Synthesis,characterization, reactivity ratios by nuclear magnetic resonance spectroscopy,and application of (2,5‐Dichlorophenyl acrylate‐co‐glycidyl methacrylate) polymers as adhesives for the leather industry

2,5‐ Dichlorophenyl acrylate (DPA)‐co‐glycidyl methacrylate (GMA) polymers having five different compositions were synthesized in 1,4‐dioxane using benzoyl peroxide as a free‐radical initiator at 70 ± 0.5°C. Using ¹H‐NMR spectroscopy, the composition of the two monomers in the copolymers was calculated by comparing the integral values of the aromatic and aliphatic proton peaks. The reactivity ratios were calculated by Fineman–Ross (r₁ = 0.31 and r₂ = 1.08), Kelen–Tudos (r₁ = 0.40 and r₂ = 1.15), and extended Kelen–Tudos (r₁ = 0.39 and r₂ = 1.16) methods. The nonlinear error‐in‐variables model was used to compare the reactivity ratios. The copolymers were characterized by ¹H and proton decoupled ¹³C‐NMR spectroscopes. Gel permeation chromatography was performed for estimating the M_w and M_n and M_w/M_n of the poly(DPA) and copolymers (DPA‐co‐GMA: 09 : 91 and 50 : 50). Thermal stability of the homo‐ and copolymers was estimated using TGA [poly(DPA) > DPA‐co‐GMA (50 : 50) > DPA‐co‐GMA (09:91)], while DSC was utilized for determining the glass transition temperature. T_g increased with increased DPA content in the copolymer. The 50 : 50 mol % copolymer was chosen for curing with diethanolamine in chloroform. The cured resins were tested for the adhesive properties on leather at different temperatures (50, 90, 100, and 110°C). The resin cured at 50 °C exhibited a maximum peel strength of 1.6 N/mm, revealing a good adhesive behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1167–1174, 2006     

Silylated poly(4-hydroxystyrene)s as negative electron beam resists

Silylated poly(4-hydroxystyrene)s and radical polymerized 4-tert-butyldimethylsilyloxystyrene (TBDMSOSt) were examined as electron beam resists. Commercial poly(4-hydroxystyrene) (PHS) with M_w = 1.69 × 10⁴ and M_w/M_n = 5.41 was silylated with 1-(trimethylsilyl)imidazole and tert-butylchlorodimethylsilane. Both silylation reactions proceeded quantitatively to afford trimethylsilylated PHS with M_w = 3.93 × 10⁴ and M_w/M_n = 4.91, and tert-butyldimethylsilylated PHS with M_w = 4.08 × 10⁴ and M_w/M_n = 3.81. These 2 silyl ether polymers acted as a negative working resist to electron beam (EB) exposure. Sensitivity and contrast of tert- butyldimethylsilylated PHS were not affected by prebake temperature around its T_g of 97°C, while those of PHS were dependent on prebake temperature around its T_g of 160°C. At a prebake temperature of 125°C, the sensitivity parameter and the contrast γ value were obtained as follows: 3.93 × 10⁻⁴ C cm⁻² and 0.91 for PHS; 1.49 × 10⁻⁴ C cm⁻² and 1.06 for trimethylsilylated PHS; 1.84 × 10⁻⁴ C cm⁻² and 1.44 for tert-butyldimethylsilylated PHS. The silylation procedures obviously improved the sensitivity of PHS. TBDMSOSt was polymerized in bulk at 60°C with 2,2′-azobisisobutyronitrile (AIBN) as an initiator. The resultant poly(TBDMSOSt) possessed M_w = 3.01 × 10⁵ and M_w/M_n = 1.92 and exhibited a sensitivity of 1.60 × 10⁻⁵ C cm⁻² and a γ value of 1.47. More than 10 times enhancement of sensitivity was observed compared with tert-butyldimethylsilylated PHS. Such a high sensitivity is probably due to the high molecular weight of the bulk polymerized material. Poly(TBDMSOSt) resolved an isolated line of 0.20 μm width and 0.5 μm line and space patterns. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1151–1157, 1998     

