填料对双组分缩合型室温硫化硅橡胶性能的影响

考察了多种补强填料和半补强(或增量)填料如硅藻土、碳酸钙和氧化铝等对室温硫化(RTV)硅橡胶的机械性能和介电性能的影响。结果表明,采用经六甲基二硅氮烷处理的气相法白炭黑或沉淀法白炭黑作填料时,RTV硅橡胶多方面的性能都有所提高;采用补强填料和半补强填料并用的RTV硅橡胶的性能优于使用单一补强填料的RTV硅橡胶;随着填料用量的增加,RTV硅橡胶的机械性能、相对介电常数和介质损耗因数都有一定程度的提高,但体积电阻率有所降低。     

Effect of blend ratio and compatibilisation on the electrical and dielectric properties of nylon copolymer (6, 66)/EPDM rubber blends

In this work, morphological, electrical, and dielectric performance of nylon copolymer (PA6, 66)/ethylene propylene diene rubber (EPDM) blends were systematically studied with reference to blend ratio and compatibilisation. As the concentration of PA6, 66 and the percentage of compatibiliser in the blend increases the resistivity values decreases. The existence of two phases, PA6, 66 and EPDM with different conductivity and interfacial polarization are responsible for the increase in the dielectric properties of the blends. Compatibilisation of the blends improved the dielectric constant of the blend system. Addition of 2.5% of compatibiliser gave the highest value of dielectric constant. At a high concentration of EPM‐g‐MA, the polarity of the compatibilised blends was found to be increased, which resulted in the substantial increase in the value of loss and dissipation factor. The dielectric values of the blends were correlated with blend phase morphology. Finally the experimental data was compared with various theoretical predications. POLYM. ENG. SCI., 59:2195–2201, 2019. © 2019 Society of Plastics Engineers     

Blended graft copolymer of carboxymethyl cellulose and poly(vinyl alcohol) with banana fiber

Conducting hydrogel copolymer was prepared by graft copolymerization of carboxymethyl cellulose (CMC) and boric acid onto poly(vinyl alcohol) (PVA). The dielectric properties of CMC‐g‐PVA/prehydrolyzed banana blend have been investigated as a function of frequency, with special reference to pure prehydrolyzed banana. Also, the static bending for the blend was determined and no abrupt failure was observed. The dielectric properties measured were dielectric constant (ε′), dissipation factor (tan δ), and loss factor (ε″). At high frequencies, a transition in the relaxation behavior was observed, whereby the dielectric constant, loss tangent, and loss factor decreased with frequency. Experimental ε′ values of the blend are greater than those of prehydrolyzed banana. The dielectric behavior depends greatly on the nature of the present group, the crystallinity of the system, and the degree of hydrogen bonding between the different chains. The variation of the dielectric properties was correlated with blend morphology and also to the possibility for interfacial polarization that arises because of the differences in conductivities of the two phases. It was found from the infrared spectra that the incorporation of CMC‐g‐PVA copolymer decreases the crystallinity of the blend and also decreases the degree of hydrogen bonding, which results in a high dielectric constant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1842–1848, 2006     

Electrical and mechanical properties of ethylene propylene diene monomer–chloroprene rubber blend loaded with white and black fillers

The permittivity ε′ and dielectric loss ε" for different ratios of an ethylene propylene diene monomer (EPDM)–chloroprene rubber (CR) blend ranging from 0 to 100 phr were measured over a frequency range from 400 Hz to 60 kHz. The measurements were carried out at room temperature (25°C). The values of ε′ and ε" were found to decrease with increasing EPDM content in the EPDM–CR blend. The sample which possesses the best mechanical and electrical properties was a 50 EPDM–50 CR blend. This sample was chosen to be loaded with 40 phr of some white fillers, namely, calcium carbonate, silica, silitan z, and talc. From the electrical and mechanical investigations, it was found that the use of silica and calcium carbonate in these blends could improve these properties. The electrical and mechanical properties were also studied for the investigated blends loaded with both silica and calcium carbonate with different contents (10–40 phr). It was found that 20 phr is the most promising concentration which can possess better properties. The same trend was obtained by the addition of 20 phr SRF black in addition to the white fillers to the above blends. On the other hand, from the compatibility study between both investigated rubber, it is found that both types are incompatible, in which some improvement may occur by the addition of PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2061–2068, 1998     

