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Luffa is expected to become a substitute for mattress filling materials due to its natural biodegradability, light texture, good air permeability, higher water absorption, and desorption. In this paper, two-variety luffa cylinders (LCs) as mattress filling materials were investigated. The results showed that the compressive strength and plateau stress of both the high-density and low-density LCs significantly related to their density. However, the compressive strength and plateau stress of the high-density LCs were about 3 times that of the low-density LCs, while the firmness of the high-density luffa mattresses was no more than 3 times that of the low-density luffa mattresses. Furthermore, the compression treatment of the LCs has a great effect on the firmness of the luffa mattresses. The compressive treatment of the LCs to the densification stage increased the Dcore of the low-density luffa mattresses but decreased the Dcore of the high-density luffa mattress. The firmness of the low-density luffa mattress was lower than that of 3D jute, carvel jute, and palm mattresses. [ABSTRACT FROM AUTHOR]

Cylindrical luffa has potential to be a lightweight mattress cushioning material with good air permeability, dryness and comfort. However, it is extremely firm and requires suitable softening treatment prior to use. In this work, the effects of three alkali-based softening treatments on the chemical composition, microstructure, physical and mechanical properties, and water absorption and desorption properties of high-density (HD) luffa fiber bundles were investigated. The softening treatment with 5% NaOH/5% H2O2 significantly lowered the compressive strength and plateau stress of HD cylindrical luffa by 77% and 73%, respectively. Moreover, large amounts of lignin, hemicellulose and amorphous cellulose were removed from HD luffa fibers after the treatment, resulting in loosening of the HD luffa fiber cells and fiber bundles. Although the softening treatment with 10% NaOH/20% CH3COOH only slightly reduced the compressive strength and plateau stress of HD cylindrical luffa, it significantly improved the flexibility of HD luffa fiber bundles. After being separately treated by 5% NaOH/5% H2O2, 10% NaOH/20% CH3COOH, and 18% NaOH/1.6% CO(NH2)2, the water desorption ratios of HD luffa after 12 h were all increased and reached 94%, 90% and 93%, respectively. The results indicated that the softening treatment with 10% NaOH/20% CH3COOH was a suitable method for obtaining softer and durable HD cylindrical luffa as potential mattress cushioning material. The schematic diagram of three softening treatments. (a) Hierarchical structures of the luffa cylinders, (b) and (c) changes in the microfibril structure before and after HD luffa cylinders were treated by Methods 1, 2, and 3. [ABSTRACT FROM AUTHOR]

Luffa is a lightweight porous material with excellent biocompatibility and abundant resources. In this paper, three kinds of softening treatment methods, alkali-hydrogen peroxide (Method 1), alkali-acetic acid (Method 2), and alkali-urea (Method 3), were used to soften high-density (HD) cylindrical luffa (CL) mattress-filling materials (MFM). Microscopic observation, mechanical performance testing and other analyses were performed to evaluate the effects of the three kinds of softening methods on the wettability, compression resilience and support performance of CL MFM. The results showed that: (1) After the treatment by Method 1, Method 2 and Method 3, the peak stress of CL decreased by 73%, 10% and 27%, respectively. In addition, after three kinds of softening treatments, the uniformity of CL increased. (2) When the CL MFM of high density rank treated by Method 1 was compressed by 40%, the firmness values of the surface, core and bottom reduced by 53.49% 40.72%, and 46.17%, respectively, compared to that of untreated CL. In addition, for the CL MFM of high density rank treated by Method 3 and then compressed to 60%, the firmness of the surface layer, core layer and bottom layer reduced by 41.2%, 33.7%, and 36.9%, respectively. (3) The contact angle of luffa treated by Method 3 was the smallest, next came Method 1 and Method 2, and untreated was the largest. (4) After the treatment by Method 3, the fiber bundle of luffa was intact, and the compression resilience of the CL was obviously increased. Therefore, this method can effectively reduce the firmness of MFM and also improve the uniformity and wettability of CL. [ABSTRACT FROM AUTHOR]

Luffa sponge (LS) is a resourceful material with fibro-vascular reticulated structure and extremely high porosity, which make it a potential candidate for manufacturing light mattress. In this study, two types of LS columns, namely high-density (HD) and low-density (LD) columns, were investigated as materials for filling the mattress. The results showed that the compressive strength of HD LS columns was significantly greater than that of LD LS columns. However, the densification strains of the two types of LS column were both in the range of 0.6 to 0.7. Besides, HD LS columns separately pressed to the smooth plateau region and the initial densification region exhibited a partial recovery of instant height when they were unloaded, and then both of them showed no more than 4.2% of height recovery after being allowed to rest at a constant temperature and humidity for 24 h. In contrast, when LD LS columns were compressed to the smooth plateau region, the height recovery was less than 1.62% compared to when they were pressed to the initial densification region, and that was more than 15.62%. Similar to other plant fibers used as mattress fillers, the two types of LS columns also showed good water absorption capacity—both of them could absorb water from as much as 2.07 to 3.45 times their own weight. At the same time, the two types of LS columns also showed good water desorption. The water desorption ratio of HD and LD LS columns separately reached 76.86 and 91.44%, respectively, after being let rest at a constant temperature and humidity for 13 h. [ABSTRACT FROM AUTHOR]