Effect of recycled content and rPET quality on the properties of PET bottles,part I: Optical and mechanical properties

The effect of recycled content and type of recycled poly (ethylene terephthalate) (rPET) on the haziness; colour parameters L*, a*, and b*; total colour change; ultraviolet-visual spectrum (UV-VIS) absorption; and environmental stress cracking (ESC) of PET bottles was studied. Three series of PET bottles were made at a small scale production facility with same type of virgin PET and three different types of rPET with recycled contents of 25%, 50%, 75%, and 100%. Also, the particle contamination of the produced PET bottles was studied by dissolving bottle fragments and counting the insoluble particles. A linear relationship was found between the haziness of PET bottles and the particle contamination, with a coefficient of determination of 0.96. Linear relationships were also found between the colour parameters L* and b* and the particle contamination of the PET bottles, but the slope differed for each type of rPET. The origin of rPET (mono-collection or cocollection) seems to be the crucial factor determining particle contamination and colour of the produced bottles. No correlation was found between the recycled content and the incidence of ESC. However, PET bottles in which high intrinsic viscosity (IV) values were measured showed lower chances of ESC than PET bottles with low IV values     

Migration of Tinuvin P,a UV stabilizer,from PET bottles into fatty‐food simulants

Tinuvin P migration from Polyethyleneterephthalate (PET) bottles was investigated using several fatty‐food simulants such as olive oil, soybean oil, n‐heptane and iso‐octane, at exposure conditions of 2–10 days at 40°C (total immersion). The stability of several UV stabilizers (BHT, Cyasorb UV 5411, Tinuvin P, Tinuvin 326 and Tinuvin 327) in n‐heptane and iso‐octane was also studied. After 10 days at 40°C, losses of 6% and 10% in iso‐octane and n‐heptane respectively, were verified for Tinuvin P. Other UV stabilizers at the same experimental conditions showed higher losses (up to 30% for Tinuvin 327). These results confirm that, when carrying out specific migration studies, the stability of the substance of interest should be established in the food simulant to avoid underestimating the real migration behaviour. In order to quantify UV stabilizer migration, n‐heptane and iso‐octane solutions were concentrated and directly analysed by SIM mode GC–MS. For olive and soybean oils, Tinuvin P was isolated using size‐exclusion chromatography and quantified by SIM mode GC–MS. Iso‐octane proved to be a more suitable fatty‐food simulant than n‐heptane for the migration study of Tinuvin P from PET. Higher levels of Tinuvin P migrated to olive and soybean oils rather than to n‐heptane. These results suggest that the MERCOSUL recommended official methods for specific migration studies should be revised, since the migration levels using n‐heptane as a fatty‐food simulant could be underestimated when compared to edible oils. Copyright © 1999 John Wiley & Sons, Ltd.     

扩链剂对反应挤出回收PET瓶分子量的影响

分别使用双口恶唑啉(BOZ)、均苯四酐(PMDA)及两者的混合物作为回收PET瓶的扩链剂,研究扩链剂的种类、扩链剂用量和反应挤出机加工工艺条件对PET产品相对分子质量(η)的影响。实验结果表明:在扩链剂用量均为0.2%(质量分数)时,BOZ可使产品的η提高4600 g/mol;BOZ和PMDA联用有一定的扩链效果,但不够理想;而使用PMDA可使产品的η提高9300 g/mol,达到33300 g/mol,扩链效果显著。使用PMDA为扩链剂时,反应挤出机的最佳工艺条件为:反应段温度260℃、螺杆转速45 r/min、真空度0.1 MPa。     

Studies on polyester packaging. Effects of basic washing on multi‐use PET and PEN bottles

Washing PET or PEN bottles intended for reuse with sodium hydroxide solutions appeared to affect the surface of the materials. The possible hydrolysis of the ester chemical function during the process was investigated. A new method for extracting and separating neutral and acidic products from the polymers was developed, and relative quantification of the isolated molecules was carried out by gas and liquid chromatography. Some adjuvants were no longer present after washing, but others were more easily extracted. A very weak hydrolysis reaction for PEN could not be excluded but it did not seem to occur for PET. Copyright © 1999 John Wiley & Sons, Ltd.     

