ABSTRACT:In this study, pH-and temperature-responsive hydrogels based on linear sodium alginate (SA) and crosslinked poly(N-isopropylacrylamide) (PNIPAAm) were prepared by semi-interpenetrating network (semi-IPN) technique. The dually responsive hydrogels were characterized by FTIR, DSC, and SEM, and their temperature-and pHresponsive behaviors were investigated by measuring equilibrium swelling ratios and pulsatile swelling experiments. The results showed that these hydrogels underwent volume phase transition at around 33°C irrespective of the pH value of the medium, but their pH sensitivity was evident only below their volume phase transition temperature. Under basic conditions, the swelling ratios of SA/PNIPAAm semi-IPN hydrogels were greater than that of pure PNIPAAm hydrogel and increased with increasing SA content incorporated into the hydrogels, but the case was inverse under acidic conditions. The pulsatile swelling experiments indicated that the higher the SA content in SA/PNIPAAm semi-IPN hydrogels, the faster the response rate to both pH and temperature change.

Poly(cis-1,4-butadiene) (PCB) gels were prepared by the crosslinking polymerization of 4-tert-butylstyrene (tBS) and divinylbenzene (DVB) onto unvulcanized butadiene rubber with a solution polymerization technique with benzoyl peroxide (BPO) as an initiator. The effects of the reaction conditions, such as the amount of the solvent, the amount of DVB and tBS, and the initiator (BPO), on the equilibrium swelling ratio (Q e ) were also investigated. The highest oil absorbencies of crosslinked gels in xylene and cyclohexane were 51.35 and 32.98 g/g, respectively. A swelling kinetic equation was proposed for this system:, where Q t is the swelling ratio at time t, Q 0 is the initial swelling ratio, and K is the swelling kinetic constant. This equation fit the experimental results quite well. The diffusion of organic solvents in PCB gels was Fickian.

This paper increases product modal frequency and improves machine dynamic performance while ensuring product static accuracy in method of design, simulation analysis, and testing verification for the purpose of improvement of PCB boring machine gantry support frame integrated modal based on Abaqus finite element software platform as well as Impact Testing module and Modal Analysis module of Test.lab