Acrylic rubber‐fluorocarbon rubber miscible blends: Effect of curatives and fillers on cure,mechanical, aging,and swelling properties

The cure characteristics and mechanical properties of gum and filled acrylic rubber (ACM), fluorocarbon rubber (FKM), and their blends of varying compositions were studied both under unaged and aged conditions. The rheometric study showed that optimum cure properties were obtained using a mixed curing system of blocked diamine, hexamethylenediamine carbamate (Diak #1), and ammonium benzoate. From varying the curing agents, the optimum levels of Diak #1 and ammonium benzoate were found to be 1.5 and 2.5 phr, respectively. The addition of different fillers and their loading influenced the cure properties, with increased torque and reduced scorch safety. The gum and filled 50:50 (w/w) ACM‐FKM showed overall performance in strength properties. Postcuring improved the strength of all the systems, especially the systems with a higher proportion of FKM. None of the properties changed significantly during aging of the blends. FKM and the blends containing a higher proportion of FKM were affected least by aging. Swelling of the blends was reduced by the addition of fillers. Dynamic mechanical thermal analysis showed a single tan δ peak corresponding to a single phase transition for both cured and filled blends. The storage modulus of the blend increased from the gum blend to the filled blend, indicating the presence of polymer‐filler interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1442–1452, 2003     

Studies on electrical properties of nanoclay filled thermoplastic polyurethane/polypropylene blends

The electrical properties of ester/ether‐based thermoplastic polyurethane (TPU) and polypropylene (PP) blends are presented in this article. Special attention has been paid to analyze the effect of blend ratio, compatibilization, and effect of nanoclay on the electrical properties of TPU/PP blends. The electrical properties measured were dielectric constant (ε′), volume resistivity (ρ_υ), loss factor (ε″), and dissipation factor (tan δ). Addition of PP into TPU increases the volume resistivity and reduces the dissipation and loss factor due to the decrease in the overall polarity of the system. Further addition of compatibilizer and nanoclay to this system reduced the dissipation factor and loss factor with increased volume resistivity. Compared with the ether‐TPU based blend nanocomposites, the ester‐TPU blends show better compatibility as confirmed by analysis. POLYM. COMPOS., 35:1671–1682, 2014. © 2013 Society of Plastics Engineers     

Effect of filler on the mechanical,dynamic mechanical,and aging properties of binary and ternary blends of acrylic rubber,fluorocarbon rubber,and polyacrylate

We studied the effects of fillers on the mechanical, dynamic mechanical, and aging properties of rubber–plastic binary and ternary blends derived from acrylic rubber, fluorocarbon rubber, and multifunctional acrylates. The addition of fillers, such as carbon black and silica, changed the nature of the stress–deformation behavior with a higher stress level for a given strain. The tensile and tear strengths increased with the addition of the fillers and with loading, but the elongation at break decreased, and the tension set remained unaffected. The aging properties of carbon‐black‐filled blends were better because of the thermal antioxidant nature of carbon black. The swelling resistance of the binary and the ternary blends in methyl ethyl ketone increased with the incorporation of fillers. From dynamic mechanical thermal analysis, we concluded that the filler altered the height and half‐width of the damping peak at the glass‐transition temperatures. There was little change in the loss tangent values at higher temperatures. A higher loading of the filler increased the storage modulus at all of the temperatures measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 278–286, 2003     

聚磷酸铵/氢氧化镁复配填充阻燃硅橡胶的研究

分别采用聚磷酸铵（APP）、氢氧化铝（ATH）和APP/ATH复配阻燃剂填充甲基乙烯基硅橡胶,制成阻燃型硅橡胶。研究了APP、ATH和APP/ATH用量及复配方式对硅橡胶阻燃性能、介电性能和力学性能的影响。结果表明,硅橡胶的阻燃性能随APP、ATH用量的增加而增加,同等填充量下,APP/ATH复配阻燃剂填充硅橡胶的阻燃性能比单一APP或ATH填充硅橡胶更佳;随着APP/ATH复配阻燃剂用量的增加,硅橡胶的拉伸强度与拉断伸长率降低,邵尔A硬度、介电常数和介质损耗因数增加。当100份硅橡胶中加入80份APP/ATH复配阻燃剂（APP与ATH的质量比为3∶2）时,硅橡胶的氧指数达44%,拉伸强度、拉断伸长率、邵尔A硬度、介电常数及介质损耗因数分别为6.8 MPa、438%、62度、3.92、249%。     

