The vibration welding of poly(methyl methacrylate) to itself and to polycarbonate,poly(butylene terephthalate), and modified poly(phenylene oxide)

The weldability of poly(methyl methacrylate) (PMMA) to itself and to polycarbonate (PC), poly(butylene terephthalate) (PBT), and modified poly(phenylene oxide) (M-PPO) is assessed through 120 and 250 Hz vibration welds. Weld strengths equal to those of the base resin have been demonstrated in welds of PMMA and M-PPO to themselves. In welds of PMMA to PC and to M-PPO, weld strengths equal to those of PC and M-PPO, respectively, have been demonstrated. PMMA does not weld well to PBT; the highest weld strength obtained was 21% of the strength of PBT resin.     

Vibration weld strength data for a poly(phenylene oxide)/polyamide blend

The weldability of a commercial, impact-modified blend of poly(phenylene oxide) and polyamide 6,6 is assessed through 120 Hz vibration welds. Relative weld strengths on the order of 100%, with very high strains to failure, have been demonstrated.     

The vibration welding of polycarbonate/acrylonitrile‐butadiene‐styrene blends to themselves and to other resins and blends

The weldabilities of two commercial blends of polycarbonate (PC) and acrylonitrile‐butadiene‐styrene (ABS) to themselves and to several other resins and blends are assessed through 120 Hz vibration welds of 6.35‐ and 3.2‐mm‐thick specimens. While the thicker specimens of both blends have relative weld strengths of 83%, the thinner specimens in one of the grades have a lower relative weld strength of 73%. Welds of thicker specimens of both grades to PC have relative strengths of 85%. Again, welds of thinner specimens of one of the grades to PC have a lower relative strengths of 68%. Welds of the thinner specimens of this grade with ABS have relative strengths of 85%. Welds of this material with poly(butylene terephthalate) (PBT), a PC/PBT blend, modified poly(phenylene oxide), and a poly(phenylene oxide)/polyamide blend, have relative weld strengths of 45%, 26%, 76%, and 20%, respectively.     

The vibration welding of poly(butylene terephthalate) and a polycarbonate/poly(butylene terephthalate) blend to each other and to other resins and blends

Vibration welding is used to assess the weldability of poly(butylene terephthalate) (PBT) and a polycarbonate/poly(butylene terephthalate) blend (PC/PBT) to each other and to other resins and blends: PBT to PC/PBT, PBT to modified poly(phenylene oxide) (M-PPO), PBT to polyetherimide (PEI) and PEI to a 65 wt% mineral-filled polyester blend (65-PF-PEB), PBT to a poly(phenylene oxide)/polyamide blend (PPO/PA), PC/PBT to M-PPO, and PC/PBT to PPO/PA. Based on the tensile strength of the weaker of the two materials in each pair, the following relative weld strengths have been demonstrated: PBT to PC/PBT,98%; PBT to PEI, 95%; 65-PF-PEB to PEI, 92%; and PC/PBT to M-PPO, 73%. PBT neither welds to M-PPO nor to PPO/PA, and PC/PBT does not weld to PPO/PA.     

Vibration welding of glass-filled poly(styrene-co-maleic anhydride)

Vibration welding is used to assess the weldability of 16 wt% glass-filled poly(styrene-comaleic anhydride) (16-GF-SMA). Data are presented on the strengths of butt welds for two specimen thicknesses and T-welds for one specimen thickness. The maximum weld strength of butt joints is shown to be only 35% of the tensile strength of the material. T-joints are shown to have only 61% of the strength of butt joints. The relative butt-weld strengths of 16-GF-SMA are much lower than those measured in other glass filled resins: 71% in a 20-wt% glass-filled modified poly(phenylene oxide); 68 and 60%, respectively, in 15- and 30-wt% glass-filled grades of poly(butylene terephthalate); and 58% in a 40-wt% glass-filled polyamide 6,6.     

Vibration welding of thermoplastics. Part IV: Strengths of poly(butylene terephthalate), polyetherimide,and modified polyphenylene oxide butt welds

In vibration welding of thermoplastics, frictional work done by vibrating two parts under pressure, along their common interface, is used to generate heat to effect a weld. The main process parameters are the weld frequency, the amplitude of the vibratory motion, the weld pressure, and the weld time or weld penetration.; The effects of these parameters on weld quality were systematically studied by first butt welding thermoplastic specimens under controlled conditions, over a wide range of process parameters, and by then determining the strengths and ductilities of these welds by tensile tests. The three thermoplastics investigated are poly (butylene terephthalate), polyetherimide, and modified polyphenylene oxide. Changes in the weld pressure are shown to have opposite effects on the strengths of polyetherimide and modified polyphenylene oxide welds; Also, the weld frequency is shown to have a significant effect on the weldability of polyetherimide. The weldability data for these three thermoplastics are compared with data for polycarbonate. Under the right conditions, the strengths of butt welds in these materials are shown to equal the strength of the virgin polymer.     

