The changes of LD-PE films after exposure in different media (original) (raw)
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European Polymer Journal, 2015
A method for the study of structure-properties relationships of polyethylene (PE)-based films of potential use in food packaging has been set up. The approach has been demonstrated in the case of films obtained by blow-molding using model mixtures of two different polyethylenes, namely a metallocene-made grade of linear low density polyethylene (mLLDPE) and a low density polyethylene (LDPE). We show that physical properties important for application in food packaging of these films, such as water vapor and oxygen permeability, toughness and stress strength, are related to the molecular structure and structural and morphological parameters of the blends, in particular, thickness of 2 amorphous layers in lamellar stacks, lamellar thickness, lamellar twisting, and degree and type of branching.
Structural changes of polyethylene in blown films with different pro-oxidants
Polímeros, 2021
The accumulation of polymeric residues has been one of the most impacting environmental problems in recent human history, coming, above all, from disposable artefacts, such as plastic bags. Processing polyolefins with pro-oxidant additives is an alternative to favour the abiotic degradation process of macromolecules, including thermooxidation, so that the oxygenated fragments produced can be assimilated by microorganisms. The objective of this work was to evaluate the process of thermomechanical oxidative degradation of polyethylene (PE) during tubular extrusion of HDPE/LDPE films, without and with 1% of two different pro-oxidants, d2w TM and benzoin. The results of viscosimetric and MFI analyses indicated smaller chain sizes in the additivated films. The FTIR spectra and contact angles indicate a higher presence of polar functional groups in the samples with pro-oxidants. The surface morphological analysis by SEM indicated difference of PE homogeneity in the films. Benzoin, however, proved to be a better pro-oxidant than d2w TM .
Studies on the photo-oxidative degradation of LDPE films in the presence of oxidised polyethylene
Polymer Degradation and Stability, 2007
This paper reports the results of photo-oxidative degradation studies of LDPE in the presence of varying amounts of oxidised polyethylene (OPE), which was prepared by heating LDPE films containing 0.1% cobalt stearate in oxygen atmosphere at 100 C. OPE, with a CI of 12 was used as an additive for LDPE. Varying amounts of OPE (0.5e5%) were blended with polyethylene in an extruder and films of 70 mm thickness were prepared by film blowing process. The physico-chemical properties of the films were evaluated and these were found to be proportional to the amount of OPE. The films thus obtained were subjected to UV-B exposure at 30 C for extended time periods. The chemical and physical changes induced by UV exposure were followed by monitoring the changes in mechanical properties (tensile strength and elongation at break), carbonyl index (CI), morphology, molecular weight, MFI and DSC crystallinity. Incorporation of OPE was found to be effective in initiating the photo-degradation of LDPE in relatively short span of time and the degradation was found to be proportional to the amount of OPE in the formulation.
2020
Background: Food loss and spoilage is a major issue facing the world today. To overcome it, polymer food packaging is being developed to have antimicrobial functionality in improving food safety. With this aim, radiation-induced grafting has been used to covalently bond low density polyethylene with antimicrobial additive, sorbic acid (SA) to develop a non-migrate antimicrobial active film. Objective To determine the effect of grafting of sorbic acid onto polyethylene film using radiation grafting technique with respect to their oxygen permeability, water contact angle and mechanical properties. Results: Oxygen permeability and water contact angle of the grafted film slightly increased compared with raw LDPE film. Tensile strength increased from 20.48 MPa to 32.61Mpa, while elongation at break increased from 193.25 % to 254.47% when 10% of SA was incorporated.. Conclusion: The results obtained will be a guide for subsequent novel development of LDPE film with sorbic acid attributes ...
International Journal of Engineering Sciences & Research Technology, 2014
Polyethylene, Specially the LDPE is one of the most widely used thermoplastic in packaging industries, due to its low cost, broad range of properties like excellent moisture barrier and chemical resistance which are need for food packaging sectors. As mentioned above LDPE is most widely used plastic for packaging film applications but the major disadvantage is that the surface of the LDPE film is smooth and non polar also shows the lack of chemical functionality which is a requirement for adhesive bonding, hence surface preparation/modification become necessary. Often which adhesion properties increase of all the available methods to modify the polymer surface for enhancing adhesion properties, here in this study we have used Corona treatment and Chromic acid treatment to modify surface of LDPE film. The modification in surface due to the treatments were correlated by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups etc. The improvement in ink adhesion, both water based and solvent based inks was studied by standard Scotch tape adhesion test. Furthermore Surface property and Surface morphology was characterized by contact angle measurement and Scanning Electron Microscope (SEM). Surface energy and surface roughness can be directly correlated to the improvement in surface-related properties.
