Effect of low molecular additives on the electrospinning of nonwoven materials from a polyamide-6 melt

The effect of low molecular additives on the structure and properties of polyamide-6-based nonwoven materials obtained via electrospinning from a melt is studied. The introduction of up to 10% salts of higher fatty acids into the polymer melt leads to a decrease in its viscosity and to an increase in its electrical conductivity, thereby making it possible to produce nonwoven materials with an average fiber diameter of <1.5 µm. With the use of DSC, IR spectroscopy, and X-ray diffraction, it is shown that, in nonwoven materials based on polyamide-6, the metastable γ form of crystals prevails, while, in the native polymer, the stable a form predominates. The resulting materials demonstrate high filtration characteristics, and their surface properties are close to superhydrophobic.     

硅橡胶/蒙脱土复合材料的制备、结构与性能

用溶液法和熔融法制备了硅橡胶／蒙脱土复合材料，测定了力学性能、耐热性、耐溶剂性等性能．并与通常采用的２＃气相法白碳黑填充补强硅橡胶的性能作了对比．实验表明，溶液法能使蒙脱土更好地分散在硅橡胶基体中，所得到的复合物的性能有了很大的提高，与２＃气相法白碳黑填充补强的硅橡胶性能相当．     

Thermal properties and structure of electrospun blends of PVDF with a fluorinated copolymer

We report the structure and thermal properties of blends comprising poly(vinylidene fluoride) (PVDF) and a random fluorinated copolymer (FCP) of poly(methyl methacrylate)‐random‐1H,1H,2H,2H‐perfluorodecyl methacrylate, promising membrane materials for oil–water separation. The roles of processing method and copolymer content on structure and properties were studied for fibrous membranes and films with varying compositions. Bead‐free, nonwoven fibrous membranes were obtained by electrospinning. Fiber diameters ranged from 0.4 to 1.9 μm, and thinner fibers were obtained for PVDF content >80%. As copolymer content increased, degree of crystallinity and onset of degradation for each blend decreased. Processing conditions have a greater impact on the crystallographic phase of PVDF than copolymer content. Fibers have polar beta phase; solution‐cast films contain gamma and beta phase; and melt crystallized films form alpha phase. Kwei's model was used to model the glass transition temperatures of the blends. Addition of FCP increases hydrophobicity of the electrospun membranes. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 312–322     

Structure and properties of linear polyethylene-montmorillonite nanocomposites

Nanocomposites based on PE and three types of montmorillonite are prepared by melt blending on a Brabender plastograph. The structure of hybrid materials is studied with the use of X-ray diffraction analysis and transmission electron microscopy. The type of modifier and the polarity of the polyolefin matrix affect the character of the filler structure (intercalated and exfoliated) formed during blending with the polymer. A correlation is found between the parameters of structural organization and the mechanical and barrier properties of nanocomposites. The tensile modulus of the nanocomposites containing 3?C5 wt % modified montmorillonite is 75% higher than that of the unfilled PE, whereas the time of combustion and the rate of flame propagation are 20 and 10% smaller, respectively.     

聚苯乙烯/蒙脱土熔融插层复合的研究

用熔融法制备了聚苯乙烯／蒙脱土插层复合材料，用Ｘ 射线衍射、ＤＳＣ等手段研究了复合材料的结构与性能．聚苯乙烯熔体不能插层于钠基蒙脱土中，但能插层于经有机化合物处理过的蒙脱土中．     

New poly(butylene succinate)/layered silicate nanocomposites. II. Effect of organically modified layered silicates on structure,properties, melt rheology,and biodegradability

A series of new poly(butylene succinate) (PBS)/layered silicate nanocomposites were prepared successfully by simple melt extrusion of PBS and organically modified layered silicates (OMLS). Three different types of OMLS were used for the preparation of nanocomposites: two functionalized ammonium salts modified montmorillonite and a phosphonium salt modified saponite. The structure of the nanocomposites in the nanometer scale was characterized with wide-angle X-ray diffraction and transmission electron microscopic observations. With three different types of layered silicates modified with three different types of surfactants, the effect of OMLS in nanocomposites was investigated by focusing on four major aspects: structural analysis, materials properties, melt rheological behavior, and biodegradability. Interestingly, all these nanocomposites exhibited concurrent improvements of material properties when compared with pure PBS. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3160–3172, 2003     

