Styrene dicyclopentadiene

The first resins to be produced on a commercial scale were the coumarone—indene or coal-tar resins (1) production in the United States was started before 1920. These resins were dominant until the development of petroleum resins, which were estabHshed as important raw materials by the mid-1940s. Continued development of petroleum-based resins has led to a wide variety of aHphatic, cyclodiene, and aromatic hydrocarbon-based resins. The principal components of petroleum resins are based on piperylenes, dicyclopentadiene (DCPD), styrene, indene, and their respective alkylated derivatives. 

Novolacs are often modified through alkylations based on reactions with monomers other than, and in addition to, aldehydes during their manufacture. Examples might be inclusion of styrene, divinyl benzene, dicyclopentadiene, drying oils, or various alcohols. Despite significant production of all of these variants, most novolac volume is produced using phenol and formaldehyde. 

A recent patent describes the synthesis and catalytic use of Al-containing TUD-1 materials. Some of the reactions demonstrated inclnde hydrogenation of mesitylene (Pt as active metal) and dehydration of 1-phenyl-ethanol to styrene. Several other conceptnal reactions were also described, amongst others the Diels-Alder reaction of crotonaldehyde and dicyclopentadiene and the amination of phenol with ammonia. 

The isoprene units in the copolymer impart the ability to crosslink the product. Polystyrene is far too rigid to be used as an elastomer but styrene copolymers with 1,3-butadiene (SBR rubber) are quite flexible and rubbery. Polyethylene is a crystalline plastic while ethylene-propylene copolymers and terpolymers of ethylene, propylene and diene (e.g., dicyclopentadiene, hexa-1,4-diene, 2-ethylidenenorborn-5-ene) are elastomers (EPR and EPDM rubbers). Nitrile or NBR rubber is a copolymer of acrylonitrile and 1,3-butadiene. Vinylidene fluoride-chlorotrifluoroethylene and olefin-acrylic ester copolymers and 1,3-butadiene-styrene-vinyl pyridine terpolymer are examples of specialty elastomers. 

Hydrocarbon resins comprise a range of low-molecular-weight products (M < 3000) used as adhesives, hot-melt coatings, tackifying agents, inks, and additives in rubber. These include products based on monomers derived from petroleum as well as plant sources. The petroleum-derived products include polymers produced from various alkenes, isoprene, piperylene, styrene, a-methylstyrene, vinyltuolene, and dicyclopentadiene. The plant-derived products include polyterpenes obtained by the polymerization of dipentene, limonene,... 

Tsendrovskaya VA. 1973. [Separate determination of indene, coumarone, styrene, cyclopentadiene and dicyclopentadiene by thin-layer chromatography.] Gig Sanit 38 62-65. (Russian)... 

The simultaneous ROMP of norbornene or dicyclopentadiene on the one hand, and the radical polymerization of styrene or methyl methacrylate on the other, gives a polymer blend627. 

This chapter reports the study of the chemical composition of the polysulfide fraction in dicyclopentadiene and styrene modified materials, the mechanical properties of modified materials, and their use in the preparation of composite materials by the impregnation of polypropylene and glass-fiber fabrics. 

There is a strong possibility that in the examination of both these dicyclopentadiene products and those of styrene to be described, the process of extraction and examination will cause some transformation of the products because of the lability of polysulfide linkages. Thus these results should be treated with caution, but the authors believe the results give a good indication of the type of products formed. 

Figure 5. Shore D hardness vs. log time plots of modified sulfur materials. Samples are identified by percentage of modifier used (w/w sulfur) and heating time at 140°C. The onset of sample shattering is indicated by X. (a) Sulfur (b) 5% dicyclo-pentadiene, 3 hr (c) 10% dicyclopentadiene, 3 hr (d) 25% dicyclopentadiene, 3 hr (e) 5% styrene, 3 hr (f) 10% styrene, 3 hr (g) 25% styrene, 3 hr (h) 25% myrcene, 0.8 hr.

