Search Results (3)

This study focused on examining the reinforcement of milkweed fibers in polylactic acid (PLA) bio-composites used for dashboards in car interiors. Milkweed fiber is a natural fiber with a hollow structure that provides tremendous thermal insulation and noise resistance properties. Firstly, the milkweed fibers were blended with PLA fibers in a weight ratio of 75:25 using an air-laying process. Then, several layers of nonwoven material were compressed in a hydraulic press to obtain bio-composites. Finally, three bio-composites were obtained with different numbers of layers. The density, microstructure, thermal conductivity, sound transmission loss (STL), mechanical properties, dynamic mechanical analysis (DMA), and contact angles of the bio-composites were evaluated. The microstructure analysis revealed that some milkweed fibers collapsed due to the high-pressure molding process, which does not affect the bio-composite properties. The bio-composite with a higher number of nonwoven layers presented a poor interface between PLA and milkweed fibers, thus making it less homogeneous. This bio-composite showed a decrease of 5% in thermal conductivity values and a 19% increase in STL values. In addition, it exhibited a 160% increase in specific flexural strength and a 335% increase in specific flexural modulus compared to samples with a lower number of nonwoven layers. Therefore, it offers the best mechanical-property-to-density ratio, with values that conform to the specifications required for automotive dashboards. Full article

Milkweed (MW) fiber is a natural fiber that provides tremendous thermal insulation properties due to its lightweight hollow structure. This study aimed to investigate the effect of milkweed fiber as a thermal fiber in nonwovens. Milkweed fibers were blended with a low-melt fiber consisting of a polyethylene terephthalate core, a polyolefin sheath (LM 2.2), and polylactic acid (PLA) fiber. Nonwovens with different fiber contents were manufactured using an air-laid Spike process to determine their effect on thermal and mechanical properties. Then, the nonwovens were compared with Thinsulate^® and Primaloft^®, two commercially synthetic insulation products. Structural properties, including mass per unit area, thickness, and porosity and thermal properties were studied. Furthermore, compression and short-term compression recovery were also evaluated. The results revealed that milkweed-based nonwovens that contained 50 wt% or 70 wt% of milkweed presented a lower thermal conductivity than synthetic nonwovens. Milkweed nonwovens of the same thickness provided identical thermal resistance as Thinsulate^® and Primaloft. Sample 3, composed of 50 wt% MW, 20 wt% LM 2.2, and 30 wt% PLA, demonstrated the same thermal insulation as Thinsulate^® with a weight three times lighter. Milkweed nonwovens presented higher moisture regain values than Thinsulate^® and Primaloft^®, without affecting thermal conductivity. Full article

Fibers from milkweed, which grows in Quebec (Canada), offer a distinct and outstanding advantage compared to other natural fibers: their ultra-lightweight hollow structure provides excellent acoustic and thermal insulation properties for the automobile industry. To highlight the properties of milkweed fibers and reduce the use of synthetic materials in vehicles, nonwoven carpeting made from a blend of milkweed fibers and polylactic acid (PLA) fibers was produced using the air-laid process. Some of the nonwovens were compressed to investigate the effects of increased mass per unit area on their thermal, acoustic, and mechanical properties. The nonwovens’ mass per unit area, thermal insulation, sound absorption coefficient, airflow resistivity, compression, and resistance to moisture were evaluated and compared to other carpets made of natural and synthetic fibers. The findings indicate that milkweed and PLA carpets have lower thermal conductivity values of 37.45 (mW/m·K), (mW/m·K) less than carpets made from cotton and polypropylene. At low frequencies, none of the carpets absorbed sound. At high frequencies, milkweed and PLA carpets showed sound absorption values of at least 0.6, which provide better acoustic insulation than nonwoven materials made from jute and polyethylene (PE) fibers. Milkweed and PLA carpets exhibited better compression values than polypropylene (PP) carpets. Full article