The choice of sampling tube material in the determination of nitrogen oxide concentrations in products of combustion

It has been confirmed that when hot products of combustion containing traces of nitrogen oxides are sampled through metal tubes the concentration falls. The mechanism is in part due to the conversion of nitrogen dioxide to nitric oxide. Glass tubing may be used as a substitute at high sampling temperatures and PTFE is suitable at lower temperatures; nylon, EVA and PVC tubing should not be used since significant losses may occur in these materials even at room temperature.     

Radiation effects on LDPE/EVA blends

Radiation effects of low‐density polyethylene/ethylene‐vinyl acetate copolymer (LDPE/EVA) blends were discussed. EVA content in the LDPE/EVA blends was an enhancement effect on radiation crosslinking of LDPE/EVA blends, and the highest radiation crosslinking was obtained when the EVA content was reached at 30% when irradiated by γ‐ray in air. The phenomenon was discussed with the compatibility, morphology, and thermal properties of LDPE/EVA blends and found that the enhanced radiation crosslinking of the LDPE/EVA blends was proportional to the good compatibility, the increasing degree of the amorphous region's content of the LDPE/EVA blends, and the vinyl acetate content of EVA. We also found that the vinyl acetate of EVA in the blends is easily oxidized by γ‐ray irradiation in air. The possible radiation crosslinking and degradation mechanism of LDPE/EVA blends was discussed quantitatively with a novel method “step‐analysis” process of irradiated LDPE/EVA blends in the thermal gravimetric analysis (TGA) technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1296–1302, 2002     

环保型无卤阻燃热缩管的研制

环保型无卤阻燃热缩管以乙烯-乙酸乙烯共聚物(EVA)和低密度聚乙烯(LDPE)为基体树脂,以微胶囊红磷和氢氧化镁为阻燃剂,加入自制的增容剂、复合润滑剂以及复合抗氧剂,制备的环保型无卤阻燃热缩管的环境物质指标符合欧盟RoHS指令要求,产品性能符合UL224标准要求,达到了国外同类产品水平。自制的增容剂能够显著提高微胶囊红磷、氢氧化镁与基体树脂EVA/LDPE的相容性,产品表面光滑而且拉伸强度明显提高。     

Study on thermoplastic polyurethane/polypropylene (TPU/PP) blend as a blood bag material

Blends with different ratios of thermoplastic polyurethane/polypropylene (TPU/PP) were prepared by melt mixing using an internal Haake mixer. Properties of the blends were investigated using SEM micrographs of cryofractures and measurement of the mechanical strength, water absorption, cell culture, and platelet adhesion in vitro tests, which were compared with those of PVC blood bags. The effect of the addition of the ethylene–vinyl acetate (EVA) copolymer on the TPU/PP blend properties was investigated. The results indicated that a TPU/PP/EVA = 80/20/5 blend can be used as a new blood bag material. It was observed that the blend is homogeneous with higher mechanical strength than that of the commercial PVC blood bag. This blend also showed a compatible cell response in contact with L929 fibroblast cells and fewer tendencies to interaction with platelets compared to the PVC blood bag. Although the blends were immissible and no chemical reaction at the interface could be found, the blood compatibility of the blends were improved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2496–2501, 2003     

DinCH and ESBO actual migration from PVC infusion tubings used in an oncopediatric unit

Plasticizer leaching from poly(vinyl chloride) (PVC) tubing is a well‐studied phenomenon and is a real issue in medical care today. The present study focuses on the release of two plasticizers 1,2‐cyclohexane dicarboxylic acid diisononyl ester (DINCH) (primary) and epoxidized soy bean oil (ESBO) (secondary) from PVC extension tubings used in an oncopediatric unit. The release of plasticizers is calculated by comparison to unused tubings with the same batch number. Both the DINCH and ESBO ratio diminishes in used versus new extension tubings. The loss of plasticizers has not been related to the presence of a specific drug. Our results confirm the leaching of classic plasticizers like the DINCH and of secondary plasticizers like the ESBO from tubings in real life. It confirms too the existence of a complex phenomenon in which exchanges between drugs, lipids, PVC matrices, and the administration sequences can change the global release of plasticizers. Considering all the variables involved in real‐life data, the in vitro testing appears to be the most efficient way to confirm these observations. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46649.     

