Effect of glass fiber length on the creep and impact resistance of reinforced thermoplastics

Impact and flexural creep testing were conducted at temperatures between −22°F (−30°C) and 250°F (121°C) to evaluate and compare the end-use performance of continuous long glass fiber-reinforced thermoplastic sheet composites to that of short glass fiber-reinforced thermoplastics. The matrices studied consisted of amorphous (polycarbonate and acrylonitrile-butadiene-styrene) and semicrystalline (polypropylene) polymers. Data were obtained from both injection-molded specimens (short fibers), and from specimens machine-cut from compression-molded test panels (continuous long fibers). The creep results of this study demonstrated that continuous long fibers are more efficient than short fibers in reinforcing the thermoplastic matrices, resulting in enhanced load-bearing ability at elevated temperatures. The addition of continuous long glass fibers to the thermoplastic matrices led to a significant increase in the notched Izod impact strengths between the temperatures of −22°F (−30°C) and 77°F (25°C), and only slight improvement in the drop-weight impact strengths. The lack of correlation between notched Izod impact and drop-weight strengths is largely due to the difference in crack propagation and fracture initiation energies. Results of the Rheometrics instrumented impact test indicated a higher total fracture energy for the long glass-reinforced thermoplastic sheet composites than for the short glass-reinforced injection-molded thermoplastics. The decreased ease of crack propagation in thermoplastic sheet composites is associated with the high energy-absorbing mechanisms of fiber debonding and interply delamination. The results of this study point to the significant property improvement of continuous long fibers vs. short fibers. The creep strength of short fiber-reinforced thermoplastics are greatly affected by the nature of the stress transfer which in turn is influenced by the critical fiber length and temperature, which is not the case for the long fiber-reinforced thermoplastic sheet composites. Long fibers dramatically increase the impact resistance of thermoplastics. The retention of toughness at low temperatures coupled with elevated temperature performance greater than similar short glass fiber-reinforced thermoplastics effectively extends the capabilities of thermoplastic sheet composites at both temperature extremes.     

The physical and mechanical properties of polymer composites filled with Fe‐powder

In this study, the effect of Fe powder on the physical and mechanical properties of high density polyethylene (HDPE) was investigated experimentally. HDPE and HDPE containing 5, 10, and 15 vol % Fe metal–polymer composites were prepared with a twin screw extruder and injection molding. After this, fracture surface, the modulus of elasticity, yield and tensile strength, % elongation, Izod impact strength (notched), hardness (Shore D), Vicat softening point, heat deflection temperature (HDT), melt flow index (MFI), and melting temperature (T_m) were determined, for each sample. When the physical and mechanical properties of the composites were compared with the results of unfilled HDPE, it was found that the yield and tensile strength, % elongation, and Izod impact strength of HDPE decreased with the vol % of Fe. As compared with the tensile strength and % elongation of unfilled HDPE, tensile strength and % elongation of 15 vol % Fe filled HDPE were lower, about 17.40% and 94.75% respectively. On the other hand, addition of Fe into HDPE increased the modulus of elasticity, hardness, Vicat softening, MFI, and HDT values, such that 15 vol % Fe increased the modulus of elasticity to about 48%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Mechanical Properties of Polymers Filled with Iron Powder

Mechanical properties of metal-polymer matrix composites were investigated experimentally. High density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) were used as the polymer matrix and Fe powder in 5, 10, and 15 vol% was used as the metal. The modulus of elasticity, yield and tensile strength, % elongation, Izod notched impact strength, Shore D hardness, and fracture surfaces of the composites were determined. It was found that vol% Fe reduced the Izod impact strength of HDPE much more than that of PP and PS, while Fe powder increased the hardness of HDPE more than that of PP and PS. Among the composites, PS-Fe composites had higher yield, tensile strength and modulus of elasticity than HDPE-Fe and PP-Fe composites. However, % elongation of PS-Fe composites was lower than that of the other composites. In addition, HDPE- and PP-based composites exhibited ductile type fracture, while PS-Fe composites exhibited brittle type fracture.     

