Modification of PP/HDPE blends by PP-PE sequential polymerization product

The morphology and mechanical properties of polypropylene/high-density polyethylene (PP/HDPE) blends in a wide range of compositions modified by a sequential Ziegler-Natta polymerization product (PP-PE) have been investigated. PP-PE contains multiple components such as PP, ethylene-propylene copolymer (EPC), and high molecular weight polyethylene (HMWPE). The effects of PP-PE on the mechanical properties and morphology of the PP/HDPE blends are the aggregative results of all its individual components. Addition of PP-PE to the blends not only improved the tensile strength of the blends, but the elongation at break increased linearly while the moduli were nearly unchanged. Morphological studies show that the adhesion between the two phases in all the blends of different compositions is enhanced and the dispersed domain sizes of the blends are reduced monotonously with the increment of the content of PP-PE. PP-PE has been demonstrated to be a more effective compatibilizer than EPC. Based on these results, it can be concluded that the tensile strength of the blends most on the adhesion between the two phases and the elongation at break depends most on the domain size of the dispersed component. © 1995 John Wiley & Sons, Inc.     

Effect of triblock copolymers on homogeneity,mechanical properties and swelling behavior of IIR/SBR rubber blends

The present research concerns with the preparation and characterization of isobutylene isoprene/butadiene–styrene rubber (IIR/SBR) blends with different blend ratios, in the presence and absence of styrene–isoprene–styrene (SIS) and styrene–isobutylene–styrene (SiBS) triblock copolymers to be tested as compatibilizers. Effect of the triblock copolymers on the blend homogeneity was investigated with the aid of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements. Characterization of the rubber blends was conducted by measuring the physico-mechanical properties after and before thermal aging, in presence and absence of the triblock copolymers. In addition, weight swell % in toluene, motor oil and brake fluid of the rubber blend vulcanizates was assessed. The incorporation of SIS and SiBS triblock copolymers improved the homogeneity of IIR/SBR blends as well as increased both tensile strength and elongation at break of the rubber blend vulcanizates. Of the entire blend ratios examined, IIR/SBR (25/75) blend containing SIS compatibilizer possessed the best physico-mechanical properties (12.6 MPa tensile strength and 425 % elongation at break) and (14 MPa tensile strength and 555 % elongation at break) after and before thermal aging, respectively. Utilization of SIS and SiBS triblock copolymers enhanced the thermal stability of IIR/SBR blend vulcanizates. Moreover, IIR/SBR blends of different blend ratios showed superior swelling resistance in the brake fluid. IIR/SBR (25/75) blend containing SIS compatibilizer and cured with CBS/ZDEC/S vulcanizing system possessed the best physico-mechanical properties (14.4 MPa tensile strength and 440 % elongation at break) and (16.5 MPa tensile strength and 610 % elongation at break) after and before thermal aging, respectively.     

Structure and properties of PP/POE/HDPE blends

This work was aimed to counteract the effect of ethylene‐α‐olefin copolymers (POE) by reinforcing the polypropylene (PP)/POE blends with high density polyethylene (HDPE) particles and, thus, achieved a balance between toughness and strength for the PP/POE/HDPE blends. The results showed that addition of HDPE resulted in an increasing wide stress plateau and more ductile fracture behavior. With the increase of HDPE content, the elongation at break of the blends increased rapidly without obvious decrease of yield strength and Young's modulus, and the notched izod impact strength of the blends can reach as high as 63 kJ/m² at 20 wt % HDPE loading. The storage modulus of PP blends increased and the glass transition temperature of each component of the blends shifted close to each other when HDPE was added. The crystallization of HDPE phase led to an increase of the total crystallinity of the blend. With increasing HDPE content, the dispersed POE particle size was obviously decreased, and the interparticle distance was effectively reduced and the blend rearranged into much more and obvious core‐shell structure. The fracture surface also changed from irregular striation to the regularly distant striations, displaying much obvious character of tough fracture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

