Heat Seal Strength Research Articles

Influence of storage period on properties of biopolymer packaging materials and pouches

Bilayer biodegradable films based on pumpkin oil cake (PuOC) and zein, as well as pouches made from these materials, were prepared, and the changes of their mechanical, physicochemical and barrier properties were analyzed during four weeks of storage. Heat seal quality of formed pouches and composition of the gas atmosphere in the pouches were also monitored. The results showed that the bilayer film had a thickness of 300 ? 10 (?m), and no its changes were observed during the storage time. The tensile strength of the tested film increased slightly in the third week, but the elongation at break showed a decreasing trend during the whole storage period. The decreases in the moisture content, total soluble matter and swelling of the obtained film, were also observed. After one month of storage, the O2 transmission rate of tested films, increased from 27 to 64 (ml/m2 24h 1 bar), and the CO2 gas transmission rate from 147 to 188 (ml/m2 24h 1 bar). The heat seal strength of the PuOC/Zein pouches decreased during the whole storage period. The percentage of O2 in PuOC/Zein pouches increased up to 7 times during the storage period; however, the percentage of CO2 decreased up to 18 times already after one week, and then remained stable in the rest of the storage period. These results are, to a smaller extent, due to the gas transmission rate through the material, especially for CO2 , and to a greater extent, due to the low heat seal strength, which decreased through the storage period, and probably influenced the content of the gases in the pouches.

Influence of lithium hexafluorophosphate/ethylene carbonate/dimethyl carbonate electrolyte soaking on heat seal strength of polyamide 6/aluminum/cast-polypropylene laminates used as lithium-ion battery packaging

The heat-seal strength of polymer–metal–polymer laminates, widely used in the packaging industry and more recently for pouch lithium-ion batteries, is a critical factor for the integrity of flexible package structures during service. The influences of lithium hexafluorophosphate/ethylene carbonate/dimethyl carbonate (LiPF6/EC/DMC) electrolyte soaking time and storage temperature on heat-seal strength were investigated through T-peel testing using a universal testing machine. Sealed multilayer laminates’ heat-seal strength and their failure modes were measured for specimens sealed at various heat-sealing temperatures and dwell times before and after exposure to room temperature and 60℃ soaking conditions. The soaking condition significantly influences heat-seal strength, especially for the packages heat-sealed at low temperatures and short heat-sealing times. Higher storage temperature during electrolyte-soaking accelerates the heat-seal strength decrease. Failure modes are affected by the soaking conditions and become more complicated than the packages without soaking. The optimized heat-sealing processing window is obtained under a certain soaking condition. The electrolyte hydrogen ion concentration (pH) decreases with longer soaking time and higher storage temperature, indicating that acidification may also contribute to decreased heat-seal strength. The results are important for understanding how stored lithium-ion batteries deteriorate and can help to guide battery design to maximize their shelf life.

Scale-up of the production of soy (Glycine max L.) protein films using tape casting: Formulation of film-forming suspension and drying conditions

The processing variables used to produce biopolymer films may have great influence on the material's properties and production time. The aim of this work was to determine i) a suitable formulation (concentration and rheological properties) for tape casting processing of soy protein suspensions ii) the effects of the drying method (heat conduction, C; and infrared radiation, IR) and temperature (40, 50 and 60 °C) on the drying kinetics and physical properties of resulting films. A soy protein isolate (SPI) concentration over 10.5% w/v was required for proper tape casting processing. Conduction drying at 60 °C (C60) and IR60 showed short drying times and similar drying kinetics. However, drying by IR60 yielded films having poor mechanical properties. Raising the drying temperature increased film's tensile strength, Young's modulus, glass transition temperature (Tg), and heat seal strength. The results of this study demonstrated that it is possible to produce soy protein films at large scale by tape casting. The influence of the processing method and drying conditions on soy protein film properties are discussed.

