Greaseproof Paper Research Articles

Influence of Polymer Charge, Temperature, and Surfactants on Surface Sizing of Liner and Greaseproof Paper With Hydrophobically Modified Starch

The aim of this study was to investigate the properties of hydrophobically modified (HM) quaterna-ry ammonium starch ethers for paper sizing. These starches possess temperature-responsive properties; that is, gelation or phase separation occurs at a certain temperature upon cooling. This insolubility of the HM starches in water at room temperature improved their performance as sizing agents. The contact angles for water on sized liner were substantially larger than on unsized liner. When the application temperature was well above the critical phase-separation temperature, larger contact angles were obtained for liner independently of pH compared with those at the lower application temperature. Cobb60 values for liner decreased upon surface sizing, with a low pH and high application temperature giving lower water penetration. Contact angles on greaseproof paper decreased upon sur-face sizing as compared to unsized greaseproof paper, independently of pH and temperature. Greaseproof paper showed no great difference between unsized substrates and substrates sized with HM starch at different pH. This is probably due to the already hydrophobic nature of greaseproof paper. However, the Cobb60 values increased at low pH and low application temperature. Surfactants were added to investigate how they affect the sized surface. Addition of surfactant reduces the contact angles, in spite of indications of complex formation.

Oxygen permeability of polyethylene-extrusion-coated greaseproof paper

Polyethylene-extrusion-coated greaseproof paper exhibited significantly lower oxygen permeability than predicted from the oxygen permeability of polyethylene and greaseproof paper itself. Two mecha ...

Influence of paper structure on barrier properties of starch-coated greaseproof paper

Greaseproof paper has a dense structure and therefore provides a natural barrier against materials like fat and oils. The barrier is obtained by extensive refining of the pulp. This refining is however a costly operation, not only in terms of direct costs for the refining but also in terms of indirect costs because the energy consumption for the drying of the paper is affected by the refining. A full-scale trial was performed to investigate the role of the pulp with respect to the energy demand and the barrier properties of the final papers. Paper made of 100% sulphite pulp with a low degree of refining exhibited the lowest energy consumption at a given level of air permeance. In addition, the effect of refining on the air permeance was compared with that of calendering. The calendering affected the air permeance less than the refining. The papers produced in the full-scale trial were later used as substrates for coatings and for detailed studies of the paper structure. Coating with chitosan was examined on a bench-scale and on a pilot scale. The studies showed that greaseproof paper can be upgraded with an oxygen barrier, but also that suitable coating techniques are lacking for the application of the coating in a sufficient amount. The influence of the base paper on the barrier properties of chitosan-coated paper was investigated in another study, in which it was found that greaseproof paper possesses a unique coating hold-out which cannot be met by other types of paper with a more open structure. It was also found that the coated paper had a lower oxygen permeability than the chitosan coating itself, and this indicates that the dense surface layer of greaseproof paper contributed to the oxygen permeability of the coated paper. The pore volume fraction of the greaseproof paper was found to be approximately 40% and it is therefore surprising that its air permeance is so low. To bring understanding to this question, the structure of greaseproof paper was studied using several methods. It was found that the structure was dominated by very small pores with a median diameter of <0.3 µm. The fraction of closed pores was also substantial. A porosity gradient was also found, indicating that the papers used in the study had a closed surface. The hypothesis that the surface layer of the paper contributed to the oxygen barrier was tested in an experiment in which greaseproof paper was extrusion-coated with polyethylene. The oxygen permeability was measured at 0%, 50% and 90% relative humidity, and the permeability was found to increase with increasing moisture content. Because only the cellulose layer in the paper and not the polyethylene layer in the coating is affected by moisture, this result supports the hypothesis that the surface layer of the paper contributed to the oxygen barrier properties of the coated paper.

Neutron activation analysis of recycled paper and board in contact with food

Recycling of wastepaper has been shown to increase the concentration of metals in the product. Although it is generally assumed that there is no risk of migration of chemical contaminants from recycled paper and board into food, the UK Food Standards Agency has identified limited evidence of such migration. Therefore, it is important to carry out research to establish the concentration of metals in recycled paper and board in contact with food. A previous study at Imperial College had resulted in the development of a neutron activation analysis method to determine trace metals in plastic packaging. This paper describes an initial study to establish whether the same methodology could be applied to paper and board and to carry out a preliminary investigation into a small range of recycled paper and board products. The study was made on 22 elements in 17 products including pizza boxes, fries boxes, kitchen towel, table napkins, greaseproof paper, tea bags and cake cases. This work has shown elevated levels of some elements including barium (69 mg/kg in pizza bases) and chromium (5 mg/kg in napkins, 50 mg/kg in greaseproof paper, 2 mg/kg in cake cases, 90 mg/kg in baking parchment, 5 mg/kg in fries boxes and 5 mg/kg in pizza bases).

