Study of the miscibility of poly(styrene-co-4-vinylbenzoic acid) with poly(ethyl methacrylate) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] by inverse gas chromatography.
Poly(styrene) is immiscible with poly(ethyl methacrylate). The introduction of a small amount of 4-vinylbenzoic acid units along poly(styrene) chains (PS-VBA) enhanced its miscibility with poly(ethyl methacrylate) (PEMA) or with poly[ethyl methacrylate-co-(2-N,N-dimethylaminoethyl) methacrylate] (PEMA-DAE), as observed from the appearance of a single composition dependent glass transition temperature for each binary system using inverse gas chromatography. The negative values of the apparent polymer-polymer interaction parameter, chi(23)app, determined with different families of molecular probes, for three blend compositions and over a range of temperature confirm quantitatively the miscibility of these blends. The chi(23)app values for PEMA(PS-VBA) and (PEMA-DAE)-(PS-VBA) blends are dependent of the chemical nature of the probes, the temperature and the blend composition.
Determination of Some Thermodynamic Parameters of Poly(Styrene‐Graft‐Ethyl Methacrylate) Using Inverse Gas Chromatography
In this study, the specific retention volumes, Vg o, were determined for poly(styrene‐g‐ethly methacrylate) obtained from grafting of poly(styrene‐co‐p‐chloromethyl styrene) having a 54% (by mole) chlorine content with ethyl methacrylate and a series of nonsolvent as probe, five n‐alkans, five alcohols and carbon tetrachloride, with the aid of inverse gas chromatography, in a temperature range of 333 to 463 K. Some thermodynamic properties, such as the sorption enthalpy, ΔHs, sorption free energy, ΔGs, sorption entropy, ΔSs, in the 373–403 K temperature range, the partial molar free energy, ΔG∞, and the partial molar heat of mixing, ΔH∞, in the temperature 413‐463 K range, were calculated from the relationships between the specific retention volumes and related properties. The weight fraction activity coefficients of probes as logarithmic value, ln Ω1 ∞, and Flory‐Huggins interaction parameters, χ12 ∞, between the polymer and probes, were estimated. Also, the glass transition temperature,Tg, and the solubility parameter, δ2, of the graft copolymer, were found to be about 85°C, and between 5.0–6.8 (cal/cm3)1/2 in the 413–463 temperature range K, respectively, and some extrapolations to room temperature were done and the results were discussed.
Stroking different body regions of dairy cows: effects on avoidance and approach behavior toward humans.
Understanding perception of dairy cows to common human contact such as stroking is important for improving the human-animal relationship, animal welfare, and production. We hypothesized that repeated stroking of body regions licked most during social grooming, especially the ventral neck, would reduce cows' avoidance of and increase their approach to humans. Sixty tethered dairy cows were randomly allocated to 4 treatment groups that received 5 min of daily human contact 5 d/wk during 3 consecutive weeks: 3 groups were stroked on different body regions. The first group was stroked on the ventral part of the neck (neck); the second group on the withers (both licked often in social grooming); the third group on the lateral side of the chest (chest, licked rarely); and the last group (control) was exposed to simple human presence. The reactions to the person who had provided the treatment were measured using 2 tests in the home tie-stall assessing avoidance from an approaching person who tried to touch the head (approaching person test) and avoidance/approach reactions to a stationary person (stationary person test). Approach behavior was recorded in a novel environment using a standard arena test. In the home tie-stall, cows stroked on the neck showed less avoidance (median avoidance score: 3.33) in the approaching person test compared with cows stroked on the chest and the controls (both: 4.00). That is, at least 75% of the animals stroked on the neck tolerated the touching of their heads (75th percentile <or= 3.75), whereas at least 50% of the cows in the other treatment groups did not accept it. The stationary person test did not reveal any differences between the treatment groups. In the arena test, the 3 stroked groups showed more approach behavior (median latencies to contact: from 145 to 240 s) compared with simple human presence (300 s), but stroking treatments did not differ from each other. Stroking, particularly the neck, reduced avoidance of and increased approach reactions to humans in both the home tie-stall and the arena. Increasing acceptance of being touched after being stroked on the neck suggests that this procedure should be adopted to improve routine handling of dairy cattle.