Physical and Mechanical Properties of Polypropylene Reinforced with Fe Particles

ABSTRACT

The physical and mechanical properties of Polypropylene (PP) and Fe-PP polymer composites containing 5, 10, and 15 vol% Fe were investigated experimentally. After preparing PP and Fe–PP polymer composites with a twin screw extruder and injection molding, the following properties were determined: yield and tensile strength, the modulus of elasticity, % elongation, hardness (Shore D), Izod impact strength (notched), melt flow index (MFI), Vicat softening point, Heat deflection temperature (HDT), and melting temperature (Tm) of PP and metal-polymer composites. As compared to PP, It was found that by increasing the vol% of Fe in PP, notched Izod impact strength, yield and tensile strength, and % elongation decreased. On the other hand, the modulus of elasticity, hardness, MFI, vicat softening point, and HDT values increased with the amount of iron.     

Mechanical and thermal properties of ABS and leather waste composites

To determine the possibility of using leather waste as reinforcing filler in the thermoplastic polymer composite, acrylonitrile–butadiene–styrene (ABS) as the matrix and leather buffing powder as reinforcing filler were used to prepare a particulate reinforced composite to determine testing data for the physical, mechanical, and thermal properties of the composites, according to the filler loading in respect to thermoplastic polymer. The ABS and leather powder composites were prepared by the extrusion of ABS with 2.5, 5, 7.5, 10, 12.5, and 15 wt % of leather powder in corotating twin screw extruder. The extruded strands were cut into pellets and injection molded to make specimens. These specimens were tested for physicomechanical properties like tensile and flexural strengths, tensile and flexural modulus, Izod and charpy impact strength, abrasion resistance, Rockwell hardness, density, Heat deflection temperature (HDT) and Vicat softening point (VSP), water absorption, and thermal degradation analysis. The incorporation of leather waste powder does not affect the tensile, flexural strengths, Izod impact strength, abrasion resistance, Rockwell hardness, density, HDT and VSP values drastically. However, the tensile modulus, tensile elongation, and charpy impact strength values are reduced significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3062–3066, 2006     

Mechanical and dynamic mechanical properties of waste rubber powder/HDPE composite

Mechanical and dynamic mechanical properties of a waste rubber powder‐filled high‐density polyethylene (HDPE) composite are investigated. Rubber powder is surface‐modified with acrylamide (AAm) using ultraviolet. Rubber powder and HDPE are extruded using a single‐screw extruder and maleic anhydride‐grafted polypropylene is added as a compatibilizer to improve the adhesion between rubber powder and HDPE. The tensile stress and strain of AAm‐grafted rubber powder/compatibilizer/HDPE composites always exhibit higher values than those of unmodified rubber powder/HDPE composites. Surface modification of rubber powder is shown to decrease the magnitude of the tan δ of the HDPE composite. Higher values of the notched Izod impact strength of a surface‐modified rubber‐filled composite is observed compared to those of unmodified rubber‐filled composite. Experimental results show that acryl amide‐grafted rubber powder reacts with maleic anhydride and it results in improved mechanical properties of the HDPE composite. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2595–2602, 2000     

Low temperature impact properties of long fiber thermoplastic composite molding materials

Four long fiber thermoplastic resin matrices, nylon 6, polypropylene, polyethylene terephthalate, and styrene maleic anhydride, containing differing amounts of long fiber glass reinforcement, were tested for notched Izod impact strength over the temperature range of 22 to −32°C. The notched impact properties of the long fiber thermoplastic composite molding materials are substantially greater than literature values for short fiber analogues. The fiber dominant performance of the long fiber materials is evidenced by increasing impact values with corresponding increases in weight percent fiber content. No apparent ductile/brittle transition in the fracture mode was observed for the long fiber materials that were tested.     

Processing-property relationships in compression molding of sheet molding compounds

An experimental investigation was conducted into establishing relationships between the processing variables and the mechanical properties of compression-molded parts of sheet molding compounds (SMC). Emphasis was placed on investigating the effects on the tensile properties, impact strength, and dynamic mechanical properties of composite specimens, of low-profile additives, and of treating glass fibers (for reinforcement) with sizing chemicals. The processing variables investigated were cure time, mold temperature, and mold pressure. It was found that: (1) An optimum cure time and mold temperature exist for achieving molded SMC composites of the greatest tensile and impact strengths; (2) Of the four different types of low-profile thermoplastic additives employed, the poly(vinyl acetate) modified with acrylic acid gives rise to molded SMC composites having the greatest tensile and impact strengths; (3) An optimum cure time and mold temperature exist for achieving the highest glass-transition (T_g) of the low-profile additive; (4) The values of cure time and mold temperature that have yielded the greatest tensile and impact strengths also yield molded specimens having the highest T_g of the low-profile additive.     