Effectiveness of SC2053 as a chemical hybridizing agent for winter wheat

The use of chemical hybridizing agents (CHA) allows production of hybrid wheat seeds. We evaluated the effectiveness of a new CHA (SC2053) to induce male sterility on winter wheat in controlled growth conditions. CHA effectiveness was measured with the application of 4 doses (0–400–700–1000 g.ha−1) at 7 stages. These stages were defined by the length of the main stem spike (1–4–7–11–15–20–40 mm). At heading, individual ears were isolated with a greaseproof paper bag. The seeds formed were counted on treated and control ears. The spikes' sterility was calculated three weeks after flowering. The sterility of the main stem's spike reached 95% to 100% for application of 700 g.ha−1 and 1000 g.ha−1 for main stem spike length of 7 mm to 20 mm. The effects of ear tillering (5 tillers per plant) on CHA effectiveness were also investigated. We observed a significant delay of ear development between the main stem and tillers so that complete sterilities were not reached for each dose. Since tillering in field conditions rarely exceeds 3 ears per plant, CHA effectiveness was studied on plants bearing 3 ears. The mean sterility of the first 3 ears was close to 100% for applications with 700 g.ha−1 and 1000 g.ha−1 at stages from 11 mm to 20 mm of main stem spike length.

Water hyacinth — A potential source of raw material for greaseproof paper

The potential use of water hyacinth as a pulp material for producing greaseproof paper was investigated. The proximate chemical analyses of the raw materials, the morphology of the water hyacinth stalk and fibre, pulp characteristics, and data on the physical properties of the paper hand-sheets formed from water hyacinth and bamboo pulps and their blends are presented. A comparative study of the pulp freeness (°SR) and drainage properties of water hyacinth and bamboo pulps showed that with a high freeness value of the pulps the drainage time increased. Blending of water hyacinth and bamboo pulps increased the physical strength. Paper hand-sheets made with a blend of water hyacinth pulp (75°SR) and bamboo pulp (80°SR), at 75:25 proportion, gave a tear index of 4·90 mN m 2 g −1, tensile index of 51·10 N mg −1 and burst index of 7·25 kPa m 2 g −1. These were higher than the values obtained from sheets made with pulp blends (water hyacinth:bamboo) of 80:20 or 90:10. The pulp sheets at a blend proportion of 75:25 also gave satisfactory greaseproof properties.

Reduction and oxidation of cellulose surfaces by means of cold plasma

Hydrogen and oxygen plasma treatment of two cellulose materials, a filter paper of pure cellulose and a greaseproof paper with a fairly high surface content of wood resin, has been studied with ESC ...

Adhesion between plasma‐treated cellulosic materials and polyethylene

AbstractFilter paper and greaseproof paper have been exposed to hydrogen or oxygen plasma. The paper surface composition was determined by ESCA measurements. The unmodified and modified papers then were laminated with polyethylene and the adhesive strength was measured. The hydrogen plasma treatment reduces the cellulose surface and forms low‐molecular‐weight degradation products. It is shown that the reduction of the cellulose surface has no influence on the adhesion, but the degradation products strongly decrease the adhesion. Oxygen plasma treatment increases adhesion, probably by removing low‐molecular‐weight wood resin from the surface and by forming covalent bonds across the interface.

Postharvest Decay Control of Grapes by Using Sodium Metabisulfite in Cartons Enclosed in Plastic Bags

Grapes of the <i>Vitis vinifera</i> L. varieties Verigo and Mavro were kept at 1° to 2°C for three months, when 4 g of sodium metabisulfite (Na₂S₂O₅) were spread between sheets of greaseproof paper at the bottom of 40 x 30 x 10 cm cartons which were enclosed in plastic bags. Decay was reduced considerably, the berries were turgid, the stems remained green, bleaching of the berries by SO₂ was insignificant, and the appearance and taste of the grapes were rated as excellent.

Evaluation of Permethrin as an Insect-Resistant Treatment on Paper Bags and of Tricalcium Phosphate as a Suppressant of Stored-Product Insects1

Long-term warehouse tests in Egypt and simulated warehouse tests in the United States were conducted to determine the insect resistance of permethrin-treated, pyrethrins-treated, and untreated, multiwall paper bags. The bags contained a high-protein, blended cereal (ICSM) fortified with either tricalcium phosphate (TCP), an insect suppressant, or a combination of calcium phosphate and calcium carbonate (Ca). During 12 months of storage in Egypt, fewer permethrin-treated bags were infested (10.2–16.0%) than pyrethrins-treated bags (22.4–41.7%) or untreated bags (41.4–48.7%). Similar results were obtained in simulated warehouse tests. TCP was less effective than the treated bags and decreased the quantity of ICSM containing excessive populations (> 1,000 insects per bag) by ca. 7.72% compared with ICSM with Ca. A grease-proof paper barrier prevented movement of permethrin into the ICSM in bags stored for 28 months. During 1 year of storage, permethrin at up to 0.72 ppm was found in the ICSM in bags without a barrier ply. During 1 year of storage, there was little loss of permethrin from the outer treated ply of empty bags with or without a grease-proof barrier ply.

