Polyethylene Treatment Research Articles

Effect of microplastics on greenhouse gas and ammonia emissions during aerobic composting

The aim of this study was to investigate the effect of polyethylene (PE), polyvinyl chloride (PVC) and polyhydroxyalkanoate (PHA) microplastics on greenhouse gas and ammonia emissions during 60 days composting. PE, PVC and PHA microplastics were respectively mixed with the cow manure; and a treatment without microplastics was used as the control. Compared to the control, PE and PVC inhibited organic matter degradation. Conversely, PHA accelerated temperature increases and organic matter degradation. Meanwhile, PE and PHA aggravated CH4 and NH3 emissions by 7.9–9.1% and 20.9–33.9%, respectively. PVC decreased CH4 and NH3 emissions by 6.6% and 30.4%, respectively. Additionally, the N2O emissions of the PE and PVC treatments were higher than those of the control while PHA decreased N2O emissions by 11.8%. Furthermore, PE, PVC and PHA microplastics reduced the NO3−-N contents and compost maturity. The results indicated that microplastics reduced compost quality while the effects of microplastics on greenhouse gases and ammonia emissions were related to their sources.

Effects of biodegradable plastic film mulching on soil microbial communities in two agroecosystems.

Plastic mulch films are used globally in crop production but incur considerable disposal and environmental pollution issues. Biodegradable plastic mulch films (BDMs), an alternative to polyethylene (PE)-based films, are designed to be tilled into the soil where they are expected to be mineralized to carbon dioxide, water and microbial biomass. However, insufficient research regarding the impacts of repeated soil incorporation of BDMs on soil microbial communities has partly contributed to limited adoption of BDMs. In this study, we evaluated the effects of BDM incorporation on soil microbial community structure and function over two years in two geographical locations: Knoxville, TN, and in Mount Vernon, WA, USA. Treatments included four plastic BDMs (three commercially available and one experimental film), a biodegradable cellulose paper mulch, a non-biodegradable PE mulch and a no mulch plot. Bacterial community structure determined using 16S rRNA gene amplicon sequencing revealed significant differences by location and season. Differences in bacterial communities by mulch treatment were not significant for any season in either location, except for Fall 2015 in WA where differences were observed between BDMs and no-mulch plots. Extracellular enzyme assays were used to characterize communities functionally, revealing significant differences by location and sampling season in both TN and WA but minimal differences between BDMs and PE treatments. Overall, BDMs had comparable influences on soil microbial communities to PE mulch films.

Plastic Mulches Improved Plant Growth and Suppressed Weeds in Late Summer-planted Floricane-fruiting Raspberry

Planting floricane-fruiting red raspberry (Rubus ideaus L.) propagated through tissue culture (TC) is becoming increasingly popular in the Pacific Northwest. However, there is a challenge associated with their establishment compared with traditional planting materials (dormant roots and canes), especially regarding weed management due to their sensitivity to herbicides. In addition, there has been an increased interest in late summer planting compared with traditional spring planting because growers find improved establishment in late summer planting. Although polyethylene (PE) and biodegradable plastic mulches (BDMs) have demonstrated excellent weed control and increased plant growth and yield in spring-planted TC raspberry, their impacts in late summer plantings are still unknown. The overall objective of this study was to investigate whether PE mulch and BDMs have similar effects on weed management and raspberry growth and yield in late summer plantings as in spring plantings. One PE mulch, four BDMs (BASF 0.5, BASF 0.6, Novamont 0.5, and Novamont 0.6), and a bare ground (BG) control were evaluated in a commercial ‘WakeHaven’ raspberry field planted in Aug. 2017. Mulch performance [percent soil exposure (PSE)], mulch mechanical properties (elongation and breaking force), soil temperature and moisture, plant growth, fruit yield and quality, and weed suppression were measured from 2017 to 2019. Average PSE was 1.4% and 2.0% to 15.0% by Dec. 2017 in the PE and BDM treatments, respectively. PE mulch generally had greater elongation and breaking force than BDMs. All BDMs were removed by Mar. 2018 because of the damage caused by on-farm activities and strong winds. Although average primocane height was greater for plants grown with PE mulch compared with all the other treatments except BASF 0.5 in Sept. 2018, there was no difference in yield between PE and the BG treatments, potentially because of cold damage on the buds in PE plots. There were no weeds in any of the mulched treatments in Sept. and Oct. 2017 and in PE mulch in Sept. 2018. In contrast, the BG plots had 51, 51, and 266 weeds/m2, respectively, and required handweeding and herbicide applications. In addition, early season application of herbicides to suppress primocane emergence was not required in the PE plots. Overall, PE mulch could be a viable tool for growers planting raspberry in late summer. The suitability of BDMs with similar thicknesses and formulations as used in this experiment is uncertain for late summer plantings because of the damage caused by on-farm activities and strong winds.