Migration of Aluminum and Silicon from PET/Clay Nanocomposite Bottles into Acidic Food Simulant

Poly(ethylene terephthalate) (PET)/clay nanocomposite samples were prepared by melt blending PET and Cloisite 20A nanoparticles. A stretch blow‐moulding machine was used to produce bottles from neat PET and PET nanocomposite. Tests were performed on the migration of aluminum and silicon from PET nanocomposite bottles into acidic food simulant. The samples were stored at room temperature (about 25°C) and 45°C for time durations ranging from 7 to 90 days. A specific surface of sheets (prepared from PET/clay nanocomposite) immersed in acidic food simulant, and two‐sided migration of Al and Si was investigated. According to X‐ray diffraction analysis, the nanoclays show intercalated structure in the PET matrix. Transmission electron microscopy and atomic force microscopy micrographs displayed both intercalation and exfoliation morphology for PET/clay nanocomposites. Inductively coupled plasma was used to quantify amounts of Al and Si that had migrated into the acidic food simulant. It was observed that the migration process is dependent on storage time and temperature, and the molar ratio of aluminum and silicon in the acidic aqueous solution (Al/Si)_aq to the ratio in the solid phase of prepared nanocomposites (Al/Si)_solid was about 23% higher in the samples stored at 45°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental direct evaluation of functional barriers in PET recycled bottles: comparison of migration behaviour of mono‐ and multilayers

Recycling of used bottles into new bottles is associated with possible migration of pollutants arising from the previous life of the packages. To reduce or delay such migration, the recycled resin is depolluted or a functional barrier layer made of virgin plastics is used. Testing migration from such recycled bottles relies on the use of model pollutants (surrogates). In order to enable modelling of migration kinetics, each step of the use of surrogates is carefully investigated here in the case of PET. First, criteria underlying the selection of surrogates are carefully examined; together with volatility, polarity and diffusion behaviour, it is shown here that their solubility in the food simulant and their chemical stability strongly influence migration results. For aqueous test media, 2,4‐pentanedione and phenol should be used as surrogates. Second, a procedure is developed to impregnate surrogates at very large concentrations (several thousands of mg/kg PET) which are necessary to monitor migration kinetics. This procedure, which uses dichloromethane as solvent, allows a quick and reproducible impregnation, not sensitive to temperatures between 11–23°C, factors which favour its use at a plant scale. Third, flakes impregnated with this procedure are processed into bottles, and their physicochemical properties are compared to those of commercial bottles. Last, monolayer and tri‐layer polluted bottles (model pollutants in inner layer) are tested for migration for more than 1.5 years. With multilayers, the migration lag time of the fastest surrogates is 6 months with 3% acetic acid and 3 months with ethanol as the simulant, due to plasticization of PET by ethanol. The sequence of migration of surrogates is different with monolayer and multilayer bottles, which shows that partition effects (solubility) play an essential role, especially with monolayer materials. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of carbonation of modeled recycled coarse aggregate on the mechanical properties of modeled recycled aggregate concrete

The modeled recycled aggregate concrete (MRAC) which is an idealized model for the real recycled aggregate concrete (RAC) was used in this study. The MRCAs prepared with two types of old mortars were modified by an accelerated carbonation process. The effects of carbonation of MRCA on the micro-hardness of MRCA and the mechanical properties of MRAC were investigated. The results indicated that the micro-hardness of the old interfacial transition zone (ITZ) and the old mortar in the carbonated MRCAs was higher than that in the uncarbonated MRCAs, and the enhancement of the old ITZ was more significant than that of the old mortar. The compressive strength and modulus of MRACs increased when the carbonated MRCAs were utilized, and the improvement was more significant for MRAC prepared with a higher w/c. In addition, a numerical study was carried out and it showed that the improvement in strength by carbonation treatment was less obvious when the difference between the new and old mortar was larger.     

