Decoupling the effects of screw speed and particle surface functionality on the filler suspension state in PBS/fumed silica nanocomposites

This work assessed the relative effects of processing conditions and interfacial interactions on the structure and properties of PBS/fumed silica nanocomposites. Rheology and scattering were used to investigate the dispersion state of silica particles with different surface treatments in nanocomposites produced by ultra‐high speed twin‐screw extrusion. Structural parameters of the silica, such as fractal dimension and Fisher exponent, were estimated by low‐frequency rheology responses and lower q scattering data. This study demonstrates that both decreased bulk polymer properties and improved filler suspension caused by high shear compounding determine the final properties of these PBS based nanocomposites. While the molecular weight of bulk polymer matrix was significantly reduced, the extreme shear increased the probability of forming percolated clusters, leading to remarkable reinforcement (up to 4000%) as evidenced by the low‐frequency rheological response. Further, the improvement in dispersion was enhanced when the filler was functionalized with a compatibilizing surface treatment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1820–1828     

Effect of Surface Treatment of Titanium Dioxide Nanoparticles on Non-Isothermal Crystallization Behavior,Viscoelastic Transitions and Cold Crystallization of Poly(Ethylene Terephthalate) Nanocomposites

The effect of untreated and tri-n-octylphosphine oxide (TOPO) surface-treated TiO₂ nanoparticles when included as filler in poly(ethylene terephthalate) on its compatibility, non-isothermal crystallization behavior, viscoelastic transitions and cold crystallization has been studied. The effectiveness of the surface treatment has been studied using infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA). The effect of the untreated and surface-treated nanofiller content in the polymer, added by an extrusion process, on the non-isothermal crystallization has been studied by differential scanning calorimetry (DSC). The influence on the viscoelastic transitions and cold crystallization of PET nanocomposites has been studied through thermomechanical analysis (TMA). The surface treatment and the concentration of nanofiller influence the non-isothermal crystallization behavior, the viscoelastic transitions and the cold crystallization of the PET nanocomposites, enables us to evaluate the compatibility and the level of dispersion/aggregation of the nanofiller in the poly(ethylene terephthalate).     

Plasma polymerization of acetylene onto silica: an approach to control the distribution of silica in single elastomers and immiscible blends

Surface modification of silica by acetylene plasma polymerization is applied in order to improve the dispersion in and compatibility with single rubbers and their blends. Silica, used as a reinforcing filler for elastomers, is coated with a polyacetylene (PA) film under vacuum conditions. Water penetration measurements show a change in surface energy due to the PA‐film deposition. The weight loss measured by thermo‐gravimetric analysis (TGA) is higher for the PA‐coated silica compared to the untreated filler, confirming the deposition of the PA film on the silica surface. Time of flight‐secondary ion mass spectrometry (ToF‐SIMS) shows the well‐defined PA cluster peaks in the high mass region. Scanning electron microscopy (SEM) measurements show silica aggregates, coalesced by the coating with smooth and uniform surfaces, but without significant change in specific surface area. Elemental analysis by energy dispersive X‐ray spectroscopy (EDX) measurements also confirms the deposition of the polymeric film on the silica surface, as the carbon content is increased. The performance of single polymers and their incompatible blends based on S‐SBR and EPDM, filled with untreated, PA‐ and silane‐treated silica, is investigated by measurements of the bound rubber content, weight loss related to bound rubber, cure kinetics, reinforcement parameter, Payne effect, and mechanical properties. The PA‐ and silane‐modified silica‐filled pure S‐SBR and EPDM samples show a lower filler–filler networking compared to the unmodified silica‐filled elastomers. Decrease in the reinforcement parameter (α_F) for the plasma‐polymerized silica‐filled samples also proves a better dispersion compared to silane‐modified and untreated silica‐filled samples. On the other hand, the PA‐silica‐filled samples show a higher bound rubber content due to stronger filler–polymer interactions. Finally, the PA‐silica‐filled pure EPDM and S‐SBR/EPDM blends show high tensile strength and elongation at break values, considered to be the result of best dispersion and compatibilization with EPDM. Copyright © 2008 John Wiley & Sons, Ltd.     

