scholarly journals Temperate UV-Accelerated Weathering Cycle Combined with HT-GPC Analysis and Drop Point Testing for Determining the Environmental Instability of Polyethylene Films

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2373
Author(s):  
Celine Moreira ◽  
Richard Lloyd ◽  
Gavin Hill ◽  
Florence Huynh ◽  
Ana Trufasila ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Outdoor Exposure ◽  
Accelerated Weathering ◽  
Polyethylene Films ◽  
Parallel Testing ◽  
Mapping Analysis ◽  
Environmental Instability ◽  
Weight Analysis ◽  
Physical Changes ◽  
Ir Spectroscopic

Polyethylene films are one of the most frequently used packaging materials in our society, due to their combination of strength and flexibility. An unintended consequence of this high use has been the ever-increasing accumulation of polyethylene films in the natural environment. Previous attempts to understand their deterioration have either focused on their durability using polymer analysis; or they have focused on changes occurring during outdoor exposure. Herein, this study combines those strategies into one, by studying the chemical and physical changes in the polyethylene structure in a laboratory using molecular weight and IR spectroscopic mapping analysis, combined with temperate UV-accelerated weathering cycles. This approach has been correlated to real-world outdoor exposure timeframes by parallel testing of the sample polyethylene films in Florida and France. The formation of polyethylene microparticles or polyethylene waxes is elucidated through comparison of drop point testing and molecular weight analysis.

scholarly journals Correlation of a Temperate UV-Weathering Cycle to Outdoor Exposure for the Determination of the Environmental Instability of Polyethylene Films Using HT-GPC Analysis

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 591
Author(s):  
Gavin Hill ◽  
Celine Moreira ◽  
Florence Huynh ◽  
Ana Trufasila ◽  
Faith Ly ◽  
...  
Keyword(s):  
Physical Property ◽  
Gel Permeation Chromatography ◽  
Outdoor Exposure ◽  
Accelerated Weathering ◽  
Micro Particles ◽  
Exposure Site ◽  
Plastic Materials ◽  
Physico Chemical ◽  
Environmental Instability ◽  
Insight Into

Accelerated UV-weathering cycles are predominately used for evaluating the durability of plastic materials, particularly polyethylene (PE) films. The point of failure for this testing is usually the loss of a physical property, such as the loss of tensile strength over time. For plastics designed to be instable under environmental conditions, the accelerated weathering cycles are yet to be defined and their correlation to outdoor exposure has yet to be made. This study demonstrates the utility of a newly defined temperate accelerated UV-weathering cycle, recently codified in the British Standard PAS 9017:2020. In addition, the effectiveness of the laboratory weathering cycle has been correlated to real-world outdoor exposure through simultaneous testing of the same samples at a specialist outdoor exposure site in Florida. The utility of the testing methodology and the performance of the polyethylene samples was demonstrated through the use of High Temperature Gel Permeation Chromatography (HT-GPC) analysis. The data led to a detailed insight into the physico-chemical changes occurring in the PE films upon exposure to environmental stimuli. By comparison, and surprisingly, the techniques employed appear to provide an insight into the processes in which secondary micro-particles of PE are formed from macro-polyethylene samples. The temperate accelerated UV-weathering cycle over 14 days demonstrated an approximate correlation to 90 days of outdoor exposure in Florida for the PE film studied.

The analysis of “Gels” in polymer films

1989 ◽  
Vol 47 ◽  
pp. 362-363
Author(s):  
G. M. Brown ◽  
D. F. Brown ◽  
J. H. Butler
Keyword(s):  
Molecular Weight ◽  
Film Industry ◽  
Local Stress ◽  
Melt Index ◽  
Polyethylene Films ◽  
Crosslinked Polymer ◽  
Polymeric Gels ◽  
Mineral Particles ◽  
Polymeric Species ◽  
Special Concern

The term “gel”, in the jargon of the plastics film industry, may refer to any inclusion that produces a visible artifact in a polymeric film. Although they can occur in any plastic product, gels are a principle concern in films where they detract from the cosmetic appearance of the product and may compromise its mechanical strength by acting as local stress concentrators. Many film gels are small spheres or ellipsoids less than one millimeter in diameter whereas other gels are fusiform-shaped and may reach several centimeters in length. The actual composition of gel inclusions may vary from miscellaneous inorganics (i.e. glass and mineral particles) and processing additives to heavily oxidized, charred or crosslinked polymer. The most commonly observed gels contain polymer differing from the bulk of the sample in its melt viscosity, density or molecular weight.Polymeric gels are a special concern in polyethylene films. Over the years and with the examination of a variety of these samples three predominant polymeric species have been observed: density gels which have different crystallinity than the film; melt-index gels in which the molecular weight is different than the film and crosslinked gels which are comprised of crosslinked polyethylene.

