Polyethylene Terephthalate Preform Research Articles

Vendor Managed Inventory (VMI) Implementation in Recycled PET Preform for The Beverage Industry

The beverage industry is a company that is focused on producing mineral water in Polyethylene Terephthalate (PET) bottles. PET bottles serve as the primary packaging choice in the beverage industry, making the use of preforms as a material for bottles unavoidable. On the other hand, the public is more aware of using sustainable materials. Adapting market awareness, the company shifted from virgin material to recycled material. Due to the significant initial investment, the company has decided on a single supplier strategy for recycled PET preform suppliers. This policy forces the company to manage the supplier to meet the company’s delivery accomplishment target. Currently, in the management of beverage found in the industry, the supplier only reaches 50% of delivery accomplishments, whereas the company target is 90%. The beverage industry strived for a revolution, so the company’s target was achieved. The vendor managed inventory method is implemented in this study to create a new revolution for PET preform suppliers, a new replenishment system. After the implementation of Vendor Managed Inventory (VMI), there has been an improvement, reaching 95% in delivery accomplishment. The adoption of vendor managed inventory ensures the attainment of the company’s objectives.

Infrared heating modeling of recycled PET preforms in injection stretch blow molding process

Relatively recent citizen’s consciousness about plastic pollution forces industrial actors of packaging to re-invent their shaping processes and materials. Specifically, for plastic bottle industry shaping, classical Polyethylene Terephthalate (PET) material is little by little replaced by recycled PET (rPET). The change in material composition due to recycling loops leads to an inevitable adaptation of the Injection Stretch Blow Molding (ISBM) process used to shape bottles at a satisfactory production rate. Indeed, rPET contains contaminants which modify its optical properties, so the heating stage becomes material-dependent and unstable regarding the polymer supplier. The approach adopted in this article is to build a numerical model able to simulate the infrared heating of rPET preforms, sensitive enough to predict changes in temperature due to the recycling rate. To do so, the optical properties of 50% and 100% rPET are measured by spectrometry and implemented in the simulation. Thermal radiative heat transfer between infrared lamps and rPET preforms is simulated by ray tracing method using an in-house software so-called RAYHEAT. Then, the result of the infrared ray tracing computation is used as the input heat source for thermal simulation by commercial software COMSOL Multiphysic®in order to simulate the temperature distribution of the preform. The numerical results are then confronted to experimental ones obtained on a research Stretch Blow Molding pilot, instrumented with thermography. The results show that the temperature obtained at the end of a classical heating cycle of the 100% recycled grade is 8 °C higher than the virgin one. Also, simulations confirm that this difference is attributed to changes in optical properties. Finally, heating 100% rPET at a sufficient forming temperature is about 8% less energy consuming than for virgin PET.

Focusing dielectric slabs for the optimization of heating patterns in single mode microwave applicators

• Specific temperature distributions are difficult to obtain in microwave applicators. • Dielectric slabs with adjustable positions are proposed as focusing lenses. • Numerical and experimental results are provided for a TE101 rectangular cavity. • The slabs allow the optimization of heating patterns with great flexibility. • Their effect is illustrated on plastic preforms with a predefined heating pattern. A new approach based on dielectric slabs with adjustable position is proposed as near-field focusing lenses inside a single-mode microwave applicator to provide specific temperature distributions within a material heated by microwaves. Numerical and experimental results in a TE 101 rectangular cavity at 915 MHz have been used to evaluate the capability of these focusing dielectrics to optimize the temperature profile of Polyethylene terephthalate (PET) preforms. Measurements of the temperature profile on the preforms verified the strong effect of the slabs on the electric field distribution, allowing the optimization of the heating patterns with great flexibility. The successful application applied to PET preforms with different sizes and geometries showed the versatility of this approach which can be extended to the application of other type of loads and microwave cavities.

Linear and cyclic oligomers in PET, glycol-modified PET and Tritan™ used for food contact materials

