Mechanical and rheological behavior of highly filled polystyrene with lignin

The mechanical, rheological, and morphological properties of polystyrene (PS)/lignin blends over a wide range of lignin content (0–80 wt%) have been studied in this work. PS/lignin blends were compounded in an internal batch mixer with and without the addition of a linear triblock copolymer based on styrene, ethylene, and butylene (SEBS). A morphological analysis was carried out by scanning electron microscopy to determine the state of dispersion and the interfacial adhesion between the lignin particles and the PS matrix. It was found that the flexural and torsion moduli both increased, while the tensile properties decreased with increasing lignin content. Nevertheless, compatibilizer addition was found to improve the tensile properties of the lignin/PS blend. The shear rheological behavior of the lignin/PS blends was also studied in this work where viscosity, dynamic moduli, and activation energy were found to be very sensitive to both lignin and compatibilizer contents. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Mechanical behaviour of highly filled lignin/polyethylene composites made by catalytic grafting

Highly filled lignin/polyethylene composites, with enhanced mechanical properties, were studied. Composites are prepared using the catalytic grafting technique of polyethylene on lignin particles. This technique improves wetting and dispersion of additives in the matrix as well as interactions between these two components. Mechanical properties (tensile and impact) and morphology of the composites were measured. The experimental results showed that highly filled HDPE/lignin composites (up to 73 vol%) could be produced by catalytic grafting. Tensile properties of the composites were quantitatively analysed using a micromechanical model for particulate composites based on an energy balance. Model predictions for Young's modulus are in excellent agreement with experimental results. The adjustable parameters of the model were varied from one composite to the other in a way which corresponds to the basic concepts related to particulate composites in general and to catalytic grafting in particular.     

The effect of marine environment on a vinyl ester resin and its highly filled particulate quartz composites

The accelerated effects of immersion in seawater at 60°C, in comparison to distilled water, on a vinyl ester resin and on its highly quartz particles filled system were studied. The studied resin was cured at room temperature for 48 h and postcured at 100°C for 12 h, and the filled system contained 93 wt % quartz particles of a wide size distribution, either as received or silane-treated. The immersion in water results mainly in further curing and some extraction of low molecular substances, as reflected by the flexural mechanical properties and the DSC thermograms. The silane coupling agent treatment of the filler significantly improves the composite properties and its resistance to the water environment. No practical difference was observed in any of the studied systems between the effects of sea and distilled water, as tested by the immersion in boiling water for 48 h. Weatherometer conditions, cycles of ultraviolet radiation at 60°C and water condensate at 50°C, for up to 1000 h, also cause postcuring effects, without extractables' leaching effects. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2229–2234, 1998     

Preparation and properties of some filled poly(vinyl chloride) compositions

Different samples of filled poly(vinyl chloride) (PVC) compositions were formulated from PVC, a polar plasticizer mixture consisting of dioctylphthalate (DOP) and a chlorinated paraffin, and variable proportions of a white filler such as barite, calcium carbonate, kaoline, quartz, or talc; a conductive filler such as High Abrasion Furnace (HAF) carbon black; or a hydrated mineral filler such as aluminium hydroxide, magnesium hydroxide, or calcium hydroxide. Epoxidized soybean oil as a heat stabilizer and sandorin red (BRN) pigment were added. Electrical and mechanical studies show that the incorporation of white fillers produces a plasticized PVC of good electrical insulation character whereas the addition of HAF carbon black produces a sample with some electrical conductivity; both of them have good mechanical properties. Of the hydrated fillers studied aluminium hydroxide has been found to impart the best fire retardancy and good electrical properties for electric wires and cables. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2657–2670, 1999     

Thermal processability and properties of highly filled poly(vinyl alcohol)/talc composite

Abstract

A highly filled PVA/talc composite was prepared through our invented thermal processing technology without using any coupling agent or compatibiliser. The results showed that compared with neat PVA, the melt temperature of the composite decreased and the degradation temperature increased, providing a big temperature window for thermal processing of PVA/talc composite. The composite melt exhibited shear thinning behaviour while its viscosity increased with increasing talc, still satisfied the requirement of thermal processing. The morphology analysis confirmed that talc was well dispersed in PVA, improving heat deflection temperature (HDT), tensile strength and modulus of PVA. When talc was 50 wt-%, the HDT, tensile strength and modulus of the composite were 115°C, 48 MPa, 1·23 GPa respectively, increased by 92, 16 and 150%, compared with PVA, and the elongation at break was 100% of the composite, confirming that the high filled PVA/talc composite was a novel PVA based material with excellent thermal and mechanical properties.     

