Polymerization of lactams, 43. Hydrolytic copolymerization of 6-caprolactam with 12-dodecanelactam

The copolymerization of 6-caprolactam with 12-dodecanelactam with 2 mol-% 6-aminocaproic acid as the initiator was investigated at 260°C within a broad concentration range of both comonomers. With increasing content of 12-dodecanelactam in the initial mixture the equilibrium content of the copolymer increased and the rate of copolymerization decreased. In the initial stage of copolymerization 12-dodecanelactam disappeared very quickly from the initial mixture; it was not incorporated into the copolymer directly, but through oligomers, probably through a cyclic dimer. The effect of temperature on the copolymerization process was examined for an equimolar composition of the initial mixture. It was demonstrated that starting with the polymerization temperature of 260°C, the copolymers underwent degradation on long-termin heating. At 280°C, degradation occured already after 50 h of polymerization. The apparent activation energy of copolymerization, 62 kJ/mol, was calculated from the temperature dependence.     

Polymerization of lactams, 44. Molecular characterization of the copolymers of 6-caprolactam and 12-dodecanelactam

Equilibrium copolymers of 6-caprolactam and 12-dodecanelactam differing in chemical composition have been prepared, fractionated and characterized by light scattering, viscometry and ¹³C-NMR. It has been found that the copolymers have a statistical distribution of comonomer units and are practically homogeneous in chemical composition. Intrinsic viscosities for the copolymer fractions in m-cresol, regardless of their chemical composition, fit fairly well the same Mark-Houwink relationship whose constants K = 7.55.10^?4 and a = 0.71 have the values between those for polycaprolactam and polydodecanelactam.     

Polymerization of lactams, 38. Copolymerization of 6-caprolactam with some of its non-homopolymerizing derivatives

It was demonstrated that non-homopolymerizing derivatives of 6-caprolactam: 7-cyclohexyl-1-aza-2-cycloheptanone (I) and 7-isopropyl-5-methyl-1-aza-2-cycloheptanone (II) were polymerizing with 6-caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).     

Polymerization of lactams, 96 anionic copolymerization of ε-caprolactam with ω-laurolactam

Poly[(ε-caprolactam)-co-(ω-laurolactam)] was prepared at two different experimental arrangements — pseudoadiabatically and isothermally. Polymerization activity of two initiators ε-caprolactam magnesium bromide (CLMgBr) or sodium salt of ε-caprolactam (CLNa) in combination with N-benzoyl-ε-caprolactam (BzCL) was compared. The copolymerizations were carried out in the whole concentration scale of both monomers and in the temperature range from 120 to 240 °C. Prepared materials were evaluated by means of polymer yield, DSC, DMA and WAXS. The results have shown fundamental differences between both initiators. Copolymers prepared by initiation with CLNa have random character, one melting endotherm and display one crystalline form opposite copolymers prepared by initiation with CLMgBr having heterogeneous character proved especially by two melting endotherms (∼140 and ∼210 °C) and two types of crystalline form (α and γ).     

Polymerization of lactams, 49. Hydrolytic polymerization of 6-caprolactam in the presence of its cyclic dimer

The hydrolytic polymerization of 6-caprolactam has been studied at 260–280°C in the presence of 5, 10 and 15 mol-% of cyclic dimer of 6-caprolactam and 2 mol-% of 6-aminocaproic acid as an initiator. The content of monomer and cyclic oligomers, including pentamer, was determined by HPLC. It has been proved that the rate of polymerization decreases with increasing content of cyclic dimer in the initial mixture and the time required to attain the equilibrium content of polymer increases as much as by an order of magnitude. The cyclic dimer is incorporated into the polymer above all in the final reaction stage.     

Polymerization of lactams

Summary The following limit (ceiling) temperatures of polymerization were extrapolated from kinetic data for the anionic polymerization of 2-pyrrolidone initiated with potassium salt of 2-pyrrolidone and the initiation systems of optimum compositions: 66°C for the nonactivated polymerization, 68°C and 73°C for the polymerization accelerated with 1-(1-pyr-rolin-2-yl)-2-pyrrolidone and carbon dioxide, respectively, 73°C and 76°C for the polymerization activated with N-benzoyl-2-pyrrolidone and N-acetyl-2-pyrrolidone,respectively.     

Polymerization of lactams, 94. Formation of cyclic oligomers in anionic polymerization of 6-hexanelactam

HPLC analysis of the methanol-extractable fractions of polymers was used to study the formation of cyclic oligomers during the non-activated anionic polymerization of 6-hexanelactam initiated by sodium or magnesium salt of 6-hexanelactam and ethylmagnesium bromide at 190°C. It was demonstrated that the nature of the counterion of the substance which initiates the anionic polymerization has a crucial effect on the mechanism of the formation of the cyclic oligomers. It was proved that in the course of the 6-hexanelactam polymerization in presence of magnesium compounds, the cyclic oligomer formation is distinctly slower, as compared to the sodium 6-hexanelactam-initiated polymerization.     