HDPE/sPS共混体系结构与性能的研究

用2种分子量不同的苯乙烯-(乙烯/丁烯)-苯乙烯三嵌段共聚物(SEBS)和一种苯乙烯-b-乙烯/丁烯(SEB)两嵌段共聚物为增容剂,对高密度聚乙烯(HDPE)/间规聚苯乙烯(sPS)共混物进行增容.采用扫描电镜(SEM)及拉伸试验研究了增溶剂的分子量及结构对共混物形态结构及力学性能的影响.结果表明:3种增容剂SEBS(SEB)均可有效地降低sPS分散相的尺寸并增加HDPE/sPS共混物的界面强度,从而提高其力学性能.sPS 的掺入可以显著提高HDPE的耐热性能.     

In situ compatibilization of polypropylene–polyethylene blends: a thermomechanical and spectroscopic study

Polypropylene (PP) and low density polyethylene (LDPE) were melt blended in proportions of 75/25, 50/50 and 25/75 w/w, respectively. Poly(propylene-g-maleic anhydride) (PP-g-MA) with 0.8 mol% maleic anhydride content and poly(ethylene-co-vinyl alcohol) (EVAL) with 7.5 mol% vinyl alcohol content were added at a 50/50 w/w proportion as in situ reactive compatibilizers. Four series of compatibilized blends were produced containing 2.5, 5, 10 and 20 wt% compatibilizer in the final blend. The compatibilization reaction was followed by a torque increase during mixing and by FTi.r. spectroscopy. A notable improvement in tensile strength, elongation at break and impact strength was observed for all blends after compatibilization and, in particular, for the blends containing 10 wt% compatibilizer. Scanning electron microscopy (SEM), aided by micro-Raman spectroscopy, was used for investigating the morphology of the blends.     

Compatibilization of high‐impact polystyrene/high‐density polyethylene blends by styrene/ethylene–butylene/styrene block copolymer

Compatibilization of polymer blends of high‐impact polystyrene (HIPS) and high‐density polyethylene (HDPE) blend by styrene/ethylene–butylene/styrene (SEBS) was elucidated. Polymer blends containing many ratios of HIPS and HDPE with various concentrations of SEBS were prepared. The Izod impact strength and elongation at break of the blends increased with increases in SEBS content. They increased markedly when the HDPE content was higher than 50 wt %. Tensile strength of blends increased when the SEBS concentration was not higher than 5 pphr. Whenever the SEBS loading was higher than 5 pphr, the tensile strength decreased and a greater decrease was found in blends in which the HDPE concentration was more than 50 wt %. The log additivity rule model was applied to these blends, which showed that the blends containing the HIPS‐rich phase gave higher compatibility at the higher shear rates. Surprisingly, the blends containing the HDPE‐rich phase yielded greater compatibility at the lower shear rates. Morphology observations of the blends indicated better compatibility of the blends with increasing SEBS concentration. The relaxation time (T₂) values from the pulsed NMR measurements revealed that both polymer blends became more compatible when the SEBS concentration was increased. When integrating all the investigations of compatibility compared with the mechanical properties, it is possible to conclude that SEBS promotes a certain level of compatibilization for several ratios of HIPS/HDPE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 742–755, 2004     

PP/有机硅树脂阻燃体系的性能研究

采用有机硅树脂阻燃剂阻燃改性聚丙烯(PP),研究有机硅阻燃剂用量对PP共混体系的阻燃性能及其力学性能的影响。结果显示:随着有机硅树脂阻燃剂用量的增加,PP共混物的极限氧指数逐渐增大,共混体系的拉伸强度和弯曲强度有一定程度的降低,而断裂伸长率和冲击强度则下降幅度较大。当加入20%的有机硅树脂阻燃剂时,其极限氧指数由纯PP的17.8%增加到25.5%,当有机硅树脂阻燃剂的质量分数20%,PP的拉伸强度和弯曲强度分别降低了18.48%、12.47%,而断裂伸长率和冲击强度分别降低了57.72%、68.90%。     

Compatibilization of PP/PE blends and scraps with Royalene: Mechanical properties,SAXS, and WAXS