Hot‐tool and vibration welding of poly(vinyl chloride)

The weldability of poly(vinyl chloride) (PVC) is assessed through hot‐tool and 120‐Hz vibration welds. Equivalent strengths have been demonstrated for welds made by both of these welding techniques. For two grades of PVC, relative weld strengths of 85 and 97%, with corresponding failure strains of about 2.5 and 3.3%, respectively, have been demonstrated.     

Thermal studies of blends of poly(phenylene sulfide) (PPS) with poly(phenylene sulfide sulfone) (PPSS) and with poly(phenylene sulfide ether) (PPSE)

The miscibilities of poly(phenylene) sulfide/poly(phenylene sulfide sulfone) (PPS/PPSS) and poly(phenylene) sulfide/poly(phenylene sulfide ether) (PPS/PPSE) blends were invesigated in terms of shifts of glass transition temperatures T_g of pure PPS, PPSS, a dn PPSE. The crystallization kinetics of PPS/PPSS blends was also studied as a function of molar composition. The PPS/PPSS and PPS/PPSE blends are respectively partially and fully miscible. PPSE shows a plasticizing effect on PPS as does PPS on PPSS, which necessarily improves te processibility in the respective systems. We can control T_g and melting temperature T_m of PPS by varying amounts of PPSE in blends. The melt crystallization temperature T_mc of PPS/PPSE blends was higher than that of the PPSE homopolymer. Therefore, these blends require shorter cycle times in processing than pure PPSE. The overall rate of crystallization for PPS/PPSS blends follows the Avrami equation with an exponent ?2. The maximal rate of crystallization for PPS/PPSS blends occurs at a temperatre higher by 10°C than that for PPS, while the crystallization half time t_1/2 is 4 times shorter. In the cold crystallization range, crystal growth rates increase and Avrami exponents decrease significantly as the temperature increases.     

Blends of thermotropic polyester with poly(phenylene oxide)

A thermotropic liquid crystalline polymer (LCP) based on wholly aromatic copolyesters based on hydroxynaphthoic and hydroxybenzoic acid was melt-blended with a thermoplastic poly(phenylene oxide) by corotating twin screw extruder. Rheological properties, temperature transitions, dynamic and mechanical properties, and electron microscopy study have been performed. Rheological study indicated significant viscosity reductions with increasing LCP content leading to ease of processing. From the differential scanning calorimeter (DSC) and dynamic mechanical thermal analyzer results, these blends showed incompatibility for the whole range of concentrations. Mechanical properties were found to be slightly improved at low LCP and dramatically improved at above 50% LCP contents. In addition, impact strength was significantly increased up to two times after adding 10% LCP into the matrix. The morphology of blends was affected by composition. Droplets and stubby fibrils structures caused lower tensile strength, whereas fibrillar structure improved this property.     

Thermal and mechanical properties of phenolphthalein polyethersulfone/poly(phenylene sulfide) blends

The thermal and mechanical properties of phenolphthalein polyethersulfone/poly(phenylene sulfide) (PES-C/PPS) blends were studied using a differential scanning calorimeter, a dynamic mechanical analyzer, and mechanical characterization. The morphologies of fracture surfaces were observed by scanning electron microscopy. The blends are multiphase systems with strong interaction between the two phases. It is of interest that, although the strength and ductility of PPS are lower than those of PES-C, the addition of PPS can improve markedly the impact strength of PES-C without changing its higher strength. The PPS can also act as a flow aid for PES-C. © 1995 John Wiley & Sons, Inc.     

