分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-05-09
摘要: A unique non-planar ring structure 1,4-cyclohexanedicarboxylic acid (CHDA) is introduced to synthesize a poly(butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate) (PBAC) copolyester. The impact of the stereochemistry of CHDA on the structure and properties of PBAC, especially the role of cis-CHDA in tuning the thermal, tensile and elastic properties of PBAC is explored in depth. Instead of considering PBAC as a diblock random copolymer consisting of poly(butylene adipate) (PBA) and poly(butylene 1,4- cyclohexanedicarboxylate) (PBC), our results reveal that PBAC can be considered as a random copolymer consisting of actually three blocks, namely PBA, a PBC unit with only trans-CHDA (trans- PBC), and PBC unit with only cis-CHDA (cis-PBC). The role of cis-CHDA is found to be rigid which initiates a high modulus and strength, and soft which results in a decreased melting temperature and increased elongation at break and elasticity.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-08
摘要: Compared with the rapid progress on bio-based thermoplastics, research on bio-based thermosetting resins should have attracted much more attention, considering that they will have a bright future. In this paper, the current research progress on bio-based thermosetting resins is reviewed. We pay special attention to the synthesis and investigation of properties of epoxies and unsaturated polyesters derived from renewable plant oil, cardanol, rosin acid, lignin, glycerol, gallic acid, furan, isosorbide, itaconic acid, etc. This mini review gives an overall perspective for bio-based thermosets. © 2015 Society of Chemical Industry
提交时间: 2017-05-02
摘要: Poly[butylene terephthalate]-poly[tetramethylene glycol] [PBT-PTMG] copolymer is prepared with terephthalic acid [PTA] rather than its dimethyl ester [DMT] as starting material by a two-step melt polycondensation. This process includes the synthesis of PB
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A series of bio-based unsaturated polyesters was synthesized by melt polycondensation of itaconic acid with 1,4-butanediol and glycerol. Their chemical structures were confirmed by FT-IR, 1H NMR, acid and hydroxyl values. Waterborne UV curable dispersion coatings based on these polyesters and acrylated epoxidized soybean oil (AESO) were formulated. The average particle size and their stability before curing as well as the coating properties after curing, including adhesion, flexibility, pencil hardness and solvent resistance, were investigated. Results demonstrated that the glycerol segment in the polyesters together with AESO led to the excellent coating properties in terms of highest grade of adhesion (5B), 0T flexibility, pencil hardness of 5H and excellent solvent resistance (no appearance change after 250 double rubs with ethanol and acetone). This work provided us the coating systems combining the merits of being bio-based, UV-curable and water dispersible.vv
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A biobased monofunctional compatibilizer (called Epicard) is first synthesized by the reaction of cardanol with epichlorohydrin as confirmed by Fourier transform infrared and 1H NMR. Subsequently, biosourced polymers, polylactide (PLA) and starch, are melt-blended by a twin-screw extruder with Epicard. Confirmed by the measurements of contact angle and 1H nuclear magnetic resonance of the extracted starches from PLA/starch/Epicard blends, the Epicard only possesses a monoepoxy group to mainly react with starch and then increased the hydrophobicity of the starches during the melt-blending process. As a result, an obvious improvement to the interfacial adhesion between starch and PLA is observed by the scanning electron microscopy. Furthermore, the tensile properties of PLA/starch blends are effectively improved with the addition of Epicard. This study suggests a simple but effective material technique by utilizing a novel plant oil modifier to increase interfacial adhesion in fabricating fully biobased PLA/starch blends with superior tensile properties.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Polyurethanes (TPUs) containing carbon–carbon double bonds are synthesized for use as novel materials with the ability to form functionalizable ultrafine fibers via electrospinning. By adjusting the molecular structure, a series of TPU products with different amounts of carbon–carbon double bonds are obtained. After investigating the reactivity of the TPU with 1H,1H,2H,2H-perfluorooctanethiol, all of the TPU samples exhibit effective functionalizability. The more carbon–carbon double bonds contained in the molecular structure, the stronger the functionalizability. Besides, these TPUs can easily form uniform ultrafine fibers via electrospinning. Upon comparison, the functionalizability of the electrospun fibers is similar to that observed in the bulk TPU materials. This work suggests a feasible methodology to produce a functionalized ultrafine fibrous carrier. Accordingly, TPU containing carbon–carbon double bonds is expected to be exploited as a fibrous carrier of solid catalysts in the future.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: This paper reported the synthesis of bio-based unsaturated poly(ester- urethane)s via a nonisocyanate route, by metal-catalyzed melt poly- condensation of itaconic acid with urethanediols. Three novel types of bio-based unsaturated poly(ester-urethane)s, namely, poly- (urethanediol 2-itaconic acid), poly(urethanediol 4-itaconic acid) and poly(urethanediol 6-itaconic acid) (poly(U2-IA), poly(U4-IA) and poly (U6-IA) for short code, respectively), were prepared by a green synthetic route. The urethane linkage was formed by the reaction of two equivalent of ethylene carbonate with 1,6-hexanediamine, 1,4- butanediamine and 1,2-ethanediamine to form urethanediols. The urethanediols underwent polymerization with itaconic acid (IA) in the presence of metal catalyst dibutyltin dilaurate (DBTL) to produce low- molecular-weight bio-based unsaturated polyurethanes. Then, these bio-based unsaturated poly(ester-urethane)s were formulated with free radical photoinitiator and curing promoter to prepare UV curable polyurethane systems. After UV curing, the tensile properties, thermal properties and general coating properties of the three UV-cured polyurethane films were similar to that of UV cured polyurethane films prepared by polyurethane-acrylate (PUA). The results suggested that the obtained bio-based unsaturated polyurethanes could serve as coating materials.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Non-planar ring contained polyester is synthesized as an effective toughening agent to modify poly- lactide (PLA). By systematically researching the relation between molecular structure and properties, the two key factors to pursue high toughness of PLA with non-planar ring contained polyester are carefully distinguished. For one thing, the polyester must own the ability to be well compatible with PLA. For the other, the polyester should have a rigid molecular chain but “non-rigid” aggregation structure. By suit- ably controlling the molecular design, poly(butylene adipate-co-1,4-cyclohexanedicarboxylate) (PBAC) is obtained. After using PBAC to toughen PLA, the elongation extremely increases to 196.1 ± 3.6% and the notched impact strength is also effectively improved with several times. Finally, our research establishes an important methodology to toughen PLA and thus fabricates tough PLA based blends.
提交时间: 2017-05-02
摘要: In this manuscript, a toughened PLA/nanosilica composite with good storage stability was obtained in the presence of the epoxidized soybean oil [ESO]. The composite was fabricated via a twin-screw extruder, and characterized by the FTIR, selective distrib