Improvement of properties of silica‐filled styrene‐butadiene rubber composites through plasma surface modification of silica

The performance of plasma surface modified silica filler in styrene‐butadiene rubber (SBR) matrix has been analyzed. The conditions of plasma modification have been optimized by taking secant modulus as a standard parameter and the occurrence of the modification has been confirmed by surface area determination and Fourier transform infrared spectroscopy. The plasma‐modified surface of silica has been found to be composed of carbon–carbon double bonds and carbon–hydrogen bonds. Silane treatment also has been carried out on silica filler surface for a comparative assessment of its influence in the curing behavior and filler–rubber interaction. The cure reactions of all the rubber compounds have been found to be proceeded according to first‐order kinetics. A reduction in the cure reaction rate constant has been observed with the loading of unmodified and surface modified silica, emphasizing the cure deactivation of the matrix rubber by the silica filler. The filler dispersion, as revealed by scanning electron microscopy, has been found to be greatly improved by the plasma as well as silane treatment. The filler–rubber interaction has been found to be greatly improved by both surface treatments, but the best balance of mechanical properties has been observed with plasma surface modification only. Copyright © 2004 John Wiley & Sons, Ltd.     

Conductive polymer composites (CPC): influence of processing conditions,shear rate and temperature on electrical properties of poly(butylene terephthalate)/poly(amide12-b-tetramethyleneglycol) – carbon black blends

Conductive Polymer Composites (CPC) have been obtained by blending two immiscible polymers, poly(butylene terephthalate) (PBT) and poly(amide12-b-tetramethyleneglycol) (PEBAX) with carbon black (CB). The extrusion process allows to obtain anisotrope co-continuous structures of various morphologies depending on composition and experimental conditions. It is possible to enhance CPC conductivity with appropriate processing temperature (T_p) and screw speed (Ω), without changing the composition of the blend. The best results are obtained with Ω =5 rpm and T_p=260°C. PBT/PEBAX-CB resistivity evolution with T_p and Ω doesn't follow a linear law as expected from previous studies with poly(butylene terephthalate)/poly(ethylene)-CB and poly(butylene terephthalate)/poly(ethylene-co-ethyl acrylate)-CB systems. CB distribution has a more important impact on conductivity than polymers phase morphology. A good control of these parameters is essential to reproduce and optimize electrical properties.     

Effects of filler type and processing apparatus on the properties of the recycled “ light fraction” from municipal post‐consumer plastics

Plastic waste or scraps are generated from two main sources: industrial wastes and post‐consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post‐consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post‐consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous mixer, single and twin screw extruder—on the properties. Although the similar chemical nature of the two main components, polyethylene and polypropylene of the light fraction, the mechanical properties of the recycled mixture are quite scarce, mainly because of the incompatibility and the possible presence of some heterogeneous particles. The recycling of the light fraction can significantly change the properties of the polymer system because of the thermomechanical stress and of the residence time during processing. The adding of the three fillers type leads to an increase of the thermomechanical and of some of the mechanical properties. The elastic modulus increases with the three fillers; in particular, glass fibres show the best results. The effect of the three fillers is quite similar for tensile strength, elongation at break and impact strength. The adding of inert filler strongly improves the rigidity of light fraction from municipal post‐consumer plastics. Copyright © 2001 John Wiley & Sons, Ltd.     

Payne effect in silica‐filled styrene–butadiene rubber: Influence of surface treatment

The nonlinear effect at small strains (Payne effect) has been investigated in the case of silica‐filled styrene‐butadiene rubber. The originality of this study lies in the careful preparation of samples in order to fix all parameters except one, that is, the modification of the silica surface by grafting silane (introduced at different concentrations) via reactive mixing. The organosilane can be either a coupling or a covering surface treatment with an octyl alkyl chain. A careful morphological investigation has been performed prior to mechanical characterization and silica dispersion was found to be the same whatever the type and the amount of silane. The increasing amount of covering agents was found to reduce the amplitude of the Payne effect. A similar decrease is observed for low coupling agent concentration. At higher concentrations, the evolution turns through an increase due to the contribution of the covalent bonds between the matrix and the silica acting as additional crosslinking. The discussion of the initial modulus was done in the frame of both the filler–filler and filler–polymer models. It is unfortunately not possible to distinguish both scenarios, because filler–filler and filler–matrix interactions are modified in the same manner by the grafting covering agent. On the other hand, the reversible decrease of the modulus versus strain (Payne effect) is interpreted in terms of debonding of the polymeric chains from the filler surface. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 286–298, 2007     

