Reactive styrenic polymers

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-... 

Rimmer [118] and Caffetera [119] focused their studies on the reactivity of polymers bearing double bonds in order to synthesize macroinitiators able to give block copolymers. These authors copolymerized monomers such as methyl methacrylate (MMA) or styrene (St) with 2-3 dimethyl butadiene giving copolymers presenting the structure shown in Scheme 36 with... 

Characteristic functions and the representative structures of plastics additives providing marketable and durable materials are included in this chapter. Types of additives for plastics used in contact with food are listed in Table 3-1. Similar additives as for PS are used for elastomer-modified plastics forming multilayer systems (blends) and used rather exceptionally in contact with food, such as high-impact polystyrene (HIPS) or acrylonitrile-butadiene-styrene polymer (ABS). Some of the additives, stabilizers in particular, are very reactive and are present in the plastic matrix in a chemically transformed form. 

Note-. 2 - sufficient thermal stability and limited reactivity with polymer allows broad use, 1 = marginal thermal stability or potential reactivity with polymer restricts use, 0 = generally unsuitable for use. FPVC, Flexible Polyvinyl Chloride RPVC, Rigid Polyvinyl Chloride PS, Polystyrene LDPE, Low Density Polyethylene HDPE, High Density Polyethylene PP, Polypropylene ABS, Acrylonitrile-butadiene-styrene copolymer PET, Polyethylene terephthalate PA, Polyamide PC, Polycarbonate... 

An inverted sequence of the same procedure has also been used [139] to prepare the same three-block copolymers. Indeed, thermal polymerization of MMA by ABME gives rise to a polymer mainly containing only one benzoin methyl ether moiety per macromolecule, since growing MMA radicals terminate mostly by disproportionation. Thus, terminally photoactive poly(MMA) is used to obtain the photoinitiated block copolymerization of styrene. In this case, a 90% yield of block copolymers is obtained, appreciably higher than in the preceding method, fully consistent with the usual assumption that the termination in styrene polymers occurs by combination. In fact, coupling of the growing styryl radicals with the less reactive poly(MMA)-bound methoxy benzyl radicals also contributes to the formation of block copolymers. 

Ethylbenzene is a colorless aromatic liquid. It is only slightly soluble in water, but infinitely soluble in alcohol and ether. Additional properties are listed in Table 1. Ethylbenzene is chemically reactive with the most important reaction being its dehydrogenation to form styrene. Styrene is used to produce polystyrene, which is used in the manufacture of many commonly used products such as toys, household and kitchen appliances, plastic drinking cups, housings for computers and electronics, foam packaging, and insulation. In addition to polystyrene, styrene is used to produce acrylonitrile-butadiene-styrene polymer (ABS), styrene-acrylonitrile polymer (SAN), and styrene-butadiene synthetic rubber (SBR). 

Functionahzation of styrene polymers and their blends have been treated in several studies (3) dealing with the preparation of compatibilizers for blends containing engineering thermoplastics. It is worthy to note that in presence of peroxides (DCP), polystyrene (PS) suffers preferable degradation in the melt (64,65). The grafting power of MAH and its derivatives (diethyl maleate, dimethyl maleate) is much lower to PS than to PO, and this fact—in Xue et al. s opinion (64)—indicates a low reactivity of benzyl macroradicals. 

Fig. 8.1 Refilling of the voided nano-channels of an organic DG template via atomic layer deposition of titania, which is illustrated in the inset. 1 Chemical modification of the styrenic polymer scaffold to introduce functional surface groups and improve the thermal stability. This enables the uniform nucleation of the ALD growth 2 Ideally, the nano-channels are gradually filled until a non-porous layer is formed at the free-surface. 3 This layer is removed by reactive ion etching. 4 Finally, the combined organic/inorganic deposit is calcinated to remove the template and ideally, crystallize the titania...

A large portion of all styrene polymers produced commercially are copolymers. Therefore, the understanding of the Q-e schemeof Alliey and Price (18,19) is important in designing copolymers for specific end uses. The Q-e scheme is a way to correlate structure and reactivity of comonomers. In Equations 2 and 3, Q, and Qj are measures of the resonance stabilization of M, radical and Mj monomer, respectively. The terms e, and e represent measures of the polar properties of the comonomers. In Table 5, styrene s Q-e values are Q=-0.80 and e=l. 00. By selecting comonomers with proper Q-e values, copolymerizations of styrene can give random copolymers, alternating copolymers, or block copolymers. 

Styrene polymer having reactive (2-oxazoline) groups... 

Sailer, C.F. (2008) Blends of polyamide-6 and styrenic polymers Influence of reactive compatibilization on melt rheology and morphology, PhD thesis. Die Eidgenossische Technische Hochschule Zurich (ETH - Zurich). 

