environmental friendly polymeric packaging materials. Polyethylene, one of the widely used packaging materials, can be made biodegradable by blending with biopolymers such as starch and/or pro-oxidants which are metal complexes (e.g. cobalt stearate, cerium stearate). Recent studies on polyethylene degradation have found that addition of nanoclay, which is used as filler in polymer composites mainly to enhance their mechanical properties, also increases their photo-oxidative degradation. The present study investigates the photo-degradation of low density polyethylene (LDPE) formulated with nanoclay and evaluates the effect of nanoclay concentration on the overall photo-oxidation process. Photo-oxidative aging of polyethylene and its nanocomposites were carried out in a QUV weathering tester for a maximum period of two weeks. The degradation progress was followed by monitoring the physical and chemical changes of the samples using tensile tests, Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The results indicate that the incorporation of nanoclay significantly enhances the degradation of polyethylene

Photo-oxidation of polyethylene/montmorillonite nanocomposites

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Biodegradation of photo-degraded polyethylene nanocomposites

Abstract not availabl

Photo-oxidation of polyethylene nanocomposites

Increasing environmental concerns about plastic wastes in the community has led to the development of environmental friendly polymeric packaging materials. Polyethylene, one of the widely used packaging materials, can be made biodegradable by blending it with biopolymers such as starch and/or pro-oxidants which are metal complexes (e.g. cobalt stearate, cerium stearate). However recent studies on polyethylene degradation have found that addition of nanoclay, which is used as filler in polymer composites mainly to enhance their barrier, thermal and mechanical properties, increases the photo-oxidative degradation of polymer nanocomposites. However the influence of pro-oxidants on the photo-oxidation of polymer nanocomposites is not yet known in detail. The present study aims to investigate the effects of pro-oxidants and nanoclay, and their concentrations on the photo-oxidation of polyethylene composites. Photo-oxidation of polyethylene film samples was conducted in an accelerated QUV weathering tester which reproduces the damage caused by sunlight, rain and dew at various temperatures to mimic large scale composting. Oxidation rate of the film was determined by measuring the carbonyl absorbance using FT-IR spectroscopy and molecular weight changes were determined using Gel Permeation Chromotography. Changes in mechanical properties were measured using universal testing machine (Instron). Preliminary results show that the rate of photo-oxidative degradation of polyethylene nanocomposites with or without pro-oxidants is much faster than that for polyethylene. It is also found that the pro-oxidant has relatively greater influence on the rate of photo-oxidation of the polymer as compared to nanoclay

Herbage Quality and Animal Performance in a Coconut Cattle Inte grated System

The effect of controlled grazing on the natural herbage growing in coconut plantation on the performance of cross-bred heifers as well as on herbage yield, botanical composition and the quality were examined in an experiment for one year duration in a coconut estate at Kotawila, Kamburugamuwa. There were four treatments namely coconut without fertilizer (T1); coconut with fertilizer (CRI recommended levels) (T2); heifers grazed natural herbage (T3); and heifers grazed natural herbage with tree fodder (2 kg/d) and concentrate supplement (250 g/d) (T4). The experiment design was a RCBD with 3 replicates and the stocking rate was 2 heifers/ 0.4 ha. The daily weight gain (19.60 g/head/d) and body condition (-0.07) were poor when no feed supplements were given. Provision of tree fodder and concentrate (Gava thriposha) greatly improved the daily weight gain (28.23 g/ head/d) and body condition (0.09) of heifers. It was also observed that the season had an influence on growth and body condition.Herbage yield was higher in T2 as compared to T1 due to non grazing and fertilizer application. When compared the two treatments with animals, herbage yield of T4 were higher due to low grazing pressure imposed by supplementation. The N percentage of herbage also showed a similar trend. Over grazing without supplements (T3) would have depleted the soil and herbage N, and thereby conservation of N through recirculation within the animal. The dry period would have aggravated this condition by reducing the dung decomposition rate and increasing the urine evaporation rate. Grazing also improved the botanical composition of herbage. T3 and T4 treatments contained 55.35, 18.84 and 25.82% of grasses, legumes and other species, respectively. Herbage of T1 and T2 contained 18.5, 22.54 and 58.96% of grasses, legumes and other species, respectively. Axonopus affinus, A. compressus and Puraria phaseoloides like prostate species were dominant in T3 and T4 while Ocimum tenuiflorum and Urena lobota and Eupatorium odoratum like upland erect weed species were dominant in T1 and T2.The results show that the integrated management system based on coconut and cattle, could achieve sustain able improvements on stock performance, even within a short period of time. Actual benefits should be investi gated in the long term