Film Performance of Poly(lactic acid) Blends for Packaging Applications

Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. PLA based films for food packaging has been an area of both commercial and research interest within the context of sustainability. In spite of its high strength, packaging applications have been limited because PLA is more brittle than traditional oil-based plastics. Because of this, films display low tear and impact resistance and produce a loud crackling sound when manipulated. Although many studies address the toughening of PLA in the bulk, little attention has been placed on the film performance. The present study is aimed at providing a survey of binary PLA based blends with other biodegradable and non-biodegradable plastics. Acrylic impact modifier (AIM, 5 wt. %), ethylene vinyl acetate (EVA, 20 wt.%), polyhydroxyalkanoate (PHA, 10 wt.%), polycaprolactone (PCL, 30 wt.%), polybutylene succinate (PBS, 20 wt.%) and polypropylene carbonate (PPC, 30 wt.%) were each blended with PLA through single-screw extrusion and converted into films via the blown-film process. Tear and impact resistance, heat seal strength, and noise level were measured. EVA, PHA, PCL, and PBS improved the tear resistance with EVA having the highest effect (>2x). Similarly AIM, EVA and PPC improved the resistance of the film to impact-puncture penetration. Heat seal strength was significantly improved by the PHA and moderately increased by AIM (2x) and EVA. Additionally, we proposed a method to quantify the annoyance of the noise made by the films upon manipulation. PCL and PBS significantly reduced the annoyance level of the films.

Investigation on the influence of electrolyte on the heat-sealing strength of aluminum plastic composite foil

Investigation on the influence of electrolyte on the heat-sealing strength of aluminum plastic composite foil

Fabrication and characterization of soluble soybean polysaccharide and nanorod-rich ZnO bionanocomposite

In this study, a novel bionanocomposite film was prepared by the casting method. Different concentrations [i.e., 0%, 1%, 2%, and 4% (w/w)] of nanorod-rich ZnO (ZnO-nr) were incorporated into soluble soybean polysaccharide (SSPS). The mechanical, thermophysical, antimicrobial, and barrier properties of the resultant bionanocomposite films were evaluated. Incorporation of 4% ZnO-nr into the SSPS matrix reduced water vapor permeability from 8.19×10−11 to 5.25×10−11 (gm−1s−1Pa−1) and oxygen permeability from 223 to 127(cm3μmm−2day−1atm−1). The elongation at break and heat seal strength of the films increased by over 20%. The moisture content, glass transition temperature, and tensile strength of the SSPS films significantly decreased by ZnO-nr incorporation. SSPS/ZnO-nr (4%) films showed 0% UV transmittance and were able to absorb over 70% of the near-infrared spectrum. The SSPS/ZnO-nr films exhibited excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. In summary, ZnO-nr is an excellent potential filler for SSPS-based films used as packaging materials.

Influence of processing conditions on heat sealing behavior and resultant heat seal strength for peelable heat sealing of multilayered polyethylene films

Abstract The effects of processing conditions for peelable heat sealing of multilayered polyethylene (PE) films on heat sealing behavior and heat seal strength were investigated. Two sets of seal bars, knurled shape and flat shape, were used for heat sealing. After the heat sealing, the sealed portion was cooled using a set of cooling bars. Heat sealing temperature was adjusted to yield the heat seal strength of 4.0 N/15 mm, 6.0 N/15 mm and 8.0 N/15 mm at the heat sealing pressure of 0.4 MPa for each set of heat sealing bars. The heat seal strength increased with the increase of heat sealing pressure for the knurled shape bars, while it was less affected by heat sealing pressure for the flat shape bars. In situ measurements of the sealing bar clearance and interface temperature revealed that the reduction speed of clearance was significantly affected by the pressure for knurled shape bars, while it was almost independent of pressure for flat shape bars. Even though the temperatures set for the similar heat seal strength were different between knurled and flat shape bars, the maximum temperatures at the interface were almost identical. The effect of the shape of seal bars on heat seal strength became less significant after the sterilization process.

