The toughness of polypropylene (PP)/ethylene-propylene-diene monomer (EPDM) blends was studied over wide ranges of EPDM content and temperature. In order to study the effect of notch radius (R), the toughness of the samples with different notch radii was determined from Izod impact test. The results showed that both toughness and brittle-ductile transition (BDT) of the blends were a function of R, respectively. At test temperatures, the toughness tended to decrease with increasing 1/R for various PP/EPDM blends. Moreover, the brittle-ductile transition temperature (TBT) increased with increasing 1/R, whereas the critical interparticle distance (IDc) reduced with increasing 1/R. Finally, it was found that the different curves of IDc versus test temperature (T) for different notches reduced down to a master curve if plotting IDc versus TBTm-T, where TBTm was the TBT of PP itself for a given notch, indicating that TBTm-T was a more universal parameter that determined the BDT of polymers. This conclusion was well in agreement with the theoretical prediction. 相似文献
It was theoretically pointed out that the product of the yield stress and yield strain of matrix polymer that determined the brittle-ductile transition (BDT) of particle toughened polymers. For given particle and test condition, the higher the product of the yield stress and the yield strain of the matrix polymer, the smaller the critical interparticle distance (IDc) of the blends was. This was why the IDc (0.15 μm) of the polypropylene (PP)/rubber blends was smaller than that (0.30 μm) of the nylon 66/rubber blends, and the IDc of the nylon 66/rubber blends was smaller than that (0.60 μm) of the high density polyethylene (HDPE)/rubber blends. 相似文献
The compatibilization of mixtures of polyolefins or of polyolefins with polystyrene using either liquid polybutadiene (l-PB)/organic peroxide or styrene-butadiene-styrene (SBS) block copolymers was investigated. Tensile impact strength was chosen as a measure of compatibility. Binary blends LDPE/high-impact polystyrene (HIPS) and LDPE/poly(propylene) (PP) as well as LDPE/HDPE/PP/HIPS blends were prepared by blending in the chamber of a Brabender Plasticorder. Composition of the blends corresponds to real commingled plastic waste. It was found that l-PB-based compatibilizer enhanced the impact strength of LDPE/HIPS blends with LDPE contents higher than 60 wt.-% only. Also SBS copolymer enhanced the impact strength of LDPE/PP blends with LDPE contents higher than 40 wt.-%. Both the compatibilizers substantially increased the toughness of LDPE/HDPE/PP/HIPS blends with composition similar to the municipal plastic waste. 相似文献
Studies are reported on tensile and impact properties of several binary and ternary blends of polypropylene (PP), styrene-b-ethylene-co-butylene-b-styrene triblock copolymer (SEBS), high-density polyethylene (HDPE), and polystyrene (PS). The blend compositions of the binary blends PP/X were 10 wt % X and 90 wt % PP, while those of the ternary blends PP/X/Y were 10 wt % of X and 90 wt % of PP/Y, or 10 wt % Y and 90 wt % PP/X (PP/Y and PP/X were of identical composition 90:10); X, Y being SEBS, HDPE, or PS. The results are interpreted for the effect of each individual component by comparing the binary blends with the reference system PP, and the ternary blends with the respective binary blends as the reference systems. The ternary blend PP/SEBS/HDPE showed properties distinctly superior to those of PP/SEBS/PS or the binary blends PP/SEBS and PP/HDPE. Differences in the tensile yield behavior of the different samples and their correlation with impact strength suggested shear yielding as the possible mechanism of enhancement of impact strength. Scanning electron microscopic study of the impact fractured surfaces also supports the shear yielding mechanism of impact toughening of these blends. 相似文献
This article is concerned with the effect of the inherent matrix properties (matrix molar mass and crystallinity) as well as the temperature on the impact behaviour of rubber toughened semicrystalline polyethylene terephthalate (PET). The dispersed phase consists of a blend of an ethylene-co-propylene rubber (EPR) and a copolymer of ethylene and 8 wt% glycidyl methacrylate (E-GMA8) acting as a compatibilising agent, leading to PET/(EPR/E-GMA8) blends. The influence of the matrix molar mass on the impact behaviour of rubber toughened PET is found to primarily originate from its effect on the blend phase morphology, rather than from an inherent effect of the molar mass itself. The dispersed phase particle size is seen to decrease with increasing PET molar mass. A direct correlation between the impact strength and the interparticle distance could be established. A critical interparticle distance (IDc) of 0.1 μm could be determined, independent of the PET molar mass. The brittle-ductile transition temperature (Tbd) of the blends with a varying matrix molar mass also displayed a strong correlation with the interparticle distance, independent of the matrix molar mass. However, this correlation appears to depend on the crystalline characteristics of the PET matrix material since an incompletely crystallised PET matrix leads to an increase of the Tbd. 相似文献
Summary
The glass transition behavior of ternary blends of polypropylene (PP), polystyrene (PS) and styrene-ethylene-propylene-styrene
block copolymer (SEPS) was investigated. The blends were prepared by an internal mixer, and their dynamic mechanical properties
and morphology were measured. The blends showed phase inversion at around 75wt% PS composition. The glass transition temperature
(Tg) of the PP phase shifted to lower temperature as the PS contents were increased in PP/PS binary blends, probably due to the
mismatch of thermal expansion coefficients between two components. As the SEPS copolymer contents were increased, the Tg's of the PP phase in the blends increased. In particular, the large increase in Tg of the PP phase was observed in the PP/PS (25/75) blends where the phase inversion takes place.
Received: 2 February 1998/Revised version: 24 March 1998/Accepted: 13 April 1998 相似文献
AbstractThe effect of SBS and nano-CaCO3 on the mechanical properties of PS blends was studied, and their morphologies were characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Izod impact strengths of notched samples of PS/SBS/CaCO3 blends with nanometre particles of nano-CaCO3 and SBS are higher than those of PS and PS/SBS blends with the same content of SBS, and the tensile strengths are higher than those of PS/SBS blends. The inclusion of nano-CaCO3 within the dispersed phase of SBS enlarges the volume of the domains of SBS, which increases the toughness of the ternary blends (PS/SBS/CaCO3). The mass ratio of SBS/CaCO 3 plays an important role in the properties of the ternary blends because it affects the concentration of SBS in these blends, the dispersion of nano-CaCO3 and the morphology of the ternary blends. 相似文献
Summary: Polyoxymethylene (POM)/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane(TPU) and an inorganic filler, CaCO3, were used to achieve balanced mechanical properties of POM. A two‐step processing method, in which the elastomer and the filler were mixed to a masterbatch first and then the masterbatch was melt‐blended with pure POM, was used to obtain a core‐shell microstructure with CaCO3 covered by TPU. A brittle‐ductile transition phenomenon was observed with increasing TPU content for this ternary system. To better understand the toughening mechanism, we investigated the fractured surface, interparticle distance, and the spherulite size of POM as function of the TPU and CaCO3 content. The critical TPU content depended on not only the content of CaCO3, but also the size of CaCO3 particles. The observed brittle‐ductile transition was discussed based on the crystallinity and spherulite size of POM as well as Wu's critical interparticle distance theory. The results showed that the impact strength of POM/TPU/CaCO3 ternary system depends on a critical, interparticle distance, which varies from one system to another. The dependence of the impact strength on the spherulite size was considered for the first time, and a single curve was constructed. A critical spherulite size of 40 micron was found, at which brittle‐ductile transition occurs, regardless of the TPU and CaCO3 content or the size of CaCO3 particles. Our results indicate that the spherulite size of POM indeed plays a role in determining the toughness, and must be considered when discussing the toughening mechanism.
Izod impact strength vs. the crystal size for POM/TPU blends and POM/TPU/CaCO3 ternary composites. 相似文献