A novel approach toward the effect of seal process parameters on final seal strength and microstructure of LLDPE

Najarzadeh, Zahra; Ajji, Abdellah

doi:10.1080/01694243.2014.907465

Cited by 23 publications

(36 citation statements)

References 42 publications

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“…45 Also, within the optimum sealing temperature range, seal strength increases as dwell time and temperature increase because it enhances the formation of entanglements. 47 According to Najarzadeh et and Ajji, 43 there is a linear correlation between the strength of the seal and the square root of dwell time, and the slope of the t 1/2 versus seal strength graph will increase when the sealing is performed at the higher temperatures. This means the maximum seal strength is obtained faster at higher temperature levels.…”

Section: Dwell Timementioning

confidence: 99%

“…the operating window, the sealant will not sufficiently melt and full seal integrity cannot be achieved. 43,44 A certain amount of flow behavior in the sealing area is desirable during the sealing to fill all the voids and gaps and prevent the leakages and polymer molecules get more movable around their melting temperature. So, when the temperature is increased and becomes close to the melting temperature, the viscosity of the sealant layer decreases; thus, diffusion between sealing surfaces enhances.…”

Section: Factors Behind the Heat Sealing Problemsmentioning

confidence: 99%

“…So, at the interdiffusion stage, increasing the pressure will not help the entanglement and mechanical strength development in sealing. 43 In addition, a research was done by Farris et al based on response surface methodology (RSM), showing that seal strength is affected negatively by increasing the bar pressure and the positive effect of temperature will be disrupted at high-pressure levels. 50 Also, the elevated temperatures enhance this negative effect of high pressure by decreasing the polymer viscosity critically.…”

Section: Pressurementioning

confidence: 99%

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Understanding the factors affecting the seal integrity in heat sealed flexible food packages: A review

et al. 2021

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Seal area represents the most problematic part in food packaging for controlling the moisture and gas ingress and preserving product quality. Understanding the mechanism of heat sealing, which is a widely used method in flexible packaging, is critical for maintaining product quality throughout the storage and preventing food waste.Likewise, understanding the factors causing the leak formation in the seal interface helps to avoid failures and increase integrity for all seal types produced by heat sealing methods. This review looks at heat sealing and its mechanisms in flexible food packaging materials and particularly focuses on the reasons behind the encountered seal integrity problems that have a detrimental effect on food quality and shelf life.Heat sealing mechanisms, form fill seal systems and seal types were analyzed. Then, factors affecting the leak formation have been grouped as process parameters, material properties, contaminants, and further processes, which is uncharted territory in open literature. Finally, the details of these groups and their interrelationships were examined and discussed. Revealed key factors as shown in this study are expected to guide future research for understanding leak formation mechanisms in flexible food packaging.

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Section: Dwell Timementioning

confidence: 99%

Section: Factors Behind the Heat Sealing Problemsmentioning

confidence: 99%

Section: Pressurementioning

confidence: 99%

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Understanding the factors affecting the seal integrity in heat sealed flexible food packages: A review

et al. 2021

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“…For heat conductive sealing, the effect of the sealing parameters on the seal quality was the subject of several studies. 5,6,[11][12][13][14][15] In most of these studies, the effect of the sealing parameters (time, temperature, and pressure) on the seal/peel strength was evaluated, and this was done by varying one of the seal parameters at a time while keeping the others constant. Meka and Stehling considered the effect of the seal parameters not only on the seal strength of PE films but also on the seal elongation and energy.…”

Section: Introductionmentioning

confidence: 99%

“…For heat conductive sealing, the effect of the sealing parameters on the seal quality was the subject of several studies . In most of these studies, the effect of the sealing parameters (time, temperature, and pressure) on the seal/peel strength was evaluated, and this was done by varying one of the seal parameters at a time while keeping the others constant.…”

Section: Introductionmentioning

confidence: 99%

Multicriteria evaluation and optimization of the ultrasonic sealing performance based on design of experiments and response surface methodology

et al. 2019

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Proper closure is an essential packaging quality aspect and can, amongst others, be achieved with ultrasonic sealing. The ultrasonic sealing performance depends on the film type, and the seal settings, such as seal time, applied force and ultrasonic amplitude. Because these parameters are less intuitive than heat seal parameters and optimal settings are undefined for many films, this work presents an efficient approach to evaluate the effect of these settings on the ultrasonic sealing performance. An experimental design defines the experiments to perform. A response surface methodology is then used to model the relation between seal settings and sealing performance. Based on these models, the seal settings are optimized. As there are several criteria to express sealing performance, single-criteria and multicriteria optimizations are described.The approach was illustrated for a polyethylene terephthalate/linear low-density polyethylene-C4 film. The seal settings were optimized to obtain high seal strength, limited ultrasonic horn displacement, and low seal energy. The optimum settings were 0.1 seconds (seal time), 4.32 N/mm (force), and 28.75 μm (amplitude). The predicted optimum strength, horn displacement, and energy were 2.32 N/mm, 40 μm, and 11.66 J, respectively. Besides the optimum, the seal window is also of interest. A broad seal window ensures sufficient seal strength for a wide range of settings. For the polyethylene terephthalate/linear low-density polyethylene-C4 film, a strength of ≥90% of the optimum was obtained for 39% of the input combinations within the design space.The presented approach is widely applicable (other films and sealing processes) since it is flexible in the input parameters, design, and responses. KEYWORDSdesign of experiments, multicriteria seal optimization, polyolefin packaging, response surface methodology, ultrasonic sealing

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Effect of Back‐layer on seal performance of multilayer polyethylene‐based sealant films

Aghkand

Saffar

Ajji

2021

J of Applied Polymer Sci

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This work studies effects of back‐layer materials, thickness of sealant layer, and sealing condition on seal performance of multilayer polyethylene‐based films. Multilayer films with back‐layers of high‐density polyethylene (HDPE), or low‐density polyethylene (LDPE), or linear low‐density polyethylene (LLDPE) were produced with different thicknesses of the metallocene layer. It was found that increasing the thickness of the metallocene layer improved hot tack properties. In addition, films with back‐layers of LLDPE or LDPE showed higher hot tack strength compared to those with HDPE back‐layer. Increasing sealing temperature reduced significantly the hot tack strength and its dependency on metallocene layer thickness. It was found that increasing delay time after sealing, before peeling test, increased hot tack strength, but the rate of hot tack evolution and the type of peeling behavior were considerably affected by the type of back‐layer material. The effect of dwell time was also examined, and it was observed that increasing dwell time in the studied range did not affect the hot tack evolution. The mechanisms involved in the development of hot tack evolution were discussed, and it was shown that the back‐layer effects can be explained by bulk viscoelastic energy dissipation theory.

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A novel approach toward the effect of seal process parameters on final seal strength and microstructure of LLDPE

Cited by 23 publications

References 42 publications

Understanding the factors affecting the seal integrity in heat sealed flexible food packages: A review

Understanding the factors affecting the seal integrity in heat sealed flexible food packages: A review

Multicriteria evaluation and optimization of the ultrasonic sealing performance based on design of experiments and response surface methodology

Effect of Back‐layer on seal performance of multilayer polyethylene‐based sealant films

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