Maleation of polypropylene

Figure 7.18 shows how crystalline structure is affected by the presence of fiber. Here, bamboo fiber was used for polypropylene reinforcement. A nucleation occurs on the surfaces of fiber. Spherulites grow from the fiber surface. Such growth results in transcrystallinity. The maleation of polypropylene increases interaction because of reactivity with OH groups on the fiber surface. This organization contributes to the reinforcement. 

Demarquette, N. R., and Kamal, R. M., Influence of maleation of polypropylene on the interfacial properties between polypropylene and ethylene-vinyl alcohol copolymer, J. Appl. Polym. 

BJ Kim, JL White. Thermal/peroxide induced degradation and maleation of polypropylene by reactive extrusion. Int Polym Proc 10(3) 213-220, 1995. 

Another family of adhesion promoters is based on the maleation of polypropylene, polyethylene, and other thermoplastic polymers. The polymer backbone in these coupling agents gives interpenetration into ethylene, propylene, or other thermoplastic polymers and adhesion to those polymers occurs via van der Waals and other atomic forces. The carboxy group on the adhesion promoter will give interaction and bonding to metals, mineral fillers, and glass to promote adhesion to those materials. 

Figure 5.25 Scanning electron micrographs of fracture surfaces of polypropylene/wood fibres composites. Left with maleated PP right without MAPP...

Polypropylene-based maleated coupling agents can be used in HDPE-based WPCs, particularly if a small amount of polypropylene is added to the system. Table 5.11 compares two HDPE-based composites, containing rice hulls and Bio-dac as cellulosic/mineral fillers, with Polybond 3009 (HDPE-based) and Polybond 3200 (polypropylene-based). As one can see, in all the cases both flexural strength and modulus are significantly increased. 

Vainio et al. (27) have studied the grafting of ricinoloxazoline maleate to PP and reported that the use of styrene did not increase the reaction efficiency in some instances it decreased the latter while the degradation of polypropylene decreased markedly. The copolymerization constant value could be the basic point in explaining the effect of styrene on the grafting of vinyl monomers to polyolefins and concurrent secondary reactions (27). 

Wang, Y., Chen, F.-B., Li, Y.-C., and Wu, K.-C. 2004. Melt processing of polypropylene/clay nanocomposites modified with maleated polypropylene compatibilizers. Composites Part B 35 111-124. 

When considering the properties of the layered structures, adhesion between the layers becomes a critical issue. If the materials are highly incompatible, the adhesion will be weak at the interface, leading to delamination. To circumvent this problem, tie layers can be used to increase the interfacial toughness. In the case of polypropylene (PP) and polyamide coextrusion, maleated PP has been used to increase the interfacial toughness of the... 

Similar types of results are reported with the use of maleated polypropylenes. In an article by Borden et al. (34), mechanical property improvements of 9-29% are shown with the addition of 10% maleated polypropylene. Another article by Hyche et al. (32) indicated that the use of medium-molecular-weight, highly functionalized PPgMAH works better than high-molecular-weight, low functionalized material in mica filled polypropylene. Chapter 14 provides a detailed discussion of mica reinforcement of polypropylene resins. 

Helmert, A., Champagne, M.F., Dumoulin, M.M. and Fritz, H.G. (1995) Compatibilization of polypropylene/polyamide-bb blends via reactive blending with maleated polypropylene, in Proceedings of the Conference on Polyblends 95, October 19-20, Boucher e, Canada, National Research Council Canada, BouchervUle, Canada. 

I. Aravind, P. Albert, C. Ranganathaiah, J.V. Kurian, and S. Thomas, Compatibilizing effect of EPM-g-MA in EPDM/poly(trimethylene tere-phthalate) incompatible blends. Polymer, 45(14) 4925-4937, June 2004. Y, Wang, F.B. Chen, and K.C. Wu, Twin-screw extrusion compounding of polypropylene/organoclay nanocomposites modified by maleated polypropylenes, /. Appl. Polym. Sci., 93(1) 100-112, July 2004. 

Y. Wang, F.-B. Chen, and K.-C. Wu. Twin-screw extrusion compounding of polypropylene/organoclay nanocomposites modified by maleated polypropylenes. Journal Applied Polymer Science, 93 (2004), 100-112. 

Kazayawoko M, Balatineoz J J and Woodhams R T 1997 Diffuse refleotanoe Fourier transform infrared speotra of wood fibers treated with maleated polypropylenes J. Appl. Polymer Sci. 66 1163-73... 

Specialty waxes include polar waxes for more polar adhesive systems. Examples would be castor wax (triglyceride of 12-hydroxy stearic acid) or Paracin wax N- 2 hydroxy ethyl)-12-hydroxy stearamide) which are used in polyester, polyamide, or with high VA EVA copolymer-based systems. Other common polar waxes are maleated polyethylenes, which are used to improve the specific adhesion of polyethylene-based adhesives, and low molecular weight ethylene copolymers with vinyl acetate or acrylic acid, which are used to improve low temperature adhesion. High melting point isotactic polypropylene wax (7 155°C) and highly refined paraffin wax (7,n 83°C) are used where maximum heat resistance is critical. Needless to say, these specialty waxes also command a premium price, ranging from 2 to 5 times that of conventional paraffin wax. 

Antony P., Bandyopadhyay S., and De S.K., Thermoplastic elastomers based on ionomeric polyblends of zinc salts of maleated polypropylene and maleated EPDM rubber, Polym. Eng. Sci., 39, 963, 1999. Weiss R.A., Sen A., Pottick L.A., and Willis C.L. Block copolymer ionomers. Thermoplastic elastomers possessing two distinct physical networks, Polym. Commun., 31, 220, 1990. 

So far there has been little use in the volume thermoplastics such as PVC and polyolefins. The main exception would seem to be the use of amino-silane treated glass in conjunction with maleated polypropylene in polypropylene compounds. 

Figure 19.3 Relative tensile strength of starch-filled polypropylenes showing the effect of maleation. (Data adapted from reference 47)...

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