Renewable resource-based composites of recycled natural fibers and maleated polylactide bioplastic: Characterization and biodegradability

The thermal properties of composite materials composed of polylactide (PLA) and green coconut fiber (GCF) were evaluated. Blends containing maleic anhydride-grafted PLA (PLA-g-MA/GCF) exhibited noticeably superior thermal properties due to greater compatibility between the two components. The dispersion of GCF in the PLA-g-MA matrix was highly homogeneous as a result of ester formation, and the consequent creation of branched and cross-linked macromolecules, between the carboxyl groups of PLA-g-MA and the hydroxyl groups in GCF. In addition, the PLA-g-MA/GCF blend was more easily processed due to a lower melt viscosity. Each composite was subject to biodegradation tests in a Burkholderia cepacia BCRC 14253 compost. The bacterium completely degraded both the PLA and the PLA-g-MA/GCF composite films. Morphological observations indicated severe disruption of the film structure after 9-12 days of incubation. The PLA-g-MA/GCF (10 wt%) films were not only more biodegradable than those made of PLA, but also exhibited lower molecular weight and intrinsic viscosity, implying a strong connection between these characteristics and biodegradability.     

Surface treatment of LLDPE and LDPE blends by nitric acid,sulfuric acid,and chromic acid etching

Surface treatment of linear low density polyethylene and low density polyethylene blends is investigated herein using nitric acid, sulfuric acid, and chromic acid. These chemical treatments not only make the surface rough but also introduce polar groups. A new method, “sulfonic groups index” (SI) is employed to quantify the newly generated polar groups in the wavenumber of 1,250–840 cm⁻¹ in the Fourier transform infrared spectra. The SI values effectively indicate that the most polar groups are incorporated into the chromic acid-etched samples among the three inorganic acids, which is also confirmed by scanning electron microscopy and roughness tests. Besides, annealing treatment can enhance the crystallinity X _c of all etched samples which plays a predominant role in the increase of roughness within 2 h. As etching time increases, chain scission and destruction of amorphous parts happen and roughness increases a lot for chromic acid-treated samples, but for sulfuric acid- and nitric acid-treated samples, the destruction of amorphous parts may not happen so that the roughness has not many changes.     

Preparation and characterizations of PMMA-PVDF based polymer composite electrolyte materials for dye sensitized solar cell

Blend polymer composite gel electrolytesare prepared using thepoly vinyledene fluoride (PVDF), polymethyl methacrylate (PMMA) with alumina (Al₂O₃) in variance of alkali metal iodide saltsystem. The alumina doped blend polymer electrolytes characterized by the XRD diffraction and FT-IR spectra. This is supportive to the conformation of the crystallinity behaviour and the composite formation.The high-resolution scanning electron microscopy (HR-SEM) have used to find the composite electrolyte membrane porous size (10 μm) and it has support to understand the morphological structure of the membrane. To analyze the ionic conductivity of the potassium iodide based composite polymer electrolyte by the impedance measurements, which is 4.62 × 10⁻³ Scm⁻¹ at room temperature. Finally, different alkali metal iodide based dye-sensitized solar cells (DSSCs) fabricated and monitored an energy conversion efficiency.     

NOVEL POLYPROPYLENE MATERIALS

Recent progress in transition metal catalyzed propylene polymerization based upon single-site catalysts and melt compounding of polypropylene is stimulating the development of novel polypropylene materials with unconventional property combinations such as improved low temperature toughness, low haze, elasticity, and improved toughness/stiffness balance. As a function of metallocene architectures, polypropylene microstructures can be varied over a very wide range in order to produce thermoplastic elastomers and highly flexible polymers as well as stiff engineering thermoplastics and fibers. Control of polypropylene molecular architectures, especially random placement of steric irregularities in the polypropylene main chain, and the addition of clarifiers represents the key to producing novel transparent polypropylenes. Metallocene-based ethene/1-olefin copolymers such as poly(ethylene-co-1-butene) are attractive blend components to afford either single-phase flexible or two-phase rigid blends with improved low temperature impact strength as a function of the 1-butene content. New families of polypropylene nanocomposites, containing nanowhiskers and anisotropic nanoparticles derived from organophilic layered silicates, exhibit effective matrix reinforcement at low filler content.     

PVC／PE交联共混体系的动态力学研究

在ＰＶＣ／ＰＥ共混体系中加入交联剂和引发剂能产生ＰＶＣ－ＣＯ－ＰＥ共聚物，这种共聚物在共混物中可起到增容剂的作用。通过动态力学分析和扫描电镜研究了ＰＶＣ／ＰＥ交联共混体系的相容性。发现引发剂、交联剂、稳定剂和增塑剂等对共混物中的交联反应均有较大的影响。     

MELT BLENDS OF POLY (BUTYLEN TEREPHTHALATE) AND A THERMOTROPIC LIQUID CRYSTALLINE POLYMER

With the help of differential scanning calorimetry, cone-plate and capillary rheometry andscanning electron microscopy, a research has been conducted on rheological behavior,crystallization and morphology of poly (butylene terephthalate) (PBT) blends containing athermotropic LCP. The blend has zero entrance pressure loss, although the LCP has rather largeone. The viscosity curve of the blend lies between those of the LCP and PBT. The crystallizationof PBT is not affected by the presence of the LCP together with no indication oftransesterification between the two ingredients. LCP spheres and ellipsoids with the size of 0. 5--1. 5 μm disperse in PBT matrix uniformly, which is related to the viscosity ratio of the twocomponents.     