Effect of electron beam irradiation and vinyl acetate content on the physicochemical properties of LDPE/EVA blends

The radiation‐induced crosslinking, compatibility, and surface modification of low density polyethylene/ethylene vinyl acetate blends (LDPE/EVA) were investigated. The structural and physical properties were characterized in terms of gel content, hot set, mechanical properties, contact angle, and surface free energy. The highest crosslink density was obtained at 20 wt % of EVA. Gel content of LDPE/EVA blends was increased with increasing irradiation dose, vinyl acetate (VA), and EVA contents. The hot set results are consistent with the gel content data. Mechanical testing showed that the tensile strength of samples increased with increasing irradiation dose up to 180 kGy, whereas the elongation at break was decreased with increasing irradiation dose. Contact angle measurements showed that the surface hydrophillicity of LDPE blend was increased with increasing irradiation dose and contents of both VA and EVA. The surface free energy was greatly dependent on irradiation dose and content of both VA and EVA. The total surface free energies of different LDPE formulations were in the range 17.25–32.51 mN/m, in which the polar (^pσ) and disperse (^dσ_s) values were within the range 16.52–26.6 and 0.9–5.91 mN/m, respectively. In conclusion, electron beam irradiation and blending LDPE with EVA improved the wettability or adhesion properties of LDPE/EVA blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Blood,guts and chemical engineering

Basic chemical engineering sciences have been used to address selected medical problems. The natural anticoagulant, heparin, has been immobilized to a polyvinyl alcohol (PVA) coating on polyethylene or polyurethane, to prepare a blood compatible material. Modelling of the relationship between the rate of heparin leakage from the coating and the blood heparin concentration at the blood material interface supported the conclusion that the observed inhibition of clot formation induced by the material was due to the activity of the covalently immobilized heparin. The relationship between flow resistance and tube diameter was used to devise an ex vivo system for demonstrating this activity: 1 mm ID heparin-PVA coated tubing was tested in a parallel flow circuit with a 3 mm ID silicone tubing so as to control the blood flow through the 1 mm test tubing. In another area of chemical engineering activity in biomedical sciences, live mammalian cells have been microencapsulated in a polymer membrane to prevent the host's antibodies, that are outside the capsule, from causing the immune destruction of the to-be-transplanted cells (e.g., pancreatic islets for the treatment of diabetes). These works illustrate the use of chemical engineering in nontraditional ways, consistent with what some consider the new “paradigm” for our profession.     

Quantifying adsorption of heparin on a PVC substrate using ATR‐FTIR

The surface modification of poly(vinyl chloride) (PVC) tubing by heparin was performed to increase its blood compatibility. A solution of benzalkonium heparinate was used in the treatment of two types of plasticized PVC. The modification of the PVC surface was monitored after various treatment conditions, and quantitative results were obtained by using ATR‐FTIR spectroscopy. The treatment times and the PVC type have a strong influence on the observed amount of heparin. A partial removal (20–30 %) of heparin was observed after rinsing the PVC surface with a 0.9 wt% NaCl aqueous solution. The more flexible PVC tubing, having a lower T_g, had a higher concentration of heparin. Final heparin concentrations on the PVC surfaces were found to be in the range 1–17 µg cm^?2. Copyright © 2004 Society of Chemical Industry     

Investigation of radiation-crosslinked foam of LDPE/EVA blends

Low-density polyethylene/ethylene–vinyl acetate copolymer (LDPE/EVA) blend was irradiated by γ-ray and then expanded by heat as a foamed material. The EVA content in the LDPE/EVA blend was benefited to form a gel. The gel fraction values of LDPE/EVA blend with 30% EVA content were higher than those of other blends in a same given dose; its gel fraction value was 1.7 times as those values of the LDPE without EVA. The gel fractions of the LDPE/EVA blend were increased with radiation dose in oxygen, in air, and in nitrogen, and the formation of gel was limited by oxygen. The oxidation products of the foam of the LDPE/EVA blend were observed in nitrogen, in oxygen by Fourier transform IR spectra. The LDPE/EVA blend system has no protection effect from oxidation in comparison with the LDPE system without EVA, which has less oxidation product than those without EVA in a same given gel fraction. The gel fraction of the LDPE/EVA blend around 25–35%, radiation dose 25±5 kGy, irradiated by γ-ray in air or in nitrogen, with higher expansion ratio (19), smaller cell diameter (0.175 mm), lower apparent density (0.042 g/cm³), higher tensile strength (0.40 MPa), and longer elongation at break (290–360%) foam of the LDPE/EVA blend were selected. These were optimum condition for application in this system. The relations among gel fraction of the LDPE/EVA blend, expansion ratio, apparent density, average cell diameter, and mechanical properties of the foam were discussed. © 1996 John Wiley & Sons, Inc.     