PRELIMINARY INVESTIGATION OF POLYMERIC FILMS FOR FOOD PACKAGINGS
The properties of packaging materials have been investigated and have been found to have effects on packaged foods either positively or negatively, hence the need for appropriate packaging materials for food products. This study investigated the barrier properties (permeability values) of food packaging materials as they affect the stability of packaged food products. The focus of this study was on two different packaging materials, namely Low Density Polyethylene (LDPE) and Polyethylene Terephthalate (PET) films and how their barrier properties affect the stability of packaged foods, particularly, the dried grinded pepper selected for this study. The barrier properties of the two selected packaging materials were investigated through direct method of shelf life study. The selected packaging materials of 0.08mm thickness each were developed into pouches of equal sizes and shapes with length 50cm and breadth 30cm each. 50g of the dried grinded pepper (Piripiri) was packaged with the pouches made with low density
2019
Crystallinities of high-density polyethylene (HDPE) films containing various amounts of an oxo-biodegradable additive (HES-W) were investigated immediately after preparation and 6 weeks after ultraviolet (UV) irradiation (λ=254 nm). HDPE granules were mixed with oxo-biodegradable masterbatch in a twin-screw extruder and the extrudates were converted into films with thicknesses of 35±5 micrometers. The films were exposed to UV light for 6 weeks. Crystallinities of the films are investigated by X-ray diffraction spectroscopy (XRD) and differential scanning calorimetry (DSC). The XRD results show that upon UV exposure, the crystallinities of the films enhance. The DSC thermograms have confirmed the XRD results and also show a decrease in melting points of the samples after UV exposure. Further investigations on viscosity average molecular weights (Mv) of the samples show that their Mv decrease sharply after UV exposure. Scanning electron microscopy (SEM) shows clear cracks on the sampl...
Polymer Degradation and Stability, 1999
Thermo-oxidation of blown low density polyethylene (LDPE) films modified with different combination of biodegradable filler, prooxidant and photosensitizers was conducted in oven at 60 and 100°C for a period of 14 days. Volatile and semivolatile degradation products were extracted by solid phase micro extraction (SPME) technique and identified utilizing gas chromatography–mass spectrometry (GC–MS). Chemical and morphological changes were monitored and
2014
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013Bu çalışmada, çeşitli formülasyonlar kullanılarak sol-jel yöntemiyle cam yüzeyler için hem kolay temizlenebilen hem de anti-bakteriyel etkiye sahip çok fonksiyonlu polimerik kaplamalar hazırlanmıştır. Hazırlanan kaplamanın su sevmez (hidrofobik) ve yağ sevmez (oleofobik) özelliğini flor gruplarının katkısıyla geliştirebilmek için, farklı oranlarda florosilan içeren iki ticari florosilan bileşiği de kullanılmıştır. Ayrıca florosilan içermeyen ve çeşitli mol oranlarında TEOS:MTES (1:1, 1.5:1 ve 1:1.5) içeren kaplamalar da hazırlanmış ve anti-bakteriyel özellik sağlamak için ZnO nano tanecik süspansiyonu tüm formülasyonlarda kullanılmıştır. Kaplamanın yüzeye uygulanması döndürmeli kaplama yöntemiyle yapılmıştır. En uygun kürlenme sıcaklığının belirlenebilmesi için, kaplanmış cam yüzeyler çeşitli sıcaklıklarda (60°C, ...
Degradation of polyethylene film samples containing oxo- degradable additives
The introduction of the so called oxo-biodegradable additives in the Argentine market motivated the assessment of the effects of abiotic and biotic factors on the structure and mechanical behavior of polyethylene (PE) with oxo-degradable additives (PE+AD). Samples of oxo-degradable packaging films found in local shops together with polyethylene films with and without d 2 w ® additive were annealed at different temperatures between 50 and 110ºC and submitted to ultraviolet radiation at different irradiances (0,35; 0,45; 0,89 and 1,20 W/m 2). Furthermore, aged oxo-degradable films were set in a controlled compost bioreactor in order to evaluate their biodegradation ability. Experimental results showed that elongation at break was the mechanical property more sensitive to the polymeric degradation. The structural changes determined by FT-IR remarked the importance of the UV degradation time over the irradiation rate; the carbonyl index of the degraded samples pointed out that chain scission was a thermally activated process. Regarding degradation due to UV radiation, at the same dose, the elongation at break is lower at lower irradiance both in PE and PE+AD samples. On the other hand, thermal degradation of PE without additive is more susceptible to degradation than PE + AD. At the beginning of the biodegradation tests, PE + AD showed a higher CO 2 production rate with respect to PE; however, this rate reduced along the first 30 days, reaching the CO 2 production of PE without additive. The maximum biodegradation observed for both PE and PE+AD samples was 24 % after 90 days of incubation.