Radical polymerization behavior of dimethyl vinylphosphonate: Homopolymerization and copolymerization with trimethoxyvinylsilane

Dialkyl vinylphosphonates such as dimethyl vinylphosphonate (DMVP) and diethyl vinylphosphonate were quantitatively polymerized with dicumyl peroxide (DCPO) at 130°C in bulk. The polymerization of DMVP with DCPO was kinetically studied in bulk by fourier transform near‐infrared spectroscopy (FTNIR) and electron spin resonance (ESR) spectroscopy. The initial polymerization rate (R_p) was given by R_p = k[DCPO]^0.5[DMVP]^1.0 at 110°C, being the same as that of the conventional radical polymerization involving bimolecular termination. The overall activation energy of the polymerization was estimated to be 26.2 kcal/mol. The polymerization system involved ESR‐observable propagating polymer radicals under the practical polymerization conditions. ESR‐determined rate constants of propagation (k_p) and termination (k_t) were k_p = 19 L/mol s and k_t = 5.8 × 10³ L/mol s at 110°C, respectively. The molecular weight of the resultant poly(DMVP)s was low (M_n = 3.4 ? 3.5 × 10³), because of the high chain transfer constant (C_m = 3.9 × 10^?2 at 110°C) to the monomer. DMVP (M₁) showed a considerably high reactivity in the radical copolymerization with trimethoxyvinylsilane (TMVS) (M₂) at 110°C in bulk, giving an inorganic component‐containing functional copolymer with potential flame‐retardant properties; r₁ = 1.6 and r₂ = 0. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Copolymerization of butadiene with styrene using a rare‐earth metal compound – dialkylmagnesium – halohydrocarbon catalytic system

Copolymerizations of butadiene (Bd) with styrene (St) were carried out with catalytic systems composed of a rare‐earth compound, Mg(n‐Bu)₂ (di‐n‐butyl magnesium) and halohydrocarbon. Of all the rare earth catalysts examined, Nd(P₅₀₇)₃–Mg(n‐Bu)₂–CHCl₃ showed a high activity in the copolymerization under certain conditions: [Bd] = [St] = 1.8 mol l^?1, [Nd] = 6.0 × 10^?3 mol l^?1, Mg/Nd = 10, Cl/Nd = 10 (molar ratio), ageing for 2 h, copolymerization at 50 °C for 6–20 h. The copolymer of butadiene and styrene obtained has a relatively high styrene content (10–30 mol%), cis‐1,4 content in butadiene unit (85–90%), and molecular weight ([η] = 0.8–1 dL g^?1). Monomer reactivity ratios were estimated to be r_Bd = 36 and r_St = 0.36 in the copolymerization. © 2002 Society of Chemical Industry     

Copolymerization of 4-chlorophenyl acrylate with methyl acrylate: synthesis,characterization, reactivity ratios,and their applications in the leather industry

4-Chlorophenyl acrylate (CPA) was prepared by reacting 4-chlorophenol and acryloyl chloride in the presence of triethylamine in ethyl acetate solution. Poly(4-chlorophenyl acrylate) and copoly(4-chlorophenyl acrylate–methyl acrylate) were synthesized by the free radical polymerization in ethyl acetate at 70°C. All the polymers were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic techniques. The composition of the copolymers was determined by the ¹H-NMR spectroscopic technique, that is, by integrating the aromatic peaks corresponding to the 4-chlorophenyl acrylate unit against the carbomethoxy group in the methyl acrylate unit. The reactivity ratios were calculated by Fineman–Ross, Kelen–Tudos (K–T), and the extended Kelen–Tudos methods. The values of r₁ and r₂ obtained by these methods were in close agreement with each other; that is, r₁(CPA) = 0.64 and r₂(MA) = 0.13 by the K–T method. The number-average molecular weight (M̄_n = 1.55 × 10³), the weight-average molecular weight (M̄_w = 8.39 × 10³), and the polydispersity index (M̄_w/M̄_n = 5.42) of poly(CPA) were determined by gel permeation chromatography (GPC). Thermal properties of the polymers were studied in a nitrogen atmosphere using thermogravimetric analysis (TGA). As the CPA increases in the copolymer, thermal stability of the copolymer increases (e.g., 90% weight loss occurs at 480°C for 20 mol % CPA, whereas the same weight loss occurs at 571°C for 80 mol % CPA). Acrylic binders, based on the CPA–MA–BA terpolymer, of different glass transition temperatures were prepared for applications in leather industry as top coat and base coat materials. These acrylic emulsions were cast into thin films, and their characteristics were tested for physical properties. These acrylic emulsions were applied as a base coat on leather, and the compositions having T_g values of 1.08 and 9.25°C were found to have excellent properties as base coats for leather when compared with commercial samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1153–1160, 1999     