Polymerization of lactams, 95 Preparation of polyesteramides by the anionic polymerization of ε-caprolactam in the presence of poly(ε-caprolactone)

Preparation of polyesteramides-poly[(ε-caprolactam)-co-(ε-caprolactone)]s by anionic polymerization of ε-caprolactam in the presence of poly(ε-caprolactone) at 150 °C was studied in this paper. ε-Caprolactam magnesium bromide was used as an initiator of polymerization and polymeric materials containing 5-25 wt% ε-caprolactone units were obtained. Thermal methods (DSC and DMA) were employed for characterization of poly[(ε-caprolactam)-co-(ε-caprolactone)]s and their mechanical properties were also evaluated. By introducing the activator with N-acyllactam structure, the polymerization rate increased and it was possible to carry out the polymerization at 110 °C. Mechanical properties of polyesteramides were influenced by both the content of ε-caprolactone units incorporated into copolymer and polymerization temperature. The mechanism of incorporation of poly(ε-caprolactone) is discussed. The results show that it is not possible to restrict exchange transacylation reactions, progressing in the course of polymerization, by kinetic tools.     

Polymerization of lactams,XLI. Molecular characterization of linear and branched polycaprylolactam

Samples of linear polycaprylolactam have been prepared and fractionated, and the [η]-M_w relationship has been established in m-cresol. Statistically branched samples have been obtained by copolymerizing 8-caprylolactam with bislactams. The degree of branching as well as the branching ability of different bislactams are discussed and compared with the corresponding data for branched polycaprolactams.     

Die polymerisation der lactame XI. Die copolymerisation von 6-caprolactam mit 12-laurolactam

The course of the incorporation of 6-caprolactam and 12-laurolactam into polymer chains during the hydrolytic, cationic and anionic copolymerization for an equimolar ratio of the monomers was studied. During the hydrolytic copolymerization 6-caprolactam is incorporated more rapidly at 260, 230 or 200°C at the beginning of the polymerization process; the differences between incorporation rates of the lactams into the copolymer increase with decreasing temperature. During the cationic copolymerization the incorporation of 12-laurolactam is more rapid by orders of magnitude for the above temperatures at the beginning of the process. Changes in the composition of cationic copolymers as compared to the hydrolytic copolymers are independent of the temperature during the copolymerization. The anionic copolymerization is characterized by a more rapid incorporation of 6-caprolactam into the polymer chain. The differences in the polymerization activity of the two lactams decrease with increasing temperature of the anionic copolymerization. The described course of incorporation of individual monomers, with the various mechanisms of the polymerization, also corresponds to melting points of copolymers in accordance with their composition.     

Polymerization of lactams, 87. Block copolymers of poly(ϵ-caprolactam) and polybutadiene prepared by anionic polymerization. Part I: Preparation and properties

The effect of the polymerization conditions on the properties of poly(?-caprolactam)-polybutadiene block copolymers prepared by polymerization casting through anionic polymerization of ?-caprolactam initiated with potassium salt of ?-caprolactam in the presence of α,ω-dihydroxy-polybutadiene and isocyanates or their blocked derivatives as functionalizing agents was investigated. The influence of the content of telechelic polybutadiene, its molecular weight, type of diisocyanate, and polymerization temperature on the fundamental mechanical properties of the prepared materials and on the polymerization rate was evaluated.     

Morphology and Thermal Behavior of MCPA6/SAN Blends Prepared by Anionic Ring-Opening Polymerization of ε-caprolactam

Summary In this article, a series of blends of monomer casting polyamide 6 and styrene-co-acrylonitrile (MCPA6/SAN) were prepared by in situ anionic ring-opening polymerization of ε-caprolactam (CL). Their morphology and thermal behaviors were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD), respectively. The SAN phase had much finer domain in MCPA6/SAN than that in the polyamide6/SAN (PA6/SAN) blends prepared by melt blending of PA6 and SAN. All the melting and crystallization parameters of MCPA6/SAN blends decreased gradually with the increase of SAN content, while the melting temperature was almost unchanged. These results were due to the hydrolysis reaction of SAN occurred during the anionic polymerization of ε-caprolactam (CL). In addition, WAXD results showed that only α crystal forms existed in the MCPA6/SAN blends.     

Polymerization of Cyclic Monomers, 12

Summary: The radical polymerization of different substituted methyl 2‐(bicyclo[3.1.0]hex‐1‐yl) acrylates, 1a – f , was initiated by 2,2′‐azoisobutyronitrile (AIBN) at 65 °C in chlorobenzene. The radical homopolymerization of 1a – f occurred through the opening of the cyclopropane ring, and lead to polymers with number‐average molecular weights of 13 000 to 434 400 g · mol^?1 and glass transition temperatures between 77 and 121 °C. The monomers 1a – f showed a similar reactivity to MMA (in the copolymerization with MMA). Selected monomers were determined to be diluent monomers for dental filling composites and enable the preparation of composites that show a significantly reduced polymerization shrinkage, compared to composites based on dimethacrylate diluents.

