Strength, stiffness and abuse resistance of multilayer flexible packaging films

Morris, Barry A.

doi:10.1016/b978-0-323-85435-1.00012-0

Cited by 15 publications

(55 citation statements)

References 69 publications

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“…Some types of plastics are difficult to recycle. For example, polystyrene is hard to recycle because it is often contaminated by the food it contained . In addition, mixed plastic recycling can have negative consequences.…”

Section: Resultsmentioning

confidence: 99%

Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes

Smith

Rao

Riegerix

2022

ACS Sustainable Chem. Eng.

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As efforts are made toward establishing a circular economy that engages in activities that maintain resources at their highest values for as long as possible, an important aspect is understanding the systems which allow recycling to occur. In this article a common plastic, polyethylene terephthalate, i.e., PET or plastic #1, has been studied because it is recycled at relatively high rates in the U.S. as compared to other plastics. A material flow analysis is described for PET resin showing materials collected, reclaimed for flake, and converted into items with recycled content. Imports/exports, reclaimer residue, and disposal with mismanaged waste are all shown for U.S. flows of PET. Barriers to recycling PET exist in the collecting, sorting, reclaiming, and converting steps, and this article describes them, offers some solutions, and suggests some research that chemists and engineers could focus on to improve the systems. This effort also models sorting at material recovery facilities (MRF) and reclaimers, with detailed descriptions of the material streams involved, to characterize the resource use and emissions from these operations that are key processes in the recycling system. Example results include greenhouse gas intensities of 8.58 kg CO2 equiv per ton of MRF feed and 103.7 kg CO2 equiv per ton of reclaimer PET bale feed. The results can be used in system analyses for various scenarios and as inputs in economic input-output and life cycle assessments.

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Section: Resultsmentioning

confidence: 99%

Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes

Smith

Rao

Riegerix

2022

ACS Sustainable Chem. Eng.

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“…During heat sealing, if the given time (

t

) is in between the Rouse relaxation time of the whole chain and the reptation time (

t_{Ro} < t < t_{r}

) segments start to diffuse through the interface and seal strength, development starts. When the given time reaches above

t_{r}

, the interfacial barrier between two layers disappears 12,24 . Thus, time levels above the reptation time (

t

t_{r}

) can be associated with good sealing.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Therefore, to prevent the sealing problems such as the squeeze-out problem that occurs when the polymer viscosity drops too much, the heat seal temperature and dwell time need to be optimized by considering the melt behaviour of the polymer. 12 Also, knowing the relationship between the dwell time at a certain process temperature and the time required to supply sufficient heat transfer and molecular diffusion at the seal interface largely affects the final bond quality and helps avoiding the excessive energy and material usage.…”

Section: Introductionmentioning

confidence: 99%

Estimating minimum required dwell time for the heat sealing of talc containing polypropylene/low‐density polyethylene packaging films

et al. 2023

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Dwell time is one of the main parameters influencing heat seal quality and process efficiency in flexible packaging. In this study, the rheological behaviour of polypropylene (PP)/low-density polyethylene (PE-LD)-based compound films containing different ratios of talc was examined. The minimum dwell time required to supply a sufficient sealing was estimated based on heat conduction time and reptation time.Reptation is a rheological concept used to described the behaviour of a polymer melt, and the reptation time is the time required for a molecule to escape from its surrounded entangled structure. The results showed that increased levels of talc are associated with elevated complex viscosities, storage and loss modulus as well as an increased seal strength. The estimated minimum required dwell time at the seal initiation temperature (SIT) dropped sharply with the initial introduction of 10 wt% talc.However, increasing the talc ratio to 30 wt% did not create any major change in the estimated time value. Also, observed T-peel strength values for 0.1 and 0.5 s dwell time at SIT confirmed the predicted minimum required dwell time values. On the other hand, when the seal temperature is increased to the higher end of the operation window, time estimations did not match with the observed seal strengths. Here, the melting already starts and the molecules diffuse up to a certain distance before the interface temperature reaches the desired level. Recalculation of the average diffusion distance by including this pre-melting situation can present a better approach for the temperatures above SIT. When the molecules diffused around halfway along the sealant thickness observed, seal strengths reached a sufficient level (2.5 N/25 mm) for both SIT and the highest end of the operation window. In conclusion, it has been revealed that knowing the reptation time and the required time for the heat conduction during the sealing process can help to predict the minimum required dwell time to achieve quality sealing, especially at low sealing temperatures.Additional surface characterizations also helped to elaborate on the influence of changing insoluble filler ratio on the seal initiation properties. It has been showed that the added talc increases the surface free energy and supplies easier wetting at

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“…One of the fastest growing sectors in recent years is polymer packaging. Among all polymeric materials, flexible films are becoming increasingly popular, mainly due to their versatility, light weight, strength and printability, among other properties (Hou et al, 2018;Morris, 2016). However, as a result of this activity, one of the main residues generated from the production of flexible packaging is photopolymer plates used in the flexography step of polymeric film production.…”

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confidence: 99%

Influence of the incorporation of flexographic photopolymer plate residues on the mechanical properties of epoxy

et al. 2023

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A thermosetting epoxy polymer composed of diglycidyl ether of bisphenol A and triethylenetetramine (DGEBA/TETA) was modified by incorporating flexographic photopolymer plate residues (rubber microparticles). The photopolymer plate residues were processed in two ways: (a) by grinding and performing particle size classification (where the resulting samples were denoted PP) and (b) by polyester layer separation and grinding the elastomeric fraction by cryogenic grinding (where the resulting samples were denoted ER). Both residual particles were incorporated into the epoxy at concentrations of 2.5, 5 and 7.5 wt%. The main results indicate that PP was not efficient as a modifier of the epoxy system. A reduction in mechanical properties (maximum tensile strength and deformation) was observed in the samples produced with PP in different concentrations. But, when the ER is incorporated, an increase in tensile property and in the deformation capacity, as well as impact resistance was observed in samples produced with ER. Scanning electron microscopy analysis showed a greater presence of voids in formulations produced with PP, which corroborates the decrease in the tensile strength of these samples.

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Strength, stiffness and abuse resistance of multilayer flexible packaging films

Cited by 15 publications

References 69 publications

Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes

Recycling of Plastics in the United States: Plastic Material Flows and Polyethylene Terephthalate (PET) Recycling Processes

Estimating minimum required dwell time for the heat sealing of talc containing polypropylene/low‐density polyethylene packaging films

Influence of the incorporation of flexographic photopolymer plate residues on the mechanical properties of epoxy

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