Structures of plastics material
    4.
    发明公开
    Structures of plastics material 失效
    Kunststoffstrukturen。

    公开(公告)号:EP0256825A2

    公开(公告)日:1988-02-24

    申请号:EP87307064.3

    申请日:1987-08-10

    申请人: British Gas plc

    IPC分类号: B29C71/04 B29C65/02 B29D23/22

    摘要: Large fittings or other structures are made by rotationally moulding a first component 18 of polyethylene and joining cylindrical pups 20, 22, 24 of polyethylene to the component by butt fusion joints 26, 28, 30. The structure within the boundary 50 is irradiated with gamma radiation followed by post-heating to remove free radicals. The extremities of the pups are shielded to prevent irradiation. Their capability to be joined to polyethylene pipes 12, 14, 16 by butt-fusion joints 32, 34, 36 is unimpaired. The irradiation introduces cross-linking to give improved properties such as impact resistance and stress crack resistance and to bring the fitting within the specification for polyethylene pipe for natural gas distribution. The joints 26, 28, 30 are made using differential heating of the ends to be joined to compensate for differences in melt flow index. Alternatively, the component 18 is slightly irradiated to lower its MFI before pups are joined to it.

    摘要翻译: 通过旋转模制聚乙烯的第一部件18和将聚乙烯的圆柱形小狗20,22,24与对接熔接接头26,28,30的部件旋转成型来制造大型接头或其它结构。边界50内的结构用γ 辐射后进行后加热以除去自由基。 屏蔽小狗的四肢以防止辐射。 它们通过对接熔接32,32,36,36与聚乙烯管12,14,16接合的能力是不受损伤的。 辐射引入交联以提供改进的性能,例如抗冲击性和抗应力开裂性,并使配件符合聚乙烯管道用于天然气分配的规格。 接头26,28,30使用待接合端部的差加热来制造,以补偿熔体流动指数的差异。 或者,组件18稍微照射以在小狗连接到它之前降低其MFI。