The influence of fiber size on the behavior of the araucaria pine nut shell/PU composite

Abstract

ObstractThe use of araucaria pine nut shell in polymer composites may increase the pine nut value and help protec araucaria (Araucaria angustifolia) itself, which is an endangered species. The aim of this work is to study the influence of the size of pine nut shell fiber on the mechanical properties of composites made of this shell and polyurethane derived from castor oil. Composites with different polyurethane contents were manufactured with dried untreated pine nut shell sieved through 30 and 50 mesh sieves (0.6 and 0.3 mm, respectively). Composites were shaped by mechanical mixing of the components followed by hot pressing. Properties such as density, water absorption, and flexural strength were measured. Specimens were also characterized by SEM, FTIR, and TGA. The flexural strength of PU/0.3mm pine nut shell composites with 30% PU (wt%) was 57.7 MPa, and their water absorption was 7.37% after 24 hours of immersion.

Performance of castor oil polyurethane resin in composite with the piassava fibers residue from the Amazon

“…The third degradation stage occurred in the same range of temperature, between 400 and 500 °C (43% loss mass), as displayed by D2DSC (Fig. 2 d) correlating to ester bond decompositions presented in the prepolymer structure, besides flexible regions and functional groups (N–H and C=O) 7 , 8 .…”

“…In the second event, around 350-450 °C, high energy may correspond to CO degradation, soft polyurethane segments, and single or double bands, as C=O, C=C, C-O, C-O-H29 . The third degradation stage occurred in the same range of temperature, between 400 and 500 °C (43% loss mass), as displayed by D2DSC (Fig.2d) correlating to ester bond decompositions presented in the prepolymer structure, besides flexible regions and functional groups (N-H and C=O)7,8 .…”

“…The research constantly advances the application of diversified residues of lignocellulosic fibers as reinforcement and replacing the polymeric matrix, such as rice husk 5 , banana stem 6 , pine nut husk 7 , and sugar cane straw 8 . The "green" polyurethane composed of vegetable oils was initially developed by university researchers and recently applied by the industry following the tendency.…”