The combined effect of ozone treatment and polyethylene packaging on postharvest quality and biodiversity of Toona sinensis (A.Juss.) M.Roem

The young leaves and sprouts of the Toona sinensis (TS) are nutritious and popular in Asia, however they are highly perishable and, thus, have a short shelf life, which impacts negatively on their market performance. This study investigated the effects of ozone (OZ) and polyethylene (PE) treatments on the postharvest quality of TS during near-freezing temperature storage. The results revealed that TS subjected to OZ + PE treatment had higher levels of peroxidase, superoxidase dismutase, catalase, thiophenes, CIS, TRANS, malondialdehyde and hue angle, and lower levels of weight loss, respiration rate, ethylene production rate, total chlorophyll content, vitamin C, total plate count, coliforms, yeast and mold, and polyphenol oxidase compared to the control (CK) and PE treatments. In the next-generation sequencing analysis of TS biodiversity, microbial communities of TS treated with OZ +PE were found to differ significantly from those treated with CK and PE. The combination treatment inhibited most order bacteria, however, the fungal communities present in TS, such as orders of Dothideales, Agaricales, Erysiphales and Filobasidiales, proved resistant to OZ treatments. The results of the principal components analysis and co-occurrence network patterns further confirmed that OZ, used in combination with PE, could improve postharvest quality and extended the shelf life of TS.

Effect of fruit size and polyethylene wrapping on the storage ability of citrus ‘Harumi’

'Harumi' citrus is usually harvested from December to January to avoid cold injury of the peel. After a storage period between January and February, fruit are shipped until the middle of March. However, an extended shipping period until late March or April is desired. In this experiment, the effects of fruit size and polyethylene (PE) wrapping on storage ability were investigated. Fruit size was associated to soluble solids (SS, °Brix) and fruit flesh percentage (w/w), but not to titratable acidity at harvest time. In the middle of May, without wrapping, fruit weight loss, the occurrence of peel puffing and peel wrinkles were detrimental in small fruit, however, the taste index of middle-sized fruit remained relatively high. Granulation was observed, especially in the very large non-wrapped fruit. Fruit size and forty days of PE wrapping bag affected the fruit weight, fruit and flesh specific gravity (SG), as well as flesh weight percentage after storage at ambient temperature. Fruit weight loss exceeded 10% in the middle-sized fruit without wrapping, but about 1% in PE treatment. In the larger fruit wrapped with PE, fruit SG was lower than 0.80 g cm(-3) in early March. Consequently, by selecting fruit size, and wrapping with PE, storage ability can be improved thereby allowing the shipping period to be longer in citrus 'Harumi'.

Plastic Biodegradable Mulches Reduce Weeds and Promote Crop Growth in Day-neutral Strawberry in Western Washington