Dynamic mechanical behavior of highly filled polymers: Dewetting effect

This paper describes the results of simultaneous dynamic measurements in tension and torsion made on propellant samples. The complex dynamic moduli E′, E″, G′, and G″ at low frequencies were determined within a temperature range from room temperature to ?90°C. Time temperature shift factors and reduced master curves for both tension and shear properties are discussed. The effect of dewetting on the dynamic properties in tension and shear was also investigated. A preliminary attempt is made to compute the degree of dewetting in a propellant by applying Beer-Lambert's law.     

Flame retardancy of some ethylene–vinyl acetate copolymer‐based formulations

The combustion behaviour and thermal decomposition of ethylene–vinyl acetate copolymer (EVA) (26 wt% vinyl acetate content) formulations containing alumina trihydrate, ammonium polyphosphate, melamine, pentaerythritol and their co‐mixtures, were studied using cone calorimetry and thermogravimetric analysis. Formulations containing ammonium polyphosphate burned with the formation of intumescent carbonaceous chars, with EVA acting as a carbonization agent. EVA materials containing ammonium polyphosphate (20 wt%), with a sufficient amount of alumina trihydrate or melamine, were superior to the non‐intumescent alumina trihydrate and melamine containing formulations in terms of the heat release rate, mass loss rate and smoke production. Melamine showed some smoke suppressant effect and significant CO reducing properties. However, the melamine–EVA and melamine–alumina trihydrate–EVA showed a very high heat release rate. Thermogravimetric studies showed that oxygen played a favourable role in enhancing the char formation by encouraging active participation of the polymer matrix in the interaction with polyphosphoric acid. Copyright © 2000 John Wiley & Sons Ltd.     

低相对分子质量PBA在PVC中的增塑作用研究

以己二酸和1,4丁二醇为原料,通过熔融缩聚法制备一系列不同特性黏度的低相对分子质量聚己二酸1,4丁二醇酯(PBA)。将低相对分子质量PBA作为增塑剂用于聚氯乙烯(PVC)中, 通过测定其玻璃化转变温度(Tg)、拉伸强度、断裂伸长率、极限氧指数和液相迁出,研究不同特性黏度的低相对分子质量PBA的增塑效率。结果表明,当添加量为30份时,PVC/PBA的Tg低于PVC/邻苯二甲酸二辛酯(DOP),并随着特性黏度的增加而增加;特性黏度为0.115 dL/g的PBA加入PVC时具有最佳断裂伸长率,可达271.9 %,优于加入同等量的DOP体系;此外PBA液相迁出率随特性黏度的增加而降低,最低几乎为零;且PVC/PBA比PVC/DOP具有更好的热稳定性和阻燃性。     

Performance of Di-n-Hexyl phthalate in flexible vinyl formulations

Low-molecular-weight esters have been available to the PVC compounder for many years. They have found a significant niche in the performance vs. permanence compromise as a compound ingredient that provides manufacturing efficiency or some special property with adequate permanence for many vinyl applications. In many respects, low-molecular-weight esters are the processing aids of the plasticizer family. This group of plasticizers may be said to include C₄ to C₇ dialkyl phthalates, the benzyl phthalates and the benzoic acid esters. This paper will introduce and compare di-n-hexyl phthalate (DNHP) to other phthalates against which it will directly compete.     

Replacing 100% of phenol in phenolic adhesive formulations with lignin

Lignin, produced as a byproduct of pulp and paper and bioethanol industries, is a polyphenolic compound that has excellent potential to be used as phenol replacement in phenolic adhesive formulation. In this study, the phenol portion of phenol formaldehyde (PF) resin has been replaced by an agricultural‐based lignin, which was produced as a byproduct of a cellulosic bioethanol process through dilute‐acid pretreatment and enzymatic hydrolysis from corn stover. The PF resol resin was formulated using isolated lignin under alkaline condition. Chemical, physical, and thermal properties of the isolated lignin, PF resin and adhesive were measured using advanced analytical techniques such as Fourier transformed infrared spectroscopy (FTIR), size exclusion chromatography (SEC), phosphorous nuclear magnetic resonance spectroscopy (³¹P NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The developed 100% lignin‐based adhesive and a commercially formulated phenol resorcinol formaldehyde (PRF, as reference) were used to prepare single‐lap‐joint samples for mechanical testing. The plywood samples were pressed under exactly the same conditions (time, temperature, and pressure) as what recommended for the commercial PRF formulation. According to two‐way ANOVA results, statistically there was no significant difference between the shear strengths of plywood samples made with 100% lignin‐based adhesive and those made with the commercial PRF resin. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45124.     

