机械活化制备PVC/石墨导热复合板材的热性能

Preparation of PVC /Graphite Thermal Conductivity Composite through Mechanical Activation

以自制的搅拌球磨机作为机械活化固相反应器,聚氯乙烯(PVC)作为基料,石墨为导热添加剂,采用粉末共混法将石墨与PVC在球磨反应器中共混制备PVC/石墨导热复合板材,考察了球磨转速、机械活化反应时间、石墨含量等因素对其导热性能的影响,采用扫描电子显微镜、差示扫描量热仪及热重分析仪分别对复合板材中石墨填充的内部形态、软化温度及热分解温度进行研究。当球磨转速为150 r/min,机械活化时间为60 min,石墨质量分数为35%时,在165℃及5 MPa下热压15 min,复合板材热导率为0.839 4 W/(m·K),是纯PVC树脂的近6倍,是未经活化单纯混合的复合板材热导率的2.6倍。扫描电子显微镜测试结果表明,通过机械活化可以使石墨片层剥离并包裹于PVC表面,压板后片状的石墨填充于板材之间形成导热网链使PVC的热导率升高,改性后的板材具有较高的软化温度和热分解温度。

In the condition of the ball mixing mill machine as the solid phase mechanical activation reactor, PVC as base material, and graphite as the thermal agent, PVC and graphite powder were mixed through mechanical activation method in the reactor. The mechanical activating speed, mechanical activating time, the content of graphite of the composite which impacted the thermal conductivity were investigated. The internal structure of the composite, softening and decomposition temperature were studied by SEM, DSC and TGA. Under the condition of the speed 150 r/rain, mechanical activated time 60 rain, the additive content 35 wt%, hot-pressing temperature 165 ℃, hot-pressing pressure 5 MPa, hot-pressing time 15 min, the thermal conductivity of the composite would be 0. 839 4 W/m · K, which was six times of the pure PVC and was 2.6 times of the materials without any activation. The results of SEM showed that the peel layers of graphite could separate and wrap around the surface of PVC, so the thermal conductivity of PVC would improve as the result of forming the thermal network with flaky graphite being filled into the composite. The modified composite had a high softening point and the thermal decomposition temperature.