Day-neutral strawberry (Fragaria ×ananassa) is typically grown in plasticulture production systems that use black polyethylene (PE) mulch for weed management and promotion of crop growth and yield. The objectives of this research were to evaluate several commercial plastic and paper biodegradable mulch (BDM) products [Bio360, Experimental Prototype (Exp. Prototype), and WeedGuardPlus] in comparison with standard black PE mulch and bare ground cultivation in day-neutral strawberry grown in an annual system in northwestern Washington. Mulch performance [as percent visual cover (PVC)], weed suppression, marketable yield, plant biomass, and fruit quality were evaluated in ‘Albion’ and ‘Seascape’ strawberry grown in 2014 and 2015. PVC measured at the end of the production season was lowest for the Exp. Prototype (8%) in 2014 and was greatest for Bio360 (90%), WeedGuardPlus (90%), and PE (98%). In 2015, PVC at the end of the production season was again lowest for Exp. Prototype (62%), followed by WeedGuardPlus (64%), Bio360 (93%), and PE mulch (97%). Overall, weed pressure was higher in 2015 relative to 2014 and was greatest in the bare ground treatment in both years of the study. By the end of the 2015 season, weed cover in the bare ground treatment was 95%, followed by WeedGuardPlus (50%), Exp. Prototype (34%), PE (25%), and Bio360 (15%). Yield showed year and cultivar effects and was higher in mulched treatments. Plant biomass showed varying effects; root biomass was lowest in ‘Seascape’ in 2015 under the bare ground treatment and greatest under Bio360, which was similar to PE mulch and WeedGuardPlus. Leaf biomass was lowest in the bare ground treatment and highest in mulched treatments (except in 2015, when leaf biomass was intermediate for plants grown with WeedGuardPlus). Crown biomass showed a similar trend and was overall greater for plants grown in mulched treatments except for Bio360 in 2014, which was the same as the bare ground treatment. Overall, fruit quality was maintained among strawberry grown with BDMs, with soluble solids concentration (SSC, %) and titratable acidity (TA) being the only variables to show treatment effects. SCC tended to be lower in fruit from bare ground plots. TA was different for ‘Seascape’ in 2015 with fruit from bare ground and Exp. Prototype treatments having higher TA than the PE treatment. This study demonstrates that BDMs can be comparable to PE mulch in terms of performance and impacts on crop productivity in day-neutral strawberry, suggesting that BDMs could be a viable alternative to PE mulch for strawberry growers in the Pacific Northwest.

CHARACTERISTICS OF PYROLYSIS OIL BATCH POLYETHYLENE AND POLYSTHYRENE PLASTIC WASTE AT VARIOUS TEMPERATURES

Efforts are being carried out in order to utilize polyethylene (PE) and polystyrene (PS) plastic waste by converting them into fuel or oil. One technology that can be used is pyrolysis. This study aims to (1) determine the quantity and the characteristics of oil from the results of pyrolysis polyethylene (PE) and polystyrene (PS) plastic waste at various temperatures which include characteristics of physics (specific gravity, heating value, flash point, pour point, and kinematic viscosity) and chemical characteristics (composition compounds in oil), (2) determine the optimal conditions of process pyrolysis related to the quality and quantity of oil by pyrolysis, and (3) determine the potential treatment of PE and PS plastic waste by pyrolysis method.The materials used in this study were the type of polyethylene (plastic bags) and polystyrene/styrofoam (for fruits or vegetables) plastic waste. The selected temperature variations are T = 400oC, 450oC, and 500oC. Pyrolysis oil was weighed and measured its volume to obtain v/wo and yield.The results showed that the quantity of pyrolysis oil from polyethylene (PE) plastic waste at temperatures of 400, 450, and 500oC based on v/wo (ml/g) respectively were 0.3429 ml/g; 0.5129 ml/g; and 0.199 ml/g while the results of polystyrene (PS) plastic waste at temperatures of 400, 450, and 500oC respectively were 0.89 ml/g; 0.905 ml/g; and 0.915 ml/g. The results of pyrolysis oil based on yield of polyethylene (PE) plastic waste at temperatures of 400, 450, and 500oC respectively were 33.33 wt%; 38.61 wt%; and 15.55 wt% while polystyrene (PS) plastic waste at temperatures of 400, 450, and 500oC respectively were 80.94 wt%; 79.79 wt%; and 80.14 wt%. While the characteristics shown by the results of pyrolysis oil from PE plastic with a temperature of 400oC were closer to kerosene while at temperatures of 450 and 500oC were closer to the characteristics of diesel fuel. As for pyrolysis oil results of PS plastic with temperatures of 400, 450, and 500oC were closer to the characteristics of gasoline. Optimal conditions of pyrolysis oil related to the quantity of pyrolysis of PE plastic at a temperature of 450oC was obtained when the highest of v/wo and yield respectively were 0.5129 ml/g and 38.16 wt%, while for the pyrolysis of PS did not have any optimal conditions. For, oil produced was relatively constant despite the increasing temperatures. Based on technical analysis, handling PE and PS plastic waste using pyrolysis methods provides benefits to society making it feasible to do.