Control of the Sorption Properties and Wettability of a Nonwoven Polypropylene Material by Direct Gas Fluorination

The effect of direct gas fluorination on the surface properties of a nonwoven polypropylene material was studied. Direct gas fluorination with mixtures of different compositions allows directional variation of the surface properties of the nonwoven polypropylene material. The surface becomes more hydrophobic when using a mixture of fluorine and nitrogen but less hydrophobic when using a mixture of fluorine, oxygen, and nitrogen. The modification leads to changes in the chemical composition of the surface and in the roughness of the material. The nonwoven polypropylene materials thus obtained exhibit increased sorption capacity for spent oil or water, respectively. Variation of the properties of the nonwoven polypropylene material allows expansion of its applications.

     

Oxygen Barrier LDPE/LLDPE/Organoclay Nano-Composite Films for Food Packaging

Summary: This study intends to replace polyethylene multi-layer films used in food packaging industry with single-layer polyethylene nanocomposites films. Nanocomposites of LDPE/LLDPE/ montmorillonite organoclay were prepared by melt compounding in a twin extruder and then film blown to prepare thin films. LLDPE-g-MA was used as compatibilizer to achieve better interaction between the blend and organoclay. Various compositions of organoclay and compatibilizer were prepared. The structure of nanocomposites was characterized by XRD and TEM. Permeability properties were measured using a permeability measuring set-up and aspect ratio of the particles was evaluated using permeability data. The results showed that addition of organoclay even at low level (below 5 phr) had significant effect on barrier properties of the nanocomposites. Oxygen permeability decreased by 50% by adding only 3 phr of nanoclay into the blend. Crystalline structure of the nanocomposites was studied by DSC. Addition of clay also led to increase in melting point and somewhat decrease in the crystalline level. Given the fact that crystals are effectively non-permeable, the concomitant reduction in crystallinity of the blend with decrease in permeability suggests that barrier properties arise from tortuousity of nanoparticles in the blend.     

Solid-state polymerization of long-chain vinyl compounds. I. Effect of molecular arrangement on polymerizability of octadecyl methacrylate

γ-Ray-initiated postpolymerization of octadecyl methacrylate in polymorphic crystals and melt has been investigated to clarify the effect of molecular arrangement of the monomer on polymerizability. From thermal, x-ray, and infrared (IR) analyses this long-chain monomer exhibited three crystalline modifications that we refer to as α-, sub-α, and β-forms. The β-form (mp 28.7–29.7°C), which is obtainable from solution, is a stable state with triclinic chain packing. The α-form (mp 19.5–20.0°C), which is obtained first from the melt but transforms into β-form on storing, is a metastable state with hexagonal chain packing. The sub-α-form appears transiently in α→β transition. The polymerizability of octadecyl methacrylate in the β-form is extremely low, whereas the α-form can polymerize easily and the initial polymerization rate, saturated conversion, and polymer molecular weights increase with temperature. Polymerizability in the molten state at fairly high temperature is rather low, however. Thus maximum polymerizability is obtained just above the melting point of α-form. It has been found that particular orientation and suitable packing mode with some freedom of rotational motion of the monomer molecules in layered structure accelerate the polymerization reaction.     

Thermal and mechanical properties of PE/organoclay nanocomposites

Polyethylene/montmorillonite clay nanocomposites were obtained via direct melt intercalation. The clay was organically modified with four different types of quaternary ammonium salts. The objective of this work is to study the use of montmorillonite clay in the production of nanocomposites by means on rheological, mechanical and crystallization properties of nanocomposites and to compare to the properties of the matrix and PE/unmodified clay nanocomposites. In general, the tensile test showed that the yield strength and modulus of the nanocomposites are close to the pure PE. Apparently, the mixture with Dodigen salt seems to be more stable than the pure PE and PE/unmodified clay.     

