The role of the fiber and the bond in the hygroexpansion and curl of thin freely dried paper sheets

Brandberg, August; Motamedian, Hamid Reza; Kulachenko, Artem; Hirn, Ulrich

doi:10.1016/j.ijsolstr.2020.02.033

Cited by 20 publications

(21 citation statements)

References 20 publications

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“…Fiber‐fiber entanglements were formed prior to the drying of the boards. When water evaporated during drying, the fibers shrunk and caused residual stresses, thus appearing as macroscopic curling and shrinkage in the dry composite 49 . All treated AP boards had significantly lower areas than APC, probably due to increased fibrillation in treated AP fibers.…”

Section: Resultsmentioning

confidence: 99%

“…When water evaporated during drying, the fibers shrunk and caused residual stresses, thus appearing as macroscopic curling and shrinkage in the dry composite. 49 All treated AP boards had significantly lower areas than APC, probably due to increased fibrillation in treated AP fibers. These highly fibrillated fibers bonded with water prior to drying.…”

Section: Wr Values Of Treated Ap Fibersmentioning

confidence: 94%

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Investigation of eco‐friendly chemical treatments of apple pomace for producing high quality molded pulp biocomposite

Lang

Wang

Zhao

2021

J of Applied Polymer Sci

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Eco-friendly chemical treatments using citric acid (CA) and sodium bicarbonate were employed to remove pectin, hemicellulose, and extractives from apple pomace (AP) for improving AP fiber quality and maximizing its utilization in producing biocomposite boards with newspaper (NP) fibers (AP:NP ratio of 2:1) using molded pulp technique. CA treatment was further optimized at different pH and temperature and cellulose nanofiber (CNF, 0.15, 0.3% w/w pulp solids) was used as reinforcement agent to enhance mechanical property and water resistance of biocomposite boards. CA treatment improved AP fiber strength and cellulose content. AP treated by CA at pH 2.5 and 75 C with 0.15% CNF reinforcement produced AP/NP biocomposite board with high flexural strength, and dimension stability, and low density. Thermal analysis verified increased cellulose content, crystallinity, and thermal stability of CA treated AP fibers. This study provided new insight to improve fiber functionality and utilize AP for developing sustainable packaging.

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Section: Resultsmentioning

confidence: 99%

Section: Wr Values Of Treated Ap Fibersmentioning

confidence: 94%

Investigation of eco‐friendly chemical treatments of apple pomace for producing high quality molded pulp biocomposite

Lang

Wang

Zhao

2021

J of Applied Polymer Sci

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“…During the real tray forming operation the temperature of the die is in the range of 140–180°C, and the punch 30–55°C. Paperboard is affected by temperature and highly affected by moister change 9,33 . In this case, the operation takes about 1 s, and the temperature and moisture change of the paperboard blank during this time is not fully known.…”

Section: Methodsmentioning

confidence: 99%

Tray forming operation of paperboard: A case study using implicit finite element analysis

Lindberg

Kulachenko

2021

Packag Technol Sci

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The possibility to perform advanced forming operations of initially plane paperboard paves the way to making products like food trays, plates, cups and other containers as a part of shifting towards a circular bioeconomy. As a part of the ongoing efforts of expanding the product range using paperboard, we performed analyses of the forming operation using simulations. An implicit non‐linear finite element model is built to more accurately than previous studies simulate the tray forming process of paperboard. Two different commercial paperboards are investigated. The use of an implicit solver enabled the inclusion of the creasing pattern into the geometry of the paperboard blank resolving the formation of wrinkles during forming. The material data is extracted from tensile test curves of the investigated paperboards and was fitted accurately using Hill's plasticity with difference in tension and compression accounted for with subsequent failure evaluation. The results showed that the inclusion of the creases in the geometry is vital for getting a correct shape of the formed tray and important for decreasing the risk of failure. The results also showed that friction has a big impact on the formed shape and hence on the stress levels, and therefore supports the means of lowering friction between the blank holder and the blank during the tray forming operation. A stochastic approach is proposed to determine the probability of failure for the boards. The performed failure evaluation is consistent with the field observations. The developed approach enables more precise simulations of paperboard tray forming.

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“…Various advanced models have been proposed in the literature to predict the sheet hygro-expansion from fiber characteristics, e.g. 2D fiber bond and homogenized network models (Bosco et al, 2015a(Bosco et al, ,b, 2017a, XFEM fiber models (Samantray et al, 2020), and 3D discrete network models (Motamedian and Kulachenko, 2019;Brandberg et al, 2020). However, quasi-3D characterization of orthogonal inter-fiber bonds in (Vonk et al, 2023b) will show that a simple analytical bi-layer laminate model suffices to accurately predict the bending deformation of the bonded area, due to the hygro-expansion differences of the two fibers.…”

Section: Introductionmentioning

confidence: 99%

Transient hygro- and hydro-expansion of freely and restrained dried paper: the fiber-network coupling

Vonk¹,

Spreuwel²,

Anijs³

et al. 2023

Preprint

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The transient dimensional changes during hygro-expansion and hydro-expansion of freely and restrained dried, softwood and hardwood sheets and fibers is monitored, to unravel the governing micro-mechanisms occurring during gradual water saturation. The response of individual fibers is measured using a fullfield global digital height correlation method, which has been extended to monitor the transient hydroexpansion of fibers from dry to fully saturated. The hygro-and hydro-expansion is larger for freely versus restrained dried and softwood versus hardwood handsheets. The transient sheet-scale hydro-expansion reveals a sudden strain and moisture content step. It is postulated that the driving mechanism is the moisture-induced softening of the so-called "dislocated regions" in the fiber's cellulose micro-fibrils, unlocking further fiber swelling. The strain step is negligible for restrained dried handsheets, which is attributed to the "dislocated cellulose regions" being locked in their stretched configuration during restrained drying, which is supported by the single fiber hydro-expansion measurements. Finally, an inter-fiber bond model is exploited and adapted to predict the sheet-scale hygro-expansion from the fiber level characteristics. The model correctly predicts the qualitative differences between freely versus restrained dried and softwood versus hardwood handsheets, yet, its simplified geometry does not allow for more quantitative predictions of the sheet-scale hydro-expansion.

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The role of the fiber and the bond in the hygroexpansion and curl of thin freely dried paper sheets

Cited by 20 publications

References 20 publications

Investigation of eco‐friendly chemical treatments of apple pomace for producing high quality molded pulp biocomposite

Investigation of eco‐friendly chemical treatments of apple pomace for producing high quality molded pulp biocomposite

Tray forming operation of paperboard: A case study using implicit finite element analysis

Transient hygro- and hydro-expansion of freely and restrained dried paper: the fiber-network coupling

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