ABSTRACT Polyesters are commonly used as food contact materials. During manufacture of polyesters different low molecular mass oligomers (<1000 Da) are formed in the polymer melt. These so-called non-intentionally added substances (NIAS) are potential migrants into foods. In this work, different polyester samples made of polyethylene terephthalate (PET), glycol-modified PET (PETG) and Tritan™ were investigated on their qualitative and quantitative oligomer composition. The analysis of acetonitrile extracts by HPLC-DAD/ESI-MS revealed the presence of about 100 linear (different combinations of hydroxyl-, carboxyl-, methyl ester end groups) and cyclic oligomers depending on the main and co-monomers. The identified oligomers were quantified in different extracts and after reprecipitation by HPLC-DAD using bis-hydroxyethylene terephthalate (BHET) as external standard. The amount of oligomers isolated by reprecipitation ranged between 0.80 and 3.4% in the respective polyester. Cyclic oligomers generally made up 90% or more of the isolated oligomers. Compared to the exhaustive extracts the leaching of oligomers into 20% ethanol (1 h, 60 °C) resulted in a considerable change of the oligomer distribution with a predominant detection of linear oligomers. This suggests linear oligomers to be relevant for migration into aqueous foods despite the dominant amount of extractable cyclic oligomers in polyesters. Analysis of the extractable oligomers of a PET preform and a PETG container and their corresponding raw material pellets revealed that the injection moulding process did not significantly change the amount of cyclic oligomers but did increase the amount of low molecular mass linear oligomers about twofold.

Numerical simulation of self heating during stretch blow moulding of PET: viscohyperelastic modelling versus experimental results

During the stretch blow moulding (SBM) process of polyethylene terephthalate (PET) bottle, high viscous dissipation generates self heating phenomena. Since the influence of temperature on polymer’s behavior is important, it is necessary to evaluate the self heating values in order to manage accurately the simulation of the process. An anisotropic visco-hyperelastic model has been developed to manage numerical simulations of free blowing. The model takes into account the anisotropy and the effect of the temperature. It has been computed in a user-interface VUMAT implemented in the software ABAQUS/Explicit. The identification of the model is based on experimental data of biaxial tension tests. We identified the characteristics taking into account the self-heating effect by a semi analytical process followed by an adjustment using finite element. For sake of validation, PET preforms have been blown from different initial temperature and followed using a thermal camera. The increase of temperature is measured by comparing initial temperature and final temperature. Comparison between the experimental and numerical simulations is discussed and influence of initial temperature or blowing pressure is highlighted in a large numerical investigation.

Mechanism design and simulation analysis of a new high-speed PET preform removal machine

In this article, a new type of polyethylene terephthalate (PET) preform removal machine and its auxiliary device are designed. The structure design of rotating module, traverse module, vertical module and crosswise module of the new type of preform removal machine, and the safety check and feasibility simulation analysis of the core components of each module are described. Among them, the speed multiplication mechanism is adopted in the traverse module, which greatly reduces the traverse time and improves the working efficiency of the preform removal machine; the counterweight balance device is used in the vertical module, which effectively balances the moment difference caused by the vertical motion of the rotating and traverse modules, makes the vertical motion more stable and saves the cost; and the design of slope track makes the unloading and placement of PET preforms proceed in an orderly manner, which can effectively avoid the collision between PET preforms and ensure the quality of products. Communicated by Joerg Fehr.

An Adaptive Method for Inspecting Illumination of Color Intensity in Transparent Polyethylene Terephthalate Preforms

Machine vision systems are applied in industry to control the quality of production while optimizing efficiency. A machine vision and AI-based inspection of color intensity in transparent Polyethylene Terephthalate (PET) preforms is especially sensitive to backgrounds and lighting, therefore, much attention is given to its illumination conditions. The paper examines the adverse factors affecting the quality of image recognition and presents an adaptive method for reducing the influence of changing illumination conditions in the color inspection process of transparent PET preforms. The method is based on predicting measured color intensity correction parameters according to illumination conditions. To test this adaptive method, a hardware and software system for image capture and processing was developed. This system is capable of inspecting large quantities of preforms in real time using a neural network with a modified gradient descent and momentum algorithm. The experiment showed that correction of the measured color intensity value reduced the standard deviation caused by variable and uneven illumination by 61.51%, demonstrating that machine vision color intensity evaluation is a robust and adaptive solution under illuminated conditions for detecting abnormalities in machine-based PET inspection procedures.

On Induced Properties and Self Heating during Free Blowing of PET Preform

Abstract The great influence of temperature on polymer's behavior is well known and a 10°C increase can lead to a 10-time reduction of the viscosity near the glass transition temperature. To manage accurate simulation of thermoforming processes, and particularly the stretch blow molding process that is managed in the vicinity of Tg, it is necessary to take into account the self heating phenomena that may have impact on induced properties. In the particular case of polyethylene terephthalate (PET), injected preforms have been blown with different initial temperature and followed using a thermal camera. For an identical final volume of the blown preform, the influence of initial temperature on self-heating is discussed. Back to room temperature, induced mechanical properties are measured using digital image correlation: bottles are blown under different pressures and the strain fields are measured. Using the virtual field method on a region of interest of the bottle, these results allow the identification of the induced mechanical properties. Comparison between the self-heating and the induced modulus is managed and the effect of the self heating on the free blown shapes and induced properties is discussed.

PET 생수병 내 휘발성 물질의 동정 및 이행량 분석

본 연구에서는 PET preform, 성형된 PET병, 그리고 PET병 생수에서 HS-SPME GC/MS를 통해 휘발성 물질을 동정하고 HDPE cap으로부터 생수에 이행된 2,4-DTBP의 이행량을 분석하였다. PET preform과 완성된 PET에서 nonanal과 decanal이 확인되었다. 이 물질들은 이취의 원인 물질로서 preform보다 PET병에서 농도가 더 높게 나타났으며, PET병에 대해 온도 증가에 따른 휘발성 물질을 분석한 결과 온도가 증가할수록 물질의 농도가 증가하였다. 특히 nonanal, vinyl benzoate, 그리고 decanal과 같이 온도에 민감한 휘발성 물질이 크게 증가하였다. 그리고 생수병의 HDPE cap에서 항산화제인 Irgafos 168을 정량한 결과 <TEX>$206{\pm}20.1{\mu}g/g$</TEX>의 농도를 나타내었다. 2,4-DTBP는 항산화제인 Irgafos 168의 분해 물질이므로 생수에서 검출된 2,4-DTBP는 cap에서 생수로 이행된 휘발성 물질로 확인되었으며 이행량은 <TEX>$4.8{\pm}0.2{\mu}g/L$</TEX>로 확인되었다. 따라서 PET병 생수의 관능학적 품질을 높이고 소비자의 안전을 위하여 PET 및 HDPE 제조 공정에서 가능한 온도를 낮게 제어하는 기술이 요구되며, 생수 제품의 유통 및 소비자 취급 시 적절한 온도 유지와 올바른 제품 보관을 통하여 저분자의 이취 원인 물질들을 줄이는 것이 중요할 것으로 판단된다. This study was carried out to identify the volatile organic compounds (VOCs) in polyethylene terephthalate (PET) bottles and to determine the extent to which VOCs migrate into mineral water during the bottling process and storage. A greater amount of nonanal and decanal was generated from the PET bottles than from the PET preforms. Benzene, ethylbenzene, nonanal, and vinyl benzoate were identified from the PET bottles when the incubation temperature of the headspace solid-phase microextraction (HS-SPME) sampler was set to 60, 80, and <TEX>$100^{\circ}C$</TEX>. As the incubation temperature increased, the concentrations of nonanal, vinyl benzoate, and decanal increased significantly. When the high-density polyethylene (HDPE) PET bottle caps were extracted with dichloromethane, the level of Irgafos 168 was found to be <TEX>$206{\pm}20.1\mu}g/g$</TEX>. The concentration of 2,4-di-tert-butylphenol in water was <TEX>$4.80{\pm}0.2{\mu}g/L$</TEX>. Therefore, it is necessary to avoid exposing PET and HDPE resins to high temperatures during the manufacturing process and storage of bottled water.

Validating injection stretch‐blow molding simulation through free blow trials

AbstractA 2D isothermal finite element simulation of the injection stretch‐blow molding (ISBM) process for polyethylene terephthalate (PET) containers has been developed through the commercial finite element package ABAQUS/standard. In this work, the blowing air to inflate the PET preform was modeled through two different approaches: a direct pressure input (as measured in the blowing machine) and a constant mass flow rate input (based on a pressure–volume–time relationship). The results from these two approaches were validated against free blow and free stretch‐blow experiments, which were instrumented and monitored through high‐speed video. Results show that simulation using a constant mass flow rate approach gave a better prediction of volume vs. time curve and preform shape evolution when compared with the direct pressure approach and hence is more appropriate in modeling the preblowing stage in the injection stretch‐blow molding process. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

Modelling of the Injection Stretch Blow Moulding of PET Containers via a Pressure-Volume-time (PV-t) Thermodynamic Relationship

A 2-D isothermal finite element simulation of the injection stretch-blow moulding (ISBM) process for polyethylene terephthalate (PET) containers has been developed via the commercial finite element package ABAQUS/standard. In this work, the blowing air to inflate the PET preform was modelled via two different approaches; a direct pressure input (as measured in the blowing machine) and a constant mass flow rate input (based on a Pressure-Volume-time relationship). These two methods were tested with a simplified stretch blow moulding process where a preform was blown with and without a stretch rod in free air (no mould). The results clearly show that simulation with a constant mass flow rate as input gave an excellent prediction of volume vs. time curve and preform shape evolution when compared with the direct pressure approach. In addition to this, rapid inflation of the PET preform (∼0.03s) was found to occur in the direct pressure approach which was not observed in reality. This result reveals that the constant mass flow rate approach is more appropriate in modelling the blowing stage in ISBM process.