Standard Polyethylene Film Research Articles

Influence of the nature of pro-oxidants on the photooxidation of polyethylene blown films

In an attempt to reduce the accumulation of polymeric waste in the environment, such as plastic bags, the use of pro-oxidants has been adopted in polyolefins, including polyethylene (PE), which is one of the most used polymers in film production. The incorporation of this additive to PE film aims to accelerate its oxidation in the process of abiotic degradation, generating oxygenated groups that can facilitate the biotic degradation. Commercial pro-oxidants are commonly organic salts of transition metals. However, their use can lead to a secondary problem, the inappropriate accumulation of transition metals at the site where the polymeric waste was deposited and, for this reason, it has been sought pro-oxidants metals free and that can also be biodegraded. In this context, this work aimed to evaluate the photodegradation of PE blown films obtained by extrusion using a commercial pro-oxidant, d2w™, an alternative organic pro-oxidant, benzoin, and also a standard film, without pro-oxidant. After undergoing 96 and 144 h of UV light exposure, the blown films were evaluated by dilute solution viscometry, FTIR and SEM analysis. The results showed that the pro-oxidants lead to the formation of more macromolecular fragments containing carbonyl groups than in the standard PE film. The film extruded with benzoin showed greater fragmentation, which may be associated with a greater reduction in the average viscosimetric molar mass, therefore, this additive being a promising organic substance in the induction of photooxidation, as demonstrated by the other results obtained by FTIR and SEM.

Effect of sealing strategy on the feeding value of corn silage for growing dairy heifers

Our objective was to compare the performance of dairy heifers fed diets based on whole-plant corn silage stored in bunker silos sealed with either standard polyethylene film (white-on-black, actual thickness 121 ± 3.1 µm) covering the top surface, held in place with rows of tires every 3 m (PE) or an oxygen barrier system comprised of an ethylene-vinyl alcohol film (actual thickness 46.7 ± 2.5 µm) lining side walls and covering the silage, protected with a woven anti-UV cover and gravel bags placed around the edges and every 3 m across the silo (OB). Whole-plant corn was mechanically harvested at 39% dry matter (DM), packed in bunker silos, and sealed with PE or OB covering methods. After 6 mo of storage, silos were opened and fed to 26 Holstein heifers (260 ± 89.1 kg of shrunk body weight) for 60 d. Heifers were blocked by initial weight (13 blocks with 2 heifers each block) and housed in individual pens. Diets contained (on a DM basis) 80% corn silage (PE or OB), 17.5% soybean meal, and 2.5% mineral mix. Dry matter intake was measured daily, whereas shrunk body weight, hip height, heart girth, and body condition score were measured at the beginning and end of the experiment. Feeding behavior was recorded on d 24 and 46, and total-tract digestibility was measured from d 26 to 30 and 48 to 52. Data of intake, feeding behavior, and digestibility were averaged by animal for the whole feeding period before the statistical analysis. Data of animal performance were analyzed as a randomized complete block design. Initial shrunk body weight was used as a covariate for analyses of intake and body measures. During feed-out, silage quality was also assessed at the top (15 cm depth from upper surface) and bottom layer (135 cm depth from upper surface) and analyzed as a split-plot design. Silage stored under the OB sealing system had less yeast, mold, and NH3-N, and more lactic acid and ethanol-soluble carbohydrates. An interaction between sealing strategy and silo layer showed that OB silage had lower values of temperature, pH, anaerobic spores, acetic acid, and DM loss, and greater in vitro DM digestibility and aerobic stability, especially in the top layer. The proportion of inedible silage was lower in OB than in PE treatment (0.82 vs. 4.00% DM). Total-tract digestibility was similar between treatments, but animals that received the OB diet had higher DM intake by approximately 9% (9.39 vs. 10.20 kg/d) due to a faster eating rate and a greater number of meals per day. Therefore, OB treatment increased the digestible energy intake by 8% (26.3 vs. 28.3 Mcal/d) and average daily gain by 12% (1.08 vs. 1.21 kg/d). Body condition score change was similar between treatments, but heifers fed OB had greater heart girth and tended to have higher hip height. In conclusion, replacing a standard PE film with an OB sealing system improved silage conservation and performance of growing dairy heifers.