Development of environmentally friendly high‐density polyethylene and turmeric spent composites: Physicomechanical,thermal, and morphological studies

High‐density polyethylene (HDPE)/turmeric spent (TS) composites were prepared by the extrusion of an HDPE resin with 5, 10, 15, or 20 wt % TS. HDPE granules and TS master‐batch flakes were compounded on a corotating and intermeshing twin‐screw extruder. The extrudate strands were cut into pellets and injection‐molded to make test specimens. These specimens were tested for physicomechanical properties such as the tensile, flexural, and impact strengths, surface hardness, abrasion resistance, density, and water absorption and thermal characteristics such as the heat distortion temperature (HDT) and melt flow index (MFI). Test results revealed that the incorporation of TS affected the tensile, flexural, and Izod impact strengths of the HDPE/TS composites to some extent, whereas the tensile modulus increased from 606.9 to 752.0 N/mm² and the HDT increased from 61 to 65°C. Furthermore, the addition of TS yielded only marginal variations in the surface hardness, abrasion resistance, density, water absorption, and MFI values of the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚甲醛/弹性体/纳米碳酸钙复合材料的制备及性能研究

采用双螺杆熔融共混的方法,以4种不同的混合顺序,制备了聚甲醛/热塑性聚氨酯弹性体/纳米碳酸钙（POM/TPU/nano-CaCO3）复合材料。通过力学性能测试、偏光显微镜、差示扫描量热仪、熔体流动速率仪和扫描电子显微镜,考察了nano-CaCO3的用量对POM/TPU(90/10)复合材料力学性能的影响,并探讨了共混方式对复合材料力学性能及微观结构形态的影响。结果表明,4 %的nano-CaCO3与TPU预先混合制成母粒再与POM共混得到的复合材料中POM晶粒发生明显细化,缺口冲击强度高达12.5 kJ/m2,冲击性能较为优异。     

Processing–Nanostructure–Property Relationships of All‐Polyethylene Composites Reinforced by Flow‐Induced Oriented Crystallization of UHMWPE

All‐polyethylene composites exhibiting substantially improved toughness/stiffness balance are readily produced during conventional injection molding of high density polyethylene (HDPE) in the presence of bimodal polyethylene reactor blends (RB40) containing 40 wt% ultrahigh molar mass polyethylene (UHMWPE) dispersed in HDPE wax. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses shows that flow‐induced crystallization affords extended‐chain UHMWPE nanofibers forming shish which nucleates HDPE crystallization producing shish‐kebab structures as reinforcing phases. This is unparalleled by melt compounding micron‐sized UHMWPE. Injection molding of HDPE with 30 wt% RB40 at 165 °C affords thermoplastic all‐PE composites (12 wt% UHMWPE), improved Young's modulus of 3400 MPa, tensile strength of 140 MPa, and impact resistance of 22.0 kJ/m². According to fracture surface analysis, the formation of skin‐intermediate‐core structures accounts for significantly improved impact resistance. At constant RB40 content both morphology and mechanical properties strongly depend upon processing temperature. Upon increasing processing temperature from 165 °C to 250 °C the average shish‐kebab diameter increases from the nanometer to micron range, paralleled by massive loss of self‐reinforcement above 200 °C. The absence of shish‐kebab structure at 250 °C is attributed to relaxation of polymer chains and stretch‐coil transition impairing shish formation.     