PP/PE 93/7 model virgin blends and recycled scraps were compatibilized with Royalene (EPDM/PE 65/35 blend) and mechanically tested. No differences in impact and tensile properties between them were found. However, the tensile-impact strength increased almost twice with 10%-compatibilized sample in comparison with uncompatibilized ones. The yield stress of blends containing 10% Royalene decreased to 75–80% of the original value. This effect is in agreement with microhardness measurements; the increase in the compatibilizer content causes softening of the blend. The elongation at break and elongation at yield do not depend on the compatibilizer concentration. The compatibilizer does not influence the degree of crystallinity (WAXS data) of the blends either. Vickers microhardness is in good agreement with Tabor's relationship. The differences between long periods of HDPE in Royalene and LDPE in PP/PE blends (SAXS) proved PE/EPDM interaction. The interaction plays a key role in the toughening of PP/PE blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The Use of Ethylene/Propylene Copolymers as Compatibilizers for Recycled Polyolefin Blends

Compatibilizing effects of ethylene/propylene (EPR) diblock copolymers on the morphology and mechanical properties of immiscible blends produced from recycled low‐density polyethylene (PE‐LD) and high‐density polyethylene (PE‐HD) with 20 wt.‐% of recycled poly(propylene) (PP) were investigated. Two different EPR block copolymers which differ in ethylene monomer unit content were applied to act as interfacial agents. The morphology of the studied blends was observed by scanning‐ (SEM) and transmission electron microscopy (TEM). It was found that both EPR copolymers were efficient in reducing the size of the dispersed phase and improving adhesion between PE and PP phases. Addition of 10 wt.‐% of EPR caused the formation of the interfacial layer surrounding dispersed PP particles with the occurrence of PE‐LD lamellae interpenetration into the layer. Tensile properties (elongation at yield, yield stress, elongation at break, Young's modulus) and notched impact strength were measured as a function of blend composition and chemical structure of EPR. It was found that the EPR with a higher content of ethylene monomer units was a more efficient compatibilizer, especially for the modification of PE‐LD/PP 80/20 blend. Notched impact strength and ductility were greatly improved due to the morphological changes and increased interfacial adhesion as a result of the EPR localization between the phases. No significant improvements of mechanical properties for recycled PE‐HD/PP 80/20 blend were observed by the addition of selected block copolymers.     

增容剂对HDPE／AS合金流变和力学性能的影响

研究了增容剂氯化聚乙烯接枝（丙烯腈／苯乙烯）共聚物对ＨＤＰＥ／ＡＳ共混体系加工流变性能和力学性能的影响。增容剂使共混体系的塑化时间减少,且随着增容剂用量的增加,共混体系的平衡扭矩和拉伸强度增大,而断裂伸长率在ＨＤＰＥ／ＡＳ／ＰＥ－Ｃ－ｇ－ＡＳ＝８０／２０／４时出现极大值;螺杆转速的增加使共混体系的平衡扭矩增大。     

Studies on mechanical and thermal properties of ternary blends of polyethylenes. I

Six film samples of varying compositions of linear low‐density polyethylene (LLDPE), 10–35 wt %, and high‐density polyethylene (HDPE), 40–65 wt %, having a fixed percentage of low‐density polyethylene (LDPE) at 25 wt % were extruded by melt blending in a single‐screw extruder (L/D ratio = 20 : 1) of uniform thickness of 2 mil. The tensile strength, elongation at break, and impact strength were found to increase up to 60 wt % HDPE addition, starting from 40 wt % HDPE, in the blends and then decreased. The blend sample B‐500 was found to be more thermally stable than its counterparts. The appearance of a single peak beyond 45 wt % HDPE content in the blend in dynamic DSC scans showed the formation of miscible blend systems and this was further confirmed by scanning electron microscopic analysis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1691–1698, 2005     

