Compatibilization reactive

In order to be able to modify and control the interfadal interactions in the above-described manner, it is extremely important to monitor the structure of the interfadal layer. Ellipsometry was used [15,40,50,51] to deted the procedure and influence of reactive compatibilization on polymer blends. In an early study, the reactive blending of polypropylene (PP) with amorphous polyamide (aPA) was carried out using maleic anhydride-grafted PP (MAH-gPP) as a reactive PP [50]. The emulsifying effect of the in situ-formed PP-aPA graft copolymer was indicated by finer particles and a better stability of the dispersed phase obtained in bulk. In accordance with these findings, ellipsometry showed that the interface established in the reactive system was rather thick (ca. 40 nm), indicating an improved compatibility. 

Considering the possible mechanism of fracture at the nonreactive interface of annealed immiscible polymers, it is reasonable to estimate higher fracture toughness, Go at higher interfacial thickness, X, where the polymer chains are interdif-fused X. Although at the reactive interface more factors are involved, the 

One of the early examples of maleic anhydride grafting of polyolefins to compatibihze polyamides and polyolefins involved PP-g-MA in PP/PA6 blends [68]. The formation of a graft polymer of PP-g-PA6 was noted, yielding improved dispersion of the components and a marked improvement in the mechanical properties. The grafting of acrylic acid and maleic 

MA modified polymers can also be employed to compatibilize polyesters (e.g., PET, PBT) with other polymers due to the potential of anhydride reaction with terminal -OH groups. PBT/LDPE blends modified with EVA or EVA-g-MA addition were compared [87]. EVA-g-MA exhibited much better impact strength improvement and higher viscosity of the blend than EVA. HDPE-g-MA/PET blends that showed improved strength and toughness and domain size reduction compared to the control HDPE/PET blend [88]. PET/PP blends were compared with PET/PP-g-MA blends with marked improved in dispersion observed along with strength 

SAN containing 2 mole% of primary amine or carbamate reactive groups was blended with EPDM containing 50% of the EPDM grafted with MA (SAN/EPDM = 75/25) [91]. The carbamate thermolysis reaction to the amine followed by MA reaction proceeds at a slower rate than the direct amine-MA reaction. The morphology development was influenced by the reaction rate, and the amine based SAN gave improved rubber domain stabihty and 

PET PS Isobutylene- MA (IMA) copolymers Phenol substituted IMA (PIMA) copolymers PIMA better than IMA in reducing domain size and enhancing blend strength 119 

HOPE PET Ozone treated HDPE grafted with MMA, EA, HEMA, GMA and MA Improved strength and elongation at break, PE-g-MA and PE-g-GMA were most effective 120 

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Moreover, commercially available triblock copolymers designed to be thermoplastic elastomers, not compatihilizers, are often used in Heu of the more appealing diblock materials. Since the mid-1980s, the generation of block or graft copolymers in situ during blend preparation (158,168—176), called reactive compatibilization, has emerged as an alternative approach and has received considerable commercial attention. 

Blends that contain no nylon can also be prepared by reactive compatibilization. However, interest in these systems has been limited somewhat by lack of control of the reaction pathways. Eor polyester-based systems, epoxide functionaHty appears to be an effective chemistry, involving reaction of the polyester chain ends (183,184). 

Compatibility of immiscible PP-NBR blends was improved by the reactive compatibilization technique using various modified polypropylenes. In this study. 

Greco et al. [50] studied the effect of the reactive compatibilization technique in ethylene propylene rubber-polyamide-6 blends. Binary blends of polyamide-6-ethylene propylene rubber (EPR) and a ternary blend of polyamide-6-EPR-EPR-g-succinic anhydride were prepared by the melt mixing technique, and the influence of the degree of grafting of (EPR-g-SA) on morphology and mechanical properties of the blends was studied. 

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

Baker and Saleem [51] have reported on the reactive compatibilization of oxazoline modified PS and carbox-ylated polyethylene. The coupling reaction results in amide-ester linkages at the time of melt mixing. A schematic representation of the reaction is shown in Scheme 2. 

Reactive compatibilization of engineering thermoplastic PET with PP through functionalization has been reported by Xanthos et al. [57]. Acrylic acid modified PP was used for compatibilization. Additives such as magnesium acetate and p-toluene sulfonic acid were evaluated as the catalyst for the potential interchange or esterification reaction that could occur in the melt. The blend characterization through scanning electron microscopy, IR spectroscopy, differential scanning calorimetry, and... 