同向啮合双螺杆挤出机挤出过程的计算机模拟

计算机模拟研究了聚苯乙烯在TSE-35A型同向啮合双螺杆挤出机的挤出过程.计算得到不同喂料速率与不同转速下的停留时间分布,并与在线荧光法测量值对比,二者基本相符.确定了停留时间与螺杆转速及喂料速率之间的函数关系式.模拟结果还预测了喂料速率、螺杆转速等工艺参数对双螺杆内流场变量,如温度、填充率、压力及粘度等的影响.模拟计算有助于了解双螺杆挤出机内部聚合物材料流动状态及停留时间长短,从而指导实际聚合物生产.     

Analysis and evaluation of biobased polyester of PTT/PBAT blend: thermal,dynamic mechanical,interfacial bonding,and morphological properties

Novel blends were prepared from biobased poly(trimethylene terephthalate) (PTT) and poly(butylene adipate‐co‐terephthalate) (PBAT) using a twin screw extrusion process as a function of different weight ratios. Thermal stability, mechanical, and interfacial properties of PTT/PBAT blends were investigated using a thermogravimetric analyzer and mechanical analyzer. Phase behavior and surface morphology of the blends were characterized using scanning electron microscopy. Interfacial bonding value of the PTT/PBAT blend was evaluated from the Pukanszky empirical relationship. Viscoelastic properties of PTT/PBAT blends were investigated using the dynamic mechanical analyzer. PTT/PBAT blend exhibited higher thermal stability than the neat PTT matrix. The entire blend showed better interfacial adhesion between the matrixes. Storage and loss modulus of the PTT/PBAT blend reduces with increasing PBAT content. PTT/PBAT blend exhibited higher impact energy than the neat PTT matrix, because of its flexible and amorphous nature of PBAT polymer and increasing toughness. Copyright © 2016 John Wiley & Sons, Ltd.     

A study on the surface free energy of modified silica fillers and poly(ethylene terephthalate) fibers by inverse gas chromatography

The surface free energy of modified silica fillers and poly(ethylene terephthalate) (PET) fibers was analyzed by inverse gas chromatography in order to investigate the relationship between their surface characteristics and the performance of the composite formed from these materials. The adsorption isotherms of n-heptane and 1-propanol were determined by the elution-peak-maximum method. The dispersive and polar components of the surface free energy were determined by use of the Young–Dupré equation and the Fowkes equation on the basis of the saturated spreading pressure derived from the Gibbs adsorption equation. The acidity and the basicity of the surface were estimated by the specific retention volume of each probe molecule with different donor number and acceptor number. It was found that the dispersive component of the surface free energy for modified silica fillers was mostly lower than that for original silica filler. The polar component of the surface free energy for ethylene glycol modified silica filler became large, while that for n-butanol modified silica filler decreased remarkably. It was also found that original silica filler exhibited high acidity, while modified silica fillers exhibited low acidity. Although these methods have been applied to PET fibers, the surface free energy could not be determined quantitatively because of the surface change during the pretreatment of PET fibers. It was observed that the polar component of the surface free energy decreased when the pretreatment was made at a temperature higher than the glass-transition temperature of PET. It became clear that the interaction between modified silica fillers and PET fibers correlated well with the basicity of the fillers, but not with their acidity. Received: 18 October 1999 Accepted: 8 February 2000     

The influence of non-rubber constituents on performance of silica reinforced natural rubber compounds

An in-rubber study of the interaction of silica with proteins present in natural rubber show that the latter compete with the silane coupling agent during the silanisation reaction; the presence of proteins makes the silane less efficient for improving dispersion and filler–polymer coupling, and thus influences the final properties of the rubber negatively. Furthermore, the protein content influences the rheological properties as well as filler–filler and filler–polymer interactions. Stress strain properties also vary with protein content, as do dynamic properties. With high amounts of proteins present in natural rubber, the interactions between proteins and silica are able to disrupt the silica–silica network and improve silica dispersion. High amounts of proteins reduce the thermal sensitivity of the filler–polymer network formation. The effect of proteins is most pronounced when no silane is used, but they are not able to replace a coupling agent.     