Influence of PET bottle weight,closure performance and filling Technique on the oxygen content of soya cooking oil

The use of PET bottles for edible oil in Brazil is increasing but there is a trend to reduce bottle weight for economic reasons, which decreases the oxygen barrier of the package. The barrier performance of a 20 g PET bottle for 900 ml soya oil, submitted to gas flushing with gaseous N₂ and pressurization with liquid N₂, was compared with a 27 g PET conventional bottle. During 8 months storage at 25°C the internal pressure, dissolved oxygen and oxygen in the headspace were evaluated and did not change significantly. Liquid N₂ pressurization did not improve the efficiency of reducing O₂ in the headspace compared to N₂ gas flushing. Copyright © 2001 John Wiley & Sons, Ltd.     

Effect of waste plastic bottles on the stiffness and fatigue properties of modified asphalt mixes

Nowadays, the use of recycled waste materials as modifier additives in asphalt mixes could have several economic and environmental benefits. The main purpose of this research was to investigate the effect of waste plastic bottles (Polyethylene Terephthalate (PET)) on the stiffness and specially fatigue properties of asphalt mixes at two different temperatures of 5 and 20 °C. Likewise, the effect of PET was compared to styrene butadiene styrene (SBS) which is a conventional polymer additive which has been vastly used to modify asphalt mixes. Different PET contents (2–10% by weight of bitumen) were added directly to mixture as the method of dry process. Then the resilient modulus and fatigue tests were performed on cylindrical specimens with indirect tensile loading procedure. Overall, the mix stiffness reduced by increasing the PET content. Although stiffness of asphalt mix initially increased by adding lower amount of PET. Based on the results of resilient modulus test, the stiffness of PET modified mix was acceptable and warranted the proper deformation characteristics of these mixes at heavy loading conditions. At both temperatures, PET improved the fatigue behavior of studied mixes. PET modified mixes revealed comparable stiffness and fatigue behavior to SBS at 20 °C. However, at 5 °C the fatigue life of SBS modified mixes was to some extent higher than that of PET modified ones especially at higher strain levels of 200 microstrain.     

PET膜中26种化学元素向酸性食品模拟物的迁移

目的 研究4种印刷不同油墨的PET薄膜在酸性条件下26种化学元素的迁移行为。方法 采用电感耦合等离子体发射光谱（ICP-OES）,测定铅、镉、铬等26种化学元素在PET薄膜中的初始含量;采用电感耦合等离子体质谱（ICP-MS）测定这26种化学元素向食品模拟物（体积分数为3%的乙酸）的迁移量。结果 铅、镉、铬等26种元素的迁移量随着温度和时间的增加而增大,并且均能达到各自的迁移平衡。ICP-OES方法的加标回收率为80.2%~109.7%,其相对标准偏差（RSD）为0.3%~12.9%;ICP-MS方法的加标回收率为83.1%~118.6%,其相对标准偏差为0.7%~14.8%。结论 26种化学元素向体积分数为3%乙酸的最大迁移量均低于标准限量值。     

环氧类扩链剂的合成及对回收PET的扩链效果

采用悬浮聚合方法合成了环氧类扩链剂苯乙烯-EMC的共聚物SMC,并对其进行红外分析表征。SMC中含有活性环氧基团,可与回收PET链端的羧基反应,将其用于PET(聚对苯二甲酸乙二醇酯)的反应共混,能够大大提高回收PET的分子量,特性黏度从0.448 dL/g提高至0.57 dL/g,羧基含量减少至很低,扩链效果显著。DSC分析扩链后的PET其固有性能保持不变。这种共聚物可作为PET的扩链剂使用。     

The Barrier Effect of EVOH versus 1,4,7‐Triaxocyclotridecane‐8,13‐Dione,a Non‐intentionally Added Compound from Polyurethane Adhesives in Multilayer Food Packaging