聚甲基乙烯基硅氧烷增韧聚苯硫醚的力学性能研究

通过熔融共混制备了聚苯硫醚/无苯基聚甲基乙烯基硅氧烷(PPS/NPMVS)共混物及聚苯硫醚/单苯基聚甲基乙烯基硅氧烷(PPS/SPMVS)共混物,并对该共混物体系的微观形貌及力学性能进行了分析表征。结果表明,弹性体在共混物中均匀分散,弹性体的加入对PPS基体起到明显的增韧效果;当弹性体的含量为3 %（质量分数,下同）时,2种共混材料的增韧性能最佳,PPS/NPMVS共混材料的断裂伸长率相对于PPS基体提高了3.9倍,PPS/SPMVS共混材料的断裂伸长率相对于PPS基体提高了2.4倍;当NPMVS含量为10 %时,PPS/NPMVS共混材料的冲击强度相对于PPS基体提高了1.8倍,当SPMVS含量为3 %时,PPS/SPMVS共混材料的冲击强度相对于PPS基体提高了1.4倍。     

Izod impact fracture morphology of rubber-toughened polysulfone and poly(phenylene sulfide) blends

Blends of polysulfone (PSF) and poly-phenylene sulfide (PPS) exhibit ductile behavior, below 35% by weight PPS, under tensile loading conditions. However, the blends are notch sensitive to Izod impact. The use of a core-shell type rubber-modifier effectively toughens the blends. Notched Izod impact strength rises, from ～ 50 J/m to about 900 j/m, by increasing rubber content from 0% to 10–15%. It remains constant at a rubber content > 10–15%. Scanning electron microscopy (SEM) is used to study the morphology of the fracture surfaces. At low modifier content (5%), smooth or mesa-like fracture surfaces are observed. Voids and interfacial debonding are revealed. With a higher concentration of toughening agent (> 10%), some crazing is evidence but not consistent. However, matrix yielding and extensive plastic flow of the PSF/PPS matrix are seen throughout, with a higher level of rubber modifier.     

Compatibilization and elastomer toughening of polyamide‐6 (PA6)/poly(phenylene ether) (PPE) blends

In the elastomer‐modified (polyamide‐6/poly(phenylene ether) (PA6/PPE) = 50/50 blends, poly(styrene‐co‐maleic anhydride) (SMA) was demonstrated to be an efficient reactive compatibilizer. The G1651 elastomer was shown to be an effective impact modifier to result in superior toughness and heat‐deflection temperature (HDT) than is the 1901X elastomer for the SMA‐compatibilized blends because G1651 particles exclusively reside within the dispersed PPE phase but 1901X particles tend to distribute in the PA6 matrix and/or along the interface. The apparent average diameter of the dispersed PPE phase is insignificantly dependent on the elastomer content in the G1651‐modified blend, whereas it increases with increase of the elastomer content in the 1901X‐modified blend. Moreover, there exists a critical elastomer content, 15 phr, for the ductile–brittle transition of the G1651‐modified SMA‐modified PA6/PPE blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 23–32, 1999     

Polysulphone and poly(phenylene sulphide) blends: 2. Mechanical behaviour

This paper reports the mechanical behaviour of injection moulded blends of polysulphone (PSF) and poly(phenylene sulphide) (PPS). The blends prepared by melt-extrusion and subsequent injection moulding are phase separated. Depending on moulding conditions, thermal history, and composition, tensile behaviour ranged from brittle to ductile, with or without cold drawing. Cold drawing was observed in compositions as-moulded with up to 50% by weight PPS. Upon annealing for 2h at 160°C, ductile failure was maintained for blends containing up to 35% by weight PPS. All other compositions failed in brittle fashion. Flexural strength and modulus, before and after annealing, exhibited negative deviation from the rule of mixtures. All the blends were found to be notch sensitive.     

Elastomer-toughened poly(phenylene sulfide)

For use as electrical and electronics parts, or automobile and mechanical parts, toughened poly(phenylene sulfide) (PPS) is desired. For these applications, our investigation centered on improving the toughness of PPS and developing elastomer-toughened PPS and elastomer-toughened compounds of PPS. Using chemically treated PPS and an olefinic elastomer with a functional group, we developed elastomer-toughened PPS using a reactive processing method. In the PPS matrix, the elastomer is finely dispersed. While the notched Izod impact strength of the original PPS is about 1 kg · cm/cm. clastomer-toughened PPS has a notched impact strength around 50 kg · cm/cm. The notched fracture surface of elastomer-toughened PPS is observed using a scanning electron microscope. We concluded that the mechanism for the toughening is attributed to energy dissipation by matrix yield.     