Measurement of AC conductivity and dielectric properties of flexible conductive styrene–butadiene rubber‐carbon black composites

Flexible conductive polymer composites were prepared using styrene–butadiene rubber (SBR) as a matrix and conductive carbon black as filler. The filler loading was varied from 10 to 60 phr. The effect of frequency, filler loading, temperature, and applied pressure on the AC conductivity, permittivity, and loss factor of the composites was studied. The AC conductivity of low and high loaded composites was found to be frequency dependent and independent respectively. The permittivity and the loss factor were continuously decreasing with increasing frequency. The increase in filler loading increased the AC conductivity, dielectric constant, and loss factor of the composites. Increase in temperature imposed increase in conductivity and permittivity of the composites. With increasing applied pressure the properties showed exponential increase. The effect of time under a constant compressive stress was studied and dielectric relaxation times were evaluated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 986–995, 2007     

Mechanical and Viscoelastic Properties of Natural Rubber/ Reclaimed Rubber Blends

Summary Addition of reclaimed rubber affected mechanical properties, processing and rheological behavior of rubber compounds. Sulfur left in reclaimed rubber affected curing process of NR/reclaimed rubber blends. The most suitable curing was achieved with ratio 1:1 of natural rubber and reclaimed rubber which was used in this study. Presence of fillers in reclaimed rubber, non-homogeneity of phases, non-uniform filler dispersion and lower molecular weight of reclaimed rubber due to chain scission in reclaiming process caused diminishing of mechanical properties of NR/reclaimed blends, particularly dynamic-based properties. Reclaimed rubber also affected rheological behavior of natural rubber. In a strain sweep viscoelastic test, it could be observed that NR/reclaimed blend show more non-linear viscoelastic and viscous behavior than predicted one which was due to non-homogenized phases. This non-homogenized morphology was detected using scanning electron microscopy (SEM) and the blend with ratio 1:1 had the most homogenized morphology.     

Dynamic mechanical properties of thermoplastic elastomers from polypropylene–natural rubber blend

The dynamic mechanical properties of thermoplastic elastomers from polypropylene natural rubber blends have been evaluated with special reference to the effect of blend ratio and extent of dynamic crosslinking of the elastomer phase. The effects of HAF black and silica fillers have also been studied. It has been found that increasing the proportion of elastomer phase reduced the storage modulus and increased the loss tangent values of the blends. The effect of dynamic crosslinking was found to be more prominent in blends containing higher proportion of elastomer phase. The improvement in storage modulus and decrease in loss tangent values were quite remarkable with increase in extent of crosslinking in these blends. The 70:30 NR:PP blend was found to exist as a two-phase system, both the components forming continuous phases of the blend.     

Aromatic liquid transport through filled EPDM/NBR blends

The sorption and diffusion characteristics of 70/30 ethylene propylene diene monomer rubber (EPDM)/acrylonitrile butadiene rubber (NBR) blends loaded with black fillers such as ISAF (intermediate super-abrasion furnace), HAF (high abrasion furnace) and SRF (semi-reinforcing furnace) have been investigated. The penetrants used were benzene, toluene and xylene. Filled samples have been found to show a reduced solvent uptake compared to the unfilled sample for the given blend ratio. The observations have been correlated with the morphology of the systems. Blends loaded with ISAF exhibited the lowest liquid uptake among black filled systems which has been attributed to the better filler reinforcement and enhanced crosslink density of the matrix. The extent of particulate filler reinforcement has been studied by using Kraus theory. The unfilled and filled systems have been found to exhibit non-Fickian transport behaviour. The effect of fillers on the cure and mechanical properties of the blends have also been investigated. Among the black filler loaded systems used, the ISAF mix showed the highest maximum torque value. The improvement in the cure and mechanical properties has been observed to be the highest for ISAF filled samples followed by HAF and SRF filled systems, which is in compliance with the observation from the sorption studies.     