Low-Tunnel Strawberry Production: Comparison of Cultivars and Films

ABSTRACT Growing repeat-fruiting strawberries (Fragaria ×ananassa Duchesne ex Rozier) under low tunnels can extend a strawberry harvest season from a few weeks to several months. Yields from multiple dayneutral cultivars have been compared under a single film, and yields from single cultivars have been compared under multiple films, but a study of possible cultivar and film interaction effects in low tunnels has not been reported. From 2014–2018, six cultivars were compared under low tunnels covered with a standard polyethylene film and three other films purported to improve growing conditions. Traits analyzed included total yield, percent rotted yield, berry weight, percent marketable yield, and average market score. ‘Monterey’ performed above average for all traits and better under TIII TES/IR 0.102 mm thick film (TES film) or Kool Lite Plus 0.152 mm thick polyethylene film (KL film). ‘Albion’ performed above average for all traits except yield and better under TES film or Clear TIII 0.102 mm thick polyethylene film (“standard clear” or SC film). ‘Portola’ performed above average for all traits except percent rotted yield, better under SC, KL, and TES films, and had lower percent rotted yield under TES film. Because TES film was helpful to the three better-performing cultivars evaluated, it was considered a good choice for growers to try in on-farm evaluations of available repeat-fruiting cultivars. Generally, yield, berry weight, market score, and percent marketable yield were correlated positively with each other.

Effects of silage sealing films on fermentation dynamics of ensiled maize and nutrient utilization by Damara rams

An experiment was conducted to evaluate the effects of two silage sealing films on whole crop maize (WCM) fermentation, aerobic stability and nutrient digestion by rams. Prior to ensiling (day 0), triplicate samples of the WCM were collected to determine dry matter, pH, water-soluble carbohydrates (WSC), lactic acid (LA) bacterial counts and nutrient concentration. A single bunker silo was divided into eight sections that were ensiled using either a standard polyethylene film (PE) or an orange oxygen barrier (OB) Silostop film for 180 days. After 180 days of ensiling, six silage samples were collected from each replicate. Three samples were used for nutrient analysis and the other three to determine aerobic stability. Sixteen four-year-old Damara rams with an average live weight of ± 54 kg were housed individually in wooden pens (2.2 m2) to determine digestibility of nutrient in the silage. The digestibility study was conducted as a switchover design with four feeding phases. The silage was supplemented daily with 1% urea and fed to the rams ad libitum. Nutritional value of the silage was not (P >0.05) affected by the ensiling films. The OB-ensiled maize had higher (P <0.05) LA, lower pH, CO2 production and yeast and mould populations, and lower WSC compared with the PE-ensiled maize. Dry matter intake, nutrient digestion and nitrogen balance of rams fed the silage were not affected (P >0.05) by treatments. The OB film improved the fermentation and aerobic stability of WCM silage but did not influence its nutrient utilization by rams.
 Keywords: cereals, digestibility, forage, rams, nitrogen, supplementation

Emission and crop response in almond orchards fumigated with reduced rates of Telone® C-35 and low permeability film for nematode control

Many high-value tree crops are dependent on soil fumigation for control of plant-parasitic nematodes and diseases for successful orchard replanting. Due to detrimental impacts on the environment, fumigants are under stringent regulations. The study investigated if a commercially available totally impermeable film (TIF) such as VaporSafe® and reduced fumigant rates can achieve emission reduction while providing good control of plant-parasitic nematodes and improving tree establishment. Two field trials were conducted in almond orchards on a sandy soil or a sandy loam to test the effects of Telone® C-35 (containing 63% 1,3-dichloropropene and 35% chloropicrin) on fumigant movement, nematode survival, and tree performance. In the trials, Telone® C-35 was applied at various rates: 100% (610 kg ha−1), 66%, or 33%; with three surface sealing methods: bare, standard polyethylene film (PE), and TIF. The TIF greatly reduced emissions compared to PE or bare soil with very low off-edge emissions. Both 100% and 66% rates of the fumigant promoted similar tree growth regardless of surface sealing methods. The 66% rate under TIF and PE also provided 100% control of resident nematodes as the 100% rate at or above 100 cm soil depth in both trials. Fumigation at the sandy soil site was able to reduce or eliminate the nematode population at the 120-150 cm soil depth. However, none of the treatments provided 100% control of nematodes at this depth in the sandy loam soil indicating the effects of soil texture on fumigation efficacy. Thus, TIF and reduced rates of Telone® C-35 can be used to reduce the environmental impacts of soil fumigation and fumigant expenses.

