High performance films of cellulose butyral derivative having a necklace-like annular structure in the side chains

We fabricated high performance films using cellulose butyral (CB) synthesized from native cellulose. Two-step reactions were adopted to produce the derivative CB, including etherification of cellulose with glycidol in NaOH/urea aqueous solution to yield O-(2, 3-dihydroxypropyl) cellulose (DHPC), and butyralization of DHPC. Both DHPC and CB products were easily processed into a thin film by hot-press molding. The butyral modifier significantly improved the tenacity of highly ductile DHPC, by virtue of the possible chain-entangling action of the ring structures in the stretching process. Thereby the film toughness was markedly enhanced. The CB films exhibited excellent optical transparency and a good adhesive property to glass plates. Thus the films may be comparable to commercial poly(vinyl butyral) (PVB) films in optical and mechanical performances and therefore possess a potential applicability as interlayer for laminated glasses

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京都大学0048新制・課程博士博士(農学)甲第10904号農博第1410号新制||農||890(附属図書館)学位論文||H16||N3915(農学部図書室)UT51-2004-G751京都大学大学院農学研究科森林科学専攻(主査)教授 西尾 嘉之, 教授 中坪 文明, 教授 松本 孝芳学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDA

Functional Thermoplastic Materials from Derivatives of Cellulose and Related Structural Polysaccharides

This review surveys advances in the development of various material functionalities based on thermoplastic cellulose and related structural polysaccharide derivatives. First, the dependence of thermal (phase) transition behavior on the molecular composition of simple derivatives is rationalized. Next, approaches enabling effective thermoplasticization and further incorporation of material functionalities into structural polysaccharides are discussed. These approaches include: (a) single-substituent derivatization, (b) derivatization with multi-substituents, (c) blending of simple derivatives with synthetic polymers, and (d) graft copolymerization. Some examples addressing the control of supramolecular structures and the regulation of molecular and segmental orientations for functional materials fabrication, which have especially progressed over the past decade, are also addressed. Attractive material functions include improved mechanical performance, controlled biodegradability, cytocompatiblity, and optical functions

Cellulose acetate/poly(methyl methacrylate) interpenetrating networks: synthesis and estimation of thermal and mechanical properties

IPN-type composites consisting of cellulose acetate (CA) and poly(methyl methacrylate; PMMA) were successfully synthesized in film form. In this synthesis, a mercapto group (SH)-containing CA, CA-MA, was prepared in advance by esterification of CA with mercaptoacetic acid, and then intercomponent cross-linking between CA-MA and PMMA was attained by thiol–ene polymerization of methyl methacrylate (MMA) onto the CA-MA substrate. For comparison, polymer synthesis was also attempted to produce a semi-IPN type of composites comprising CA and cross-linked PMMA, via copolymerization of MMA and ethylene glycol dimethacrylate as cross-linker in a homogeneous system containing CA solute. Thermal and mechanical properties of thus obtained polymer composites were investigated by differential scanning calorimetry, dynamic mechanical analysis, and a tensile test, in correlation with the mixing state of the essentially immiscible cellulosic and methacrylate polymer components. It was shown that the specific IPN technique using thiol–ene reactions usually resulted in a much better compatibility-enhanced polymer composite, which exhibited a higher tensile strength and even an outstanding ductility without parallel in any film sample of CA, PMMA, and their physical blends

Structural characterization of poly(ε-caprolactone)-grafted cellulose acetate and butyrate by solid-state 13C NMR, dynamic mechanical, and dielectric relaxation analyses