Effect of silane coupling agent on the polymer‐filler interaction and mechanical properties of silica‐filled NR

The effects of filler loading and a new silane coupling agent 3‐octanoylthio‐1‐ propyltriethoxysilane (NXT silane) on the polymer‐filler interaction and mechanical properties of silica‐filled and carbon black‐filled natural rubber (NR) compounds were studied. Silica (high dispersion silica7000GR, VN2, and VN3) and carbon black (N330) were used as the fillers, and the loading range was from 0 to 50 phr. The loading of NXT silane was from 0 to 6 phr. Experimental results show that the maximum and minimum torques of silica and carbon black‐filled NR increase with increasing filler loading. With increasing filler loading, the scorch time and optimum cure time decrease for carbon black‐filled NR, but increase for silica‐filled NR. The minimum torque, scorch time, and optimum cure time decrease because of the presence of NXT silane. For the carbon black and silica‐filled NR, the tensile strength and elongation at break have maximum values, but the hardness, M300, M100, and tear strength keep increasing with filler loading. The mechanical properties of silica‐filled NR were improved in the presence of NXT silane. With increasing filler loading, the storage modulus of filled NR increases, but the loss factor decreases. Carbon black shows the strongest polymer‐filler interaction, followed by VN3, 7000GR, and VN2. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 573–584, 2005     

Surface modification of fine colloidal silica with copolymer silane-coupling agents composed of maleic anhydride

The reactivity of copolymer silane composed of maleic anhydride in the modification of fine colloidal silica was studied. The reaction of colloidal silica of 10 and 45-nm diameter with trimethoxysilyl-terminated poly(maleic anhydride-co-styrene) [P(MA-ST)] and poly(MA-co-methyl methacrylate) in tetrahydrofuran resulted in effective surface modification without particle aggregation. From the results that the reaction using the polystyrene silane of low molecular weight led to partial aggregation, it was suggested that the steric interaction between relatively rigid copolymer chains having a maleic anhydride moiety adsorbed on the silica prevented the aggregation in the reaction. The ²⁹Si cross-polarization magic-angle-spinning NMR spectra of P(MA-ST)-modified silica showed that the polymer silane was bound to the silica surface by the direct reaction with silica hydroxyl groups and via the polymerization. Received: 27 June 2001 Accepted: 6 September 2001     

Encapsulation of Inorganic Particles by Dispersion Polymerization in Polar Media: 2. Effect of Silica Size and Concentration on the Morphology of Silica–Polystyrene Composite Particles

Following a previous work (Bourgeat-Lami, E., and Lang, J.,J. Colloid Interface Sci.197, 293 (1998)), encapsulation of silica beads has been achieved by dispersion polymerization of styrene in an aqueous ethanol medium using poly(N-vinyl pyrrolidone) as stabilizer. Silica beads, prepared according to the Stöber method, were coated prior to polymerization by grafting 3-(trimethoxysilyl)propyl methacrylate onto the surface. A great number of silica beads per composite particle were previously found using beads that had diameters between 49 and 120 nm. In the present work, larger silica beads with diameters between 191 and 629 nm are investigated. We demonstrate by transmission electron microscopy that, consequently, only a small number of silica beads are contained in the composite particles. By counting the composite particles containing precisely zero, one, two, three, four, and more than four silica beads, it clearly appears that the encapsulation of only one silica bead can be obtained simply by increasing the size of the beads. Under our experimental conditions, the optimal bead diameter for achieving composite particles containing only one silica bead turns out to be around 450 nm. We show that increasing the silica bead size above this value results in an increased number of composite particles without silica beads. In contrast, the number of composite particles with two, three, four, or more than four silica beads increases with decreasing silica bead size. In addition to the above variations in composition of the composite particles, changes in particle shapes were also observed as a function of the size of the silica beads and the styrene concentration in the polymerization medium. Hypotheses concerning these variations are presented.     