Ceric(IV) ion‐induced graft copolymerization of acrylamide and ethyl acrylate onto cellulose

Graft copolymerization of acrylamide (AAm) and ethyl acrylate (EA) onto cellulose has been carried out from their binary mixtures using ceric ammonium nitrate (CAN) as an initiator in the presence of nitric acid at 25 ± 1 °C. The extent of acrylamide grafting increased in the presence of the EA comonomer. The composition of the grafted chains (F_AAm = 0.52) was found to be constant during the feed molarity variation from 7.5 × 10^?2 to 60.0 × 10^?2 mol L^?1, whereas the composition of the grafted chains (F_AAm) was found to be dependent on feed composition (f_AAm) and reaction temperature. The effects of ceric(IV ) ion concentration, reaction time and temperature on the grafting parameters have been studied. The grafting parameters showed an increasing trend up to 6.0 × 10^?3 mol L^?1 concentration of CAN at a feed molarity of 30.0 × 10^?2 mol L^?1 and showed a decreasing trend on further increasing the concentration of CAN (>6.0 × 10^?3 mol L^?1) at a constant concentration of nitric acid (5.0 × 10^?2 mol L^?1). The composition of the grafted chains (F_AAm) was determined by IR spectroscopy and nitrogen content and the data obtained then used to determine the reactivity ratios of the acrylamide (r₁) and ethyl acrylate (r₂) comonomers by using a Mayo and Lewis plot. The reactivity ratios of acrylamide and ethyl acrylate were found to be r₁ = 0.54 and r₂ = 1.10, respectively, and hence the sequence lengths of acrylamide (m?M₁) and ethyl acrylate (m?M₂) in the grafted chains are arranged in an alternating form, as the product of the reactivity ratios of acrylamide and ethyl acrylate (r₁ × r₂) is less than unity. The rate of graft copolymerization of the comonomers onto cellulose was found to be dependant on the ‘squares’ of the concentrations of the comonomers and on the ‘square root’ of the concentration of ceric ammonium nitrate. The energy of activation (ΔE_a) of graft copolymerzation was found to be 5.57 kJ mol^?1 within the temperature range from 15 to 50 °C. On the basis of the results, suitable reaction steps have been proposed for the graft copolymerzation of acrylamide and ethyl acrylate comonomers from their mixtures. Copyright © 2005 Society of Chemical Industry     

Copolymerization of phenylisocyanate and ϵ‐caprolactone with rare earth chloride systems

A copolymer of phenylisocyanate (PhNCO) and ε‐caprolactone (CL) was synthesized by the rare earth chloride systems lanthanide chloride isopropanol complex (LnCl₃·3iPrOH) and propylene epoxide (PO). Polymerization conditions were investigated, such as lanthanides, reaction temperature, monomer feed ratio, La/PO molar ratio, and aging time of catalyst. The optimum conditions were: LaCl₃ preferable, [PhNCO]/[CL] in feed = 1 : 1 (molar ratio), 30°C, [monomer]/[La] = 200, [PO]/[La] = 20, aging 15 min, polymerization in bulk for 6 h. Under such conditions the copolymer obtained had 39 mol % PhNCO with a 78.2% yield, M_n = 20.3 × 10³, and M_w/M_n = 1.60. The copolymers were characterized by GPC, TGA, ¹H‐NMR, and ¹³C‐NMR, and the results showed that the copolymer obtained had a blocky structure with long sequences of each monomer unit. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2135–2140, 2007     