Conversion of post consumer polyethylene to the biodegradable polymer polyhydroxyalkanoate

A process for the conversion of post consumer (agricultural) polyethylene (PE) waste to the biodegradable polymer medium chain length polyhydroxyalkanoate (mcl-PHA) is reported here. The thermal treatment of PE in the absence of air (pyrolysis) generated a complex mixture of low molecular weight paraffins with carbon chain lengths from C8 to C32 (PE pyrolysis wax). Several bacterial strains were able to grow and produce PHA from this PE pyrolysis wax. The addition of biosurfactant (rhamnolipids) allowed for greater bacterial growth and PHA accumulation of the tested strains. Some strains were only capable of growth and PHA accumulation in the presence of the biosurfactant. Pseudomonas aeruginosa PAO-1 accumulated the highest level of PHA with almost 25% of the cell dry weight as PHA when supplied with the PE pyrolysis wax in the presence of rhamnolipids. The change of nitrogen source from ammonium chloride to ammonium nitrate resulted in faster bacterial growth and the earlier onset of PHA accumulation. To our knowledge, this is the first report where PE is used as a starting material for production of a biodegradable polymer.

Plasma treated polyethylene grafted with adhesive molecules for enhanced adhesion and growth of fibroblasts

The cell–material interface plays a crucial role in the interaction of cells with synthetic materials for biomedical use. The application of plasma for tailoring polymer surfaces is of abiding interest and holds a great promise in biomedicine. In this paper, we describe polyethylene (PE) surface tuning by Ar plasma irradiating and subsequent grafting of the chemically active PE surface with adhesive proteins or motives to support cell attachment. These simple modifications resulted in changed polymer surface hydrophilicity, roughness and morphology, which we thoroughly characterized. The effect of our modifications on adhesion and growth was tested in vitro using mouse embryonic fibroblasts (NIH 3T3 cell line). We demonstrate that the plasma treatment of PE had a positive effect on the adhesion, spreading, homogeneity of distribution and moderately on proliferation activity of NIH 3T3 cells. This effect was even more pronounced on PE coated with biomolecules.

BIODEGRADABLE MULCH FILM IN A BROCCOLI PRODUCTION SYSTEM

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Organic Horticulture: Productivity and Sustainability BIODEGRADABLE MULCH FILM IN A BROCCOLI PRODUCTION SYSTEM

Effect of pre‐harvest harpin and modified atmosphere packaging on quality of cherry tomato cultivars “Alona” and “Cluster”

PurposeThe aim of this research is to determine the effects of pre‐harvest harpin (H) and modified atmosphere packaging (MAP) on the storage and fruit quality of cherry tomato (Lycopersicon esculentum Mill. cvs. “Alona” and “Cluster”).Design/methodology/approachH was used at 50 g 100 l‐1 concentration. First application was done on the seedlings in 3‐4 leaf stages and the other four applications were repeated at 20‐day intervals. Then, treated and untreated fruits were stored in plastic film materials with various O2 and CO2 permeabilities.FindingsWeight loss was significantly higher in tomatoes stored under normal atmosphere (NA) compared to MAP. Initial total soluble solids of 3‐4 percent increased to 7‐9 percent in without H (WH)+NA. Firmness was measured as 0.44 (“Alona”) and 1.20 kg (“Cluster”) in H+NA and 0.17 (“Alona”) and 0.30 kg (“Cluster”) in WH+NA at the end of storage. The acidity and ascorbic acid contents of tomatoes decreased during storage. Between H and WH treatments the levels of lycopene and β‐carotene were different significantly. At the end of the study, H gave successful results in both cultivars. This success was even higher especially when the H was combined with MAP. This combination slowed down the changes in TSS, firmness values. Therefore, H+50μ PE (polyethylene) treatment was effective with regard to delaying the maturity along the storage and fruit quality in cherry tomatoes.Originality/valueHe is a plant activator. It is the first bacterial hypersensitive response (HR)‐elicitor characterized. Effectiveness of H is evaluated on quality changes in treated cherry tomato fruits.

