Sealing strength

Sample pouches were then opened and both the food product and the film were examined at appropriate time intervals. The food product was examined for changes in texture, color, odor, and taste. The packaging material was checked for color changes, delamination, seal strength, etching of foil (if present), and any other changes noted. 

PB film is usually made by the blown film process, but also can be cast oil drill lolls. Film applications include food and meat packaging, compression wraps, and hot-fill containers. The material can be formulated to provide a wide range of seal strengths for peelable or easy-opening packaging. 

Copolymers of PE with vinylacetate, acrylic acid ester and methacrylic acid increase the heat sealability, adhesion to other materials and seal strength and they improve the polymer s cold resistance and transparency. EVA in the form of shrink films are well suited for meat packaging because of their relatively high gas permeabilities. 

PP possesses good water vapor barrier and fat resistance properties. Normal PP films have limited food packaging applications (e.g. packaging of bread) because of their low cold temperature resistance. Copolymer mixtures with ethylene are used to improve cold resistance and heat sealability as well as material strength and, above all, seal strength. 

Preliminary tests of using this system as a seal between copper and polyimide showed that a seal strength up to 4.2 N cm could be obtained with systems containing 70 mol% phenyl silane, 27.5 mol% methyl vinyl silane and 2.5 mol% EOS. Fracture investigations show that a cohesion rupture is also dominating in this case, confirming the above mentioned result that the brittleness of the seal is too high. 

Two critical outputs have been identified. The first is seal strength and the second is visible discoloration of the seal called Seal Bum. A measurement method has been developed for measuring seal strength. It involves cutting a 1-inch wide strip of the seal and measuring the force required to pull... 

This provides the details needed to complete the design of the screening experiment. It was decided to run a screening experiment with the 22 trials shown in Table 1. For each of the 22 trials, the process is set to the specified conditions, and time is allowed for the machine to reach the set conditions and then a series of units are produced. For each trial, five units were randomly selected and tested for seal strength and 50 units were inspected for burns. The resulting data is summarized in Table 1. For each trial, the average and standard deviation of the five units is shown along with the number of units with burns. 

Abbreviations. QA, cooling air pressure CB, cold bar temperature DT, dwell time HB, hot bar temperature MT, material temperature P, pressure RT, room temperature SD, standard deviation SS, seal strength TH, material thickness. 

The result of the analysis of the seal strength averages is shown in Table 2. A term is considered significant if its p-value is 0.05 or below. Those terms that are significant are shown in italic. The p-value represents the probability the observed effect for the term could result from the noise in the data alone. For each significant effect, it can be stated with 95% confidence that the term s effect is not zero. All the terms of a quadratic polynomial are shown in the effects table, including ... 

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