Extrusion of highly filled flexible polymer sheet

Highly-filled polymer systems include color masterbatches, feedstocks for powder injection molding, and rigid sheets with high levels of flame retardants, but they have not been explored for flexible sheet. This work investigated the (a) selecting a polymer matrix with enough melt strength and flexibility to form a stable sheet with high filler loading, (b) the maximum achievable filler loading for the sheet, and (c) optimizing the process of extruding a highly-filled flexible polymer system. Extrusion grade low-density polyethylene (LDPE) provided sufficient flexibility and permitted a maximum filler loading of 36 vol% (~78 wt%). Good dispersion of the nanoparticle filler, however, required two passes through multiple screw extruders and a small reduction in the viscosity of the LDPE. Sheet with thickness of 415 μm, surface roughness of <1 μm, and sufficient flexibility was extruded continuously at a rate of 10 m/min., but it required a more traditional coat hanger manifold to prevent filler hang up in the sheet die. The filler particles were distributed uniformly through the core and skin of the sheet, giving the sheet good mechanical properties.     

Rheological behavior of highly filled polymer melts

The rheological behavior of highly filled polymer melts has been examined. At concentrations near the maximum packing fraction, strain-dependent behavior was observed at strains as low as 1 percent. Selected surface treatments were shown to reduce particle agglomeration. This produced composite melts with lower viscosities and higher maximum loadings. While η* – ω plots provide information on the shear strength of the interparticle network, G′ – ω plots show evidence of phase separation.     

Melt viscosity of poly(vinyl chloride) formulations

Commercial, suspension-type PVC resin, poly (vinyl chloride), molecular weight M_w × 10^?4 = 8.6 ± 0.9, polydispersity M_w/M_n = 2.26, was mixed with plasticizer di(2-ethyl hexyl)phthalate (DOP) and organo-tin stabilizer in four different proportions. The mixtures were milled and pressed into sheets for testing. The polymer content in these samples was 97, 80, 60, and 40 wt percent. The viscoelastic properties of the materials were investigated using a Weissenberg rheogoniometer in a cone-and-plate, steady-state shearing mode. The viscosities and primary normal stress difference coefficients were measured at shear rates of 10^?2 ≤ \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} (sec^?1) ≤ 10² and at temperatures from 151 to 246°C. The zero shear viscosities, plotted as log η₀ vs 1/T (T is the absolute temperature) did not follow either a straight line dependence, reported for PVC melts at low shear rates at 170–190°C, nor was any discontinuity found near 195°C as by others; the data follows a continuous concave curve. The apparent activation energy of flow increases steeply with decreasing temperature. The data can be represented by a WLF type of equation, but the magnitudes of the parameters of this relation differ from expected values. A crossplot of log η₀ (T = const.) vs log w (where w is the polymer content) also demonstrates a faster increase of η₀ with w than expected from the straight line dependence. The primary normal stress difference coefficient was found to increase with w and decrease with T, paralleling the observed dependencies of η₀.     

Highly filled polyolefin plastomer formulations for possible PVC replacement in flooring

Calcium carbonate highly filled composites of a polyolefin plastomer (POP), and its blends with postconsumer linear low‐density or high‐density polyethylene (PC‐LLDPE or PC‐HDPE) were prepared and evaluated. The mechanical properties of compounded POP and its blends were compared with those of a PVC–calcium carbonate formulation used for flooring applications. Tensile and impact properties of calcium carbonate‐filled POP composites compare very favorably to the PVC‐based formulation at filler loadings as high as 200 phr. Moreover, postconsumer LLDPE or HDPE can replace at least 50% of the POP in these composites without affecting their main properties. DSC analyses indicate that the synergism occurring in mechanical properties for some of the blend compositions, may be related to the ability of the individual polymers to cocrystallize in the respective blends. This article presents the results of a preliminary study. Continued research is expected to contribute toward a complete characterization of the compounded POP/postconsumer PE blends to establish if they can replace plasticized PVC compounds in some or all flooring applications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1156–1168, 1999     

Irradiation of highly oriented polyethylene fibers in the atmosphere of some vinyl monomers: Effect on compressive strength