Enhanced Soil Solarization againstFusarium oxysporumf. sp.lycopersiciin the Uplands

Soil solarization tests againstFusarium oxysporumf. sp.lycopersici, the causal agent of tomato Fusarium wilt, were conducted for seven weeks through July and August 2008 and 2009 in the climatic conditions of Al-Aroub Agricultural Experimental Station, located in the southern mountains of the West Bank, Palestine. Double polyethylene (DPE) sheets, regular polyethylene (PE) sheets, and virtually impermeable films (VIF) were compared to examine their effects on soil temperature, disease severity, and plant growth. Results showed that in comparison to the control, PE, DPE, and VIF treatments increased the mean maximum soil temperatures by 10.2, 14.1, and 8.8°C, respectively, in 2008 and by 10.2, 12.6, and 8.3°C respectively, in 2009. The longest length of time recorded for temperature above 45°C under DPE sheets were 220 hours in 2008 and 218 hours in 2009. The treatments reduced the pathogen population by 86% and the disease by 43% under the DPE treatment in 2009 and to a lesser extent by the other treatments. Increases of up to 94% in fresh plant weight and up to 60% in plant dry weight were evident under the same treatment. The treatments also increased soil organic matter, both nitrogen forms, and major cations.

Using the Surface Free Energy Method to Evaluate the Effects of Polymeric Aggregate Treatment on Moisture Damage in Hot-Mix Asphalt

Moisture damage in hot-mix asphalt (HMA) occurs because of a loss of adhesion and/or cohesion, resulting in the reduced strength or stiffness of the HMA and the development of various forms of pavement distress. There are several different approaches for improving adhesion and reducing moisture sensitivity in asphalt mixtures. One convenient approach is coating the aggregate surface with a suitable agent to reverse the predominant electrical charges at the surface and reduce the surface energy of the aggregate. In this research, the effects of two types of polyethylene (PE), namely high-density polyethylene (HDPE) and low-density polyethylene (LDPE), were added to coat the aggregate, and the moisture damage to the asphalt mixtures was evaluated. Three types of aggregates representing a considerable range in mineralogy (limestone, granite, and quartzite) were evaluated during the course of this study. This paper explains the theoretical and experimental concept of predicting moisture damage in asphalt concrete mixes using the surface free energy (SFE) concept and laboratory testing analysis, respectively. It also shows the effects of polymeric aggregate treatment on moisture damage within the mixes. SFE measurements were used to compute the work of adhesion between the aggregates, asphalt, and the cohesive bond strength in the asphalt binder and aggregate. The SFE characteristics of three types of aggregate with and without PE treatment and asphalt were evaluated for moisture-damage susceptibility using a universal sorption device (USD) and dynamic Wilhelmy plate method, respectively. To validate these results, a dynamic modulus test was used to apply a repeated unconfined, compressive load to the sample in a controlled stress mode. The results of the SFE method indicate that PE increases the wettability of asphalt binder on the aggregate and the adhesion between the asphalt binder and aggregate. The same results were achieved using the values obtained by laboratory testing analysis. The aggregates treated with HDPE showed better resistance against moisture damage in both methods of study.