Relationship between Cooling Conditions After Heat Sealing and Variation of Heat Seal Strength After Sterilization Treatment for Peelable Heat Sealing of Multilayered Polyethylene Films

Relationship between Cooling Conditions After Heat Sealing and Variation of Heat Seal Strength After Sterilization Treatment for Peelable Heat Sealing of Multilayered Polyethylene Films

The Effects of Nano-SiO2 on Mechanical, Barrier, and Moisture Sorption Isotherm Models of Novel Soluble Soybean Polysaccharide Films

In this research, a novel polysaccharide-based bionanocomposite film was prepared via dispersion casting method. Nano-silicon dioxide (SiO2-N) was incorporated into soluble soybean polysaccharide (SSPS) at different concentrations (i.e., 0%, 1%, 3%, and 5% w/w dried SSPS). Mechanical (tensile strength, elongation at break, and Young’s modulus), physical (moisture content, water solubility, and moisture uptake), and barrier properties of bionanocomposite films were evaluated. Incorporation of 5% SiO2-N to SSPS matrix decreased water vapor permeability (WVP) from 7.96×10−11 to 4.75×10−11 g m−1 s−1 Pa−1 and oxygen permeability from 215 to 96 cm3 µm m−2 day−1 atm−1. Heat seal strength and mechanical properties of SSPS films were improved. Moisture sorption isotherm of SSPS films supported by SiO2-N was shifted to lower moisture content, and monolayer moisture content of the films decreased significantly (p<0.05). In summary, SiO2-N is a potential filler in SSPS-based films for packaging materials.

Functional, thermal, and antimicrobial properties of soluble soybean polysaccharide biocomposites reinforced by nano TiO2

This study describes a new polysaccharide-based bionanocomposite developed through solvent casting. Different concentrations (i.e., 0%, 1%, 3%, and 5% (w/w)) of nano titanium dioxide (TiO2-N) were incorporated into soluble soybean polysaccharide (SSPS), and the functional properties of the resultant SSPS films were estimated. Incorporation of TiO2-N into the SSPS matrix decreased water vapor permeability from 7.41 to 4.44×(10−11gm−1s−1Pa−1) and oxygen permeability from 202 to 98 (cm3μmm−2d−1atm−1). Moisture content also decreased, the glass transition temperature increased, and the mechanical properties and heat seal strength of the SSPS films improved. SSPS bionanocomposite films showed excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. In summary, TiO2-N shows potential use as a filler in SSPS-based films for the food and non-food industries.

Preparation and characterization of novel bionanocomposite based on soluble soybean polysaccharide and halloysite nanoclay

In this research, casting method was used to prepare novel polysaccharide-based bio-nanocomposite films with halloysite nanoclay (HNC). HNC was incorporated into soluble soybean polysaccharide (SSPS) at different concentrations (e.g., 1, 3, and 5%, w/w). Functional properties of SSPS films were evaluated following by ASTM standards. Incorporating HNC to SSPS matrix decreased water vapor permeability from 7.41×10−11 to 3.27×10−11(gm−1s−1Pa−1) and oxygen permeability from 202 to 84cm3(μmm−2day−1atm−1). By addition of HNC to SSPS films, glass transition temperature, tensile strength, and heat seal strength was increased and elongation at break was decreased. Uniform and smooth surface morphology revealed by scanning electron microscopy and shows no sign of phase separation among the film constitutes. In summary, HNC has the potential to be a filler in SSPS-based films for use in food and non-food packaging industries.

Molecular Orientation Effect of Heat-Sealed PP Film on Peel Strength and Structure

Heat sealing properties are optimized by controlling temperature, pressure and dwell time, while film strength depends on the drawn ratio and the molecular orientation of the film. However, heat seal strength of polymer films with high drawn ratio shows lower peel strength, because the adhesion of films needs a higher heat sealing energy for molecular orientation relaxation at heat sealing. In the present study, polypropylene films with a drawn ratio of 1.0×, 1.5×, and 2.5× are heat sealed by using the heat sealing technique. The heat sealing condition is set to heat sealing time 1.0 s, sealing pressure 0.2 MPa, and heat sealing temperature 145°C. The effect of drawn ratio and stabilization temperature of PP films for peel strength are investigated using T-Peel test, DSC, FT-IR, and Raman spectroscopy. As a result, it is found that the peel strength is decreased with increasing the drawn ratio and stabilization temperature of PP films. The difference of ?H and melting point from the result of DSC measurement are exhibited for 1.5× drawn ratio film as compared with 2.5× one. In addition, FT-IR imaging and Raman line mapping reveal the influence and variation of high order structure for heat sealed parts of the drawn PP films.