Highly oriented polyethylene fibers have been modified by γ‐irradiation in the presence of some vinyl monomer vapors, followed with further annealing in the atmosphere of the same monomer. Two types of vinyl monomers that are known to produce polymers with different glass transition temperatures, namely methyl methacrylate and vinyl acetate, were studied for their effect on the compressive strength of the fiber. It was found that a significant improvement in compressive strength, measured by tensile recoil test, was obtained. The level of improvement was affected by heat treatment and the presence of monomer during irradiation. Modification with vinyl acetate was found to be more effective than methyl methacrylate. These facts suggest that the improvement in compressive strength was attributable to several factors, including structural relaxation, the presence of graft copolymer, and energy dissipation ability of the graft copolymer. It is speculated that lateral integrity of the fiber is one of the key factors that prevents sliding of microfibril and possibly lateral or circumferential expansion of the fiber to accommodate kink band. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2494–2502, 2001     

Plasticization of poly(vinyl butyral) by water: Glass transition temperature and mechanical properties

The effect of plasticization by water on the mechanical properties of additive-free poly(vinyl butyral) (PVB) was investigated. PVB is hygroscopic and the amount of absorbed water was measured in various environmental conditions. Two kinds of interactions with hydrophilic sites was demonstrated. The thermal and thermomechanical studies (differential scanning calorimetry and dynamic mechanical thermal analysis) showed that water decreases the glass transition temperature thus acting as a plasticizer. This gives the material larger deformation capability and increased toughness. Surprisingly, the modulus remains high and this was explained by a structure consisting in two phases with different levels of plasticization, reflected by a double peak of relaxation associated to multiple phases with different glass transition temperature. Atomic force microscopy measurements on samples with high level of hydration shows evidence of nanometric hydrated domains acting as an elastomeric phase and thus inducing toughening of the material. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47230.     

Structure and properties of highly filled poly (vinyl alcohol)/talc composites prepared through thermal processing: effects of talc size

Poly (vinyl alcohol) (PVA), a multi-hydroxyl polymer with excellent comprehensive properties, is an expected candidate to prepare high-performance polymer-based composites without using any coupling agents or compatibilisers. However, the poor thermal processability of PVA is its biggest obstacle. In this paper, by adopting polyol as a plasticiser, highly filled PVA/talc composites with good mechanical properties were successfully obtained through melt extrusion and injection, and the effects of talc size on structure and properties of the composites were studied. The results showed that talc highly filled PVA composites had satisfying melt processability, and the decrease of talc particle size increased the –OH groups on the edges of the talc layers, thus improving the compatibility between talc and PVA, and making talc particles dispersed more uniformly in PVA matrix. As a result, the composites with smaller talc particles had the higher threshold filler concentration to form the filler networks and the better flow behaviour. The smaller talc flakes also exhibited higher orientation in PVA matrix and induced more PVA molecular chains to orient along the melt flow direction, leading to the enhancement of the mechanical properties of the composites.     

Molecular composite of lignin: Miscibility and complex formation of organosolv lignin and its acetates with synthetic polymers containing vinyl pyrrolidone and/or vinyl acetate units

Binary blends and pseudo-complexes of organosolv lignin (OSL) or its acetate (OSL-Ac) with synthetic polymers including poly(vinyl acetate) (PVAc), poly(N-vinyl pyrrolidone) (PVP), and poly(N-vinyl pyrrolidone-co-vinyl acetate) (P(VP-co-VAc)) were prepared by casting from mixed polymer solutions in N,N-dimethylformamide as good solvent and by spontaneous coprecipitation from solutions in tetrahydrofuran (THF) as comparatively poor solvent. Thermal analysis by differential scanning calorimetry showed that OSL was not miscible with PVAc; however, OSL(-Ac) was miscible with PVP to form homogeneous blends irrespective of the degree of acetylation of OSL. OSL formed homogeneous blends with P(VP-co-VAc) with ≥30 mol % of VP contents. Fourier transform infrared spectra measurements for the miscible blends of OSL/PVP revealed the presence of hydrogen bonding interactions between hydroxyls of OSL and carbonyls of VP units. However, there was no evidence for the development of the hydrogen bonding in miscible blends of fully acetylated OSL with PVP. For complexes via THF solutions, its formation was found to be primarily due to a higher frequency of hydrogen bonding interactions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

淀粉的塑化研究进展

淀粉具有良好的生物降解性能,但淀粉分子中含有大量的羟基,存在较强的氢键,使得淀粉不宜直接用熔融法热塑挤出加工,因此淀粉的塑化是淀粉塑料生产的关键。对以加入增塑剂的热塑性增塑方法进行了综述,并进一步探讨了淀粉塑化的机理。