ISSN:0894-3214    

DOI:10.1002/pts.2770010102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770010103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe theoretical basis for the widely accepted Damage Boundary Curve approach to product fragility and the applicability of its associated ASTM fragility assessment test procedure are first discussed. The basic assumption that the product can be modelled as a collection of linear spring/mass systems is shown to lead to specific characteristics of the product's damage boundary curve which are not borne out by the results of shock tests performed on some common consumer products. Discrepancies between theoretical predictions and experimental results are attributed to the inability of the model to account for progressive failure due to plastic deformation accumulated as a result of repeated shocks. An alternative damage boundary curve for a rigid/perfectly‐plastic model is then developed and shown to be a better estimate of fragility for a broader class of products based on the results of shock tests. Modifications to the standard ASTM test procedure required to obtain the damage boundary curve for this type of product are suggested. Finally, the damage boundary theory for a generalized model which incorporates both elastic and plastic properties is developed. The feature of the damage boundary curve which are shown to survive regardless of the choice of model for the product are the critical velocity change and critical acceleration parameters. Those which do not are the shape of the damage region and the associated test procedure

ISSN:0894-3214    

DOI:10.1002/pts.2770010104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this work, the theory and measurement of migration is discussed in terms of the assessment of the ‘change’ of migration as a function of time. Instead of residue measurement, migration can also be evaluated very quickly and with high accuracy by spectrophotometric means. From these data the maximum possible global migrationMxcan be found, which allows one to predict quality behaviour of plastics. Also other effects such as weathering and influences from transport‐conditions can be evaluated. It is clear that the proposed testing procedure does not interfere with the conventional weight‐procedure. Indeed, the simulant can be removed for residue measurements at any time. The importance of the proposed methodology is the time response wherein assessment can be performed and knowledge of the migrational behaviour of the plastics can b

ISSN:0894-3214    

DOI:10.1002/pts.2770010105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPita bread has a shelf‐life of only a few hours, mainly due to its large surface to volume ratio. Hardening, caused by staling and drying, is the main factor affecting shelf‐life. Extension of shelf‐life by packaging pita in a high barrier laminate under modified atmosphere (MAP) of 99% CO2or 73% CO2with 27% N2was studied. A shelf‐life of 14 days, as determined by microbial spoilage, was obtained for MAP pita bread. Staling, as determined by means of a penetrometer, was delayed in MAP pita. Organoleptic hedonic comparisons of MAP pita, against frozen defrosted pita from the same batch, gave almost identical results. Shelf‐life was terminated by the appearance of microorganisms

ISSN:0894-3214    

DOI:10.1002/pts.2770010106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe crack propagation that occurs in corrugated board in connection with die cutting is analysed in order to identify the most crucial liner and fluting parameters and clarify their relative importance.Based on an energy approach and the brittleness concept —Lc‐1(m‐1) —for the liner, a formula is derived. This formula is then verified exeprimentally for a large number of corrugated board qualities of different thicknesses and flat crush strengths as well as for liners with widely differing mechanical properties. The correlation can be regarded as very good.The analysis shows that crack propagation is dependent on three material parameters —the brittleness of the liner, the compression strength of the fluting in relation to the tensile strength of the liner and the breaking strain of the liner. It is shown that crack propagation increases proportionally with increasing liner brittleness, provided that the other material parameters remain unchanged. The compression strength of the fluting layer contributes somewhat more than proportionally — by a power of 1.33. The crack propagation decreases with increased breaking strain, the relation is almost inversely proportional.In practice, none of the above mentioned liner parameters car. be chosen independently of the others. The same applies to the fluting parameters. When estimating the expected crack propagation in a particular corrugated board quality, it is necessary to consider the contribution from all the mentioned parameters according to

ISSN:0894-3214    

DOI:10.1002/pts.2770010107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe tightness of retail packagings and of their closures is of primary importance both for domestic and industrial products. For this reason, a research programme designed to establish proper testing methods for a wide range of ‘packaging + product’ combinations, in order to check their tightness or permeability, was set up.All the available testing methods were reviewed, the most reliable ones selected and their sensitivity determined. More than 200 combinations of ‘packaging + product’ belonging to five families of consumer products were examined and their tightness/permeability problems noted.Finally, specific testing methods were assigned to each combination of ‘packaging + product’. All these examples are currently in use in the packaging laboratory as a guideline for the testing of every kind o

ISSN:0894-3214    

DOI:10.1002/pts.2770010108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770010109

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770010110

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0894-3214    

DOI:10.1002/pts.2770010111

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY