Thermal and mechanical properties of sorbitol‐based epoxy resin cured with quercetin and the biocomposites with wood flour

After a bio‐based epoxy resin, sorbitol polyglycidyl ether (SPE) was mixed with a flavonoid, quercetin (QC) in tetrahydrofuran at an optimized epoxy/hydroxy ratio 1/1.2, the obtained SPE/QC solution was mixed with wood flour (WF), prepolymerized at 150°C, and subsequently compressed at 170°C for 3 h to give SPE‐QC/WF biocomposites (WF content:0, 20, 30, 40 wt %). The tan δ peak temperature of SPE‐QC without WF (85.5°C) was higher than that of SPE cured with conventional phenol novolac (81.0°C). In addition, diglycidyl ether of bisphenol A cured with QC had a higher tan δ peak temperature (145.1°C) than that cured with PN (90.8°C). The tan δ peak temperatures (106–113°C) of SPE‐QC/WF biocomposites were significantly higher than that of SPE‐QC. The tensile modulus of SPE‐QC/WF biocomposites increased with increasing WF content. A lower wavenumber shift of carbonyl stretching absorption peak in the FTIR spectrum of SPE‐QC/WF as compared with that of SPE‐QC suggested that hydroxy group of woody component forms hydrogen bonding with carbonyl group of quercetin moiety. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structural effect of phenalkamines on adhesive viscoelastic and thermal properties of epoxy networks

Phenalkamine, the Mannich reaction products from cardanol, formaldehyde, and polyamines were prepared using ethylene diamine, diethylene triamine and triethlene tetraamine. These products were characterized by high‐pressure liquid chromatography (HPLC), infrared spectroscopy, and nuclear magnetic resonance spectroscopy (1H NMR). Clearly resolved peaks due to presence of triene, diene, monoene, and saturated side chain containing species of cardanol were observed in HPLC. The presence of characteristic methylene linkages of Mannich bases at δ 3.5–4.0 ppm was observed by 1H NMR. These curing agents were reacted with diglycidyl ether of bisphenol‐A at room temperature and the curing times were optimized. The cured resins showed good adhesion with different metal surfaces particularly higher values were observed with copper due to its high surface energy. The viscoelastic properties of the cured samples were determined by dynamic mechanical thermal analysis. The storage modulus (E′) was found to be in the order of 10⁹ Pa and tan δ values are around 90°C. A reduction in storage modulus (E′) and an increase in tan δ values on postcuring were observed. Thermogravimetry analysis showed two‐stage degradation above 250°C for the cured samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4741–4748, 2006     

Effect of crosslink structures on dynamic mechanical properties of natural rubber vulcanizates under different aging conditions

The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated before and after aerobic and anaerobic aging at 100°C. The three unfilled NR vulcanizates cured with the CV, SEV, and EV systems had about the same mechanical loss factor (tan δ) values at about 0°C but showed some apparent differences in the tan δ values in the order EV > SEV > CV at relatively high temperatures of 40–80°C before aging. However, N330‐filled NR vulcanizates gave higher tan δ values than the unfilled vulcanizates and showed little effect of the crosslink types on the tan δ at different temperatures over the glass‐transition temperature (T_g) before aging. Aerobic heat aging increased the T_g and tan δ values of the vulcanizates over a wide range of temperatures from ?80 to 90°C that was mainly due to the changes in the total density and types of crosslinks. The unfilled vulcanizates cured with the CV system showed the greatest change in DMP because of their poor resistance to heat aging. Aerobic heat aging of NR vulcanizates caused a more significant change in the DMP than anaerobic heat aging because of the dominant effect of the oxidative degradation during aerobic heat aging on the main‐chain structure, crosslink structures, and DMPs of the vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 710–718, 2001     

Preparation of high‐performance damping materials based on carboxylated nitrile rubber: Combination of organic hybridization and fiber reinforcement

The dynamic mechanical properties denoted by storage modulus (E′) and loss factor (tan δ) of binary and ternary systems consisting of carboxylated nitrile rubber (XNBR) filled with organic hindered phenol compound 2,2′‐methylenebis(6‐tert‐butyl‐4‐methylphenol) (AO‐2246) or/and short carbon fiber (SCF) were investigated. DMA results of binary XNBR/AO‐2246 system showed that by addition of AO‐2246, the tan δ peak maximum of XNBR was remarkably increased up to 3.5, and its peak position was also significantly shifted to room temperature, demonstrating that XNBR/AO‐2246 composite is a promising damping material. Nevertheless, application of such XNBR/AO‐2246 composite is limited due to its relatively low E′ value above glass transition temperature. Therefore, to develop a high‐performance damping material with high tan δ peak and high modulus as well as controllable tan δ peak position, the combination of organic hybridization and fiber reinforcement were adopted. DMA analysis of various ternary XNBR/AO‐2246/SCF systems revealed that by introduction of SCF, the E′ value of XNBR/AO‐2246 was increased remarkably while the tan δ peak maximum was still higher than 2.5. Thus, a new type of XNBR‐based high‐performance damping material was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of biocomposites composed of epoxidized soybean oil,tannic acid,and microfibrillated cellulose

As a new biobased epoxy resin system, epoxidized soybean oil (ESO) was cured with tannic acid (TA) under various conditions. When the curing conditions were optimized for the improvement of the thermal and mechanical properties, the most balanced properties were obtained when the system was cured at 210°C for 2 h at an epoxy/hydroxyl ratio of 1.0/1.4. The tensile strength and modulus and tan δ peak temperature measured by dynamic mechanical analysis for the ESO–TA cured under the optimized condition were 15.1 MPa, 458 MPa, and 58°C, respectively. Next, we prepared biocomposites of ESO, TA, and microfibrillated cellulose (MFC) with MFC contents from 5 to 11 wt % by mixing an ethanol solution of ESO and TA with MFC and subsequently drying and curing the composites under the optimized conditions. The ESO–TA–MFC composites showed the highest tan δ peak temperature (61°C) and tensile strength (26.3 MPa) at an MFC content of 9 wt %. The tensile modulus of the composites increased with increasing MFC content and reached 1.33 GPa at an MFC content of 11 wt %. Scanning electron microscopy observation revealed that MFC was homogeneously distributed in the matrix for the composite with an MFC content of 9 wt %, whereas some aggregated MFC was observed in the composite with 11 wt % MFC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Production and properties of highly oriented polyoxymethylene by die‐drawing

Highly oriented monofilaments were produced by a high‐temperature die‐drawing process followed by tensile drawing. It was shown that a successful high‐speed process required high‐quality melt‐extruded rod. The mechanical properties and structure of the die‐drawn products were investigated by means of tensile and bending tests, dynamic mechanical measurements, DSC, and X‐ray diffraction. The bending modulus and the tensile strength increased with increasing draw ratio. It was also observed that at high draw ratios the γ‐dispersion peak in the dynamic mechanical tan δ curve, which is associated with main chain micro‐Brownian motion in the amorphous regions, diminishes, implying that these chains become taut. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1268–1278, 2003     

Sequential interpenetrating polymer network based on styrene butadiene rubber and polyalkyl methacrylates

A series of sequential interpenetrating polymer network (IPNs) based on styrene butadiene rubber (SBR) and polyalkyl (methyl, ethyl, and butyl) methacrylates have been prepared by using tetraethylene glycol dimethacrylate as crosslinker. The IPNs were characterized by infrared spectrophotometer, dynamic mechanical analyzer, thermogravimetric analyzer, and swelling study. IPNs have exhibited higher tensile properties compared with pure SBR. IPNs based on PMMA have shown higher tensile strength compared with others. Dynamic mechanical analysis has shown that the IPNs have superior dynamic properties than SBR. Because of IPN formation, tan δ peak shifted inward between SBR and acrylates. Although the magnitude of tan δ decreased, the peaks were broadened because of micro heterogeneous phase separation. At higher concentration of methacrylate, splitting in tan δ peak was noticed because of phase separation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1120–1126, 2007     

Modification of epoxy resin with optically active carboxylic acid

L ‐leucine was converted to S‐2‐chloro, 4‐methyl pentanoic acid (CMPA) with retention of optical activity. CMPA was reacted with the epoxy resin to form chiral monoester and chiral diester compounds. The modified epoxy resin (MER) was characterized by FTIR spectrophotometer and polarimeter and was analyzed for epoxy content. The MER shows optical activity and the optical rotation increases with increasing concentration of CMPA. DSC studies indicate similar reactivity of the enantiomers of CMPA as well as the recemic mixture. The MER containing different concentrations of chiral modifier was cured with a stoichiometric amount of amine hardener. The cured film (obtained up to 21 mol % of CMPA) exhibits chiral property as well. Dynamic mechanical thermal analysis (DMTA) studies indicate high damping behavior. A shift in tan δ peak toward lower temperature was observed with increasing concentration of chiral modifier. The tan δ_max increases up to 14 mol % of CMPA in MER and decreases thereafter. However, storage modulus gradually decreases with an increase in CMPA. Cured film based on two enantiomer‐modified epoxy samples shows different damping behavior. CMPA was also blended with poly(methyl methacrylate) and the blend films were studied similarly. The system behaves in a similar fashion as observed with cured MER films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2523–2529, 2002     

Effect of liquid isoprene rubber on dynamic mechanical properties of emulsionpolymerized styrene/butadiene rubber vulcanizates

The effect of liquid isoprene rubber (LIR) on the dynamic mechanical properties of emulsion‐polymerized styrene/butadiene rubber (ESBR) vulcanizates was investigated by temperature sweep using dynamic mechanical analysis. The introduction of LIR led to ESBR vulcanizates having higher loss factor (tan δ) in the temperature range ? 30 to 0 °C, and lower tan δ in the range 60 to 80 °C. A small amount of LIR‐403 (LIR with carboxyl groups) led to a significant change in tan δ: the addition of LIR‐403 (3 phr) led to a 7.5% increase in tan δ from ? 30 to 0 °C, and a 24.9% decrease in tan δ from 60 to 80 °C. It was found that the introduction of LIR increased the bound rubber content in the ESBR compound. Equilibrium swelling experiments showed that the crosslink density of the vulcanizates increased after the introduction of LIR‐403 or LIR‐50 (general purpose LIR). The change in tan δ from 60 to 80 °C was related to polymer–filler interactions. The characteristic constant of filler–ESBR matrix interaction (m) was calculated. At a given filler volume fraction, the increase in m in the presence of LIR could be well related to the decrease in tan δ from 60 to 80 °C. The influence of LIR on filler network in the ESBR compound was also investigated by strain and temperature sweeps using a rubber processing analyzer. Copyright © 2011 Society of Chemical Industry     

Comparison of microwave and thermal cure of epoxy–anhydride resins: Mechanical properties and dynamic characteristics

The objective of this work was to compare the mechanical properties of epoxy resins cured by thermal heating and microwave heating. Epoxy–anhydride (100:80) resins were cured in a domestic microwave oven and in a thermal oven. The hardening agents included methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride. Three types of accelerators were employed. Thermal curing was performed at 150°C for 20 and 14 min for resins containing 1 and 4% accelerator, respectively. Microwave curing was carried out at a low power (207 or 276 W) for 10, 14, and 20 min. All cured resins were investigated with respect to their tensile properties, notched Izod impact resistance, and flexural properties (three‐point bending) according to ASTM standards. The tan δ and activation energy values were investigated with dynamic mechanical thermal analysis, and the extent of conversion was determined with differential scanning calorimetry. The differences in the mechanical properties of the thermally cured and microwave‐cured samples depended on the resin formulation and properties. Equivalent or better mechanical properties were obtained by microwave curing, in comparison with those obtained by thermal curing. Microwave curing also provided a shorter cure time and an equivalent degree of conversion. The glass‐transition temperatures (tan δ) of the thermally and microwave‐cured resins were comparable, and their activation energies were in the range of 327–521 kJ/mol. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1442–1461, 2005     

Mechanical and dielectric properties of cured 1,2‐bis(vinylphenyl)ethane resin modified with poly(phenylene oxide)

1,2‐Bis(vinylphenyl)ethane (BVPE) could be cured without curing agents at relatively low temperatures (～ 180°) in a nitrogen atmosphere. Cured BVPE (CBVPE) resin showed exceptionally low dielectric constant (? = 2.50 at 10 GHz) and low dielectric loss tangent (tan δ = 0.0012 at 10 GHz), and had excellent thermal resistance. Its 5 wt % weight‐loss temperature was 425°C in a nitrogen atmosphere and glass transition temperature was over 400°C. Poly(phenylene oxide) (PPO) was used to improve the toughness of CBVPE resin. PPO was an effective modifier to toughen CBVPE resin: when using 30 wt % of the modifier, the tensile strength and elongation of the modified CBVPE resin were 75 MPa and 26%, respectively. The modified CBVPE resin also showed excellent dielectric properties (? = 2.45 at 10 GHz, tan δ = 0.0015 at 10 GHz). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1252–1258, 2004     

Vibration control ability of multilayered composite material made of epoxy beam and polyurethane copolymer with shape memory effect

Sandwich‐type layered composite material was prepared with epoxy beam and polyurethane copolymer that was synthesized from 4,4‐methylene bis (phenylisocyanate), poly(tetramethyleneglycol), and 1,4‐butanediol as a chain extender. As for the polyurethane, shape recovery was improved with higher content of hard segment, and the highest damping effect as judged by tan δ was observed at 30–35% hard segment. The composite material had better impact strength and higher tan δ than epoxy beam alone, but the superiority became less as more hard segment was incorporated. The interfacial binding force between polyurethane and the epoxy beam also decreased in proportion to the hard segment content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 302–307, 2004     

Preparation and properties of biocomposites composed of sorbitol‐based epoxy resin,pyrogallol–vanillin calixarene,and wood flour

The reaction of pyrogallol (PG) and vanillin (VN), both of which are derived from plant resources, in the presence of p‐toluenesulfonic acid gave PG–VN calixarene (PGVNC) mainly composed of guaiacyl pyrogallol[4]arene. After sorbitol polyglycidyl ether (SPE) was mixed with PGVNC in tetrahydrofuran at an optimized epoxy/hydroxy ratio 1/2.65, the obtained SPE/PGVNC solution was mixed with wood flour (WF), prepolymerized at 150°C, and subsequently compressed at 190°C for 3 h to give SPE–PGVNC/WF biocomposites with WF content 0–20 wt%. The tan δ peak temperature of SPE–PGVNC was 148.1°C, which was much higher than that of the SPE cured with petroleum‐based phenol novolac (SPE–PN) at an optimized epoxy/hydroxy ratio 1/1. Although tan δ peak temperature slightly decreased with increasing WF content, the storage moduli of the SPE–PGVNC/WF biocomposites in the rubbery state at more than 150°C were much higher than those of SPE–PGVNC and SPE–PN. Also, the tensile modulus and strength for SPE–PGVNC/WF increased with increasing WF content. Field emission‐scanning electron microscopy analysis of the biocomposites revealed that WF is tightly incorporated into the crosslinked epoxy resins. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Dynamic mechanical properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) with aromatic hydrocarbon resin

The damping properties in blends of poly(styrene‐b‐isoprene‐b‐styrene) (SIS) and hydrogenated aromatic hydrocarbon (C₉) resin were investigated by dynamic mechanical analysis. SIS exhibited two independent peaks of loss factor (tan δ) corresponding to the glass transition of polyisoprene (PI) and polystyrene (PS) segments, respectively. The addition of hydrogenated C₉ resin had a positive impact on the damping of SIS. With the increasing softening point and content of the resin, the main tan δ peak shifted to higher temperatures and the useful damping temperature range was broadened. Addition of mica or PS was found to widen the effective damping range evidently in the high‐temperature region, especially when PS was mixed in the solid state. It was concluded that the dispersed PS domains played a role of reinforcing fillers at low temperatures and served as a polymer component with a tan δ peak due to its glass transition at the high temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4157–4164, 2006     