Graft copolymerization of acrylamide onto cellulose in presence of comonomer using ceric ammonium nitrate as initiator

The graft copolymerization of acrylamide (AAm) and ethylmethacrylate (EMA) monomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as initiator in presence of nitric acid at (25 ± 1)°C and varying feed molarity from 7.5 × 10^?2 mol dm^?3 to 60.0 × 10^?2 mol dm^?3 at fixed feed composition (f_AAm = 0.6). The graft yield (%G_Y) has shown a linear increasing trend upto a feed molarity of 37.5 × 10^?2 mol dm^?3. The composition of grafted copolymer chains was found to be constant (F_AAm = 0.56) during feed molarity variation but shown variations with feed composition (f_AAm) and reaction temperature. The grafting parameters have shown increasing trends up to 7.5 × 10^?3 mol dm^?3 concentration of ceric (IV) ions and decreased on further increasing the concentration of ceric (IV) ions beyond 7.5 × 10^?3 mol dm^?3. The IR and elemental analysis data were used to determine the composition of grafted chains (F_AAm) and reactivity ratio of acrylamide (r₁) and ethylmethacrylate (r₂) comonomers. The reactivity ratio for acrylamide (r₁) and ethylmethacrylate (r₂) has been found to be 0.7 and 1.0 respectively, which suggested for an alternate arrangement of average sequence length of acrylamide (mM?₁) and ethylmethacrylate (mM?₂) in grafted chains. The rate of graft copolymerization of comonomers onto cellulose was found to be proportional to square concentration of comonomers and square root to the concentration of ceric (IV) ions. The energy of activation (ΔEa) of graft copolymerization was found to be 9.57 kJ mol^?1 within the temperature range of 20–50°C. On the basis of experimental findings, suitable reaction steps have been proposed for graft copolymerization of selected comonomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2546–2558, 2006     

The Tll (>Tg) transition of atactic polystyrene

Torsional braid analysis (TBA) (～0.3 Hz) and differential thermal analysis (DTA) data are presented for the temperature for the region 0–200°C for two series of atactic polystyrenes with narrow molecular weight distributions: (a) anionic series, M?_n = 600–2×10⁶, M?_w/M?_n ? 1.1; (b) fractionated thermal series, M?_n = 2,000–1.1×10⁵, M?_w/M?_n < 1.25. Preliminary results on bimodal blends are also reported. Heating and cooling cycles were employed with TBA; only the heating mode was used with DTA. In addition to a dynamic mechanical loss peak at T_g, a higher temperature loss peak was also found. Designated the T_ll or liquid–liquid transition (relaxation), its temperature is 1.1 to 1.2 T_g (°K) for polymers with molecular weight below the critical molecular weight (M_c) for chain entanglements. Above M_c ? 35,000, it rises steeply, being ?200°C for M?_n = 110,000. The common dependence of T_g and T_ll on M?_n^?1 below M_c suggests a common molecular origin. The two facts, (a) that T_ll > T_g and (b) that T_ll reflects chain entanglements, further suggest that T_ll involves a longer chain segment length and possibly the entire molecule. Comparison of T_ll versus log M plots with T versus log M isoviscous state plots based on zero-shear melt viscosity data from the literature implies that T_ll measured by the TBA technique corresponds to an isoviscous state of 10⁴–10⁵ poises. The employment of narrow molecular weight polymers is presumably responsible for both the linear variation of the T_ll transition with M?_n^?1 (which suggests a free volume basis for the relaxation) and the form of the variation of the T_ll transition with log M (which suggests an isoviscous basis for the relaxation). The sharpness of the T_ll loss peak by TBA decreases with increasing molecular weight and dispersity. The DTA endothermic event corresponding to T_ll is clearly related to the occurrence of flow since the fused films which result from heating granules to 200°C and cooling to R.T. do not reveal a T_ll on reheating. If a fused film is crushed, a T_ll event is observed on heating. For bimodal blends with M?_n < M_c for both components, the T_ll transition was averaged; with one component less than and one greater than M_c, the T_ll transitions of the components appeared to occur independently at temperatures corresponding to those of the isolated components. In accordance with Ueberreiter and Orthmann, T_g appears to separate a glassy state from a fixed liquid state, whereas T_ll separates the fixed liquid from a true liquid state. Possible molecular interpretations for the T_ll process are discussed. Systematic bodies of data from the literature which indicate the presence of the T_ll process in other polymers are summarized.     

