In-Plane Compression and Biopolymer Permeation Enable Super-stretchable Fiber Webs for Thermoforming toward 3-D Structures

Abstract

The typically poor ductility of cellulosic fibers and ensuing bonded networks and paper webs set limits on any effort to produce associated three-dimensional structures without relying on chemical, often unsustainable, approaches. To address this challenge, we report on a facile and green method that combines mechanical and biopolymer treatment: in-plane compression and aqueous solution permeation via spraying. The first enabled network extensibility while the second, which relied on the use of either food-grade gelatin, guar gum, or polylactic acid, improved network strength and stiffness. As a result, an unprecedented elongation of ∼30% was achieved after unrestrained drying of the fiber web. At the same time, the structures experienced a significant increase in tensile strength and stiffness (by ∼306% and ∼690%, respectively). Such simultaneous property improvement, otherwise very difficult to achieve, represents a substantial gain in the material’s toughness, which results from the synergistic effects associated with the mechanical response of the network under load, fiber intrinsic strength, and interfiber bonding. The level of plasticity developed in fiber webs upon biaxial compaction (longitudinal followed by lateral compaction), which was performed to reduce property anisotropy, allowed the synthesis of 3-D packaging materials via direct thermoforming. Moreover, the formability was found to be temperature and humidity dependent (strain and creep compliance after creep/recovery cycles in dynamic mechanical analyses). Overall, an inexpensive, green, and scalable approach is introduced to expand the properties spaces for paper and related non-wovens that allows 2-D and 3-D formability of in-plane compacted fiber networks.

Enhanced strength, stiffness and elongation potential of paper by spray addition of polysaccharides

“…The paper shrinkage during restrained and unrestrained drying was measured and calculated according to the procedure described by Vishtal and Retulainen (2014a). Shrinkages of restrained and unrestrained dried sheets were measured by applying marker holes with known separations in the wet sheets as described by Khakalo et al (2017b).…”

Effect of mechanically induced micro deformations on extensibility and strength of individual softwood pulp fibers and sheets

“…The HC treatment was followed by Valley beating (LC treatment) according to the standard procedure (SCAN-C 25:76). The same batch of BSKP is described in detail in Khakalo et al (2017b) and was utilized in Khakalo et al (2017a) and . The SR numbers (ISO 5267-1) of the untreated and HC ?…”

Microfibrillated‐cellulose‐reinforced polyester nanocomposites prepared by filtration and hot pressing: Bending properties and three‐dimensional formability

“…On the other hand, three‐dimensional (3D) formation permits the widespread application of composites. The press forming of paper boards is a method for preparing 3D‐molded materials, which can be applied to various types of packaging; this method has also been examined for applications of automotive interiors . Their formation process has been typically reported to comprise several processes.…”

“…One of the processes involves the sliding of paper into the mold and the lateral contraction of paper, leading to the microfolding of paper . The other process involves the straining of paper by the improvement of paper properties . Several studies have been reported on the improvement of paper properties by the use of additives …”

“…The other process involves the straining of paper by the improvement of paper properties . Several studies have been reported on the improvement of paper properties by the use of additives …”