Improving corn silage quality in the top layer of farm bunker silos through the use of a next-generation barrier film with high impermeability to oxygen

This study examined the effect on the fermentation, chemical, and microbiological quality of corn silage covered with a new-generation high oxygen barrier film (HOB) made with a special grade of ethylene-vinyl alcohol (EVOH) compared with a standard polyethylene film (PE). Two bunkers (farms 1 and 2) were divided into 2 parts lengthwise so that half of the silo would be covered with PE film and the other with HOB film. Plastic net bags with fresh chopped corn were buried in the upper layer (close to and far from the wall) and in the central part of the bunkers. During spring-summer consumption, the bags were unloaded, weighed, and subsampled to analyze the dry matter (DM) content, neutral detergent fiber and starch contents, pH, lactic and monocarboxylic acids, yeast and mold counts, aerobic and anaerobic spore-former counts, and aerobic stability. We also determined the economic benefit of applying the novel covering. The top layer of silage conserved under the HOB film had a higher lactic acid content and lower pH; lower counts of yeasts, molds, and aerobic and anaerobic spore-formers; higher aerobic stability; and lower DM losses than the silage conserved under the PE film. The use of the HOB film prevented almost all of the silage in the upper layer from spoiling; only 2 out of 32 samples had a mold count >6log10 cfu/g. This led to a net economic gain when the HOB film was used on both farms due to the increased DM recovery and reduced labor time required to clean the upper layer, even though the HOB film cost about 2.3 times more than the PE film. Furthermore, use of the HOB film, which ensures a longer shelf life of silage during consumption, reduced the detrimental effect of yeasts, molds, and aerobic and anaerobic spore-formers on the nutritional and microbiological quality of the unloaded silage.

A meta‐analysis comparing standard polyethylene and oxygen barrier film in terms of losses during storage and aerobic stability of silage

AbstractA meta‐analysis was undertaken of 51 comparisons of standard polyethylene film with oxygen barrier (OB) film in covering systems for bunker silos, unwalled clamp silos and bales. Mean losses of DM or OM during storage from the top 10 to 60 cm of bunker and clamp silos were 195 g kg−1 for standard film and 114 g kg−1 for OB film systems (41 sets of data, P < 0·001), while mean total losses of DM from baled silage were 76·8 g kg−1 for standard film and 45·6 g kg−1 for OB film systems (10 sets of data, P < 0·001). Top surface silage judged subjectively to be inedible was 107 and 29·6 g kg−1 for standard film and OB film systems respectively (5 sets of data, P = 0·02). Aerobic stability was 75 h for silage stored under standard film system and 135 h for silage stored under OB film system (11 sets of data, P = 0·001). It is concluded that the OB film system reduces losses from the outer layers of silos and from bales and increases the aerobic stability of silage in the outer layers of silos.