Preparation and characterization of bionanocomposite films based on potato starch/halloysite nanoclay

In this research casting method was used to prepare potato starch based bio-nanocomposite films with halloysite nanoclay as the reinforcing materials. The composition included potato starch with 40% (w/w) of a mixture of sorbitol/glycerol (weight ratio of 3 to 1as plasticizer) with nanoclay (0–5% w/w). The films were dried under controlled conditions. Physicochemical properties such as solubility in water, water absorption capacity (WAC), water vapour permeability (WVP), oxygen permeability, and mechanical properties of the films were measured. Results showed that by increasing the concentration of nanoclay, mechanical properties of films were improved. Tensile strength was increased from 7.33 to 9.82MPa, and elongation at break decreased from 68.0 to 44.0%. Solubility in water decreased from 35 to 23%, and heat seal strength increased from 375 to 580N/m. Also incorporation of clay nanoparticles in the structure of biopolymer decreased permeability of the gaseous molecules. In summary, addition of halloysite nanoclay, improve the barrier and mechanical properties of potato starch films and this bionanocomposites have high potential to be used for food packaging purposes.

The relationships between crystallization characteristics and heat sealing properties of high-density polyethylene films

The relationships between crystallization characteristics and heat sealing properties of high-density polyethylene (HDPE) films were determined. HDPE with a 1.1 g/10 min melt flow index (MFI) (190℃, 2.16 kg) was melt mixed in a twin-screw extruder with a 0.04 g/10 min MFI HDPE. The high molecular weight HDPE (HMW HDPE) concentration was varied between 1 and 20 wt%. The HDPE blends were cast into a 50 µm thick film. The films were heat sealed at 125℃ and 128℃. The seal bar pressure was kept constant at 0.13 MPa. The heat seal time was varied from 0.5 to 2.0 s. Heat-sealed strength was measured by T-peel test. The molecular structure development during the heat seal process was evaluated by differential scanning calorimeter and wide-angle X-ray diffraction. The HMW HDPE decreased the film heat seal strength when sealed at 125℃. However, at 128℃ the presence of up to 10 wt% reduced the heat sealing time.

탈지겨자씨와 유청단백질을 재료로 사용한 가식성 적층필름의 개발

A laminate-composite film was developed using industry co-products of defatted mustard meal (DMM) and whey protein isolate (WPI). An individually prepared DMM-based film (DMM film) and a WPI-based film (WPI film) were thermally laminated at 130℃ at a rate of 30 cm/min. Microscopic images exhibited that the DMM film and the WPI film were continuously attached in the laminate without void spaces. The tensile strength, elongation at break, and water vapor permeability for the laminate were 0.7MPa, 4.0%, and 6.9 g · mm/kPa/h/㎡, respectively. Stretchability and heat seal strength of the laminate were higher than those of the un-laminated DMM film. The film layers of the laminate were physically overlapped, not forming new biopolymer units induced by molecular interactions. The opportunity for DMM films to be used as food packaging materials for wrapping and sealing could be increased by thermal lamination with WPI films, which improves the stretchability and heat sealability of DMM films.

Experimental and statistical analysis of the effects of the processing parameters on the seal strength of heat sealed, biaxially oriented polypropylene film for flexible food packaging applications

Seal strength is an important quality parameter for packaged products such as biaxially oriented polypropylene films. The seal quality can be insured and maintained under optimum heat sealing process parameters. This article shows that heat seal strength can be optimized through simultaneous study of dwell time, pressure, and temperature. The heat seal strength optimization trial for 18 µm thick untreated, both sides sealable biaxially oriented polypropylene film utilized response surface methods with a replicated central composite statistical experimental design. This gives a second-order model for heat seal strength. This experiment showed that dwell time, temperature, and their interaction have significant effects and that high seal strength is attained at a dwell time of 0.9 s and temperature 120°C.