Optimization of Dielectric Constant of Polycarbonate/Polystyrene Modified Blend by Ceramic Metal Oxide

We modified a polycarbonate (PC)/polystyrene (PS) blend by loading alumina (Al₂O₃) into the blend. X-ray diffraction (XRD) shows a decrease in crystallinity. The optical microscopy and atomic force microscopy (AFM) confirms the homogeneous dispersion of alumina. The differential scanning calorimetry (DSC) data shows improved results in glass transition (T_g) and melting temperature (T_m) of blend systems. The electrical properties of polymer blends modified by Al₂O₃ were studied as a function of frequency (50 Hz–35 MHz) at 323 K. The alumina showed a significant effect in resulting in a high dielectric constant with low dielectric loss and dissipation factor.     

Effects of fillers,maleated ethylene propylene diene diene rubber,and maleated ethylene octene copolymer on phase morphology and oil resistance in natural rubber/nitrile rubber blends

The phase morphology and oil resistance of 20/80 NR/NBR blends filled with different types of fillers and copolymers were investigated. In the case of filler effect, N220, N330, and N660 carbon blacks with different particle sizes were used. Additionally, the blends filled with nonblack‐reinforcing fillers, that is, precipitated and silane‐treated silica, were investigated. To study the compatibilization effect, maleated ethylene propylene diene rubber (EPDM‐g‐MA) and maleated ethylene octene copolymer (EOR‐g‐MA) were added to the blends. The results revealed that the addition of filler, either carbon black or silica, to the blend caused a drastic decrease in NR dispersed phase size. Carbon blacks with different particle sizes did not produce any significant difference in NR dispersed phase size under the optical microscope. Silica‐filled blends showed lower resistance to oil than did the carbon black–filled blends. In addition, it was determined that neither EOR‐g‐MA nor EPDM‐g‐MA could act as a compatibilizer for the blend system studied. The oil resistance of the blends with EPDM‐g‐MA is strongly affected by the overall polarity of the blend. In the case of EOR‐g‐MA, the oil resistance of the blends is significantly governed by both overall polarity of the blend and phase morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1156–1162, 2003     

A comparison of the properties of rice husk ash,silica, and calcium carbonate filled 75 : 25 NR/EPDM blends

The effects of incorporation of three different fillers, i.e., rice husk ash (RHA), silica, and calcium carbonate (CaCO₃), over a loading range of 0–60 phr on the curing characteristics, processability, mechanical properties, and morphology of 75 : 25 natural rubber (NR)/ethylene‐propylene‐diene monomer (EPDM) blends were studied using a conventional vulcanization system. Filler loading and type influence the processability of the blends in which RHA and CaCO₃ offer better processing advantage over silica. The best improvement in the tensile and tear strength and abrasion resistance of the 75 : 25 NR/EPDM blends with additional fillers was achieved when filled with silica. However, RHA and CaCO₃ were better in resilience property compared to that of silica. The RHA filled blends showed higher failure properties and abrasion resistance but lower ozone resistance than that containing CaCO₃. Scanning electron micrographs revealed that the morphology of the blend filled with silica is finer and more homogenous compared to the blend filled with RHA and CaCO₃. According to these observations, RHA can be used as a cheaper filler to replace CaCO₃ in rubber blends where improved mechanical properties are not so critical. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dielectric properties of aluminum–epoxy composites

Dielectric properties of Al–epoxy composites were characterized as a function of composition, frequency, and temperature. The dielectric constant increased smoothly with an increase in the concentration of aluminum. An increase in dielectric constant was also observed with an increase in temperature as well as with a decrease in frequency. In general, dissipation factor values for composites with higher concentrations of aluminum were greater than those with lower volume content of aluminum. Also, the dissipation factor showed an increase both with a decrease in frequency and an increase in temperature. The increase in values of dielectric constant and dissipation factor with an increase in concentration of aluminum was attributed to interfacial polarization. The absence of any discontinuity in the plot of dielectric constant versus composition was ascribed to the absence of continuous aluminum chains in the composition range investigated. The increase in dielectric constant with a rise in temperature was attributed to the segmental mobility of the polymer molecules. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3602–3608, 2003     