GLOSSARY: Methyl bromide terminology

GLOSSARY: Methyl bromide terminology

Aerobic deterioration stimulates outgrowth of spore-forming Paenibacillus in corn silage stored under oxygen-barrier or polyethylene films

The occurrence of Bacillus and Paenibacillus spores in silage is of great concern to dairy producers because their spores can survive pasteurization and some strains are capable of subsequently germinating and growing under refrigerated conditions in pasteurized milk. The objectives of this study were to verify the role of aerobic deterioration of corn silage on the proliferation of Paenibacillus spores and to evaluate the efficacy of oxygen-barrier films used to cover silage during fermentation and storage to mitigate these undesirable bacterial outbreaks. The trial was carried out on whole-crop maize (Zea mays L.) inoculated with a mixture of Lactobacillus buchneri, Lactobacillus plantarum, and Enterococcus faecium. A standard polyethylene film and a polyethylene-polyamide film with an enhanced oxygen barrier were used to produce the silage bags for this experiment. The silos were stored indoors at ambient temperature (18 to 22°C) and opened after 110 d. The silage was sampled after 0, 2, 5, 7, 9, and 14 d of aerobic exposure to quantify the growth of endospore-forming bacteria during the exposure of silages to air. Paenibacillus macerans (gram-positive, facultatively anaerobic bacteria) was able to develop during the aerobic exposure of corn silage. This species was present in the herbage at harvesting, together with clostridial spores, and survived ensiling fermentation; it constituted more than 60% of the anaerobic spore formers at silage opening. During silage spoilage, the spore concentration of P. macerans increased to values greater than 7.0 log10 cfu/g of silage. The use of different plastic films to seal silages affected the growth of P. macerans and the number of spores during aerobic exposure of silages. These results indicate that the number of Paenibacillus spores could greatly increase in silage after exposure to air, and that oxygen-barrier films could help to reduce the potential for silage contamination of this important group of milk spoilage microorganisms by delaying the onset of aerobic deterioration.

Microbial status, aerobic stability and fermentation of maize silage sealed with an oxygen barrier film or standard polyethylene film

An experiment was conducted to compare a bunker silo sealing system comprising an oxygen barrier film (OB: 45μm thickness) with protective woven polypropylene with one comprising standard black polyethylene film (S; 125μm thickness) with protective tyres. Analysis of samples taken to 30 cm depth after 365 days of storage showed no differences in pH or lactic acid between the two sealing systems. There were no differences in aerobic bacterial count between silages. Whilst 2.56 log10 CFU moulds g-1 fresh weight were found in samples of silage sealed with S, no moulds were found in samples of silage sealed with OB. Aerobic stability, averaged 249 hours and 184 hours for OB and S, respectively. The OB system probably inhibited the development of the micro-organisms responsible for the initiation of aerobic deterioration to a greater extent than the standard silo sealing system.

Effect of two UV-absorbing greenhouse-covering films on growth and yield of an eggplant soilless crop

Abstract The use of UV absorbing films as greenhouse cover material is spreading out in protected cultivation. Although their effects on pest and disease management have received much attention, few studies focus on their effects on the crop. This study aims at assessing the consequences of UV absorbing film on the behaviour and production of an eggplant crop by comparing two different UV absorbing films (0 and 3% UV transmittance) to a standard polyethylene film (5% UV transmittance). Results show that the eggplants grown in the greenhouse with 0% transmission to UV light are about 21% taller and have about 17% higher leaf product (leaf length × width) than the plants grown in the greenhouse with 5% transmission to UV light. Finally, given that the production was slightly increased in quantity (20%) and quality (bigger fruits) in the greenhouse with absence of UV light compared to that with 5% transmission coefficient, it can be concluded that growing soilless eggplant under UV-absorbing material can be achieved with the same or better results as under standard covering material. Any other enhancement that the UV-absorbing film will bring (lower pest and disease impact on the crop, lower pesticide load and costs) will therefore be to the benefit of the grower.

WETTABILITY AND HIGH INCIDENCE ANGLE LIGHT TRANSMITTANCE OF GREENHOUSE CLADDINGS

The effects of condensate on the transmittance of a vertical standard polyethylene film and a vertical standard glass plate were investigated to verify whether condensate on a greenhouse cladding material could increase the transmittance at high angles of incidence as predicted in literature. At an incidence angle of 80°, a mean transmittance increase of about 4% was measured when condensate was present on the polyethylene film. On the glass plate, however, a transmittance decrease of about 5% was measured under similar circumstances. Therefore, it was concluded that the transmittance loss or gain due to condensate at high incidence angles depended on the wettability of the cladding material.