Maleic anhydride -functionalized

The uncatalyzed or uninitiated reaction takes place at higher temperatures, i.e. >160 °C. The reaction is not affected by radical trapping agents and is characterized by a low degree of gelation and essentially no loss of unsaturation. The structure of the adduct (179) is completely different and results from an ene reaction with maleic anhydride functioning as enophile (Scheme 86). Presence of the vinylidene double bond has been confirmed by IR and NMR spectroscopy. 

Figure 21.14 TEM of a maleic anhydride-functionalized polymer in polyamide 66. The styrene domains are stained dark with Ru04- The maleic anhydride in the rubber phase reacts with the polyamide producing a diffuse interface and fine dispersion of the block copolymer...

Fig. 50. Possible mechanism by which chains with multiple reactive sites can graft to an interface. This example, which would be typical of a maleic anhydride functionalized polymer reacting on a polyamide, shows on one side end-grafted chains and on the other side of the interface, a loop structure. The effect of this loop structure on the mechanical strength of the interface is not fully clear but loops that are too short will weaken the interface...

Muratoglu et al. [40] analyzed the microstructural processes of fiacmre of nylon-6,6 modified with maleic anhydride functionalized ethylene-propylene-... 

In addition to maleic anhydride-functionalized polyolefin oligomers or polymers, a major category of compatibilizers utilized are specifically synthesized homopolymers and/or copolymers that could modify the interactions and control the structure in polyolefin/ organoclay nanocomposites. 

Immiscible blends of PA and PP have been compatibilized through copolymer formation between PA amine end-groups and maleic anhydride-functionaUzed PP to form a new imide linkage (Table 5.23). The structure of maleic anhydride-functionalized PP has been discussed, e.g., by De Roover et al. (1995) and Sclavons et al. (1996). The authors demonstrated that the free radical initiated maleation of PP in the molten state leads to anhydride groups locating mainly at PP chain ends. Consequently, unless PP has been functionalized by a process that suppresses PP chain degradation, the reaction product of amine-terminated PA with MA-functionalized PP may be predominantly a block copolymer. 

DeLeo et al. (2011) cmisidered the formation of a compatibilizer between two multifunctional reactive polymers that leads to a cross-linked copolymer at the interface. The study was conducted on model blends PDMS/PI. In this case a chemical reaction between amine-functional PDMS and maleic anhydride-functional PI formed the compatibilizer. The effects of interfacial cross-Unking... 

Polypropylene (PP) alloys with ETP are in an early stage of development. Blends with specialty resins are even less advanced. The main source of difficulties is the antagonistic immisdbility of PP with these polymers. In many cases, addition of a compatibilizer to PP/ETP blends reduces the crystallinity, which in turn lowers the performance. Optimization of composition and blending methods is not easy. The most commonly used compatibilizing agents contain maleic anhydride functionality, e.g. maleated-PP (PP-MA). Their reaction with such ETP as PA or PET depends on the reaction conditions time, temperature and stress. The compatibilizing copolymer content increases upon reprocessing. 

Hydrogenated S-EB-S block-copolymers can be used with olefinic plastics such as PP and PE because of their higher temperature allowance, and even with engineering plastics that usually need melt temperatures well above 275°C. But for polar engineering plastics, such as PA 6 and 66, maleic anhydride functionalized polymers have been developed and commercialized. Systems available to improve impact resistance of high-performance plastics are given in the table below. 

Maleic anhydride functionalized polymers ensure organosilicate dispersion and exfoliation into the polymer matrix (i.e. polypropylene) due to the interaction that may occur between maleic anhydride and hydroxyl groups on the silicate surface (Faisant et al., 1998 Vuluga et al, 2008b Utracki, 2002). 

A thermoplastic polyolefin elastomer TPO-g-PLA was prepared by grafting PLA onto maleic anhydride-functionalized TPO in the presence of 4-dimethyl aminopyridine (DMAP). A high reaction temperature and a high DMAP concentration resulted in the polymerization of PLA. These copolymers were used as a compatibilizer for PLA/TPO blends. An increase in concentration of this copolymer from 0% to 2.5% resulted in an increase in elongation at break and tensile toughness of the blends [94]. 

As shown in Fig. 5.22, it is observed that melt strength (MS) reduces with an increase in content of the starch. Addition of maleic anhydride can remarkably make MS increase (Fig. 5.23). But when the content rises to above 2%, MS would decrease. This is because that when maleic anhydride is excessive, the graft reaction is completed. The remaining maleic anhydride functions as lubricant that causes MS to decrease. 

Co(polyisobutylenene-maleic anhydride), functionalized to certain N-chloromethyl groups... 

Magnesium hydroxide filler treated with magnesium stearate has improved filler/matrix interaction and maleic anhydride functionalized EPR increased impact strength. The composition is very efficient in fire-retarded PP [20]. 

A traditional chemical extraction process that uses an alkaline sodium hydroxide solution has also been applied to the same wooden material. Fibers extracted by the two methods have been used as reinforcement for the two commercial polypropylenes the conventional isotactic polypropylene, and maleic anhydride functionalized isotactic polypropylene (iPPMA). The composites have also been subjected to a water absorption treatment. To assess the reinforcement effect of fibers, composite characterization techniques and determination of mechanical properties have been performed with particular attention to the fiber-matrix interfacial characteristic. The results have been compared with those of short glass reinforced polypropylene composites. 

Compatibilizers are frequently materials such as block or graft copolymers. A specific example would be a copolymer comprising two blocks where each is compatible with one component of the blend (in a blend of two plastics) and incompatible with the other. An A-x-B block copolymer, where A and B are long sequences of monomer that are identical to the corresponding A and B polymers forming the blend, and X is a bond between the blocks, is one of the simplest forms of compatibilizer. A functionalized polymer where the main polymer is compatible in one phase and the functionality is compatible in the other phase would be another example of a compatibilizing agent. One example of such a material would be maleic anhydride functionalized polypropylene (PP-MA) used to compatibilize blends of PP and Nylon 66. Recent advances in the production of PP-MA have seen an increase in the impact resistance of... 

Table 23 Maleic Anhydride Functionalized Reactive Polymers...

Many of the compatibihzation studies include interfacial tension measurements and several examples wiU be noted here. The interfacial tension of LDPE/PA6, determined by the breaking thread method, was measured with the addition of various compatibilizers, including poly(ethylene-co-acrylic acid), poly(ethylene-co-acrylic acid Zn + salt), styrene-ethylene/butylene-styrene (SEES) block copolymer with and without maleic anhydride functionalization [246]. The SEES block copolymer without MA showed no reduction in interfacial tension, whereas the other compatibilizers exhibited significant reductions. 

In some cases, the SPS/nylon compositions include olefinic impact modifiers that are compatibilized with the matrix nylon via a maleic anhydride-functionalized olefin. The concept is that the maleic anhdydride portion of the molecule reacts with the nylon, and the olefin part of the molecule is miscible with the olefin impact modifier. 

Maleic anhydride-functionalized polyolefins were much more effective for PET/PE compatibilization [66]. This process was successfully applied in PET/PE recycling [67]. 

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