Search results for "Ethylene"

2021

The abundance of microplastics (MPs) in the atmosphere, on land, and especially in water bodies is well acknowledged. In this study, we establish an optical method based on three different techniques, namely, specular reflection to probe the medium, transmission spectroscopy measurements for the detection and identification, and a speckle pattern for monitoring the sedimentation of MPs filtrated from wastewater sludge and suspended in ethanol. We used first Raman measurements to estimate the presence and types of different MPs in wastewater sludge samples. We also used microscopy to identify the shapes of the main MPs. This allowed us to create a teaching set of samples to be characterized …

Structure, morphology and crystallization of a random ethylene-propylene copolymer

2003

The structure, morphology, and crystallization behavior of a random ethylene–propylene copolymer, containing 2 wt % ethylene sequences, are analyzed and compared with those of a plain polypropylene sample by means of optical and scanning microscopy, wide-angle X-ray scattering, and calorimetry. For the copolymer, different polymorphs (α, γ and smectic modifications) and morphologies can be obtained through changes in the crystallization and annealing conditions. The analysis of the structural results suggests that the γ phase of isotactic polypropylene can be generated for high molecular mass samples with drastic decreases in the undercooling. The spherulite growth rate (G) data, in conjunc…

Study of thermal properties of polyethylene and polypropylene nanocomposites with long alkyl chain-substituted POSS fillers

2016

The effect of incorporation of octakis({alkyl}dimethylsiloxy)octasilsesquioxanes molecules with n-octyl, n-octadecyl and 4-methyl-hexyl substituents on thermal properties of polypropylene (PP), low-density polyethylene (LDPE) and high-density polyethylene (HDPE) was investigated. Thermal properties of those composite materials were evaluated by means of the differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The type and mass% content of POSS nanofillers influenced the crystallization and melting properties as well as thermal stability of the obtained polyolefin nanocomposites. The incorporated POSS particles—acting as nucleating agents—improved the crystall…

Kinetics of ascorbic acid degradation in fruit-based infant foods during storage

2013

The kinetics of ascorbic acid (AA) degradation in a fruit-based beikost product added with AA were determined after storage at 4, 25, 37 and 50 °C during 4, 8, 12, 16 and 32 weeks in plastic polypropylene/ethylenevinyl alcohol vacuum packaging. It was confirmed that AA degradation followed an Arrhenius first-order kinetics, with an activation energy of 20.11 ± 0.33 kcal mol−1. No AA losses at 4 °C were recorded during the entire storage period. In contrast, a time - and temperature - dependent decrease (p the degradation rate decreasing from 50 °C to 25 °C, as expected. AA percentage retention at the end of storage ranged between 6.4% (50 °C/16 weeks) and 100.9% (4 °C/32 weeks).

A New Calibration Method for the Accurate Determination of Ethylene Content in Ethylene-Propylene Copolymers by CRYSTEX-IR

2012

Summary: CRYSTEX is a fully automated instrument for the determination of Xylene Solubles in polypropylene and ethylene-propylene copolymers, providing an excellent correlation with gravimetric methods. The instrument can be equipped with a dual band infrared (IR) detector to quantify the ethylene weight percentage (C2%) in the amorphous fraction, and in the whole polymer sample. In this work, a new approach based on multiple linear regression (MLR) models is presented, which makes use of two independent IR absorbance signals acquired simultaneously by the detector. A compromise model to predict directly C2% is proposed, which balances good accuracy and reduced experimental effort. MLR mode…

“Effect of Filler Type and Processing Apparatus on the Properties of the Recycled “Light Fraction” from Municipal Post-Consumer Plastics”

2001

Plastic waste or scraps are generated from two main sources: industrial wastes and post-consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post-consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post-consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous …

Effect of the processing on the properties of biopolymer based composites filled with wood flour

2008

Wood-polymer composites (WPCs) are well known today in the field of industrial applications, because of several advantages they can grant if compared with mineral filler-polymer composites. These advantages regard the low cost of wood based fillers, the reduced specific weight, the lower hazards for production workers in case of inhalation, the special aesthetic features, environmental issues. The scientific literature reports studies regarding polymer matrices like, for instance, polyethylene and polypropylene, in combination with several natural-organic fillers. However, a limit of these composites is represented by the fact that there is not a full biodegradability: this, in fact, regard…

Effectiveness of organoclays as compatibilizers for multiphase polymer blends - A sustainable route for the mechanical recycling of co-mingled plasti…

2014

We prepare and characterize multiphase systems in which small amounts of recycled polymer, namely polyethylene terephtalate (PET) ground from waste bottles, are dispersed in a co-continuous blend of high-density polyethylene (HDPE) and polypropylene (PP). Some of such ternary systems are also filled with plate-like clay nanoparticles with different polarities, in order to assess their influence on the morphology and mechanical behaviour of the blends. On the basis of preliminary wettability considerations and inspections by means of scanning electron microscopy (SEM), the PET is found to preferentially locate within the PP phase. Such a positioning is desirable in order to minimize the pres…

On the mechanism of compatibilization of polyolefin/liquid crystalline polymer blends with graft copolymers

2000

The compatibilization mechanism of some compatibilizers for blends of polyolefins with a liquid crystalline polymer (LCP) was studied. Polyethylene (PE) and polypropylene (PP) were blended with a semirigid LCP (SBH) in a batch mixer, either with and without compatibilizers. The latter were two commercially available samples of functionalized polyolefins, that is, a PE-g-MA (HDM) and a PP-g-AA (Polybond 1001) copolymer and some purposely synthesized PE-g-LCP and PP-g-LCP copolymers. Microtomed films of the binary and the ternary blends were annealed at 240°C on the hot stage of a polarizing microscope and the changes undergone by their morphology were recorded as a function of time. The resu…

Physicochemical stability of cabazitaxel containing premix solution and diluted infusion solutions

2015

Objectives This study was conducted to investigate the extended physicochemical stability of cabazitaxel containing premix solution and diluted infusion solutions in either 0.9% sodium chloride (NaCl) or 5% glucose (G5) vehicle solution. Methods A stability indicating, reverse phase, high performance liquid chromatography assay with ultraviolet detection was developed and validated. Premix solutions of cabazitaxel were prepared in the original vials. Infusion solutions were prepared in prefilled polypropylene/polyethylene (PP/PE) infusion bags (0.9% NaCl, G5) to achieve the recommended minimum and maximum cabazitaxel concentrations (0.1 mg/mL, 0.26 mg/mL). Test solutions were stored refrige…