Effect of acetylation on dimensional stability,mechanical, and dynamic properties of jute board

Jute slivers were acetylated in pilot scale following a no catalyst‐no solvent method at 120°C for 2 h. The weight % gain was found to be 11.37. Different jute boards were pressed under heat and pressure using acetylated jute sliver and urea formaldehyde resin. Neutral salt (NaCl), acid salt (NH₄Cl), and melamine powder were used separately for curing urea formaldehyde. For comparison purposes, control boards were also prepared using nonacetylated slivers. The boards were tested for water soaking, cyclic water soaking, and cyclic humidity to see the effect of acetylation on dimensional stabilization. This chemical modification was found to improve the dimensional stability to a great extent for NaCl and NH₄Cl cured boards and to a less extent for a melamine‐cured one. Tensile and flexural strengths were tested by Instron before and after the cyclic tests. Retention values were found to be as high as 60% after cyclic water tests for acetylated boards and the same was as low as 24% for control boards. Dynamic parameters, such as storage flexural modulus (E′), loss flexural modulus (E"), and loss factor or damping efficiency (tan δ) were determined in a fixed‐frequency mode. Dynamic mechanical study revealed that tan δ peaks were lowered due to increased bulkiness of the fiber after acetylation and thus restricted mobility. A tiny additional peak was also visible at ∼90°C beside the main peak at ∼125°C for boards with modified slivers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 935–944, 1999     

Effect of thermal degradation on the mechanical properties of a diglycidyl ether of bisphenol A/1,3-bisaminomethylcyclohexane (DGEBA/1,3-BAC) epoxy resin system

The effect of thermal degradation on the mechanical properties of a diglycidyl ether of bisphenol A (DGEBA)/1,3-bisaminomethylcyclohexane (1,3-BAC) epoxy system, cured with two different curing cycles—a short cycle and a long cycle—were studied using tensile and Izod impact experiments and scanning electronic microscopy, SEM, observations. From these experiments it can be noted a loss of mechanical properties of the material cured with both cycles with aging time, although the material cured with the long cycle presents better properties at any aging time. This better behavior can be explained from the time temperature transformation, TTT, diagram of this system. A good correlation was observed between the decrease in the intensity of the peak of β transition in tan δ curve obtained by dynamic mechanical analysis, DMA, and the decrease of the Izod impact strength when thermal aging is increasing. Also, a good correlation can be found between the increase in the fragility of the material with aging time and the morphology of fractured surfaces observed by SEM. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1841–1849, 1997     

Influence of ZnO nanoparticles on the cure characteristics and mechanical properties of carboxylated nitrile rubber

Zinc oxide (ZnO) nanoparticles assembled in one dimension to give rod‐shaped morphology were synthesized. The effect of these ZnO nanoparticles (average particle size ～ 50 nm) as the curing agent for carboxylated nitrile rubber was studied with special attention to cure characteristics, mechanical properties, dynamic mechanical properties, and swelling. These results were compared with those of the conventional rubber grade ZnO. The study confirmed that the ZnO nanoparticles gave a better state of cure and higher maximum torque with a marginal decrease in optimum cure time and scorch time. The mechanical properties also showed an improvement. There was an increase in tensile strength by ～ 120%, elongation at break by ～ 20%, and modulus at 300% elongation by ～ 30% for the vulcanizate cured with ZnO nanoparticles, as compared with the one containing rubber grade ZnO. Dynamic mechanical analysis revealed that the vulcanizates exhibited two transitions—one occurring at lower temperature due to the T_g of the polymer, while the second at higher temperature corresponding to the hard phase arising due to the ionic structures. The second transition showed a peak broadening because of an increase in the points of interaction of ZnO nanoparticles with the matrix. The tan δ peak showed a shift towards higher T_g in the case of ZnO nanoparticle‐cured vulcanizate, indicating higher crosslinking density. This was further confirmed by volume fraction of rubber in the swollen gel and infrared spectroscopic studies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Impact of aliphatic amine comonomers on DGEBA epoxy network properties