1H magnetic relaxation times in isotactic polypropylene crystallized at high temperature. Effect of molecular weight

The temperature dependence of ¹H spin-lattice, T₁(H), and spin-spin, T₂(H), relaxation times of isotactic polypropylene with relatively low molecular weight, M?_w = 1.95 × 10⁵, and ultra-high molecular weight, M?_w = 1.78 × 10⁶, crystallized at high temperature (155° C) for a long time (200 h), was measured with a broad line pulse spectrometer. T₁(H) for the ultra-high molecular weight sample is shorter than that for the low molecular weight sample, while T₂(H) for the ultra-high molecular weight sample is longer than that for the low molecular weight sample. From the analysis of free induction decay (FID), three components of T₂(H), i.e. T_2c(H), T_2m(H) and T_2a(H), were obtained. These relaxation times are associated with the crystalline, intermediate and amorphous regions, respectively. Here the intermediate regions are the regions in which chain molecules have intermediate mobility between that of crystalline and amorphous regions. A decrease in signal intensity of methylene, methine and methyl carbons was measured as a function of delay time following a 90° pulse before cross-polarization. From the slope of a log (intensity) versus t² plot a relaxation time associated with rigid regions of proton nuclei, T_2r(H), was obtained, where the rigid regions are the regions in which cross-polarization occurs easily. The value of T_2r(H) lies between that of T_2c(H) and T_2m(H), indicating that the intermediate regions act as the rigid regions so far as cross-polarization is concerned.     

Study on conformational transition phenomena of poly(methyl methacrylate) in acetonitrile near theta conditions

The coil–globule transition for poly(methyl methacrylate) (PMMA) has been studied in a theta solvent, acetonitrile (Θ = 45 °C). The viscosity of PMMA was measured as a function of temperature in the range 26–55 °C. The contraction and expansion of the molecular chains are determined using the measured viscosity values. The temperature dependence of the intrinsic viscosity can be represented by a master curve in a versus |τ|M _w^1/2 (g^1/2 mol^−1/2) plot, where τ = |T − Θ|/T is the reduced temperature and M_w‐is the weight‐average molecular weight. A universal plot of reduced viscosity versus reduced blob parameter (N/N_c) shows the attainment of the collapsed state below the theta temperature. The dimensions of PMMA in acetonitrile (M_w = 3.15 × 10⁶ g mol⁻¹) decrease to 63 % at 26 °C of those in the unperturbed state. The results in this work are compared with those previously published. © 2000 Society of Chemical Industry     

Antiinflammatory polymer-bound steroids for topical applications. I. Synthesis and characterization