乙烯-醋酸乙烯酯共聚物/高密度聚乙烯的性能研究

讨论了不同高密度聚乙烯(HDPE)含量的乙烯-醋酸乙烯酯共聚物(EVA)/HDPE共混物的流变性能、热性能、相容性,以及共混纤维的可纺性、力学性能。实验结果表明:随着HDPE含量的增加,共混物的流动性变差;共混物的晶区是部分相容的。当共混物中HDPE的百分含量为15%时,共混物的可纺性及共混纤维的力学性能最佳;随着拉伸倍数的增加,共混纤维断裂强度增大、断裂伸长率降低。     

Morphology and mechanical properties of biaxially oriented films of polypropylene and HDPE blends

Biaxially oriented films of blends of high-density polyethylene (HDPE) with polypropylene (PP) homopolymer and PP copolymers prepared by twin-screw extrusion and lab-stretcher have been investigated by scanning electron microscopy (SEM), polarized microscopy, differential-scanning calorimeter, and universal testing machine. Three different kinds of PP copolymers were used: (i) ethylene–propylene (EP) random copolymer; (ii) ethylene–propylene (EP) block copolymer; (iii) ethylene–propylene–buttylene (EPB) terpolymer. In the SEM study of the morphology of films of HDPE with various PP blends, phase separation is observed between the PP phase and the HDPE phase for all blends and compositions. In all blends, HDPE serves to reduce the average spherulites size, probably acting as a nucleating agent for PP. The reduction of spherulite size appeared most significantly in the blend of EPB terpolymer and HDPE. A large increase of crystallization temperature was found in the blend of EPB terpolymer and HDPE compared with the unblended EPB terpolymer. For the blend of EPB terpolymer and HDPE, the improvement of tensile strength and modulus is observed with an increase of HDPE content, and this can be considered as a result of the role of HDPE in reducing average spherulite size. © 1994 John Wiley & Sons, Inc.     

Compatibilization effects of block copolymers in high density polyethylene/syndiotactic polystyrene blends

Three triblock copolymers of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) of different molecular weights and one diblock copolymer of poly[styrene-b-(ethylene-co-butylene)] (SEB) were used to compatibilize high density polyethylene/syndiotactic polystyrene (HDPE/sPS, 80/20) blend. Morphology observation showed that phase size of the dispersed sPS particles was significantly reduced on addition of all the four copolymers and the interfacial adhesion between the two phases was dramatically enhanced. Tensile strength of the blends increased at lower copolymer content but decreased with increasing copolymer content. The elongation at break of the blends improved and sharply increased with increments of the copolymers. Drop in modulus of the blend was observed on addition of the rubbery copolymers. The mechanical performance of the modified blends is strikingly dependent not only on the interfacial activity of the copolymers but also on the mechanical properties of the copolymers, particularly at the high copolymer concentration. Addition of compatibilizers to HDPE/sPS blend resulted in a significant reduction in crystallinity of both HDPE and sPS. Measurements of Vicat softening temperature of the HDPE/sPS blends show that heat resistance of HDPE is greatly improved upon incorporation of 20 wt% sPS.     

云母粉对注塑发泡PP/EPDM共混物泡孔结构和力学性能的改善

采用注塑发泡方法制备了质量比为75/25的聚丙烯/三元乙丙橡胶(PP/EPDM)共混物和质量比为75/25/7.5的PP/EPDM/云母粉复合材料制品,分析了两种制品泡孔结构和结晶性能的差异及其对制品力学性能的影响。结果表明:与共混物发泡制品相比,复合材料发泡制品的拉伸屈服强度、拉伸断裂强度、断裂伸长率和无缺口冲击强度分别提高约5%、48%、206%和22%,并呈现应变硬化现象。复合材料发泡制品的泡孔直径明显较小且分布较均匀,泡孔密度明显较大,结晶度较高,这些是使复合材料发泡制品具有较高力学性能的主要原因。     

Studies on binary and ternary blends of polypropylene with SEBS,PS, and HDPE. II. Tensile and impact properties

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.     