高抗冲聚苯乙烯/粘土纳米复合材料的制备、热稳定性及流变性能

用双螺杆挤出共混法制备了高抗冲聚苯乙烯 (HIPS) 有机蒙脱土 (Org MMT)插层纳米复合材料以及HIPS 无机蒙脱土 (MMT)常规复合材料 .分别用TGA和毛细管流变仪研究了它们的热性能与流变性能 ,并比较了两种结构材料的性能差异 .结果表明 ,纳米复合材料比纯HIPS和常规的复合材料具有更好的热稳定性和流动性 ,前者具有更强的剪切变稀行为 .此外 ,当蒙脱土达到纳米级分散时 ,复合材料的表面也变得更加平整光滑 .     

Influence of the layered silicate type on the structure, morphology and properties of cellulose acetate nanocomposites

This paper deals with the effect of different montmorillonite source clays, including pristine and organophilic montmorillonites, on the structure, morphology and properties of cellulose acetate (CA)/clay nanocomposites. In this study, the nanocomposites were prepared by melt extrusion in the presence of the environmentally friendly triethyl citrate plasticizer. The structure and morphology of the materials were analysed by X-ray diffraction and scattering (SAXS), X-ray microtomography and energy filtered transmission electron microscopy (EFTEM). SAXS and EFTEM results indicated that the nanocomposite morphologies were made up of tactoids together with exfoliated clay platelets in different proportions depending on the clay type. It can be concluded that well distributed clay tactoids and platelets can be achieved in CA nanocomposites prepared by melt extrusion and consequently property improvements can be found by using pristine or organophilic clays. In this case, the addition of a plasticizer, able to intercalate in the clay gallery, seems to be sufficient to promote the clay delamination mechanism under shearing inside the cellulose acetate matrix.     

全同立构聚丙烯的晶片形态

本文应用光学显微镜,扫描和透射电子显微镜从三种不同层次的结构水平上研究了α和β两种晶型的全同立构聚丙烯的球晶和晶片形态结构,特别是应用四氧化钌染色技术直接观察到两种不同晶型聚丙烯球晶中单独分离的晶片形态.结果表明,不同晶型聚丙烯球晶的形态是不同的,其所呈现的性质与其内部晶片结构的排列特征相对应.同时研究了两种晶型聚丙烯在熔体拉伸结晶条件下生成的晶片形态,倾向于相同的取向晶片结构.电子衍射数据证明了,β型聚丙烯在拉伸取向结晶时将转变为α晶型.     

Flame Retardant and Smoke Suppressant of Fe‐Organophilic Montmorillonite in Polyvinyl Chloride Nanocomposites

Two kinds of polyvinyl chloride (PVC)/organophilic montmorillonite (OMT) nanocomposites are prepared by a melt intercalation method. This study has been designed to determine if the presence of iron and zinc ions in the structure of montmorillonite (MMT) lattice can affect thermal, flame retardant and smoke suppressant properties. The information about the morphological structure of PVC/OMT nanocomposites was obtained using X-ray diffraction and transmission electron microscopy. The thermal and flame retardant properties of the nanocomposites were characterized by thermogravimetric analysis, limiting oxygen index and smoke density. The nanocomposites based on Fe-OMT exhibit better thermal, flame retardant properties and lower degradation degree than those of pure PVC. The degradation mechanism was studied by pyrolysis, gas chromatography and mass spectrometry (Py-GC-MS).     

新型茂钛催化剂原位本体聚合法制备间规聚苯乙烯/蒙脱土纳米复合材料

采用多碳氨基酸对蒙脱土进行改性 ,得到改性蒙脱土 (MTN) ,并使其层间距扩大 ,在一定条件下用茂金属催化剂Cp Ti(O C6 H4 F) 3 进行苯乙烯原位聚合发现 ,在氨基酸改性的蒙脱土存在下 ,茂金属催化剂活性有所提高 ,能制得间规聚苯乙烯 (sPS) 蒙脱土纳米复合材料 ,考察了蒙脱土用量对配位聚合的影响及该复合材料的形态结构、热稳定性和结晶性能     