Covalent binding of hydrocortisone and dexamethasone to hydrophylic biocompatible macromolecular carriers through hydrolizable carbonate linkage was investigated according to two complementary strategies. (a) Radical copolymerization of hydrocortisone-²¹C-vinylcarbonate with N-vinylpyrrolidone (NVP,60°C), or N-[tris(hydroxymethyl)methyl]acrylamide (THMMA, 50°C) in dimethylacetamide solution: In spite of a nearly zero reactivity ratio for the steroid monomer which behaves as a degradative transfer agent—C_T ～ 5.7 × 10^?2 and 6.8 × 10^?3 for NVP and THMMA, respectively–this process may afford fairly high molecular weight polymers (M?_w ? 10⁴–10⁵) with high enough hydrocortisone content (0.03–0.10 mole.fraction). (b) Condensation of the hydrocortisone or dexamethasone-²¹C-chloroformates onto poly(oxyethylene glycol) (M?_n = 6220) or hydroxypropylcellulose (HPC, M?_w = 1.35 × 10⁵) in tetrahydrofuran solution (30°C): This straightforward process is of low efficiency (yields >50%), and only HPC derivatives show good chemical homogeneity.     

The kinetics of polyarylate hydrolytic embrittlement

The hydrolysis of polyarylate in water between 55 and 98°C was found to be a zero-order process with an activation energy of 19.2 kcal/mol, determined by changes in molecular weight. The equation for the effect of temperature on the rate of hydrolysis is ln k = 34.1 ? 10⁴/T, where k is in day^?1. The decrease in molecular weight is accompanied by a loss in ductility. The transition from a ductile to brittle failure in tension occurs at M?_w of about 35,000 and M?_n of 12,700. At 27°C (80°F) and high humidity environment this would occur after 21 years. But during injection molding, the material, if not properly dried, would embrittle in a matter of seconds.     

Synthesis,characterization, and reactivity ratios of copolymers derived from 4‐nitrophenyl acrylate and n‐butyl methacrylate

Free‐radical copolymerization of 4‐nitrophenyl acrylate (NPA) with n‐butyl methacrylate (BMA) was carried out using benzoyl peroxide as an initiator. Seven different mole ratios of NPA and BMA were chosen for this study. The copolymers were characterized by IR, ¹H‐NMR, and ¹³C‐NMR spectral studies. The molecular weights of the copolymers were determined by gel permeation chromatography and the weight‐average (M _w) and the number‐average (M _n) molecular weights of these systems lie in the range of 4.3–5.3 × 10⁴ and 2.6–3.0 × 10⁴, respectively. The reactivity ratios of the monomers in the copolymer were evaluated by Fineman–Ross, Kelen–Tudos, and extended Kelen–Tudos methods. The product of r₁, r₂ lies in the range of 0.734–0.800, which suggests a random arrangement of monomers in the copolymer chain. Thermal decomposition of the polymers occurred in two stages in the temperature range of 165–505°C and the glass transition temperature (T_g) of one of the systems was 97.2°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1817–1824, 2003     

Completely amorphous high thermal resistant copolyesters from bio-based 2,5-furandicarboxylic acid

Polyesters from renewable resources with glass transition temperature (T_g) higher than 100°C are crucial in broadening their application range. In this work, a series of high molecular weight copolyesters, poly(butylene bis[4-(2-hydroxyethoxy) phenyl] sulfone 2,5-furandicarboxylate) (PBSF), was synthesized from bis[4-(2-hydroxyethoxy) phenyl] sulfone (BHEPS), bio-based 1,4-butanediol (BDO), and 2,5-furandicarboxylic acid (FDCA) via transesterification. Nuclear magnetic resonance spectroscopy (¹H-NMR and ¹³C-NMR) was used to confirm their chemical structures, composition, and sequence distribution. Characterizations demonstrated that with the increasing content of BHEPS unit, T_g of synthesized polyesters was increased from 38.2°C for PBF to 122°C for PBSF-95, in which the content of BHEPS unit was 95%. However, the weight average molecular weight (M_w) of PBSF was dramatically decreased after the addition of BHEPS, from 95,300 g/mol for PBF to only 9600 g/mol for PBSF-95, which was too low for practical application. Taking molecular weight, T_g, and mechanical properties into account, PBSF-65 was considered to be a promising polyester with M_w of 28,500 g/mol, T_g of 104.7°C, tensile strength of 82 MPa, and elongation-at-break of 98%. Besides, it was a completely amorphous polyester with a transmittance of 89.9% by cutoff at 700 nm. Summarily, PBSF-65 showed great potential to be used as raw material for the manufacture of baby bottles, children's toys, kitchen appliances, and beverage packaging, especially in the case when high transparency and heat resistance are required.     