Comparison of reinforcing efficiency between Si-69 and Si-264 in a conventional vulcanization system

Silica has long been recognized as a reinforcing filler, especially for light colored products. The degree of reinforcement is noticeably increased when silica is used in combination with silane coupling agent. Therefore, various types of silane coupling agents are now commercially available. In the present study, two types of silane coupling agents, e.g., bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) and 3-thiocyanatopropyl triethoxy silane (Si-264) were selected for comparison of their reinforcing efficiency in a conventional vulcanization (CV) system. The results reveal that the addition of silane coupling agent not only improves compound processability, but also enhances the mechanical properties of the rubber vulcanizates. Compared with Si-69, Si-264 gives rubber compounds with better processability due to its greater ability to promote filler dis-agglomeration during mixing. In addition, Si-264 also imparts a greater degree of reinforcement. This might be attributed to the combined effects of better rubber–filler interaction, better filler dispersion and higher state of cure which are obtained when Si-69 is replaced with Si-264. The dynamic properties of the rubber vulcanizates are also improved with the presence of silane coupling agent. In this aspect, Si-69 performs better than Si-264 as it provides rubber vulcanizates with lower heat build-up.     

Characterization of the reactivity of a silica derived from acid activation of sepiolite with silane by 29Si and 13C solid-state NMR

The mechanism of the reaction between a silica sample coming from acid treatment of sepiolite (denominated Silsep) and an organosilane, namely bis(triethoxysilylpropyl)tetrasulfane (TESPT), has been evaluated by solid state NMR spectroscopy, being compared with the silanization reaction of a commercial silica. The effect of the silane concentration and temperature on the course of the reaction was considered. Experimental results indicate that the silanization reaction is more effective in the case of Silsep, favoring both the reaction of silane molecules with the filler surface and the reaction between neighboring silane molecules. This different behavior is attributed to structural factors, moisture, and number of acid centers on silica surface. Environmental scanning electron microscopy (ESEM) was used to deposit micrometric water drops on the surface of these samples and to evaluate the proportion and distribution of the organophylization process.     

3-己酰基硫代-1-丙基三乙氧基硅烷的合成及其在SSBR/SiO2复合体系中偶联效果研究

以γ-巯丙基三乙氧基硅烷与己酰氯为单体,在N2保护与低温下合成偶联剂3-己酰基硫代-1-丙基三乙氧基硅烷(HXT),将HXT与双-(3-乙氧基硅基丙基)二硫化物(TESPD)分别添加于溶液聚合丁苯橡胶(SSBR)/SiO2混炼胶复合体系中.采用流变学方法表征复合体系的动态粘弹行为,发现HXT可改善填料和基体的相互作用,有效阻止SiO2粒子在加工过程中的团聚.与TESPD相比较,含HXT体系具有较高“Payne效应”临界应变值.     

高分散性SiO2/PMMA复合材料的制备与表征——纳米SiO2在MMA中的分散

用硅烷偶联剂3-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPS)对分散于乙醇中的纳米SiO2进行偶联改性,再通过介质置换和原位本体聚合制得SiO2/甲基丙烯酸甲酯(MMA)单体分散液和SiO2/PMMA复合材料.红外光谱分析(FTIR)和热重分析(TG)结合洗提实验考察了SiO2表面MPS的偶联率和偶联效率,透射电镜(TEM...     

Crystallization of poly(ethylene terephthalate) induced by inorganic compounds. I. Crystallization behavior from the glassy state in a low-temperature region

The kinetics of isothermal crystallization from the glassy state at low temperatures and the morphology of poly(ethylene terephthalate) (PET) filled with additives are reported. Talc, kaolin, silicon oxide, and titanium oxide have been used as fillers; they act as effective nucleating agents for PET. The overall rate of crystallization depends on the volume concentration, the size distribution, and the nucleating ability of the additives. An electron microscopic study reveals a transcrystalline morphology at the surface of the filler particles. The occurrence of transcrystallinity is attributed to extensive heterogeneous nucleation induced at the filler surface. From the shape of the crystallization isotherms, it can be concluded that the crystallization mechanism depends on the type of filler.     

Preparation and Characterization of PET/LDH or Clay Nanocomposites through the Microcompounding Process

Thermally stable modifier were used to modify clay or lithium aluminum layered double hydroxides (LiAl LDH) nanoparticles for preparation of poly (ethylene terephthalate)/clay or LiAl LDH nanocomposites. The effect of modify agent, studied by microcompouding process. The PET nanocomposites which were made by twin‐screw microcompounder dispersion morphology of inorganic layered materials in nanocomposites could be explained by wide‐angle X‐ray diffraction (WXRD), and transmission electron microscopy (TEM). Nanocomposite also formed the better mechanical, UV resistance, and gas barrier properties. Optical properties and crystallization behaviour of these new types of nanocomposites are investigated in this paper.