Chemical and Thermal Properties of Cellulose Acetate Prepared from White Willow (Salix alba) and Black Alder (Alnus glutinosa) as a Potential Polymeric Base of Biocomposite Materials

Abstract

Natural polymeric materials are an interesting alternative to petrochemical products with potential application in almost all areas of human activity. Wishing to expand the field of cellulose acetate application to the biocomposite wood materials, the possibilities of cellulose isolation and its acetylation from two domestic, commercially meagrely used, wood species was investigated in this paper. Cellulose isolated from white willow (Salix alba) and black alder (Alnus glutinosa) was acetylated using acetic anhydride and perchloric acid catalyst, by treatment at room temperature for 45 minutes. Analysis of the laboratory acetylation process, beside chemical analysis of the gained product by infrared spectroscopy (FT-IR), indicated the impact of hemicelluloses, present both in cellulose and cellulose acetate structure, on values of mass increase, number of acetyl groups and the degree of substitution. Results of thermogravimetric analysis (TGA) later confirmed the statement that thermal properties of cellulose acetate were also dependant on hemicelluloses.

Influence of Natural Fillers on Thermal and Mechanical Properties and Surface Morphology of Cellulose Acetate-Based Biocomposites

“…As crude Kürschner-Hoffer cellulose was used as raw material for CA synthesis, during acetylation, acetic anhydride reacted with both cellulose and hemicellulose [69]. Therefore, the small difference in T g values of neat matrices can also be attributed to the presence of xylan acetate acting as an internal plasticizer [70], which is more pronounced in black alder, as reported in our earlier work [41].…”

“…Cellulose Acetylation and CA Characterization. Cellulose was acetylated as described in our earlier work [41]. Briefly, 100 g of cellulose (per wood species) was treated for 1 minute with a reaction mixture consisting of 500 ml of acetic acid, 1000 ml of toluene, and 5 ml of perchloric acid as the catalyst.…”

“…It revealed that the structure of CA films was not porous (the porosity of the white willow-based CA film was 0.077% and that of the black alder-based CA was 0.062%) but that there were some cracks in the film structure, which were most probably due to uneven shrinkage of the biopolymer during the process of solvent evaporation [85]. The low values of CA film transparency, in the case of white willow, can be associated with the presence of hemicelluloses (glucuronoxylane) in the isolated cellulose used for CA preparation [41]. The presence of hemicelluloses influenced the acetylation process and led to nonhomogeneous substitution [86], and the use of dichloromethane as solvent induced structural changes in the solution, which are governed by the amount of acetyl and hydroxyl groups on the partially substituted CA chains.…”

“…However, the transparency of the CA film prepared from white willow (transmittance = 29 5%) is significantly lower than that of the film prepared from black alder (transmittance = 80 4%; as measured at 550 nm). Such high difference suggests that the water present in CA prior to dissolution and film casting [41] could have acted as a nonsolvent, thus initiating phase separation and leading to formation of the uneven and porous surface structure. As no pores have been noticed on the surfaces of the neat CA…”

Thermal Stability and Luminescent Properties of Tri-cellulose Acetate Composites Containing Dy(SSA)3Phen Complex

“…As for TCA and the TCA composites, the TGA thermograms are displayed in Figure 3, and the T e and T c values as well as the mass-loss values are listed in Table 1. Obviously, there is only one stage of decomposition occurring on the TGA curves of TCA and the composites, which suggests that the decomposition process of the composites is similar to that of the pure TCA, and during the processes, each chain scission reaction has an analogous energy barrier [33]. It can be seen that with the increase of the content of the added complex, the T e , T i , and T c values show a descending trend.…”