A commercially viable compatibilizer system for wood–polyethylene composites

A commercially viable compatibilizer system containing poly(diphenylmethane diisocyanate) (PMDI) and stearic acid was developed for improving the interfacial adhesion between wood and polyethylene (PE). The treatment of PE with PMDI before mixing with wood increased both the modulus of rupture (MOR) and the modulus of elasticity (MOE) of the resulting wood–PE composites. Addition of stearic acid at certain dosages further increased MOR of the resulting composites. The PMDI–stearic acid compatibilizer system was more effective in increasing both the MOR and MOE of the resulting wood–PE composites than maleic anhydride-grafted polyethylene (MAPE), a commonly used commercial compatibilizer. The compatibilization mechanisms for the PMDI–stearic acid system were investigated by Fourier transform infrared (FT-IR) spectroscopy. The water-resistance test revealed that the composites with the PMDI–stearic acid system were statistically more water-resistant than those with MAPE.

A Comparison of PE Surfaces Modified by Plasma Generated Neutral Nitrogen Species and Nitrogen Ions

The surface modification of polyethylene (PE) by neutral nitrogen species (ground and excited state N2 as well as atomic N; modified nitrogen plasma treatment) has been compared to the effect of nitrogen ion bombardment using X-ray Photoelectron Spectroscopy (XPS) and contact angle measurements. XPS results indicate that a greater nitrogen concentration was grafted during the modified nitrogen plasma treatment of PE, an effect that was attributed to surface sputtering during ion beam modification. The distribution of nitrogen-containing functionalities was strongly dependent upon the treatment strategy; the modified nitrogen plasma treatment lead predominantly to imine groups being formed at the PE surface, while amine groups were the dominant species produced during ion beam modification. The presence of electron irradiation during the modified nitrogen plasma treatment of PE did not modify the rate of nitrogen incorporation or change the nature of N-containing functional groups produced but did lead to a systematic decrease in contact angle.

Vacuum‐ultraviolet induced oxidation of the polymers polyethylene and polypropylene

AbstractThe emission from low‐pressure microwave plasmas in the vacuum‐ultraviolet (VUV) region (λ < 200 nm) was investigated in order to use these plasmas as light sources for the study of the VUV photochemistry of polyethylene (PE) and polypropylene (PP) as part of the study of plasma‐polymer interaction. These polymers, immersed in low‐presure oxygen, were exposed to radiation with wavelengths down to 112 nm, the cut off of magnesium fluoride used as a window to separate the polymer specimen from the plasma light source. Total oxygen incorporation in the surface [O], and the formation of hydroxyl, carbonyl, and carboxyl groups were measured using XPS in combination with chemical derivatizations, particularly their dependence upon the radiation spectrum and the oxygen pressure around the sample. In most experiments the surface oxygen concentration [O] attained a constant value that appears to be related to the initial oxidation rate; this suggests a competition between oxygen incorporation and chain scission reactions, followed by the removal of volatile oxidation products. PE is usually oxidized to a higher level than PP, the latter appearing to be more susceptible to reaction with atomic oxygen than PE. A general initiation mechanism for the VUV experiments is proposed that allows us to explain the observed differences in behavior between PE and PP, and the results obtained under different irradiation conditions. The nature of oxidation products is in both cases very similar to what is observed after direct plasma treatment of the polymers. We conclude that short wavelength radiation contributes very appreciably to the observed surface modification effects during plasma treatment of PE and PP. © 1995 John Wiley & Sons, Inc.

Influence of planting date and row covers on yields and crop values for bell peppers in Saskatchewan

In 1989 and 1990, bell peppers transplanted into the field in mid-May, late May or early June were grown with a black plastic soil mulch and no cover (NC) or under tunnels of perforated clear polyethylene (PT) or spunbonded polyester (ST). The ST treatment provided several degrees of frost protection, whereas the PT treatment appeared to increase the crop’s susceptibility to frost damage. Early planting had little effect on total fruit yields but did accelerate the harvest. In both years, the ST accelerated crop maturity and increased total fruit yields relative to the noncovered treatment. At times the PT improved crop development and increased fruit yields, but in many cases it reduced fruit yields relative to the noncovered treatment. By promoting early fruit set and development, early planting under the spunbonded row covers significantly enhanced the value of the crop, as early peppers command a premium price in Saskatchewan. Cumulative crop values for the PT treatments were generally similar to or poorer than those for the noncovered control.Key words: Bell pepper, Capsicum annuum, planting date, row covers, frost