Comparative Effects of Microwave and Water Bath on the Packing Films of Milk

Milk is heated by microwave or conventional water bath in our daily lives. To investigate the influence of heating modes on food package safety, the present work is designed to compare the changes to packaging materials of milk subjected to microwave treatment and water bath. The mechanical properties of milk package materials were compared, and the migration of harmful substances from the films was analyzed. The results showed that the microwave and water-bath treatments could both influence the mechanical properties of the film. For the heat-sealing strength, the susceptibility of the package materials from different manufacturers was varied. For the tensile strength, the changes were obvious after treatment. Both treatments could induce migration, but the amounts of migrating materials were within the limit permitted by the national standard.

Effects of Liquid Contaminants on Heat Seal Strength of low‐density polyethylene Film

Heat sealing is commonly applied for making form‐fill‐seal packages fabricated from thermoplastic films. One of the challenges frequently faced by the industry is inadvertent contamination of film–film interface by the product during filling, which can compromise package seal strength. In this study, the effects of dwell time (0.5–1.5 s), jaw pressure (28–1860 kPa), jaw configuration (narrow versus wide contact area) and jaw temperature (150°C–180°C) on the interface temperature and seal strength of a linear low‐density polyethylene (LLDPE) film were investigated. Three different film–film interface conditions were studied: (1) no contaminant; (2) with water contaminant; and (3) with vegetable oil contaminant. In the presence of liquid contaminant, jaw pressure played an important role in displacing the liquid from the seal area to form intact seals. Short dwell time (0.3 s) and low jaw temperature (150°C) was not favourable for forming intact seals in both water‐contaminated and vegetable oil‐contaminated films. The optimum jaw temperature and dwell time required to produce intact seals for oil contaminated films was 180°C and 0.3 s, respectively, whereas a combination of 165°C jaw temperature and 1 s dwell time was required to form intact seals for water‐contaminated films. Within the experimental conditions investigated, interface temperatures of 130°C–140°C resulted in the most optimum seal strength for both water‐contaminated and clean film specimens. Above 140°C, a weakening of seal strength was observed, presumably because of the change in melt flow characteristics and possible initiation of thermal degradation of the polymer. Copyright © 2011 John Wiley & Sons, Ltd.

고분자 분쇄 공정을 이용한 대추 소재 가식성 필름 개발

Edible films were developed from jujube (Zizyphus jujube Miller) using depolymerization processes of ultrasound and high-pressure homogenization. A 4.6% (w/w) jujube hydrocolloid was treated by ultrasound (600W, 20 min) or homogenized at high pressure (172 MPa, 6 s) and mixed with whey protein isolate, glycerol, xanthan, and sucrose esters of fatty acids to form film-forming solutions from which films were formed by drying. The film prepared by highpressure homogenization (HPH film) produced more homogeneous films without particles than those prepared without depolymerization or with the ultrasound treatment. HPH films possessed the highest tensile strength (4.7MPa), the lowest water vapor permeability (), and the most uniform and dense microstructures among the films. Flavor profiles of jujube powder and the films were distinguishable. Heat seal strength and oxygen permeability of the HPH films were 44.4 N/m and /day/Pa, respectively. Antioxidant activities of jujube power and HPH films were not significantly different.

Effect of dispersion of nanofibers on the properties of LDPE FILMS

Nanofiber reinforced composites based on dispersion of electrospun PET nanofibers and LDPE were prepared by melt extrusion. The nanofibers were dispersed in 0.1, 0.5 and 1 wt%. Test specimens were prepared in a blown film extruder. Samples of each stage of nano fibers reinforced composites’ processing were characterized by means of scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), gas permeability, mechanical testing, dart impact strength and heat seal strength. It was observed that the nanofiber dispersed films show exceptionally good resistance to gas permeability along with an improvement in mechanical, dart impact and sealing properties.