This study characterized the mechanical and thermal properties of the oligomer‐based formulations of the diglycidyl ether of bisphenol A (DGEBA) cured with series aliphatic amines (triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and O,O bis (2‐aminopropyl propylene glycol) (Jeffamine D230) with different functionalities in the glassy state. Impact Izod and three‐point bending tests were conducted to determine the networks' impact energy (E_i), elasticity modulus (E_y), yield stress (σ_y) and fracture toughness (K_IC) values. The same three‐point bending mode was also employed to characterize the systems' thermo‐mechanical properties (DMA) and storage modulus (E') and damping modulus (tan δ = E"/E') values. The DGEBA/D230 network showed greater flexibility, maximum impact energy, higher fracture toughness, and a lower yield stress than the DGEBA/TETA and DGEBA/TEPA networks. The fracture behavior of these epoxy systems was correlated to the molecular weight between the crosslink points, M_c, and the plastic zone size (r_p) at the crack tip carved in the samples. The DGEBA/D230 network had the highest storage modulus and tan δ intensity, together with higher toughness and deformation during the network's fracture. These results were a consequence of the structural characteristics of comonomers, including their chain segment flexibility, molecular weight between crosslink points and functionality. POLYM. ENG. SCI., 54:2132–2138, 2014. © 2013 Society of Plastics Engineers     

Uncured and cured state properties of fly ash filled unsaturated polyester composites

Physical properties of fly ash filled unsaturated polyester composites in both uncured and cured states have been studied with special reference to the effect of degree of loading, nature of filler surface, and surface treatment of filler. The effect of filler surface on curing and oil absorption characteristics of filler were also examined. In the uncured state, sedimentation rate test and viscosity measurement for fly ash reinforced composites were performed. For cured fly ash filled unsaturated polyester composites, tensile properties decreased with the addition of fly ash particles whereas surface treatment led to improved mechanical properties and resistance to swelling. In terms of dynamic mechanical thermal analysis, effects of both filler and surface treatment on loss factor (tan δ) were discussed. Tan δ value and damping temperature range increased to the 15% fly ash addition. The composite having 15% unsilanized fly ash was found to have the highest tan δ and damping temperature range together with maximum performance in terms of tensile properties and swelling behavior. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1128–1136, 2000     

Transition magnitudes and impact improvement in rubber-modified plastics

Impact strength at room temperature and dynamic mechanical properties over a temperature range have been studied for a number of rubber reinforced glassy state plastics. The rubber phases in every case were butadiene copolymers of known composition and particle size and selected for their good dispersion after blending into the various matrices. This dispersion was checked by electron microscopy and the in situ particle size evaluated. The matrices were based on homo- and co-polymers of styrene, methyl methacrylate and acrylonitrile. A vibrating reed apparatus was employed to measure the storage component of Young's modulus (E′) and loss factor (tan δ) at essentially constant frequency (～300 Hz) through the rubber relaxation region. The Izod impact strength was measured in accordance with the standard method ASTM D-256. A gross parallel was found between impact strength and transition magnitude as measured by the change in modulus between ?100°C and 20°C (ΔE′) or the tan δ peak area with, for example, increasing volume fraction of rubber phase. However, when the same rubber was dispersed in different matrices a more subtle effect was an inverse proportionality of tan δ area with E′ measured at the peak temperature. Conversely ΔE′ after correction for matrix modulus change was shown both theoretically and experimentally to be directly proportional to E′ of the matrix at room temperature. The impact strength actually increases with ΔE′ and not with tan δ area in these cases. However, a more important requirement for good impact is compatibility between the rubber and matrix, but neither ΔE′ nor tan δ reflect this. After correction of tan δ areas to constant matrix modulus there remains an increase of area with particle size. Impact strength also increases strongly with particle size for compatible systems. The applicability of Hashin's central equation and Mackenzie's equation in describing the systems is discussed.