两类增韧HDPE的力学性能及熔体流动性

以高密度聚乙烯(HDPE)为基体树脂、(乙烯／丙烯)共聚物和丁苯橡胶为增韧剂制得增韧母料(E-TMB)。分别采用将E-TMB与HDPE热机械共混和将(乙烯／丙烯)共聚物、丁苯橡胶与HDPE简单共混的方法制备了HDPE／E-TMB及HDPE／弹性体两类增韧HDPE。结果表明,HDPE／E-TMB的悬臂梁缺口冲击强度的提高幅度、拉伸屈服应力保持率均显著优于HDPE／弹性体,二者的弯曲弹性模量保持率基本相同;HDPE／E-TMB的熔体流动速率比HDPE／弹性体的小,但仍适宜于注射成型和挤出成型。     

Mechanical properties and foaming behavior of cellulose fiber reinforced high‐density polyethylene composites

This article investigates the effects of fiber length and maleated polymers on the mechanical properties and foaming behavior of cellulose fiber reinforced high‐density polyethylene composites. The results from the mechanical tests suggested that long fibers provided higher flexural and impact properties than short fibers. In addition, the maleated high‐density polyethylene increased flexural strength significantly, while the maleated thermoplastic elastormers increased notched Izod impact strength dramatically. On the other hand, the results from the extrusion foaming indicated that the composites with long and short fibers demonstrated similar cell morphology, i.e., a similar average cell size and cell size distribution. However, the addition of maleated high‐density polyethylene caused an increase of the average cell size and cell size distribution in the composites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

MAH原位接枝HDPE及其对HDPE/N-PCB复合材料力学性能的影响

将马来酸酐(MAH)、过氧化二异丙苯(DCP)、苯乙烯(St)、高密度聚乙烯(HDPE)和废印刷电路板非金属粉末(N-PCB)直接反应挤出,制备了HDPE/N-PCB复合材料,并研究了MAH用量对HDPE/N-PCB复合材料力学性能影响。对HDPE/N-PCB复合材料抽提残留物的红外分析结果表明,在HDPE/N-PCB复合材料中加入DCP、St、MAH之后,通过DCP引发HDPE原位接枝MAH,并随即与N-PCB粉末表面的羟基反应而起到了桥联作用,可改善HDPE基体与N-PCB粉末两相的界面作用。MAH反应增容后的HDPE/N-PCB复合材料与增容前相比,其拉伸强度、弯曲强度、缺口冲击强度及断裂伸长率的最大增幅分别为36%、12%、208%和262%。     

Multifunctional high density polyethylene nanocomposites produced by incorporation of exfoliated graphite nanoplatelets 1: Morphology and mechanical properties

This research explores the potential of using exfoliated graphite nanoplatelets, xGnP, as the reinforcement in high density polyethylene (HDPE). Two kinds of xGnP nanoparticles were used; xGnP‐1 has the thickness of 10 nm and a platelet diameter of 1 μm, whereas xGnP‐15 has the same thickness but the diameter is around 15 μm. HDPE/xGnP nanocomposite were fabricated first by melt blending and then followed by injection molding. The HDPE/xGnP nanocomposite's flexural strength, modulus and impact strength were evaluated and compared with composites filled with commercial reinforcements such as carbon fibers (CF), carbon black (CB) and glass fibers (GF). Polymer nanocomposites from HDPE/xGnP are equivalent in flexural stiffness and strength to HDPE composites reinforced with glass fibers and carbon black but slightly less than that of HDPE/carbon fiber composites at the same volume fraction. However, the Izod impact strength of HDPE/xGnP nanocomposites is significantly greater (∼250%) than all other reinforcements at the same volume fractions. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Long fiber reinforcement of polypropylene/polystyrene blends

The recycling of inseparable polymer mixtures usually results in blends with poor mechanical properties. A mixture of PP and PS was taken as a model compound for a recyclate. The effect of adding glass fibers to a mixture of PP/PS (70/30) was studied, with special attention to long glass fiber reinforcement. Test specimens were made in three different ways: by dry blending (direct injection molding), mild compounding with a single screw extruder, and compounding with a twin screw extruder. The fiber concentration was varied from 0 to 30 wt%. The fiber lengths were determined to investigate fiber attrition. The fiber lengths in the samples were 1.09 mm for dry blending, 0.72 mm for single screw compounding, and 0.33 mm for twin screw compounding. The mechanical behavior was studied by unnotched and notched Izod impact and tensile tests. The PP/PS blend had a low fracture strain and low unnotched Izod impact strength compared with a PP homopolymer. With an increasing fiber concentration and fiber length, the modulus, tensile strength, and particularly the impact strength increased. With a 30 wt% glass fiber of the long fiber compound (dry blended), the modulus was raised by a factor of 3.5, the fracture stress by a factor of 2.5 and the unnotched Izod impact strength by a factor of 10. The product quality as judged by the scatter of the data was best for the twin screw compound and poorest for the dry blend. Compounding with a single screw extruder gave fairly constant injection molding product properties, combined with excellent mechanical properties.     