Semiquantitative interference study of fatty layer of precorneal film.

Reflecting colours from the fatty layer of the precorneal film have been studied using mat filter (grease-proof paper, parchment paper, tracing paper) in front of the slit lamp mirror, maximally open light slit in a half-lit room, and magnification x 15. The palpebral fissure was narrowed until occurrence of red interference colour (2000 A). In 206 normal eyes the fatty layer was 102 +/- 3nm (+/- SEM), or about 0.1 micron, independent of age, sex and BUT (break up time). Maximum on awakening. Coefficient of variation 12.7 per cent. An increased fatty layer was noticed in cases of blepharitis (129 +/- 8 nm), in 91 per cent wearing hard contact lenses and 73 per cent wearing soft contact lenses. The fatty layer was likewise seen to be augmented in patients with acute infectious conjunctivitis (193 +/- 3 nm), chronic infectious conjunctivitis (164 +/- 7 nm), and in all states complicated by bacterial infection. The fatty layer is normal in allergic and chronic simple conjunctivitis. Silicone oil was found to effect reduction of the fatty layer.

PACKAGING: V. THE GREASE RESISTANCE OF SOME COMMON PACKAGING MATERIALS

The grease resistance of a wide variety of packaging materials was tested before and after creasing and ageing, using a modification of TAPPI method T454 m-44. Kraft and sulphite were of little or no value as grease barriers even after paraffin wax coating or impregnating. Vegetable parchment and 'greaseproof' paper were superior to kraft. The grease resistance of glassine was 5 to 10 times greater than that of either greaseproof paper or vegetable parchment. Polyethylene, in turn, was considerably more resistant than glassine, and just slightly less resistant than all grades of "Cellophane", and cellulose acetate, cellulose nitrate, ethyl cellulose, Pliofilm, vinylite, and Saran.Creasing glassine caused large reductions in its grease resistance, especially when heavy basis weights were tested. Paraffin wax coatings seemed to be more effective in improving grease resistance when dense base stocks were used. On kraft, a heavy wax coating was necessary to produce a small improvement, while on glassine only a very light coating was required, to bring about considerable improvement in grease resistance. Ageing many materials at 140° F. markedly reduced their grease resistance. An exception to this was glassine, most samples of which had greater resistance to grease penetration after ageing. Neither ageing nor creasing appreciably affected the grease resistance of Cellophane, or the thermoplastic films tested.

A film technique for the biological evaluation of pyrethrum‐in‐oil insecticides for use against stored product insects in warehouses

There is need for a technique whereby a given insecticidal preparation can be compared with a standard containing 0.8% (w/v) pyrethrin 1 in a heavy white oil and pronounced biologically equal or inferior to the standard within known and reasonable limits. A film method was investigated, Tribolium castaneum beetles being used as the test insects.Numerous factors which may influence the kill achieved are discussed. The results of preliminary work, planned to help in the standardization of some of these factors, are summarized.Several materials were tested to ascertain their suitability for reception of the insecticidal film and, as thin greaseproof paper showed promise, its possibilities were explored. Although 0.3 % pyrethrin I could be distinguished from 0.4%, 0.5% could not be distinguished from 0.8%, and the results throughout were very heterogeneous.Woven Nylon proved more satisfactory, since the test just failed to establish a significant difference between 0.6 and 0.8% pyrethrin 1. The origin of a pink coloration of the substrate, when T. castaneum beetles were confined on Nylon sprayed with pyrethrum in oil, was investigated.Whatman filter paper no. 544 proved the best substrate, and a comparative test on it will distinguish 0.65% pyrethrin 1 from the standard 0.8%; the limit could probably be raised to 0.7%.The influence of several factors on the homogeneity of the results was investigated, and the importance was shown of allowing beetles time to recover from the mechanical shock inherent in the method of counting into batches.Directions are given for carrying out the film technique for comparing preparations of relatively high pyrethrin content. The method does not measure the direct spray or fumigant action of the insecticide.The technique described is compared with the Peet‐Grady method for evaluating liquid household insecticides of low pyrethrin content. A simplified, but less accurate, design for the test is indicated.