RESUMEN
Bamboo scrimber is acknowledged for its eco-friendly potential as a structural material. Its properties are significantly affected by both its density and resin content, but the effect of resin content on the properties under high density is not yet known. In this study, the microstructure, water resistance, mechanical properties, and thermal stability of bamboo scrimbers with varying resin content at a density of 1.30 g/cm3 were investigated. The results unearthed that phenolic resin assisted in the densification of bamboo cells during hot pressing, and a higher resin content could effectively reduce the cracks in the scrimber. The inherent cellulose I structure remained unaffected, but an increase in resin content led to a noticeable decline in crystallinity. Additionally, an increase in resin content pronouncedly improved the water resistance and dimensional stability of bamboo scrimbers. The water absorption and thickness swelling were as low as 9.67% and 7.62%, respectively. The modulus of rupture (MOR) exhibited a marginal increase with the amount of resin, whereas the compressive strength and short-beam shearing strength first increased and then decreased. Their peak strengths were 327.87 MPa at a resin content of 15 wt.%, and 168.85 MPa and 25.96 MPa at 11 wt.%, respectively. However, phenolic resin accelerated the thermal decomposition of bamboo scrimbers, and more resin worsened the thermal stability. These research outcomes offer a dual advantage, providing both a theoretical foundation and concrete data that can inform the production and practical application of high-density bamboo scrimbers.
RESUMEN
With natural texture and high performance, bamboo scrimber is one of the artificial lignocellulosic composites widely used in construction, furniture and other structural applications. However, it is vulnerable to the actions of water, ultraviolet radiation and fungus, which affect its durability, especially in the open. Here, bamboo was treated with superheated steam in an attempt to improve the durability of bamboo scrimbers. The chemical composition, mechanical properties, dimensional stability, aging resistance, decay resistance and anti-mildew properties were investigated at different temperatures (160~200 °C). After superheated steam treatment, the relative contents of holocellulose and α-cellulose in bamboo decreased. The bending strength and short-beam shearing strength slightly decreased as the temperature was raised while the modulus was essentially retained. The aging resistance in terms of thickness swelling rate (≤9.38%) was substantially improved. The decay resistance reached to the level of Grade I and can be dramatically enhanced by elevating temperature. The anti-mildew properties were also improved. To take together, superheated steam treatment remarkably improves the resistance of bamboo scrimbers to water, ultraviolet radiation, rot fungi and mildew with some concomitant reduction in mechanical properties. The results will permit outdoor construction using bamboo scrimbers more resistant to environmental damage.
RESUMEN
In this study, TEMPO-oxidized bamboo cellulose nanofibers (TO-CNF) with anionic carboxylate groups on the surfaces were in-situ incorporated into poly(N-isopropylacrylamide) (PNIPAm) matrix to improve its thermo-responsive and mechanical properties during the polymerization. The microstructure, swelling behaviors, and compressive strength of resultant PNIPAm composite hydrogels with varying contents of TO-CNFs (0-10wt%) were then examined, respectively. Modified hydrogels exhibited the similar light transparency to pure PNIPAm one due to the formation of semi-IPN structure between PNIPAm and TO-CNF. FT-IR spectra demonstrated that the presence of TO-CNF did not alter the position of characteristic peaks associated with PNIPAm. SEM observation suggested that the pore size of PNIPAm hydrogels was markedly increased after the incorporation of TO-CNF. Also, the composite hydrogels showed superior swelling behavior and much improved compression properties with respect to pure PNIPAm one. Thus, TO-CNF appeared to be a "green" nanofiller that can simultaneously improve swelling and mechanical properties of PNIPAm hydrogel.