Cross-thickness vibration welding of polycarbonate,polyetherimide, poly(butylene terephthalate), and modified polyphenylene oxide

In vibration welding of thermoplastics, frictional heat generated by vibrating two parts under pressure, along their common interface, is used to effect welds. In the normal, well-understood mode, the vibratory motion is along the weld seam, which is at right angles to the thickness direction for straight boundaries. But in many applications, such as in the welding of closed seams of box-like parts, this vibratory motion occurs in the part-thickness direction, so that a portion of the molten layer along the seam is exposed to the ambient air during each vibratory cycle. The resulting reduction in temperature can affect weld quality. The process phenomenology and the weld strengths of such cross-thickness vibration-welded butt joints are investigated for four neat resins. Weld amplitudes and weld pressures are shown to affect the strengths of 120-Hz welds differently. It is shown that strengths on the order of the strengths of the neat resins can be achieved in 250-Hz butt welds.     

Morphology,rheological and mechanical properties of poly(phenylene ether) and polyamide-6 blends with a compatibilizer

Summary The compatibilizing effect of styrene-acrylic acid random copolymers (SAA) on the morphology, rheological and mechanical properties of poly(phenylene ether) (PPE) and polyamide-6 (PA6) blends was investigated. By addition of a small amount (ca. 3wt%) of SAA copolymer, the blends show non-Newtonian power-law behavior at low frequency and the contribution of the storage modulus (G) to the total response increases. The blends containing SAA copolymer having acrylic acid content higher than 36mol% show more regular and finer dispersion and exhibit about 10% increased mechanical properties. It is believed from Molau test and MFI data that these results seem to attribute to the branch formation and MWD broadening by chemical reaction between terminal amine groups of PA6 and carboxyl groups of SAA.     

Effect of processing on the recyclability of nylon 66/poly(2,6 dimethyl-1,4 phenylene oxide) (PPO) alloys

The recyclability of two commercial nylon 66/PPO [poly(phenylene oxide)] alloys has been investigated by examining the effects of multiple and abusive melt processes upon the impact strength. The loss of performance associated with these exposures has been correlated, in one instance, with the thermal degradation of polybutadiene-based impact modifier. The degradation of the rubber has been quantified using an indirect measurement of rubber mobility obtained from the NMR free induction decay of mobile and rigid protons in the material. Substitution of the unsaturated rubber modifier with a saturated hydrocarbon resulted in improved recyclability. Both formulations provide evidence of changes in morphology related to instability of the dispersed PPO phase. The coalescence of PPO particles, evident in later stages of prolonged thermal exposure, appears to cause further loss of impact strength. Currently the chemical and/or physical changes responsible for the increase in average PPO particle size are not known. It is probable that the thermal stability of the compatibilizer, formed during the reactive extrusion manufacturing process, may be insufficient to provide a durable morphology for repeated recycling of these alloys.     

Strength of glass-filled modified polyphenylene oxide vibration-welded butt joints

The strengths of glass-filled modified polyphenylene oxide (GF-MPPO) welds relative to the strengths of GF-MPPO are shown to depend on specimen thickness. (Modified polyphenylene oxide is a blend of poly (2,6-dimethyl-1,4-phenylene ether) and high-impact polystyrene.) Relative strengths on the order of 70 and 87 percent can be achieved in 6.1 and 3.18-mm-thick specimens, respectively. Welds of GF-MPPO to modified polyphenylene oxide (MPPO) can easily attain the strength of MPPO, the weaker of the two materials. In contrast to MPPO, in which weld strength decreases with increased weld pressure, the strengths of GF-MPPO to GF-MPPO welds and GF-MPPO to MPPO welds, are not affected by weld pressure.     

XPS surface studies of injection-molded poly(phenylene ether)/nylon 6,6 and poly(phenylene ether)/HIPS blends

The surface compositions of a series of poly(phenylene ether)/nylon 6,6 blends (PPE/PA), and PPE/HIPS blends, prepared by melt compounding and injection molding, have been quantitatively measured using XPS. For PPE/PA blends, the surface is dominated by the PA component for blends containing more than 25 wt % PA in the bulk. The enrichment of the PA component, which is actually the component of highest surface free energy, is rationalized in terms of the bulk morphology that consists of PPE domains in a PA continuous phase. Blends prepared by reactive extrusion processes, which form compatibilizing PPE/PA copolymers, show a decrease in surface PA enrichment with increasing copolymer content in the final blend. PPE/HIPS blends have a surface composition equal to the formulated value over the entire composition range, for both molded and solvent cast blends. The addition of 5% PVME to a 60/40 PPE/HIPS blend results in a molded surface containing 35–40 wt % PVME. © 1992 John Wiley & Sons, Inc.