| Rigid PVC foamed compasite has become one of the new type materials in recent years. It has many advantages, such as lightness, good flame retardant, non-absorbency, imputrescibility, insulativity, and good sound or heat inlulation. So it can be widely used in furniture, building materials and interior decoration etc. This composite that can replace natural wood finely is of far-reaching significance to protect forest resources and maintain ecological balance.In this paper, lime-mud/PVC foamed composite was developed with the modified lime mud as filled material and PVC as matrix material. The milling process of lime mud and the interface binding effect of composite were studied. At the same time, optimization of the hot-press process, AC foaming agent content, interface modifier aluminate content and lime mud content were deeply investigated.The milling process of lime mud, effects of hot-press time and hot-press temperature on density and mechanical properties of lime-mud/PVC foamed composite were studied. The results indicated that the optimal milling time was 60min; under this condition, the lime mud had uniform particle size distribution and its mean particle was 3.45μm. When the hot-press time was 14min, composite had minimal density and had maximal pecific impact strength, specific tensile strength and specific flexural strength. When the hot-press temperature was 187℃, composite had maximal specific impact strength, flexural strength and specific flexural strength. In this condition, lime-mud/PVC foamed composite had better comprehensive properties and lower density.Effects of AC content on density and mechanical properties of lime-mud/PVC foamed composite were studied. Because of the activation of ZnO/Zn(St)2, the decomposition temperature of AC can be reduced to 183℃, making AC can be used for processing foamed PVC. The specific strength of lime-mud/PVC foamed composite rised firstly and then declined under the increasing content of AC. When AC content was 0.5phr, composite had maximal specific strength. Observing SEM pictures of different AC content, while AC content was 0.5phr, it was found that the froth effect of lime-mud/PVC foamed composite was the best and the bubble holes were more regular and more uniform. But when AC content was lower than 0.5phr, the bubble holes of composite were little regular; when AC content was higher than 0.5phr, the bubble holes were easy to breakdown and become big holes. Considering all factors, the optimum AC content was 0.5phr.Effects of aluminate content on density and mechanical properties of lime-mud/PVC foamed composite were studied. The results showed that the density and mechanical properties of lime-mud/PVC foamed composite rised firstly and then declined under the increasing content of aluminate. When aluminate content was 0.5%, the composite had minimal density and better mechanical properties. Considering cost and properties, the optimum aluminate content was 0.5%. The lime mud modified with 0.5% aluminate had much better processing performance than the unmodified, and the main processing properties were as follows: maximum torque 42.3 N.m, balance torque 31.1 N.m, plasticizing time 90s, fusion temperature 179℃.Effects of lime mud content on mechanical properties of lime-mud/PVC foamed composite were studied. The results show that machanical properties of composite declined firstly and then rised under the increasing content of lime mud. When the lime mud content was 20phr, the impact strength and specific impact strength of composite were 71% and 31% higher than the no-filled PVC material respectively; the tensile strength, flexural strength and specific flexural strength and were 23.7%, 33.9% ang 2.5% higher than the no-filled PVC foamed material. Considering cost and properties, the optimum lime mud content was 20phr.In the condition of PVC 100phr, lime mud 20phr, AC content 0.5phr, aluminate content 0.5%, hot-press time 14min and hot-press temperature 187℃, main properties of lime-mud/PVC foamed composite were as follows: density 0.85 g.cm-3, the impact strength 35.42KJ.m-2, the specific impact strength 41.67KJ.m-2.(g.cm-3)-1, the tensile strength 20.38MPa, the specific tensile strength 23.98MPa.(g.cm-3)-1, the flexural strength 90.53 MPa, the specific flexural strength 106.50MPa.(g.cm-3)-1.The interface binding effect of lime-mud/PVC foamed composite was analyzed by means of qualitative and quantitative methods. Firstly, studied on the FTIR spectroscopy of modified lime mud, it was found that there was a peak of C-H stretching vibration around 2960～2850cm-1 and this peak was resulted from long chain alkyl of aluminate; studied on the TG curves of the modified and unmodified lime mud, we found that both of them had a similar trend, and the weight loss of modified was bigger than the unmodified obviously; studied on the contact angle of lime mud, we found that the water contact angle of the modified lime mud was bigger than the unmodified and the atolein contact angle was on the contrary; studied on the oil factor of lime mud, we found that the oil factor decreased under the increasing content of aluminate. All of above studies suggested surface free energy of the modified lime mud have decreased and combined with the PVC matrix more easily. Interfacial binding effect of lime-mud/PVC foamed composite was analyzed quantitatively by using interfacial interaction parameter B and debonding angleθ. The results showed that the value B rised firstly and then declined under the increasing content of aluminate, and when aluminate content was 0.5%, it increased by 237.7%; we also found that the valueθdeclined firstly and then rised under the increasing content of aluminate, and when aluminate content was 0.5%, it decreased by 95.6%. Both of these two conclusions suggest that the interface binding effect between lime mud and PVC was best while aluminate content was 0.5%.
|
PDF Full Text Request