Exposure of Polymeric Glazing Materials Using NREL’s Ultra-Accelerated Weathering System (UAWs)

2010 ◽  
Author(s):  
Carl Bingham ◽  
Gary Jorgensen ◽  
Amy Wylie
Keyword(s):  
Light Intensity ◽  
Thermal Effects ◽  
Outdoor Exposure ◽  
Exposure Chamber ◽  
Accelerated Weathering ◽  
Intensity Level ◽  
Design And Implementation ◽  
Different Temperatures ◽  
Exposure Testing ◽  
Ultraviolet Irradiance

NREL’s Ultra-Accelerated Weathering System (UAWS) selectively reflects and concentrates natural sunlight ultraviolet irradiance below 475 nm onto exposed samples to provide accelerated weathering of materials while keeping samples within realistic temperature limits. This paper will explain the design and implementation of the UAWS which allow it to simulate the effect of years of weathering in weeks of exposure. Exposure chamber design and instrumentation will be discussed for both a prototype UAWS used to test glazing samples as well as a commercial version of UAWS. Candidate polymeric glazing materials have been subjected to accelerated exposure testing at a light intensity level of up to 50 UV suns for an equivalent outdoor exposure in Miami, FL exceeding 15 years. Samples include an impact modified acrylic, fiberglass, and polycarbonate having several thin UV-screening coatings. Concurrent exposure is carried out for identical sample sets at two different temperatures to allow thermal effects to be quantified along with resistance to UV.

scholarly journals Effect of 1,4-Napthaquinone (NQ) and benzophenone (BPH)on the photodegradation and biodegradation of methyl cellulose film

2010 ◽  
Vol 7 (1) ◽  
pp. 737-744
Author(s):  
Baghdad Science Journal
Keyword(s):  
Molecular Weight ◽  
Film Thickness ◽  
Carbonyl Compounds ◽  
Methyl Cellulose ◽  
Chain Scission ◽  
Cellulose Derivative ◽  
Accelerated Weathering ◽  
Cellulose Derivatives ◽  
Photodegradation Rate ◽  
Aromatic Carbonyl Compounds

The induced photodegradation of methyl cellulose (MC) films in air was investigated in the absence and presence of aromatic carbonyl compounds(photosenssitizers): 1,4-naphthaquinone (NQ) and benzophenone (BPH) by accelerated weathering tester. The addition of (0.01 wt %) of low molecular weight aromatic carbonyl compounds to cellulose derivatives films(25µm in thickness) enhanced the photodegradation of the polymer films.The photodegradation rate was measured by the increase in carbonyl absorbance. Decreases in solution viscosity and reduction of molecular weight were also observed in the irradiated samples. Changes in the number-average chain scission, the degree of deterioration and in the quantum yield of chain scission values are also observed, and it was concluded that branching or cross-linking has occurred for cellulose derivative with NQ and BPH. Findings from all analytical techniques indicated that the 1,4-naphthaquinone (NQ) photosensitizer enhance the photodegradation of methyl cellulose more than benzophenone (BPH). The effect of the photosensitizer concentration, (ranging from 0.01 to 0.1 %), on the rate of photodegradation was also monitored for MC films. The rates are increased with increasing the photosensitizer concentration. The effect of film thickness is also studied at fixed sensitizer concentration (0.05%), and results show that the rate of cellulose derivative photodegradation decreases with increasing film thickness. The rate constants of the photodegradation of the photosensitizers deduced in cellulose derivatives films, [at concentration of (0.1%)by weight and thickness (25µm)]. Biodegradation of irradiated cellulose derivatives films was conclusively established with bacteria type Pseudomonas aeuroginosa Rb-19 isolated from crude oil. The amount of bacteria growth on MC after 30 days was lower, while there was no growth observed in MC with BPH

Accurate molecular weight analysis of histones using FFE and RP-HPLC on monolithic capillary columns

2009 ◽  
Vol 32 (15-16) ◽  
pp. 2691-2698 ◽  
Author(s):  
Evert-Jan Sneekes ◽  
Jun Han ◽  
Monica Elliot ◽  
Juan Ausio ◽  
Remco Swart ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Capillary Columns ◽  
Rp Hplc ◽  
Monolithic Capillary Columns ◽  
Weight Analysis
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