Abstract
To confirm the suitable synthesis process parameters of preparing bromoisobutyryl esterified starch (BBES), the influences of the synthesis process parameters—amount of 2-bromoisobutyryl bromide (BIBB), amount of catalyst (DMAP), reaction temperature and reaction time—upon the degree of substitution (DS) were investigated. Then, to produce a positive effect on the properties of graft copolymers of BBES prepared in the near future, a series of BBES samples were successfully prepared, and their sizing properties, such as apparent viscosity and viscosity stability, adhesion, and film properties, were examined. The BBES granules were characterized by Fourier transform infra-red spectroscopy and scanning electron microscopy. The adhesion was examined by determining the bonding forces of the sized polylactic acid (PLA) and polyester roving. The film properties were investigated in terms of tensile strength, breaking elongation, degree of crystallinity, and cross-section analysis. The results showed that a suitable synthesis process of BBES was: reaction time of 24 h, reaction temperature of 40 °C, and 0.23 in the molar ratio of 4-dimethylaminopyridine to 2-bromoisobutyryl bromide. The bromoisobutyryl esterification played the important roles in the properties of the starch, such as paste stabilities of above 85% for satisfying the requirement in the stability for sizing, improvement of the adhesion to polylactic acid and polyester fibers, and reduction of film brittleness. With rising DS, bonding forces of BBES to the fibers increased and then decreased. BBES (DS = 0.016) had the highest force and breaking elongation of the film. Considering the experimental results, BBES (DS = 0.016) showed potential in the PLA and polyester sizing, and will not lead to a negative influence on the properties of graft copolymers of BBES.
Highlights
Starch as one of the most abundantly occurring organic polymers in nature [1], and as a renewable [2], biodegradable [3], and economical [4,5,6] raw material, has widespread industrial applications [7,8]
By comparing the X-ray diffraction patterns of the acid-converted starch (ACS) film (Figure 14a) and BBES film (Figure 14b), we found that the intensity of the peaks for BBES film was lower than the intensity for the ACS one, the location of the peaks was almost the same
To study the properties of BBES such as adhesion-to-fibers and film properties, etc., for producing a positive effect on the properties of grafted BBES prepared in the near future, a series of BBES samples with the degree of substitution (DS) values of 0.009, 0.016, 0.027 and 0.036 and reaction efficiencies of 61.3%, 54.5%, 46.0% and 40.9%, were prepared according to the suitable synthesis process parameters
Summary
Starch as one of the most abundantly occurring organic polymers in nature [1], and as a renewable [2], biodegradable [3], and economical [4,5,6] raw material, has widespread industrial applications [7,8]. Starch has a general formula of (C6 H10 O5 )n , including two types of d-glucan macromolecules, i.e., linear amylose and branched amylopectin [9,10], and consists of interconnected anhydroglucose units, each of which includes three hydroxyls and are linked together by a-d-glucosidic bonds [11]. It can be modified enzymatically, physically or chemically to meet various requirements. Prior to the graft copolymerization by ARGET ATRP, the starch is modified to form starch macroinitiator for further conducting the ARGET ATRP technique. One of the most commonly used reagents for modifying the starch to prepare the starch macroinitiator is
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