The presence and migration of non‐intentionally added substances in food packaging materials are the big concerns nowadays in terms of food safety, and the identification and quantitation are an important analytical challenge. Among non‐intentionally added substances, 1,4,7‐trioxacyclotridecane‐8,13‐dione, a by‐product resulting from the interaction between ingredients in many polyurethane adhesives, has been identified and quantified. Migration tests were carried out with food simulant E (Tenax®) and 3% acetic acid (simulant B) stored at 40°C/10 days using different adhesives and with different film thickness in the presence and absence of EVOH layer. After the exposure, Tenax® was extracted and analysed by gas chromatography with mass spectrometry. For 3% acetic acid, the analyses were directly performed by the Acquity® ultra‐performance liquid chromatography system coupled to triple quadrupole mass spectrometer detector. A possible degradation of the lactone after migration tests with 3% acetic acid occurred, and total degradation after 8 days was confirmed. Two compounds were detected and identified, which were also found in the migration extracts. Partition experiments were carried out from laminates composed by polypropylene film, adhesive and non‐treated polyethylene film at 40°C for 10 days. After this, the polypropylene/adhesive and polyethylene layers were independently extracted and analysed by gas chromatography with mass spectrometry. Diffusion studies were carried out following the Moisan procedure. The results and conclusions are shown and discussed.     

Overestimated diffusion coefficients for the prediction of worst case migration from PET: application to recycled PET and to functional barriers assessment

This paper defines parameters that can be used to predict worst‐case migration from recycled PET bottles, with and without a functional barrier. Starting with a set of diffusion coefficients determined in well‐defined experimental conditions (temperature, presence or not of a solvent, with and without swelling effect), empirical equations for the diffusion coefficient of a migrant or a pollutant in PET at 40°C are given as a function of its molecular weight. An equation is also derived for migration from PET into water. Surrogates representative of worst‐case migrants are identified and are discussed in terms of molecular weight, structure and interaction with the PET matrix. In the second part of the paper, the empirical equations have been used to simulate the migration from monolayer bottles and from multilayer bottles with different geometries of functional barrier, as a function of the pollutants' molecular weight. Since the diffusion coefficients are overestimated, the calculated migration is also overestimated, which provides a margin of safety. The advantage of the functional barrier technology is compared to the direct food contact route, as a function of food contact time. In the last part of the paper, the effect of testing temperature is investigated. Based on a literature survey, the activation energy of pollutants is shown to increase roughly with their molecular weights. A worst‐case activation energy of 80 kJ/mol is proposed, allowing extrapolation of migration data from a higher temperature (values calculated at 40°C or determined at 60°C) to room temperature. The possible use of this activation energy to design tests for functional barriers is discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

多因素对再生混凝土力学性能及抗冻性的影响

为研究不同因素、不同水平对再生混凝土力学性能的作用。该文通过正交试验研究钢纤维掺量、再生粗骨料掺量和粉煤灰掺量对再生混凝土力学性能(抗压强度、劈裂抗拉强度和抗折强度)的影响,确定各因素对再生混凝土力学性能的影响程度,并加以量化表征,并提出多因素共同作用下再生混凝土力学性能的多元非线性回归模型且进行验证。在此基础上,该文进一步研究再生混凝土的抗冻性。结果表明:再生混凝土的力学性能随钢纤维掺量的增加而提高;随粉煤灰掺量增加而降低;再生粗骨料掺量对再生混凝土的力学性能影响较小。钢纤维的掺入可提高再生粗骨料的掺量。再生混凝土力学性能的实测值与通过建立的回归模型得到的计算值的最大误差在6.5%以内。此外,钢纤维的掺入和减少再生粗骨料的掺量均可以提高再生混凝土的抗冻性。     

Impact of particle packing mix design method on fracture properties of natural and recycled aggregate concrete