Investigations were made into the molecular dynamics and intercomponent mixing state in solid films of two series of cellulosic graft copolymers, cellulose acetate-g-poly(ε-caprolactone) (CA-g-PCL) and cellulose butyrate-g-PCL (CB-g-PCL), both series being prepared over a wide range of compositions with CAs or CBs of acyl DS ≈ 2.1, 2.5, and 2.95. It was shown by T_1ρ^H measurements in solid-state [13]C NMR spectroscopy that all the copolymer samples, except ones using CA of DS = 2.98, formed an amorphous monophase in which the trunk and graft components were mixed homogeneously at least in a scale of a few nanometers. However, those copolymer samples gave, more or less, a response of dynamic heterogeneity, when examined under mechanical oscillation. Through dielectric relaxation measurements, a clear comparison was made between the CA-g-PCL and CB-g-PCL series, regarding the cooperativeness in segmental motions of the trunk and graft chains, directly associated with the extent of the dynamic heterogeneity. The cooperativeness was generally higher in the CB-based copolymer series, probably due to working of the butyryl substituent as an internal compatibilizer

Blend miscibility of cellulose propionate with poly(N-vinyl pyrrolidone-co-methyl methacrylate).

The blend miscibility of cellulose propionate (CP) with poly(N-vinyl pyrrolidone-co-methyl methacrylate) (P(VP-co-MMA)) was investigated. The degree of substitution (DS) of CP used ranged from 1.6 to >2.9, and samples for the vinyl polymer component were prepared in a full range of VP:MMA compositions. Through DSC analysis and solid-state (13)C NMR and FT-IR measurements, we revealed that CPs of DS<2.7 were miscible with P(VP-co-MMA)s of VP≥~10mol% on a scale within a few nanometers, in virtue of hydrogen-bonding interactions between CP-hydroxyls and VP-carbonyls. When the DS of CP exceeded 2.7, the miscibility was restricted to the polymer pairs using P(VP-co-MMA)s of VP=ca. 10-40 mol%; the scale of mixing in the blends concerned was somewhat larger (ca. 5-20 nm), however. The appearance of such a "miscibility window" was interpretable as an effect of intramolecular repulsion in the copolymer component. Results of DMA and birefringence measurements indicated that the miscible blending of CP with the vinyl polymer invited synergistic improvements in thermomechanical and optical properties of the respective constituent polymers. Additionally, it was found that the VP:MMA composition range corresponding to the miscibility window was expanded by modification of the CP component into cellulose acetate propionate

Insight into miscibility behaviour of cellulose ester blends with N-vinyl pyrrolidone copolymers in terms of viscometric interaction parameters

We previously offered miscibility maps for blend systems of cellulose esters (CEs) including cellulose acetate (CA), propionate (CP), and butyrate (CB) with vinyl copolymers containing an N-vinyl pyrrolidone (VP) unit, i.e., poly(N-vinyl pyrrolidone-[co]-vinyl acetate) [P(VP-[co]-VAc)] and poly(N-vinyl pyrrolidone-[co]-methyl methacrylate) [P(VP-[co]-MMA)]; the maps were constructed based on data of thermal analysis as a function of the degree of ester substitution (DS) of the CE component and the VP fraction in the copolymer component. The blend system using CP among the three CEs imparted the largest region of miscible pairings with the vinyl copolymers, and both of the maps for the CP/P(VP-[co]-VAc) and CP/P(VP-[co]-MMA) systems comprised a "miscibility window" associated with the respective copolymer compositions at high DSs of >2.65. The present work was made to interpret the expansion of the miscible markings for the CP/copolymer systems in comparison with the cases using CA and CB, in terms of a Krigbaum–Wall interaction parameter (μ) obtained by solution viscometry for selective polymer pairs involved in the respective CE/copolymer blends. The results of μ measurements were in good accordance with the earlier miscibility estimations. The assessment of very small negative μ values (i.e., extremely weak repulsion) for CP/PVAc and CP/PMMA combinations and that of considerably larger negative μ values for PVP/PVAc and PVP/PMMA combinations enabled us to give a rational explanation for the CP systems. The strongly repellent character of the two different monomer units constituting the copolymers permits accession of the CP component (DS > 2.65) to them, which would be responsible for the advent of the miscibility window. Further expansion of the window observed when cellulose acetate propionate (CAP) was adopted instead of CP as the CE component was also well explained on the basis of a μ data indicative of additional intramolecular repulsion in the CAP side