Effect of fillers on morphological properties in NR/SBR blends for OTR tyres

Abstract

The blends of styrene butadiene rubber (SBR) and natural rubber (NR) are prepared using a two-roll mixing mill in the presence of different types of carbon blacks as reinforcing filler. The effects of fillers on cure characteristics and thermal, dynamic–mechanical, morphological properties of the blends are studied. The ISAF N231 type of carbon black shows a significant effect on tensile, tear and modulus properties by reacting at the interface between SBR/NR matrixes. The dynamic characteristics and storage modulus of SBR/NR with SAF N110 and SRF N774 types of carbon black show distinct characteristics in respect to all other blends in this system. The thermal stability of the rubber vulcanizates containing SAF N110 and SRF N774 types of carbon blacks is higher than other blend types. With the increasing percentage of SBR to NR, the thermal stability of the blend is increased. However, the heat buildup of the blends increases with the increase in SBR percentage.     

Improvement of Homogeneity of SBR/CR Rubber Blends with SBR-g-AA Grafted Rubber

The graft copolymerization of acrylic acid (AA) onto styrene butadiene rubber (SBR) was carried out in toluene at 80°C using benzoyl peroxide (BPO) as initiator. The synthesized styrene butadiene rubber-g-acrylic acid (SBR-g-AA) was characterized with Raman IR spectroscopy. A study was conducted on the use of SBR-g-AA for improving the homogeneity of styrene butadiene rubber/chloroprene rubber (SBR/CR) blend. The SBR-g-AA was incorporated into SBR/CR blend with different blend ratios. The homogeneity of such blends was examined with scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and determination of the dielectric properties. The scanning electron micrographs illustrate improvement of the morphology of SBR/CR rubber blend as a result of the incorporation of SBR-g-AA onto that blend. Also, the dielectric constant (permittivity) and the dielectric loss plots versus the SBR/CR blend ratio show straight lines upon incorporation SBR-g-AA, indicating and confirming the homogeneity of that blend. Physico-mechanical properties of the blend vulcanizates, in presence and absence of SBR-g-AA, were determined, and their thermal stability was evaluated after accelerated thermal aging. The results reveal that SBR/CR (25/75) blend possesses the best thermal stability. Swelling behavior in toluene, in motor oil, and in brake fluid of the blend vulcanizates was also assessed.     

Dielectric properties of styrene — butadiene rubber/silica mixtures

Rice husk ash (RHA) obtained from rice mill and hydrated silica from RHA were used as a filler in vulcanized SBR 1502 and the dielectric properties were measured at a frequency of 1592 Hz at room temperature. The optimum hydrated silica content giving a good dielectric constant and conductivity was 125 parts/100 parts rubber and the dielectric loss was also high so that it could be a good insulater. There was no significant change in dielectric constant, dielectric loss and conductivity of SBR 1502 filled with RHA which could be used as high frequency dielectric due to low dielectric loss.     

Electrical properties of nanostructured interpenetrating polymer networks based on natural rubber (NR)/polystyrene (PS)

The electrical properties of nanostructured sequential interpenetrating polymer networks from natural rubber (NR) and polystyrene (PS) have been studied in the frequency range of 10²–10⁷ Hz. The permittivity, volume resistivity, dielectric loss factor, and dissipation factor were analyzed as a function of frequency, blend composition, crosslinking level, and initiating system. It was found that the volume resistivity and dissipation factor first increase, reach a maximum around 10³–10⁵ Hz, and then decrease gradually with the increase of frequency. As the NR content is increased from 30 to 70%, the dissipation factor (tan δ) increases. On increasing the extent of the PS phase crosslinking, the permittivity increases. However, at higher levels of PS crosslinking, the permittivity values decrease due to the agglomeration of PS phase arising from excessive crosslinking. The morphology studies using a scanning electron microscope confirmed the agglomeration of PS phase at high crosslinking level. The permittivity values are maximum at 4% of crosslinking content. The influence of initiating system on the dielectric properties was not very significant. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2017–2026, 2005