Bleached extruder chemi‐mechanical pulp fiber‐PLA composites: Comparison of mechanical, thermal, and rheological properties with those of wood flour‐PLA bio‐composites

Abstract

An environmentally friendly bleached extruder chemi-mechanical pulp fiber or wood flour was melt compounded with poly(lactic acid) (PLA) into a biocomposite and hot compression molded. The mechanical, thermal, and rheological properties were determined. The chemical composition, scanning electron microscopy, and Fourier transform infrared spectroscopy results showed that the hemicellulose in the pulp fiber raw material was almost completely removed after the pulp treatment. The mechanical tests indicated that the pulp fiber increased the tensile and flexural moduli and decreased the tensile, flexural, and impact strengths of the biocomposites. However, pulp fiber strongly reinforced the PLA matrix because the mechanical properties of pulp fiber-PLA composites (especially the tensile and flexural strengths) were better than those of wood flour-PLA composites. Differential scanning calorimetry analysis confirmed that both pulp fiber and wood flour accelerated the cold crystallization rate and increased the degree of crystallinity of PLA, and that this effect was greater with 40% pulp fiber. The addition of pulp fiber and wood flour modified the rheological behavior because the composite viscosity increased in the presence of fibers and decreased as the test frequency increased.

Interface compatibility and mechanisms of improved mechanical performance of starch/poly(lactic acid) blend reinforced by bamboo shoot shell fibers

“…This information means that the performance of the ternary composite may satisfy the basic requirement as a whole, but a weak link may exist within it. The tensile and flexural strengths of all composites with different BSSFs contents were all lower compared with that of pure PLA, which implied that the addition of BSSFs filler and starch decreased the mechanical strength of PLA as was proved previously …”

“…PLA also has good biocompatibilities, mechanical properties, and easy processing characteristics, which make it popular in several industries, including in biomedical, automotive, and mobile phone industries . However, its inherent brittleness, relatively high price and long degradation cycle may restrict its large‐scale commercial applications …”

Comparison between polyethylene glycol and tributyl citrate to modify the properties of wood fiber/polylactic acid biocomposites

“…In recent decades, natural fibers have been used as reinforcement or filler in thermoplastics and thermosets to produce low‐cost, high‐performance materials . Wood fiber (WF) and pulp , agricultural residuals (sunflower stalk, corn stalk, and bagasse fiber) , flax , bamboo , and kenaf have been successfully used to improve the mechanical properties of thermoplastics such as PLA. However, the elongation at break and impact strength decreases due to low compatibility between the fibers and PLA matrix, resulting in a lack of toughness .…”

“…Wood fiber (WF) and pulp , agricultural residuals (sunflower stalk, corn stalk, and bagasse fiber) , flax , bamboo , and kenaf have been successfully used to improve the mechanical properties of thermoplastics such as PLA. However, the elongation at break and impact strength decreases due to low compatibility between the fibers and PLA matrix, resulting in a lack of toughness . Several strategies have been applied to improve the toughness of PLA, including copolymerization , the addition of rigid filler , physical stretching , and blending with flexible additives .…”

Reactive extrusion of bio-based polymer blends and composites – Current trends and future developments

“…On the other hand, this surprisingly did not improve the mechanical properties or thermal stability of examined biocomposites. The lack of reinforcement effect was also observed by Yang et al [88], who used bleached extruder chemo-mechanical pulp fiber as reinforcement of poly(lactic acid) matrix. This phenomenon is probably due to the intense chemical process associated with high shear forces acting on fibers during shearing reactive extrusion, which partially destroy the fiber structure and affect its size and aspect ratio.…”