Molecular orientation and optical anisotropy in drawn films of cellulose diacetate-graft-PLLA: comparative investigation with poly(vinyl acetate-co-vinyl alcohol)-graft-PLLA

Cellulose diacetate-graft-poly(L-lactide) (CDA-g-PLLA) and poly(vinyl acetate-co-vinyl alcohol)-graft-PLLA (P(VAc-co-VOH)-g-PLLA) were synthesized over a range of compositions, by ring-opening copolymerization of L-lactide at the original hydroxyl positions of the respective trunk polymers, CDA (acetyl DS = 2.15) and P(VAc-co-VOH)-g-PLLA (VAc = 64.2 mol%). All the products of both graft copolymer series were non-crystallizable and their solution-cast films showed no domain segregation of the two components that constituted the trunk and side-chains. A comparative study on the molecular orientation and optical anisotropy induced by uniaxial stretching of film samples was undertaken for the two copolymer series with various side-chain lengths. Overall behaviour of the orientation was estimated from the statistical second () and fourth () moments obtained by a fluorescence polarization method using a rod-like probe of ~2.5 nm. Upon stretching, any film of both series imparted a positive orientation function, i.e., f = (3 − 1)/2 > 0, which increased with the extent of deformation. The degree of molecular orientation was higher in the CDA-graft series with a semi-rigid trunk, and, in both series, it declined monotonically with increasing content of the PLLA side-chain. With regard to the optical anisotropy, CDA-g-PLLA films always exhibited a positive birefringence (Δn > 0) upon stretching, while drawn films of P(VAc-co-VOH)-g-PLLA displayed a negative one. This contrast in polarity reflects a difference in the intrinsic birefringence between the two trunk polymers. Of interest was the finding of a discontinuous change in Δn value with copolymer composition (PLLA content) for the respective graft series, when compared at a given stage of elongation of the films. Discussion took into consideration the locally different orientation manners of the attached PLLA chain segments

Producing a magnetically anisotropic soft material: synthesis of iron oxide nanoparticles in a carrageenan/PVA matrix and stretching of the hybrid gelatinous bulk

We propose a method for preparing magnetically anisotropic soft materials that includes chemical loading (in situ synthesis) of iron oxide nanoparticles in a matrix composed of kappa-carrageenan (Car) and poly(vinyl alcohol) (PVA) followed by mechanical stretching of the hybrid in a wet process. Anionic Car was used to accommodate the iron oxide nanoparticles and was blended in advance with PVA, which has the ability of high orientation. Scanning electron microscopy revealed that the loaded granular iron oxide nanoparticles (50-100 nm) formed elliptical clusters upon stretching of the hybrid composite. Wide-angle X-ray diffraction measurements indicated that the PVA constituent was oriented in the draw direction. With the orientation of the composite matrix, the incorporated iron oxide nanoparticles gathered to form elliptical clusters. The drawn samples showed different amplitudes in the magnetization (M-parallel to > M-perpendicular to) when measured in two setups in which the applied field was parallel (parallel to) or perpendicular (perpendicular to) to the draw direction. The specific responses of the drawn sheets to an external magnetic stimulus were visualized and were reasonably attributed to an effect of the magnetic anisotropy created by the preferred orientation of the nanoparticle aggregates

Cost reduction and feedstock diversity for sulfuric acid-free ethanol cooking of lignocellulosic biomass as a pretreatment to enzymatic saccharification

We have previously demonstrated that a sulfuric acid-free ethanol (EtOH) cooking treatment enhances the enzymatic digestibility of eucalyptus wood and bagasse flour. In the present study, a reconfigured process that achieves similar performance was developed by identifying possible cost-competitive pretreatments that provide high cellulose-to-glucose conversion during subsequent enzymatic hydrolysis. The series of reconfigurations reduced EtOH usage in the pretreatment by more than 80% in comparison with our previous research. Higher initial pressures and intensive size reduction of the starting material are not required. The reconfigured process was applied to rice straw and Douglas fir, in order to confirm the feasibility of feedstock diversity