R = CH3, CH2SiMe3),96 VO(CH2SiMe3)3, [(Me3CCH2)3V]2(/J,-N2),97 and [V(mes)3(THF)] are all isolable. The latter is a convenient starting material because it is easily prepared and reacts readily with protic sources such as a-amino acids.98 Unstable alkyls are present in the solutions of vanadium oxides or halides and A1 alkyls,99 which are used in the Ziegler-Natta type reaction for the copolymerization of styrene, butadiene, and dicyclopentadiene to give synthetic rubbers. 

Many solvents form dangerous levels of peroxides during storage e.g., dipropyl ether, divinylacetylene, vinylidene chloride, potassium amide, sodium amide. Other compounds form peroxides in storage but concentration is required to reach dangerous levels e.g., diethyl ether, ethyl vinyl ether, tetrahydrofuran, p-dioxane, l,l-diethox) eth-ane, ethylene glycol dimethyl ether, propyne, butadiene, dicyclopentadiene, cyclohexene, tetrahydronaphthalenes, deca-hydrona-phthalenes. Some monomeric materials can form peroxides that catalyze hazardous polymerization reactions e.g., acr) lic acid, acr)Ionitrile, butadiene, 2-chlorobutadiene, chlorotrifluoroethylene, methyl methacrylate, styrene, tetrafluoroethylene,... 

An important extension of Ziegler-Natta polymerization is the copolymerization of styrene, butadiene and a third component such as dicyclopentadiene or 1, 4-hexadiene to give synthetic rubbers. Vanadyl halides rather than titanium halides are then used as the metal catalyst. 

A method, using differential scanning calorimetry, has been developed to estimate quantitatively orthorhombic and monoclinic sulfur in sulfur materials. Sulfur cooled from the melt at 120°C immediately gives monoclinic sulfur which reverts to orthorhombic sulfur within 20 hr. Limonene, myrcene, alloocimene, dicyclopentadiene, cyclododeca-1,5,9-triene, cycloocta-1,3-diene, styrene, and the polymeric polysulfides, Thiokol LP-31, -32, and -33 each react with excess sulfur at 140° C to give a mixture of poly sulfides and unreacted sulfur. In some cases substantial amounts of this unreacted sulfur may be held indefinitely in a metastable condition as monoclinic sulfur or S8 liquid. Limonene, myrcene, and dicyclopentadiene are particularly effective in retarding sulfur crystallization. 

Dicyclopentadiene, dipentene, styrene, CTLA polymer, and methyl-cyclopentadiene dimer were used as modifiers. These modifiers are all available in commercial quantities at 5-12 cents/lb. All contain unsaturated double bonds suitable for direct reaction with sulfur. The materials used in this investigation were from the following sources ... 

Dicyclopentadiene-dipentene-sulfur and styrene-dipentene-sulfur mixtures produced comparable results. Penetration depths were 1-3 mm at 140-160 °C for styrene or dicyclopentadiene concentrations of 4-7%. From 7 to 10% styrene or dicyclopentadiene, the penetration depths were 3-6 mm at 140-160 °C. The dipentene concentration was varied from 1 to 3% and essentially reduced the viscosity. The penetration depth did not vary with changing dipentene concentration. 

Laboratory Reaction Tests. It was necessary to understand the reaction parameters for the modifiers dipentene, styrene, and dicyclopentadiene to aid future field stabilization tests. Laboratory tests were performed to define the typical character of the material in the liquid and solid state. The conditions necessary to form completely plastic noncrystalline sulfur with each modifier were also established. 

Sulfur can be fully plasticized by using the modifiers dipentene, styrene, and dicyclopentadiene. Sulfur can be plasticized with dicyclo-pentadiene at two minimum concentrations, as indicated in Table III 13% at reaction temperatures of < 140°C and 6% at reaction temperatures > 140 °C. This effect probably results from cracking of the dicyclopentadiene dimer molecule, which doubles the molecules available for reaction. The higher percentage dicyclopentadiene mixture was initially flexible. Upon aging, both plasticized materials became brittle. The reaction is exothermic and very difficult to control above 140 °C. When uncontrolled, extreme viscosity increases were encountered. 

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