     

Polymerization of Lactams: 57. G.l.c. and n.m.r. analysis of the anionic copolymers of 2-pyrrolidone with 6-caprolactam and 8-octanelactam

The activated anionic copolymerization of 2-pyrrolidone (PD) with 6-caprolactam (CL) or 8-octanelactam (OL) proceeds even above the ceiling temperature for PD homopolymerization. At high temperatures, the copolymerizations are accompanied by the depolymerization of PD sequences, which is more pronounced with the copolymers with CL. The copolymers obtained probably exhibit a constitutional heterogeneity and contain considerable amounts of low-molecular weight fractions. This may be the reason why the content of comonomers in the prepared copolymers determined by g.l.c. did not agree with that found by ¹H n.m.r. or ¹³C n.m.r. spectroscopy. The copolymers with CL had in part a block structure and also an alternating character, depending on temperature and polymerization time, while random copolymers were obtained at high temperatures. The copolymers with OL tended mostly to alternation.     

Polymerization of lactams, 28. Effect of reaction conditions on the anionic polymerization of 2-pyrrolidone (part 5)

The effect of temperature, activator concentration, and polymerization time on the anionic polymerization of 2-pyrrolidone was studied using the method of statistical planning of the experiments. Sodium tert-butoxide or sodium dihydrido-bis(2-methoxyethoxy)aluminate was used as initiator; N-acetylpyrrolidone served as activator in both cases. Results obtained with both initiation systems were presented in the form of explicit mathematical equations.     

Die polymerisation der lactame VI. Die copolymerisation von 6-caprolactam und 8-capryllactam

The process of incorporating 6-caprolactam and 8-capryllactam into polymer chains was studied during the hydrolytic, cationic, and anionic copolymerization in the case of equimolar ratio of the above mentioned monomers. At the beginning of the hydrolytic copolymerization at temperatures between 200 and 260°C, 6-caprolactam was more rapidly incorporated into the chains. Decreasing temperature led to a decrease in the total rate of polymerization with increasing difference between rates of incorporating the two components. Contrary to this, at the initial stage of the cationic copolymerization, the incorporation of 8-capryllactam was faster by orders of magnitude than that of 6-caprolactam, the changes of the copolymer composition being independent of temperature. Under the conditions of interest, in the course of the anionic copolymerization the two monomers were characterized with the same rates of incorporation into the polymer chains. Different melting points of products separated at various stages of the copolymerization process corresponded to the above mentioned differences in rates of incorporating individual monomers into polymer chains when different reaction mechanisms were employed.     

Vinyl Polymerization. 218. Polymerization of Methyl Methacrylate in the Presence of Nylon-6 Fiber and Water

The polymerization of methyl methacrylate in the presence of nylon-6 fibers and water was carried out. It was found that the conversion in the absence of water was the same as that of thermal polymerization, but in the presence of water the conversion was much higher. When methyl methacrylate and water existed sufficiently in the polymerization system, the rate of polymerization (R_p) was given by the following equation; R_p = k (Nylon)^1,0 (Methyl methacrylate)⁰ (Water)⁰. The over-all activation energy of the polymerization was found to be 13 kcal/mole. The polymerization of styrene, acrylonitrile, vinyl acetate, and methyl acrylate could not be initiated by the system of nylon and water. Apparent grafting efficiency of polymethyl methacrylate onto nylon was calculated from the amount of polymer which was not extracted with acetone. The efficiency was independent on the reaction time and the amount of water, and increased with the amount of nylon, while it decreased with the amount of methyl methacrylate and with reaction temperature. From the fact that a major part of the polymethyl methacrylate could not be extracted, it was concluded that the polymerization of methyl methacrylate in the presence of nylon and water occured predominantly inside the fiber. The degree of the polymerization of polymethyl methacrylate formed inside the nylon fiber was considerably higher than that of homopolymethyl methacrylate formed outside the fiber. It was qualitatively recognized that the major part of the polymethyl methacrylate generated in the fiber was not grafted onto nylon, but existed as homopolymer.     

6，12-二溴屈的合成研究

含屈基团的OLED材料被认为是很有开发前景和实用价值的一类发光材料,6,12-二溴屈是合成其他屈衍生物重要的中间体。以磷酸三甲酯为溶剂、以溴素为溴化剂合成了6,12-二溴屈,对影响反应的重要因素进行了考察和讨论。反应的最佳条件为：反应温度80℃,溴素分批加入。可以得到75％的收率。     

Polymerization of ε-caprolactam in an extruder: Process analysis and aspects of industrial application

The polymerization of caprolactam into polyamide 6 on corotating twin-screw extruders provides the processor with technically and economically interesting aspects of application. Using the extruder as a small reactor, it is possible, on the one hand, for small batches of polyamide to be optimized for specific applications, and, on the other hand, for large quantities of polymerized polyamide melts to be fed into different processes. Apart from the extrusion of filaments, films, and profiles, the continuous polymerization process also can be coupled up to discontinuous processes. This so-called rapid polymerization in the extruder not only brings price advantages as compared with standard polyamides, but also gives higher molecular weights and, hence, improved properties.