Physical and Mechanical Properties of Iron Powder Filled Polystyrene Composites

This article reports on an experimental study of the physical and mechanical properties of Polystyrene (PS) and Fe-PS polymer composites containing 5, 10, and 15 vol.% of Fe powder. After mixing Fe powder and PS in a twin-screw extruder, an injection-molding machine was used to prepare unfilled PS and Fe-PS polymer composite samples. After that, the material properties were experimentally determined for each sample. The investigated material properties included the modulus of elasticity, yield and tensile strength, % elongation, Izod impact strength (notched), hardness (Shore D), melt flow index (MFI), heat deflection temperature (HDT), Vicat softening point, and glass transition temperature (T _g ). The results indicated that, compared to the unfilled PS, an addition of Fe into PS decreases the yield and tensile strength, % elongation, and Izod impact strength. Furthermore, it was determined that the Fe particles increase the modulus of elasticity, hardness, MFI, Vicat softening point, and HDT values.     

The Effect of Bronze Particles on the Physical and Mechanical Properties of Acrylonitrile-Butadiene-Styrene Copolymer

In this study, 5, 10, and 15 vol.% of bronze (Cu-10 wt.% Sn) powder on the physical and mechanical properties of Acrylonitrile-Butadiene-Styrene (ABS) were investigated experimentally. After preparing metal-polymer matrix composites (PMC) with a twin screw extruder and injection molding, fracture surface, the modulus of elasticity, yield and tensile strength, percentage elongation, Izod impact strength, hardness (Shore D), melt flow index (MFI), heat deflection temperature (HDT), Vicat softening point, and glass transition temperature (T _g) of each sample were determined. As compared to the unfilled ABS. It was found that by increasing the vol.% of bronze in ABS, yield and tensile strength, % elongation, Izod impact strength, MFI values decreased, while the modulus of elasticity, Shore D hardness, Vicat softening point, and HDT values increased.     

Recyclability of a glass fiber poly(butylene terephthalate) composite

The recyclability of a fiber-reinforced poly(butylene terephthalate) (PET) composite has been studied. After treatment with a suitable silane, processed regrind composites are successfully recycled, with mechanical properties as good as a comparable, commercial composite. The three processing techniques investigated are injection molding, extrusion compression molding and compression molding. As expected, processing technique and processing parameters are important in determining the mechanical properties of the molded regrind. Our results show that injection- and extrusion-compression-molded regrind composites have good fiber bundle dispersion and fiber alignment, resulting in tensile properties better than the compression-molded samples. On the other hand, compression-molded samples, which show random fiber orientation and low fiber bundle dispersion, have lower tensile properties, but better impact strength than injection- and extrusioncompression-molded composites.     

Influence of compatibilizer on notched impact strength and fractography of HDPE–organoclay composites

The focus of this study was the notched impact property of high‐density polyethylene (HDPE)–organoclay composites and the resultant morphology of impact‐fractured surfaces. Composites with a different organoclay content and degree of organoclay dispersion were compared with neat HDPE under identical conditions. The degree of organoclay dispersion was controlled through the use of a compatibilizer, maleic anhydride grafted polyethylene. It was found that the addition of organoclay can slightly increase the elastic modulus and notched impact strength of the composite. When the level of organoclay dispersion was improved by using compatibilizer, elastic modulus and toughness further increased. A significant increase in yield strength was also notable. The presence of organoclay was found to suppress strain hardening of the matrix during tensile testing. The impact‐fractured surfaces of failed specimens were studied with scanning electron microscopy. The micromechanism for the increased toughness of HDPE–organoclay composites was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009