Polybutadiene, hydroxyl terminated

Liquid rubbers In order to improve the flexibihty of short glass fiber-reinforced epoxy composites, Kaynak et al. [53] modified the epoxy resin matrix with hydroxyl-terminated polybutadiene (HTPB) liquid mbber. A silane coupling agent was also used to improve the interfacial adhesion between glass fibers and epoxy matrix. However, Humpidge et al. [54] reported some unique processing problems for the resulting pasty mixmres when short textile fibers were incorporated in a hquid mbber medium. 

Model networks were prepared using hydroxyl terminated polymer and isocyanates, (a) Bifunctional hydroxyl terminated polybutadiene (Butarez, from Phillips Petroleum) was crosslinkined with tris (p-isocyanatophenyl)-thiophosphate (Desmodur RF, from Mobay Chemical Co.). This crosslinked... 

Poly butadienes. Hydroxyl-terminated polybutadienes are comparatively late comers and are still in the development stage. They combine the high specific impulse of the well-proved carboxy-terminated polybutadienes with the clean, stoichiometric urethane reaction yielding propellants with unsurpassed mechanical properties. 

Contrary to the general trend described above, hydroxyl terminated polybutadiene (a polyurethane) has a burning rate curve which bends concave downward below 0.3 atm. (Figure 16), and the extinction pressure of this propellant is rather high (0.18 atm.). The burned surface of extinguished samples of this propellant had a glistening black appearance. 

The effect of curing on the diffusion of polymer and the curing agent is studied for the system of hydroxyl-terminated polybutadiene (R-45-M)/isophorone disso-cyanate (IPDI). Both components contribute to the echo intensity and the plot of In P(x)/I(0)] vs (G5)2 (A — 5/3) consists of two exponentials (Eq. (22)) the fast component (the steep intial slope) is attributed to the IPDI, and the long component to the R-45-M. The dependence of both diffusion constants on the curing time is shown in Fig. 19. The accuracy for Dfast data is less pronounced than for the polymer D(Mn), because only the first few data points are relevant for its determination. Furthermore, the low tail of the R-45-M molecular weight distribution nearly coin-... 

The compound was examined as a propellant explosive, it proved easily detonable and more sensitive than ammonium perchlorate. A formulation with hydroxyl terminated polybutadiene binder ignited spontaneously at room temperature [1]. Other workers have found it more tractable [2]. Detailed study of properties has been made. It is too friction sensitive for safe transport [3]. 

Recently ICLwas used to follow the diffusion-limited oxidation of hydroxyl terminated polybutadiene at various temperatures and oxygen pressures. The CL intensity profiles were found to correlate well with theoretical oxygen concentration profiles [137]. 

Fig. 2.13 Homopolymeric R45HT (hydroxyl terminated polybutadiene, HTPB).

The physical data (dynamic modulus, tensile strength, hardness, elongation at break) were investigated by many groups 202,205 210) (cf., Table 4.5 as an example). These results show that the elastomer physical properties become better by increasing the molar ratio of low-molecular-weight diol to hydroxyl-terminated polybutadiene. 

Koncos, R. Present and Future Applications of Liquid Hydroxylated Terminated Polybutadiene , ARCO Chemical Company paper N° 23, read at the 3-6 October (1972) Session of the ACS... 

The high-polymeric binders in use today include polysulfides (PS), polybutadieneacrylic acid (PBAA), polybutadiene-acrylonitrile (PBAN), polyurethane (PU) and carboxyl- and hydroxyl-terminated polybutadiene (CTPB and HTPB). 

Table 4 Fractionation of hydroxyl-terminated polybutadiene using supercritical propane at 130 C...

Problem 4.11 Following are the vapor phase osmometry data for a standard polystyrene of known molecular weight and an experimental sample of hydroxyl terminated polybutadiene (HTPB) in toluene solutions at 70°C. Calculate the molecular weight of HTPB. 

Hydroxyl-terminated polybutadiene (HTPB) can be produced by such reactions. Low-molecular-weight (3000-10,000) versions of such elastomers are used as binders and liquid rubbers, which can be shaped more easily than the conventional high-viscosity elastomers. The liquid rubbers can be vulcanized by reactions of their specific end groups. Hydroxyl-ended... 

The polymeric hydrocarbon acts also as a binder for each particle to bond to, forming a propellant grain. Ammonium perchlorate (AP) is a typical crystalline oxidizer and hydroxyl-terminated polybutadiene (HTPB) is a typical polymeric fuel. When AP and HTPB decompose thermally on the propellant surface, oxidizer and fuel gases are produced and diffuse each other, and then react to produce high temperature combustion gases. 

Thus, the hydroxyl terminated polybutadiene, obtained by the radical polymerisation of butadiene initiated with hydrogen peroxide, has the following general structure [9-10, 15] ... 

The fabrication process of hydroxyl terminated polybutadiene is based on the free radical polymerisation of butadiene, initiated by hydrogen peroxide at 100-150 °C, in the presence of a solvent such as methanol [12], isopropanol [12], or in the presence of tricresyl phosphate [14]. The polymerisation in alcohols is used industrially. 

The hydroxyl terminated polybutadienes lead to PU with physico-mechanical properties significantly lower than those of PU based on polyether or polyester polyols. The nonpolar polymeric chain and the extraordinary hydrophobicity mean that hydroxy terminated polybutadienes are used for special applications, due to their excellent electrical insulation properties which are equal or superior to epoxies or silicone elastomer systems. The hydrolytic stability of PU elastomers derived from hydroxyl terminated polybutadiene is superior to the majority of other types of PU. Thus, some specific applications of... 

Hydroxyl-Terminated Hydrocarbon Polymers. Although low molecular weight hydroxyl-terminated polybutadienes have previously been reported (lOl). homopolymers and copolymers of butadiene having terminal hydroxyl groups have been commercially available (102). The homopolymers have a molecular weight range of 2500-3500 and the hydroxyl functionality varies from 2.1 to 2.6. 

Transformation of the hydroxyl-terminated polybutadienes by reaction with tosyl chloride leads to ditosylates, which upon addition of OXL yield triblock copolymers 22). Alkaline hydrolysis gives a rubbery material (fn] = 0.33 dl/g) containing 39 mol% polybutadiene ... 

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