The influence of maleic anhydride modified styrene-(ethylene-co-butylene)-styrene (SEBS) triblock copolymer as a reactive compatibilizer in a nylon-6-SEBS blend was investigated by Wu et al. [66]. When the ma]e-ated SEBS was incorporated into the PA-6-SEBS biend. 

Most of the commercially available reactive compatibilized systems contain acidic functional groups. Reactive... 

The reactive compatibilization of HDPE-NBR and PP-NBR blends has been studied by Thomas and coworkers [75,76]. The maleic anhydride modified polyolefins and phenolic modified polyolefins are used as com-patibilizers. The effect of the concentration of these compatibilizers on the compatibility of these blends was investigated in terms of morphology and mechanical properties. It was found that in these blends an optimum quantity of the compatibilizer was required to obtain maximum improvement in properties, and after that a leveling off was observed. The domain size of the dispersed NBR phase in these blends is decreased up to a certain level and then increases (Fig. 12 and 13). The reduction in domain size is attributed to the increase in... 

The applicability of Noolandi and Hong s theory of compatibilization of immiscible blends using block copolymers has been extended to the reactive compatibilization technique by Thomas and coworkers [75,76]. According to Noolandi and Hong [77], the interfacial tension is expected to decrease linearly with the addition... 

Reactive compatibilization is also carried out by adding a monomer which in the presence of a catalyst can react with one or both phases providing a graft copolymer in situ that acts as a compatibilizer. Beaty and coworkers added methyl methacrylate and peroxide to waste plastics (containing polyethylene [PE], polypropylene [PP], PS, and poly(ethylene terephthalate) [PET]). The graft copolymer formed in situ homogenized the blend very effectively [19]. 

Reactive compatibilization can also be accomplished by co-vulcanization at the interface of the component particles resulting in obliteration of phase boundary. For example, when cA-polybutadiene is blended with SBR (23.5% styrene), the two glass transition temperatures merge into one after vulcanization. Co-vulcanization may take place in two steps, namely generation of a block or graft copolymer during vulcanization at the phase interface and compatibilization of the components by thickening of the interface. However, this can only happen if the temperature of co-vulcanization is above the order-disorder transition and is between the upper and lower critical solution temperature (LCST) of the blend [20]. 

Grading systems, for flax fiber, 77 617 Gradual failures, 26 981 Graduate students, role in facilitating research partnerships, 24 383 Graft copolymerization, 20 327. See also Graft polymerization Graft copolymers, 7 650-654 20 391 compatibilization efficiency of, 20 338 formation of, 23 395 in polymer blends, 20 324—325 in reactive compatibilization,... 

In order to obtain a finely sized dispersed phase in the PET matrix, the use of reactive compatibilization has been found to be important. Small dispersed rubber particles and a small interparticle distance are necessary to induce high toughness. For effective rubber toughening of PET, it is important that the rubber domains be less than 3 im in diameter (and preferably less than 1 xm) and that the interparticle distance be between 50-300 nm. 

Compatibilizers are compounds that provide miscibility or compatibility to materials that are otherwise immiscible or only partially miscible yielding a homogeneous product that does not separate into its components. Typically, compatibilizers act to reduce the interfacial tension and are concentrated at phase boundaries. Reactive compatibilizers chemically react with the materials they are to make compatible. Nonreactive compatibilizers perform their task by physically making the various component materials compatible. 

However, a reactive styrene acrylonitrile copolymer (SAN)/gly-cidl methacrylate copolymer was found to be an effective reactive compatibilizer for the blends. Ethyltriphenyl phosphonium bromide was used as the catalyst. Probably, the epoxide groups react either with carboxyl or with hydroxyl groups of the PLLA end groups. This so modified polymer acts as the compatibilizer. Compatibilized PLLA/ABS blends exhibit an improved impact strength and an im-... 

S.C. Tjong and Y.Z. Meng, Effect of reactive compatibilizers on the mechanical properties of polycarbonate/poly(acrylonitrile-buta-diene-styrene) blends, Enr. Polym. J., 36(1) 123-129, January 2000. 

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