Montmorillonite intercalated with polyaminoamide-epichlorohydrin: preparation, characterization, and sorption behavior

Organophilic and cationic montmorillonite is desirable for pitch control in the pulp and paper industry. In this paper, polyaminoamide-epichlorohydrin (PAE)-modified montmorillonite was prepared via either solution intercalation or melt intercalation of polyaminoamide into montmorillonite, followed by the reaction with epichlorohydrin. The modified montmorillonite samples were characterized by FTIR spectroscopy, X-ray diffraction, and thermal gravimetric analysis. The amount of PAE intercalated and the surface charge densities of cationic-modified montmorillonite were determined. It was found that melt intercalation appeared to be more effective in the inclusion of PAE than solution intercalation. However, both solution- and melt-intercalated samples with various surface charge densities exhibited strong affinity toward dispersed colloidal rosin acid.     

MULTIPLE MELTING AND CRYSTALLIZATION BEHAVIOR OF NYLON 1212

The wide-angle X-ray diffraction (WAXD) patterns of isothermally crystallized Nylon 1212 show that γ-form crystals form below 90℃ and the α-form crystals can exist above 140℃. In the temperature range of 90-140℃, the α-form and γ-form crystals coexist. Variable-temperature WAXD exhibits that the nylon 1212 γ-form does not show crystal transition on heating, while α-form isothermally crystallized at 160℃ exhibits Brill transition at a little higher than 180℃ on heating. The multiple melting behaviors of Nylon 1212 isothermally crystallized from melt come from a complex mechanism of different crystal structures, dual lamellar population and melting-recrystallization. In polarized optical microscope (POM) observations, Nylon 1212 isothermally crystallized at 175℃ shows the ringed banded spherulites. However, at temperatures below 160℃ the ringed banded image disappears, and cross-extinct spherulites are formed.     

聚合物-锂改性蒙脱石复合材料离子迁移

以聚合物（ＰＥＯ,ＰＥＯ－ＰＭＭＡ）和锂改性蒙脱石作为主要原料,采用聚合物粉末直接熔融嵌入的方法,制备聚合物－蒙脱石复合材料．利用ＮＭＲ、ＡＣ阻抗等分析方法探讨了复合材料中聚合物链对 Ｌｉ＋离子迁移的影响．结果表明,聚合物（ＰＥＯ）嵌入蒙脱石层间,层间聚合物链的无序度增大,有利于Ｌｉ＋离子迁移．ＰＭＭＡ引入对ＰＥＯ链的改性,进一步加大聚合物链的无序度,更易于层间Ｌｉ＋离子迁移;复合材料的常温离子电导率接近１０－２Ｓ·ｃｍ－１,且具有良好的温度稳定性．     

Preparation of microplastics with polysulfone and montmorillonite by impregnating aramid and glass fibers

Microplastics have been prepared by impregnating aramid and glass fibers with of polysulfone melts of various viscosities unfilled and filled with montmorillonite. A minimum of the melt viscosity has been found at a montmorillonite content of 1 wt %. Radial-transverse impregnation of multifilament fiber by a thermoplastic melt has been studied by the gravimetric method. Introduction into the polysulfone melt up to 1% of the filler at the initial stage of impregnation have almost no effect on the rate of the process; however, a decrease in it is observed as compared subsequently to impregnation with the melt containing no filler. It has been shown that torsional rigidity of microplastics, along with weight change, characterizes the degree of fiber impregnation.     

The influence of a hydrolysis-inhibiting additive on the degradation and biodegradation of PLA and its nanocomposites

A carbodiimide-based additive, intended to stabilize PLA based materials to avoid hydrolytic degradation during processing, was incorporated into a series of PLA and nanofiller containing PLA films. The influence of the additive on the subsequent degradability of the materials was studied under the conditions of melt processing, biodegradation in compost and abiotic hydrolysis. Identical films without the additive were used as reference materials. Adding an anti-hydrolysis agent significantly retarded the decomposition of PLA in all the degradation processes tested. Both biodegradation and the abiotic hydrolysis of the PLA-based materials investigated were substantially retarded. This effect was much less pronounced in a material with organically modified montmorillonite.