Investigations on vinylene carbonate. IV. Radiation induced graft copolymerization of vinylene carbonate and N-vinyl-N-methylacetamide onto polyethylene films

Graft copolymerization of binary mixtures of vinylene carbonate (VCA) and N-vinyl–N–methylacetamide (VIMA) onto low density polyethylene (LDPE) films was studied by the mutual γ-irradiation technique. Sufficient amounts of functionally active VCA groups could be grafted onto the surface and the hydrophilicity of the surface was also improved. The grafting of VCA onto polyethylene films in the binary solutions was found to be promoted by the presence of VIMA, thus showing a positive synergism. The VCA content in the graft copolymers was always higher than in the copolymers obtained by homogeneous copolymerization using the same monomer feed composition. The monomer reactivity ratios, as well as a preferential partitioning of the monomers surrounding the polymeric substrate, were considered to explain the grafting reactions in the binary systems.     

A comparative evaluation of a novel flame retardant, 3-(tetrabromopentadecyl)-2,4,6-tribromophenol (TBPTP) with decabromodiphenyloxide (DBDPO) for applications in LDPE- and EVA-based cable materials

Flame retardation of polymeric materials for cables is becoming a statutory requirement due to governmental regulations to protect life and property from damages caused by fire. This and other factors such as the ever-increasing cost of existing flame retardants (FRs) have given rise to the search for better FRs. In this article, the suitability of an FR, 3-(pentadecyltetrabromo)-2,4,6-tribromophenol (TBPTP) developed from cardanol was evaluated for use in cable insulating and jacketing materials based on low-density polyethylene (LDPE) and ethylene vinyl acetate (EVA). The processability, mechanical properties, compatibility and miscibility, thermal behavior, flammability behavior, smoke generation, acid emission, aging characteristics etc., of the blends of the FR with LDPE and EVA were studied in comparison to those of decabromodiphenyl oxide (DBDPO), which is a standard FR used by the cable industry. Although TBPTP is found to be less thermally stable than is DBDPO, it exhibited better flame retardancy and has comparable thermal stability when blended with LDPE and EVA. Both LDPE—TBPTP and EVA—TBPTP blends produced less smoke than did the corresponding blends of DBDPO. In the case of the EVA—TBPTP blend, the percentage emission of smoke was almost negligible, placing EVA—TBPTP under the low smoke grade. Formulations containing a synergistic agent, promoter, and filler with the corresponding FR and polymer polymer along with an antioxidant were extruded out into wire and tested for cable properties. At 20% loading, the LOI values of the blends were 34.6 and 32.5, respectively, for the TBPTP—EVA and DBDPO—EVA blends. Vertical burning tests carried out with EVA—TBPTP cable showed that it is self-extinguishable. The processability of the compositions containing TBPTP were better than those of DBDPO. The improved processability was found to be due to the plasticising effect of TBPTP. SEM pictures of the blend showed excellent distribution of TBPTP in the polymer, indicating good compatibility and miscibility. Comparatively, DBDPO did not exhibit uniform distribution. The mechanical properties of the blends were within specifications of standard cable materials except that the % elongation of the DBDPO—LDPE blend was far too low. Aging studies also gave better properties for the TBPTP system than for those of the DBDPO system. The overall results show that the properties of EVA—TBPTP cable fall within specifications for the FARLS grade, whereas the EVA—DBDPO cable did not. In the case of LDPE, both TBPTP and DBDPO did not satisfy specifications for the FRLS grade, but the data indicate that they can be used as FRs. The superiority in properties of the TBPTP system over DBDPO is explained in terms of the structure of TBPTP characterized by the distribution of the flame-retardant element, bromine, almost evenly between the aliphatic and aromatic moieties of the molecule, which can, in contrast to the fully aromatic DBDPO, provide halogen over a wide range of temperatures to the combustion zone of the decomposing polymer. Moreover, the presence of the aliphatic segment assures improved processability and compatibility. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 3057–3073, 1997     