壳聚糖水杨酸盐-明胶共混膜结构表征及其抗菌性

以溶液共混法成功制备出壳聚糖水杨酸盐－明胶共浊膜，用FT－IR、XRD、SEM表征了其结构，并测试了其吸水率，力学性能及抑菌性能。结果表明，壳聚糖水杨酸盐－胶胶共混膜中存在强烈的氢键相互作用及良好相容性，共混膜的力学性能随明胶含量增大而明显提高，当明胶含量为30％时，共混膜的抗张强度最大，其干、湿态抗张强度分别达99．9MPa和34．9MPa，比纯壳聚糖膜干，湿态抗张强度分别提高了99．8％有83．75，共浊膜抑菌性随明胶含量增加而下降，但其抑菌性仍明显高于壳聚糖膜。水杨酸的引入有利于改善其力学性能及抗菌性能，该共漫漫经膜作为一种潜在的伤口包扎材料，将具有广阔应用前景。     

PC／PBT共混体系的研究：（Ⅱ）PC,PBT熔融共混时的相容性

采用ＤＳＣ测定了一系列ＰＣ／ＰＢＴ熔融共混物的Ｔｇ，结果显示ＰＣ、ＰＢＴ是部分相容的两相体系，ＰＣ、ＰＢＴ之间的酯交换反应有利于相容性的提高。通过对ＰＣ、ＰＢＴ两相中各组分表观质量分数的计算，发现ＰＣ溶于ＰＢＴ的能力要比ＰＢＴ溶于ＰＣ的能力大。通过对ＰＣ、ＰＢＴ相互作用参数χ１２的计算，发现在所研究的范围内（ＰＣ含量为３０～７０％）ＰＣ、ＰＢＴ之间的相互作用参数χ１２略大于其临界相互作用参数（χ１２）ｃ，表明ＰＣ、ＰＢＴ在熔融共混时会发生相分离，亦即形成部分相容的两相体系     

Reactive blending of polypropylene/polyamide-6 in the presence of tailor-made succinic anhydride-terminated oligopropene compatibilizers

Various anhydride-terminated isotactic and atactic oligopropenes of number average molecular weights ranging between 1,000 and 10,000 g/mole, prepared by maleinating vinylidene-terminated propene oligomers obtained with isospecific and nonstereospecific metallocene-based Ziegler–Natta catalysts, have been evaluated as blend compatibilizers of polypropylene/polyamide-6 (70 vol%/30 vol%) blends to study the role of blend compatibilizer molecular architecture. When added during processing, as shown by IR spectroscopic analysis, the anhydride-terminated oligopropenes react with the amine-terminated polyamide-6 to yield polypropylene-block-polyamide-6 in situ. Such block copolymers are efficient dispersing agents. While the polyamide dispersion in the polypropylene continuous phase is not affected by blend compatibilizer stereoregularities, both stiffness and yield stress as well as notched Charpy impact strength increase with increasing stereoregularities and molecular weights. With oligopropene molecular weights exceeding 1,150 g/mole, the average size of the dispersed polyamide microphases correlates with the volume fraction of the oligopropene-block-polyamide-6 blend compatibilizer and the dicarboxylic acid anhydride/amine molar ratio.     

Thermal degradation processes of poly(carbonate) and poly(methyl methacrylate) in blends coalesced either from their common inclusion compound formed with γ-cyclodextrin or precipitated from their common solution

Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of a PC/PMMA blend, coalesced from their common inclusion compound (ICs) formed with host γ-cyclodextrin (γ-CD) through removal of the γ-CD host, and a physical PC/PMMA blend, precipitated from their common solution, have been performed and compared with those of the coalesced and as-received homopolymers. A slight increase in the thermal stability of the PMMA component in the presence of PC was recorded both by TGA and DIP-MS compared to the corresponding homopolymers. The DIP-MS observations pointed out that the thermal stability and degradation products of these polymers are affected once they are included inside the IC channels created by the stacked host CDs. DIP-MS observations suggested that for both coalesced and physical PC/PMMA blends, an exchange reaction occurs between carbonates of PC and MMA, formed by depolymerization of PMMA above 300 °C, most likely due to diffusion of MMA monomer at the interface or even into the PC domains, where it can react producing low molecular weight PC bearing methyl carbonate and methacrylate chain ends. The results also indicated an ester-ester interchange reaction between PC and PMMA yielding a graft copolymer and low molecular weight PC chains bearing methyl carbonate end groups in the case of the coalesced blend. This can be atttributed to the presence of specific molecular interactions between the intimately mixed PMMA and PC chains in the coalesced PC/PMMA blend.