Packaging‐related properties of protein‐ and chitosan‐coated paper
ABSTRACT The mechanical and gas-barrier properties of paper and paperboard coated with chitosan–acetic acid salt (chitosan), whey protein isolate, whey protein concentrate and wheat gluten protein were studied. Paper sheets were solution-coated using a hand applicator. In addition, bi-layer composites of wheat gluten and paper or paperboard were produced by compression moulding, and the chitosan solution was also applied on paperboard using curtain coating. Young's modulus, fracture stress, fracture strain, tearing strength, air permeance and oxygen permeability were assessed. The mechanical and air permeance measurements of solution-coated paper showed that chitosan was the most effective coating on a coat weight basis. This was due to its high viscosity, which limited the degree of penetration into the paper. The proteins, however, also enhanced the strength and toughness of the paper. Compression-moulded wheat gluten/paper or paperboard, as well as curtain-coated chitosan paperboard laminates, showed oxygen barrier properties comparable to those of paper and paperboard coated with commercial barrier materials. None of the composites could be delaminated without fibre rupture, indicating good adhesion between the coatings and the substrates. Copyright © 2005 John Wiley & Sons, Ltd.
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ABSTRACT: The experimental results on the development of thin (∼ 1.5 μm) gelatin-based coatings and the investigation on their sealing attribute when applied onto oriented polypropylene (OPP) are reported. The sealing performance, expressed as the strain energy required to separate the sealed joints, was studied as a function of three different influencing factors. pH of the hydrogel solution was varied between 5 and 11. The highest seal strength values were obtained for pH values beyond the isoelectric point (IEP) of the gelatin molecule. The effect of the plasticizer (glycerol) was studied by changing its concentration from 2.5 wt % to 7.5 wt % to the total weight of the hydrogel solution. Glycerol concentration = 7.5 wt % was found to be the best for achieving adequate strain energy values. The influence of a hydrophobic component on the capability of the coating to act as a sealant has also been assessed. The hydrophobic component had a positive effect only up to a certain level (1 wt %, weight percent), whereas beyond this value, it affected the seal strength attribute. According to the best setting conditions, seal strength values for the OPP biocoated films of ∼ 61 N × mm were attained, with a corresponding maximum force required to break the joints of 2.4 N. These results are discussed by taking into consideration the modality of seals opening. Interestingly, the heat-seal (temperature: 90°C; dwell time: 1 s; pressure: 4 bar) failed in both peeling and tearing mode failure, as confirmed by microscopy, spectrophotometric, and particle size analyzes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010Journal of Applied Polymer Science 06/2010; 118(5):2969 - 2975. · 1.40 Impact Factor
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ABSTRACT: To improve the availability of vessel grafts for allotransplantation, the current experimental study was designed to first investigate the function of vessels obtained from non-heartbeating donor rats at various time points postmortem; second, to assess the sensitivity of vessels recovered after circulatory arrest toward prolonged cold storage; and third, to determine vessel function following cold storage with antimicrobial additives. We investigated vessel tone development and endothelium-dependent and endothelium-independent relaxations in a Mulvany myograph of aorta and saphenous artery sampled up to 24 hours after circulatory arrest. Additionally, tissue reductive capacity and lactate dehydrogenase release were measured. Vessels recovered 2 hours postmortem showed similar results as controls recovered without delay. Vessels recovered 6 hours or more after circulatory arrest showed reduced vessel tone development (ie, aorta): response to potassium <15% and response to norepinephrine <25% of vessels recovered without delay; A. saphena response to potassium: <12% and response to norepinephrine <10% of control vessels recovered without delay. All vessels recovered after circulatory arrest showed a similar cold storage sensitivity as controls, with exception of a decreased endothelial function of A. saphena harvested 6 hours postmortem (one-third response of non-stored control vessels). Treatment of vessels recovered immediately or after circulatory arrest with gentamycin, piperacillin, and metronidazole as additives to the optimized cold storage solution did not alter vessel function. Flucloxacillin as a cold storage additive reduced vessel tone development in aorta but not in A. saphena. Addition of amphotericin B to the storage solution completely abolished any vessel function and impaired tissue reductive capacity despite presence of radical scavengers. The use of vessels from non-heartbeating donors in general and subsequent prolonged cold storage seems feasible when vessels are recovered within 2 hours. The use of antibiotics needs to be carefully assessed for each intended-to-use tissue. For vessels tested, a combination of gentamycin, piperacillin, and metronidazole supported the maintenance of vessel function.Journal of vascular surgery: official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter 09/2011; 54(6):1769-77. · 3.52 Impact Factor
- Macromolecular Materials and Engineering 08/2010; 295(9):796-801. · 2.34 Impact Factor