Effect of waste polymer addition on the rheology of modified bitumen

This paper deals with the modification of petroleum bitumen with four different types of waste polymers. EVA, EVA/LDPE blend, crumb tire rubber and ABS, all of them coming from recycling plants of waste plastic materials, were used as modifying agents of the bitumen employed in the pavement building. Optical microscopy, modulated calorimetry and a set of different rheological tests were developed in order to characterise the modified bitumens. The results obtained reveal that tire rubber as well as its blends with other polymers can be considered as an interesting modifier of the bitumen in a wide range of temperatures. As an elastomer, it endows the pavement a higher flexibility, which makes it more resistant to the traffic loading. The blend composed of EVA and LDPE displays quite promising results at high in-service temperatures, due to the development of a polymer network throughout the modified bitumen. Furthermore, the calorimetry tests carried out demonstrate different degrees of compatibility between the bitumen and the polymers used.     

相容剂对PVC／PA6体系形态结构的影响

研究了SMA—g—MAH、SEBS—g—MAH和EVA—g—MAH3种相容剂对PVC／PA6共混物的增容效果。结果表明,未添加相容剂的PVC／PA6（100／20）共混物的相容性不好;添加SEBS—g—MAH和EVA—g—MAH两种相容剂后,PVC／PA6共混物的相容性得到一定程度的改善;添加SMA—g—MAH相容剂后,PA6很均匀地分散在PVC基体中。     

Experimental investigation on the abrasive wear behavior of nanoclay‐filled EVA/LDPE composites

The article presents the results of experimental investigation on three‐body abrasive wear behavior of nanoclay‐filled EVA/LDPE (NC‐EVA/LDPE) composites. NC‐EVA/LDPE composites with and without compatibilizer were prepared by Brabender Co‐Twin extruder (Make: CMEI, Model: 16CME, SPL) and poly(ethylene‐co‐glycidyl methacrylate) was used as the compatibilizer. The mechanical properties were evaluated using Universal testing machine. In three‐body wear tests, silica sand particles of size 200–250 μm were used as dry and loose abrasives. Three‐body abrasive wear studies were carried out using dry sand/rubber wheel abrasion test rig. The effect of abrading distance on the abrasive wear behavior of neat EVA, EVA/LDPE, and NC‐EVA/LDPE composites was reported. The results showed that the wear volume loss is increased with increase in abrading distance and the specific wear rate decreased with increase in abrading distance. However, the presence of nanoclay filler in EVA/LDPE composite showed a promising trend. Abrasive wear volume of the composites was correlated with mechanical properties such as hardness, tensile strength, and percentage elongation. However, higher weight percentage of LDPE in EVA increased the wear rate. The results indicate that NC‐EVA/LDPE with compatibilizer composite exhibits good abrasive wear resistance compared with NC‐EVA/LDPE without compatibilizer. Attempts to explain these differing trends are made in this work by analyzing the features observed on the worn surface samples by employing scanning electron microscopy (SEM). POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

木质素填充LDPE、EVA对复合物性能的影响

以木质素为填充剂分别与低密度聚乙烯(LDPE)、乙烯-乙酸乙烯酯共聚物(EVA)共混,经双螺杆造粒机共混挤出造粒,再经吹塑成膜。研究了木质素/LDPE、木质素/EVA共混物薄膜的表面形貌、力学性能、热性能和红外光谱。热分析表明木质素与EVA共混物的热稳定性比木质素与LDPE的共混物热稳定性好;红外光谱分析表明木质素与EVA分子间产生了强烈的相互作用,扫描电镜分析表明木质素与EVA共混的相容性较好,力学性能分析表明低于30%的木质素与LDPE、EVA共混力学性能较好。     

Effects of compatibilizer type and rubber‐wood sawdust content on the mechanical,morphological, and thermal properties of PVC/LDPE blend