Polymer welding relations investigated by a lap shear joint method

A lap shear joint method was used to study strength development during welding of polystyrene surfaces- The surfaces previously had not been in contact and care was taken to insure rapid wetting of the interface. The shear stress at failure, τ_f was measured at room temperature as a function of contact time, t, at constant welding temperatures up no 20°C above the glass transition temperature, T_g. The time dependence of welding could be well described by τ_fαt^1/4. This result is in agreement with predictions of the reptation molecular dynamics model applied to inter-diffusion at a symmetric amorphous polymer-polymer interface. The activation energy for the thermally activated increase in strength development was determined as E = 96 kcal/mol at T = 113.5°C, which compares with E = 93,2 kcal/mole as predicted by the W-L-F theory using C₁ = 13.7, C₂ = 50 and T_g = 100°C. The polystyrene samples had molecular weights, M_n = 143,000 and M_w = 262.000. The time to achieve complete healing, t_∞ ≈? 256 min at 118°C, was found to be of the same order of magnitude as the viscoelastic relaxation time and also with the time required for a polymer chain to diffuse a distance equal to its root mean square end-to-end vector.     

Simple dilatometer for polymer density and thermal expansivity measurements

A dilatometer is described to study the temperature dependence of density (ρ) of solid and semiliquid polymers and the following linear relations have been established. Atactic poly(vinylisobutyl ether) (25–90°C): ρ = 0.9166 ? 7.15 × 10^?4 × T. Isotactic poly(vinylisobutyl ether) (25–70°C): ρ = 0.9184 ? 7.13 × 10^?4 × T. Poly(n-butyl methacrylate) (90–150°C): ρ = 1.0622 ? 8.41 × 10^?4 × T. Poly(dimethyl siloxane) (30–51°C, using Lipkins pycnometer): ρ = 0.9846 ? 8.81 × 10^?4 × T; where ρ is in g.cm^?3, temperature T is in Celsius, and the linearity correlation coefficient r is better than 0.9998. Their volume–temperature plots are also linear. As the plots of polyn-butyl methacrylate curved slightly near its glass transition (20°C), the quadratic equation ρ = 1.0402 ? 4.79 × 10^?4 × T ? 1.46 × 10^?6 × T² (standard deviation = 1.57 × 10^?3) has been suggested for the entire range of 30–150°C scrutinized in this study. The data have been utilized to derive thermal expansivity and some equation-of-state parameters of the polymers at the reference temperature (ca. 20°C).     

Effect of acrylic acid neutralization on ‘livingness’ of poly[styrene‐ran‐(acrylic acid)] macro‐initiators for nitroxide‐mediated polymerization of styrene

BACKGROUND: The effect of acrylic acid neutralization on the degradation of alkoxyamine initiators for nitroxide‐mediated polymerization (NMP) was studied using styrene/acrylic acid and styrene/sodium acrylate random copolymers (20 mol% initial acrylate feed concentration) as macro‐initiators. The random copolymers were re‐initiated with fresh styrene in 1,4‐dioxane at 110 °C at SG1 mediator/BlocBuilder^® unimolecular initiator ratios of 5 and 10 mol%. RESULTS: The value of k_pK (k_p = propagation rate constant, K = equilibrium constant) was not significantly different for styrene/acrylic acid and styrene/sodium acrylate compositions at 110 °C (k_pK = 2.4 × 10^?6–4.6 × 10^?6 s^?1) and agreed closely with that for styrene homopolymerization at the same conditions (k_pK = 2.7 × 10^?6–3.0 × 10^?6 s^?1). All random copolymers had monomodal, narrow molecular weight distributions (polydispersity index M?_w/M?_n = 1.10–1.22) with similar number‐average molecular weights M?_n = 19.3–22.1 kg mol^?1. Re‐initiation of styrene/acrylic acid random copolymers with styrene resulted in block copolymers with broader molecular weight distributions (M?_w/M?_n = 1.37–2.04) compared to chains re‐initiated by styrene/sodium acrylate random copolymers (M?_w/M?_n = 1.33). CONCLUSIONS: Acrylic acid degradation of the alkoxyamines was prevented by neutralization of acrylic acid and allowed more SG1‐terminated chains to re‐initiate the polymerization of a second styrenic block by NMP. Copyright © 2008 Society of Chemical Industry     