As shown in Fig. 4.4.2, it takes a relatively small amount (at least 10%) of ionic component in a molecule for it to exhibit surfactancy. This is achievable with the FRRPP process, because one can always add an acid monomer to react with a hydrophobic polymer radical even in the presence of unreacted hydrophobic monomer. The example is when methacrylic acid was added to polystyrene radicals even at 30% styrene conversion to produce an amphiphilic S-block-(S-stat-MAA) amphiphilic material (see Section 4.2). Methacrylic and acrylic acid monomers are normally reactive to polymer radicals in general, as it can be seen from their reactivity ratios. When amine-PDMS was reacted with the acid groups of the... 

Propylene (P) is a termonomer that has received the most attention. Structure-property relationships of terpol5miers based on ethylene, styrene, and propylene, have been published (36). The terpol5miers are most differentiated from ethylene-co-styrene polymers when there is measurable crystallinity in the solid-state microstructure, because the introduction of methyl groups on the pol5mier chain modifies both the crystalline and amorphous phases of the solid-state microstructure. In another aspect of terpol5mierization, ethylene has been investigated as a catalyst reactivator in propylene-styrene copolymerization by Caporaso and co-workers (37), with the research directed at introducing styrene imits into isotactic polypropylene. 

Effect of different components in multicomponent blends based on polyamide 6 (PA 6) and styrenic polymers. Addition of a reactive compatibilizer maleic anhydride grafted styrene acrylonitrile (SANMA) changed the matrix-dispersed particle structure of PA6/styrene acrylonitrile (SAN) to a cocontinuous one. Replacement of part of SAN by polybutadiene particles led to a coarse cocontinuous structure (PA6/acrylobutadiene styrene [ABS]), which was refined after compatibUizer addition. SEM of cut surfaces etched in different solvents. (A) PA6/SAN = 50/50 wt%, SAN etched in tetrahydrofurane (B) PA6/ABS = 50/50 wt%, PA6 etched in formic add (C) PA6/ABS = 50/50 wt%, SAN etched in tetrahydrofurane (D) PA6/SAN+SANMA, PA6 etched in formic add (E) PA6/ABS+ SANMA, PA6 etched in formic add and (F) PA6/ABS = 50/50 wt%, PA6 etched in formic add. (From S. H. Jafari, P. Potschke, M. Stephan, G. Pompe, H. Warth, and H. Alberts, Polymer 43,6985-6922,2002. With permission.)... 

A more reactive styrene derivative, p-methoxystyrene (pMOS) is also polymerized through two types of active centre to a product having a bimodal molecular weight distribution under certain conditions. - With iodine initiators in CCI4 solutions a product with a low molecular weight unimodal distribution is formed exclusively and the polymer chains appear to retain their activity throughout the polymerization. /ra/w-jS-Methyl substitution was found to reduce the propagation rate constant of pMOS by a factor of 1000. ... 

They are used mostly as reactive flame retardants for epoxy resins (especially those applied for manufacturing of the printed circuit boards) and as an additive flame retardants for acrylonitrile butadiene styrene polymers used for production of electronic equipment (e.g., monitors and cellular phones). 

The radiation grafting properties of polypropylene using styrene in methanol as monomer system have been compared with those of the natural materials, cellulose and leather. Of the three, polypropylene is the most reactive trunk polymer (Table 2). Cellulose and leather exhibit comparable styrene grafting properties and all three trunk polymers show acid enhancement in copolymerisation especially in the 20-40% monomer concentration region. The polypropylene and cellulose data illustrate the... 

TBBPA has found use as a reactive flame retardant in the production of epoxy and polycarbonate resins added to circuit boards used in computers and in many other devices. In about 10% of cases TBBPA is used as an additive flame retardant, especially in the production of acrylonitrile-butadiene-styrene polymers, polystyrene, papers, textiles, televisions, office equipment and others. 

The measurement of the dipole moments of copolymers and its analysis in terms of both sequence distribution and local chain configurations has received attention Modern computer aided analytical procedures provide in ght into the dependence of mean square dipole moment per residue on reactivity ratios, polymer composition and rotamer probabilities. One such calculation for atactic cc ly-(p-chlorostyrene-p-methylstyrene) has shovm that at constant composition, the dipole moment is quite sensitive to the sequence distribution and thus to the reactivity ratios. This dependence would be even more marked for syndiotactic chains. For cop61y(propylene-vinyl chloride) and copoly(ethylene-vinyl chloride) d le moments are again very sequence dependent, much more so than the diaracteristk ratio. It would appear that in copolymer systems dielectric measurements can be a powerful method of investigating sequence distributions. Two copolymers, p-dilcxo-styrene with styrene and with p-methylstyrene have been examined experimentally The meamrements were made on solid amorphous samples above the ass-rubber transition temperature (Tg) and they are consistent with the predictions of the rotational isomeric state model udi known reactivity ratios and rea nable replication probabilities . However, it is the view of this author that deduc-... 

---