This article aimed to investigate the mechanical, morphological and thermal properties of PVC/LDPE blend with and without the addition of compatibilizers. The effects of LDPE content, compatibilizer type and rubber‐wood sawdust loading on the properties of the blend were evaluated. The experimental results suggested that as the LDPE content was increased the mechanical properties of PVC‐LDPE blend progressively decreased due to poor interfacial adhesion. The continuity and compatibility between PVC and LDPE phases could be improved through three different types of compatibilizers which included chlorinated polyethylene (CPE) poly(methyl‐methacrylate‐co‐butyl acrylate) (PA20) and poly(ethylene‐co‐methacrylate) (Elvaloy). The PA20 was found to be the most suitable compatibilizer for the blend. A radical transfer reaction was proposed in this work to explain the structure and thermal changes of the PVC in PVC‐LDPE blend. The decomposition temperature of PVC in the blend decreased with the loading of the PA20 and the wood sawdust. As the sawdust content was increased the tensile and flexural moduli increased with considerable decreased in the tensile, flexural and impact strength, a slight improvement being achieved if the PA20 was incorporated in the composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 598–606, 2006     

Thermal and mechanical properties of uncrosslinked and chemically crosslinked polyethylene/ethylene vinyl acetate copolymer blends

Uncrosslinked and chemically crosslinked binary blends of low‐ and high‐density polyethylene (PE), with ethylene vinyl acetate copolymer (EVA), were prepared by a melt‐mixing process using 0–3 wt % tert‐butyl cumyl peroxide (BCUP). The uncrosslinked blends revealed two distinct unchanged melting peaks corresponding to the individual components of the blends, but with a reduced overall degree of crystallinity. The crosslinking further reduced crystallinity, but enhanced compatibility between EVA and polyethylene, with LDPE being more compatible than HDPE. Blended with 20 wt % EVA, the EVA melting peak was almost disappeared after the addition of BCUP, and only the corresponding PE melting point was observed at a lowered temperature. But blended with 40% EVA, two peaks still existed with a slight shift toward lower temperatures. Changes of mechanical properties with blending ratio, crosslinking, and temperature had been dominated by the extent of crystallinity, crosslinking degree, and morphology of the blend. A good correlation was observed between elongation‐at‐break and morphological properties. The blends with higher level of compatibility showed less deviation from the additive rule of mixtures. The deviation became more pronounced for HDPE/EVA blends in the phase inversion region, while an opposite trend was observed for LDPE/EVA blends with co‐continuous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3261–3270, 2007     

新型尼龙／聚烯烃相容剂EVALM的合成及表征

通过一种可控制的非均相水解方法制备了部分水解的乙烯／醋酸乙烯共聚物－ＥＶＡＬ。得到的ＥＶＡＬ中醋酸乙烯（ＶＡ）基团的水解度可以通过溶用及反应的温度、时间来控制,而且水解溶剂的后处理比较简单,有利于连续化生产及环境保护。将ＥＶＡＬ在苯溶液中进行马来酸酐接枝,得到一种新型的尼龙／聚烯烃相容剂马来酸酐接枝部分水解的乙烯／醋酸乙烯共聚物（ＥＶＡＬＭ）,其中马来酸酐的接枝率也可以接枝反应时间来控制。通过Ｍｏ     

Cross-linked poly(ethylene vinyl acetate) (EVA)/low density polyethylene (LDPE)/metal hydroxides composites for wire and cable applications

Formulations of chemically cross-linked poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) blends containing metal hydroxides flame retardants such as aluminum hydroxide (ATH) and magnesium hydroxide (MH) were prepared. Comparison of both type of metal hydroxides in respect of their influence on flammability as well as mechanical, thermal, and electrical properties of EVA/LDPE composites is presented. Most of the investigated properties are better for composites containing MH in comparison with composites containing ATH. Influence of various EVA/LDPE ratios on investigated properties is presented as well. Importance of improving compatibility using compatibilizers to improve some of the investigated properties is described. Polyethylene grafted with maleic anhydride (PEgMA) was found to be better compatibilizer for ATH than vinyl silanes.     

EVA增容改性玉米淀粉／LDPE共混体系的研究

以LDPE和玉米淀粉为主要原料,与EVA熔融共混制备了玉米淀粉／LDPE／EVA共混材料,并对其热学性能和抗张性质进行了研究。DSC分析显示EVA可以明显改善LDPE和淀粉之间的相容性,机械性能也有所改善,在EVA含量为10％时,抗张强度为9．2MPa,断后伸长率为117．4％。