PP/丙烯基弹性体/SEBS医用热塑性弹性体的性能

以聚丙烯(PP)、丙烯基弹性体和苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)为主要原材料,采用熔融共混改性方法制备PP/丙烯基弹性体和PP/丙烯基弹性体/SEBS两种热塑性弹性体。采用转矩流变仪、拉伸试验机、硬度计和雾度计分别对共混体系的流变性能、拉伸性能、硬度和透光率进行分析与表征。结果表明,随着PP/丙烯基弹性体配比的增加,二元共混体系的平衡扭矩降低、硬度(邵A)提高、透光率变好、断裂伸长率增加,当其配比为1∶1时,共混体系的拉伸强度达到最大值(34.2 MPa);当PP与丙烯基弹性体配比为1:1不变时,随着SEBS含量增加,三元共混体系的平衡扭矩增大、硬度(邵A)减小、透光率变差、断裂伸长率提高;当PP、丙烯基弹性体和SEBS配比为47.5∶47.5∶5时,共混体系的透光率可达87%,硬度(邵A)为87,拉伸强度为35.2 MPa,断裂伸长率为750%,100%定伸强度为11.8 MPa,可满足医疗输液器械的要求。     

茂金属聚乙烯的共混改性研究

对三种茂金属聚乙烯 (mPE)做了DSC研究。将茂金属聚乙烯同传统聚烯烃 (HDPE ,PP ,LDPE)进行了共混研究 ,结果表明mPE的加入提高了LDPE的拉伸性能 ,使HDPE和PP的拉伸强度下降 ,但mPE含量在 2 0 %～2 5 %的范围内 ,拉伸强度和断裂伸长率下降很小。mPE的加入大大提高了PP和HDPE的冲击性能。对mPE/LDPE共混物吹膜进行了研究 ,测定了共混物的熔体流动速率 ,探索了吹膜的工艺条件 ,以及薄膜的拉伸性能、撕裂性能与共混组成比的关系。     

The effect of irradiation on morphology and properties of the PET/HDPE blends with trimethylol propane trimethacrylate (TMPTA)

The mechanical properties of poly(ethylene terephthalate)/high-density poly(ethylene) (PET/HDPE) blends were improved by γ-ray irradiation combined with using a cross-linking agent—trimethylol propane trimethacrylate (TMPTA). The effect of the weight ratio of PET/HDPE, the content of TMPTA and the absorbed dose on the phase morphology and the mechanical properties of the PET/HDPE blends were investigated through scanning electron microscopy (SEM), gel fraction, Fourier transform infrared spectroscopy (FTIR), tensile and impact tests. SEM images showed that the phase structure changed significantly as TMPTA coexistence. The results of tensile and impact tests indicated that their mechanical properties depended on their structures. FTIR spectra suggested that a new structure of HDPE-g-PET was generated. When the weight ratio of PET/HDPE blend was 80/20, the content of TMPTA was 1 wt% and the absorbed dose was 30 kGy, the tensile strength, elongation at break and impact strength of irradiated blends were improved greatly compared with non-irradiated blends.     

Effects of dynamic vulcanization on the physical,mechanical, and morphological properties of high‐density polyethylene/(natural rubber)/(thermoplastic tapioca starch) blends

Blending of high density polyethylene (HDPE), natural rubber (NR), and thermoplastic tapioca starch (TPS) have been studied. Two series of samples having 5–30 wt% of TPS were prepared: (a) unvulcanized blends (control) and (b) dynamically vulcanized HDPE/NR/TPS blends. The composition of the HDPE/NR was constant and fixed at a blend ratio of 70/30. Morphology studies by SEM showed that the TPS particles were homogeneously dispersed and well‐embedded in vulcanized HDPE/NR matrix. The SEM micrographs showed agreement with the tensile strength and elongation at break values. Tensile strength improved significanly when the HDPE/NR/TPS blends were vulcanized by using sulfur curative system. The enhancement in tensile properties is attributed to the crosslinking reaction within the NR phase. J. VINYL ADDIT. TECHNOL., 18:192–197, 2012. © 2012 Society of Plastics Engineers