Polystyrene compatibilization using

This chapter reports successful initial efforts to bond wood in the presence of hydrophobic plastic material [polystyrene (PS)] using well-defined and tailored cellulose-polystyrene graft polymers as compatibilizers or interfacial agents. The synthesis of these tailored cellulose graft polymers is also presented. 

The 80%/20% binary blends PE/PS and PP/PS were subjected to F-C reaction for compatibilization performed under nitrogen atmosphere in a Banbury mixer. Different concentrations of catalyst (AICI3) and 0.3% of cocatalyst (styrene) were added to the completely melted and mixed physical blends. The blends and catalyst concentrations are weight based. High MW commercial grades of linear low density polyethylene (LLDPE), and injection-grade polypropylene and polystyrene were used as homopolymers. The compatibilization conditions and MW of the homopolymers are given in Table 20.1. Blend names are listed in nomenclature. 

Wang, Y., Zhang, Q., and Fu, Q. 2003. Compatibilization of immiscible poly(propylene)/polystyrene blends using clay. Macromolecular Rapid Communications 24 231-235. 

Zhang, Q., Yang, H., and Fu, Q. 2004. Kinetics-controlled compatibilization of immiscible polypropylene/polystyrene blends using nano-Si02 particles. Polymer 45 1913-1922. 

In order to obtain materials stable with good properties, the blends have to be compatibilized. In this work, we have investigated the effects of the compatibilization on the structure, rheological, and mechanical properties of blends of PET and PP. The compatibilizer used in this study is a triblock copolymer consisting of polystyrene end-blocks and poly(ethylene-butylene) mid-blocks grafted with maleic anhydride, MA-g-SEBS. This copolymer was already used to compatibilize other blends of polar and apolar polymers with satisfactory results. 

The rheological behaviour of NR and polystyrene (PS) blends had been carried out in the presence and absence of the NR-g-PS compatibilizer using a capillary rheometer and a melt flow indexer. ... 

Mixing of polymers is an important process in the polymer industry by combining the strength of different polymers through blending, new products with desirable physical properties can be produced [2]. FT-IR imaging with a micro-ATR objective has been used to study the effect of a compatibilizer on the mixing of two immiscible polymers, namely polystyrene (PS) and low-density polyethylene (LDPE). The compatibilizer used in this study is a triblock copolymer of polystyrene-f -poly(ethylene-butylene)-f)-polystyrene (SEES). The blends are prepared with a micro-extruder, which allows small amounts of the materials to be blended [2]. The two polymers are easily characterized by their specific absorption bands at 1492 and 1450 cm for PS and the band at 1466 cm for LDPE. 

Chen, B., Tang, T, Xu, S., Zhang, X., Huang, B. Compatibilization of polyam-ide-6/syndiotactic polystyrene blends using styrene/glycidyl methacrylate copolymers. Polymer Journal, 35(2), 141-147 (2003). 

Park I, Barlow JW, Paul DR. The in situ reactive compatibilization of nylon-6/polystyrene blends using anhydride functionalized polystyrenes. J Polym Sci B Polym Phys 1992 30(9) 1021-33. 

Xu S, Chen B, Tang T, Huang B. Syndiotactic polystyrene/thermoplastic polyurethane blends using poly(styrene-l)-4-vinylpyridine) diblock copolymer as a compatibilizer. Polymer 1999 40 3399-3406. 

In order to overcome the build-up of these stresses, the addition of triblock terpolymers as compatibilizing agents with an elastomeric middle block and end blocks of PS and PMMA, respectively, appears advantageous. One example is the use of polystyrene-Wocfc-poly(l,4-butadiene)-W0cfc-poly(methyl methacrylate)... 

SBM) as a compatibilizer. As a result of the particular thermodynamic interaction between the relevant blocks and the blend components, a discontinuous and nanoscale distribution of the elastomer at the interface, the so-called raspberry morphology, is observed (Fig. 15). Similar morphologies have also been observed when using triblock terpolymers with hydrogenated middle blocks (polystyrene-W<9ck-poly(ethylene-C0-butylene)-Wock-poly(methyl methacrylate), SEBM). It is this discontinuous interfacial coverage by the elastomer as compared to a continuous layer which allows one to minimize the loss in modulus and to ensure toughening of the PPE/SAN blend [69],... 

As block copolymers are still rather expensive materials, it may be advantageous to use them as additives to important industrial polymers. In this domain, possibilities are extremely numerous and diverse. They include an improvement of chemical properties such as resistence to degradation agents, or rheological properties such as adhesion of vinylic paints, high impact properties of conventional thermoplastics, or a compatibilization of polyolefins, polystyrene and poly(vinyl chloride) allowing the reuse of polymeric waste products. The above examples illustrate the great intrinsic potential of block copolymers in the quest of new materials with specific properties. 

Figure 1. Exploded view of the use of graft polymers (GP) to compatibilize the linking of wood (W) and polystyrene (PS) materials.

The potential use of cellulose graft polymers to compatibilize the linking of a natural polymer (wood) with a synthetic polymer (polystyrene) is based on... 

Encouraging results on the bonding of plastics to wood using tailor-made cellulose-polystyrene graft polymers as compatibilizers or interfacial agents may offer a new approach to the engineering of wood-plastic products with improved mechanical and physical properties for a variety of applications. It also holds the potential of opening up new markets for renewable resources in the form of woody materials. For example, polystyrene production is currently 3.9 billion... 

Demonstier-Champagne et al. used atomic force microscopy (AFM) to observe microphase separation within cast films of PS-PMPS-PS/ PS-PMPS block copolymer mixtnre [43] that were nsed to compatibilize a blend of PMPS and PS. The fractnre snrface of blend films with the block copolymer incorporated show a far finer dispersion of particle sizes than those without. Matyjaszewski et al. studied PMPS-PS thin films by SFM (scanning force microscopy) and TEM (transmission electron microscopy) and Fig. 8 shows a TEM picture of a thin section of a film which was prepared by slow evaporation from THE, which is slightly selective for the polystyrene block [73]. 

---