Preparation and characterization of poly(dimethyldiallylammonium chloride) with high molar mass using high purity industrial monomer

A preparation method for high molar mass poly(dimethyldiallylammonium chloride) (PDMDAAC) is reported in this article. PDMDAAC was prepared by using the high purity industrial grade dimethyldiallylammonium chloride (DMDAAC) monomer from one‐step method and ammonium persulphate (APS) as the initiator. The initiator was added all at once and the reaction temperature was increased stepwise to complete the polymerization gradually. The effects of several polymerization condition variables on the intrinsic viscosity value ([η]) and monomer conversion rate (Conv.) of product PDMDAAC were investigated, respectively. The variables included: T₁ (42.0 to 52.0°C), T₂ (47.5 to 57.5°C), T₃ (55.0 to 75.0°C), m(DMDAAC) (60.0 to 70.0%), m(APS) : m(DMDAAC) (0.25 to 0.45%), m(Na₄EDTA) : m(DMDAAC) (0 to 0.0071%). Under an optimum condition of T₁ = 46.0°C, T₂ = 52.5°C, T₃ = 65.0°C, m(DMDAAC) = 65.0%, m(APS) : m(DMDAAC) = 0.35%, m(Na₄EDTA) : m(DMDAAC) = 0.0035%, the maximum [η] of obtained product PDMDAAC reached 3.43 dL/g, at a Conv. of 100.00%. The M_w of the product measured with GPC‐MALLS was 1.034 × 10⁶, polydespersity M_w/M_n was 2.421, and the R_g was 60.3 nm. The structure and properties of products were characterized by FTIR and NMR. Thermal decomposition was determined by TGA‐DSC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polyols production by chemical modification of autocatalyzed ethanol‐water lignin from Betula alnoides

Betula alnoides lignin, recovered as a byproduct in autocatalyzed ethanol‐water pulping process, was converted into viscous polyether polyols through oxypropylation and liquefaction methods, with the aim of adding value to this byproduct. The oxypropylation reaction was performed by reacting autocatalyzed ethanol‐water lignin (AEL) with propylene oxide under the acidic and alkaline conditions at room temperature, respectively. In contrast, the liquefaction reaction was carried out using the mixed solvents of polyethylene glycol and glycerol at 160°C with sulfuric acid as a catalyst. The resulting polyether polyols from each method was characterized by Fourier transform‐infrared (FTIR), ¹H and ³¹P nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and thermogravimetric analysis. Quantitative ³¹P NMR indicated that all the aliphatic hydroxyl group values of polyols increased significantly by the above two methods. More secondary hydroxyl groups (2.016 mmol/g) were obtained in the alkaline oxypropylation reaction, whereas more primary hydroxyl groups (4.296 mmol/g) were found in the liquefied product. GPC analysis showed that the alkaline oxypropylated product (M_w 3130 g/mol, M_n 2080 g/mol) and liquefied product (M_w 4990 g/mol, M_n 4630 g/mol) have higher molecular weights than AEL (M_w 2560 g/mol, M_n 1530 g/mol). Thermal stability analysis suggested that the polyether polyols have a lower degradation temperature than AEL. These polyols used as precursors in polyurethane synthesis give promising properties, which open new avenues of exploitation of AEL. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013