The fracture properties of four types of concrete prepared using natural coarse aggregate and recycled coarse aggregate and conventional and particle packing method (PPM) of mix design approaches are studied. The three‐point bending (TPB) test is performed using three different sizes of single edge notched beam. The fracture energy is calculated from the load‐CMOD curve obtained in the TPB test, and in this process the load‐CMOD curve is curtailed at 2% of the depth of the beam. Based on CTOD_c and w₁ relationship, appropriate softening function is used to estimate the double‐K fracture parameters. The fracture energy and fracture toughness parameters of recycled aggregate concrete (RAC) is inferior to the natural aggregate concrete (NAC). The PPM mix design improves the fracture properties of concrete in comparison to the conventional mix design approach. The fracture properties of PPM mix designed RAC are comparable to that of NAC prepared using conventional method.     

成核剂对PET结晶行为的影响

采用差示扫描量热仪(DSC)研究了PET及添加成核剂后PET的非等温结晶过程,选用7种成核剂和4种复合成核剂进行了实验对比研究.结果表明添加任何一种成核剂后PET体系的结晶峰温移向高温,半结晶时间缩短,结晶速率常数增大,结晶度提高.其中有机类成核剂对PET结晶改善效果较无机类显著,但结晶效果最好的是成核机理为化学成核的高分子类成核剂和复合成核剂.本文还采用了热台偏光显微镜(POM)对PET晶体形貌进行了研究,发现添加有机成核剂后晶体细微而且密集.     

Growth and characterization of indium tin oxide thin films deposited on PET substrates

Transparent and conductive indium tin oxide (ITO) thin films were deposited onto polyethylene terephthalate (PET) by d.c. magnetron sputtering as the front and back electrical contact for applications in flexible displays and optoelectronic devices. In addition, ITO powder was used for sputter target in order to reduce the cost and time of the film formation processes. As the sputtering power and pressure increased, the electrical conductivity of ITO films decreased. The films were increasingly dark gray colored as the sputtering power increased, resulting in the loss of transmittance of the films. When the pressure during deposition was higher, however, the optical transmittance improved at visible region of light. ITO films deposited onto PET have shown similar optical transmittance and electrical resistivity, in comparison with films onto glass substrate. High quality films with resistivity as low as 2.5 × 10^− 3 Ω cm and transmittance over 80% have been obtained on to PET substrate by suitably controlling the deposition parameters.     

碳含量对高合金铁基材料组织与性能的影响

研究了高合金铁基材料中碳含量对材料显微组织与性能的影响.采用光学显微镜、扫描电镜和能谱分析表明:碳含量对材料烧结密度和性能影响显著.热处理后,材料硬度上升,但强度和韧性下降.烧结时,碳含量增加,使液相量增加,晶界上的液相膜增厚,晶粒球化;碳化物大部分在晶界上析出,形成半连续网络组织.热处理后,由于部分碳化物的溶解,一些连续的网络组织断裂.实验得出,1250±5.°C烧结,碳含量为1.4%时,烧结致密化程度最高,相对密度达到96%,各项性能也达到最高.本实验通过合理控制碳含量,获得了高性能的铁基粉末冶金材料.     

Light barrier properties of extra virgin olive oil (EVOO) glass bottles—Effect of glass colour and decoration

The aim of this study was to evaluate the quality of some glass bottles used for extra virgin olive oil (EVOO) related to light barrier properties, including clear and coloured glass in different colour intensities, glass with shrink labels, and external ceramic decoration. Some of these glass bottles available on the Brazilian market were also evaluated for closure integrity and barrier to oxygen, headspace gas atmosphere, and the quality of the product according to legislation. An increase in light barrier properties was observed for the darkest glass bottle that depends on the pigment quantity and the wall thickness. A total light barrier was obtained for glass with black shrink labels and external ceramic decoration. Closure systems used for the analysed packaging showed good integrity and low oxygen permeability, and the inertness of headspace atmosphere ensured a lower availability of oxygen for product oxidation. In general, the products met the requirements imposed in the legislation.